,,electricity1 ,,volume #a999999 by the ,bibliothque nationale de ,france 7,bn,f_/,gallica7 at http3_/_/gallica4bnf4fr4 ,,experimental ,,researches ,,in ,,electricity by ,,michael ,,faraday1 ,d4,c4,l4 ,f4,r4,s4 ,fullerian ,profesor of ,chemistry in the ,royal ,institution4 ,corresponding ,member1 etc4 of the ,royal and ,imperial ,academies of ,science of ,paris1 ,petersburgh1 ,florence1 ,copenhagen1 ,berlin1 ,gottingen1 ,modena1 ,stockholm1 ,palermo1 etc4 etc4 ,in ,two ,volumes ,,vol4 ,i4 ,second ,edition ,reprinted from the ,,philosophical ,,transactions of #ahca-ahch4 ,london3 ,richard and ,john ,edward ,taylor1 ,printers and ,publishers to the ,university of ,london1 ,red ,lion ,court1 ,fleet ,street #ahdi ,,preface ,i have been induced by various circumstances to collect in ,one ,volume the ,fourteen ,series of ,experimental ,researches in ,electricity1 which have appeared in the ,philosophical ,transactions during the last seven years3 the chief reason has been the desire to supply at a moderate price the whole of these papers1 with an ,index1 to those who may desire to have them4 ,the readers of the volume will1 ,i hope1 do me the justice to remember that it was not written as a whole1 but in parts2 the earlier portions rarely having any known relation at the time to those which might follow4 ,if ,i had rewritten the work1 ,i perhaps might have considerably varied the form1 but should not have altered much of the real matter3 it would not1 however1 then have been considered a faithful reprint or statement of the course and results of the whole investigation1 which only ,i desired to supply4 ,i may be allowed to express my great satisfaction at finding1 that the different parts1 written at intervals during seven years1 harmonize so well as they do4 ,there would have been nothing particular in this1 if the parts had related only to matters well-ascertained before any of them were written3--but as each professes to contain something of original discovery1 or of correction of received views1 it does surprise even my partiality1 that they should have the degree of consistency and apparent general accuracy which they seem to me to present4 ,i have made some alterations in the text1 but they have been altogether of a typographical or grammatical character2 and even where greatest1 have been intended to explain the sense1 not to alter it4 ,i have often added ,notes at the bottom of the page1 as to paragraphs #ei1 #cfj1 #dci1 #eba1 #eeb1 #eee1 #eih1 #feg1 #hhc1 for the correction of errors1 and also the purpose of illustration3 but these are all distinguished from the ,original ,notes of the ,researches by the date of ,dec4 #ahch4 ,the date of a scientific paper containing any pretensions to discovery is frequently a matter of serious importance1 and it is a great misfortune that there are many most valuable communications1 essential to the history and progress of science1 with respect to which this point cannot now be ascertained4 ,this arises from the circumstance of the papers having no dates attached to them individually1 and of the journals in which they appear having such as are inaccurate1 i4e4 dates of a period earlier than that of publication4 ,i may refer to the note at the end of the ,first ,series1 as an illustration of the kind of confusion thus produced4 ,these circumstances have induced me to affix a date at the top of every other page1 and ,i have thought myself justified in using that placed by the ,secretary of the ,royal ,society on each paper as it was received4 ,an author has no right1 perhaps1 to claim an earlier one1 unless it has received confirmation by some public act or officer4 ,before concluding these lines ,i would beg leave to make a reference or two2 first1 to my own ,papers on ,electro-magnetic ,rotations in the ,quarterly ,journal of ,science1 #ahbb4 xii4 #gd4 #ahf4 #bhc4 #daf1 and also to my ,letter on ,magneto-electric ,induction in the ,annales de ,chimie1 li4 p4 #djd4 ,these might1 as to the matter1 very properly have appeared in this volume1 but they would have interfered with it as a simple reprint of the ,experimental ,researches of the ,philosophical ,transactions4 ,then ,i wish to refer1 in relation to the ,fourth ,series on a new law of ,electric ,conduction1 to ,franklin's experiments on the non-conduction of ice1 which have been very properly separated and set forth by ,professor ,bache 7,journal of the ,franklin ,institute1 #ahcf4 xvii4 #ahc474 ,these1 which ,i did not at all remember as to the extent of the effect1 though they in no way anticipate the expression of the law ,i state as to the general effect of liquefaction on electrolytes1 still should never be forgotten when speaking of that law as applicable to the case of water4 ,there are two papers which ,i am anxious to refer to1 as corrections or criticisms of parts of the ,experimental ,researches4 ,the first of these is one by ,jacobi 7,philosophical ,magazine1 #ahch4 xiii4 #dja471 relative to the possible production of a spark on completing the junction of the two metals of a single pair of plates 7#iae474 ,it is an excellent paper1 and though ,i have not repeated the experiments1 the description of them convinces me that ,i must have been in error4 ,the second is by that excellent philosopher1 ,marianini 7,memoria della ,societa ,italiana di ,modena1 xxi4 #bje71 and is a critical and experimental examination of ,series viii1 and of the question whether metallic contact is or is not productive of a part of the electricity of the voltaic pile4 ,i see no reason as yet to alter the opinion ,i have given2 but the paper is so very valuable1 comes to the question so directly1 and the point itself is of such great importance1 that ,i intend at the first opportunity renewing the inquiry1 and1 if ,i can1 rendering the proofs either on the one side or the other undeniable to all4 ,other parts of these researches have received the honour of critical attention from various philosophers1 to all of whom ,i am obliged1 and some of whose corrections ,i have acknowledged in the foot notes4 ,there are1 no doubt1 occasions on which ,i have not felt the force of the remarks1 but time and the progress of science will best settle such cases2 and1 although ,i cannot honestly say that ,i wish to be found in error1 yet ,i do fervently hope that the progress of science in the hands of its many zealous present cultivators will be such1 as by giving us new and other developments1 and laws more and more general in their applications1 will even make me think that what is written and illustrated in these experimental researches1 belongs to the by-gone parts of science4 ,,michael ,,faraday4 ,royal ,institution1 ,march1 #ahci4 ,,contents4 ,par4 ,series ,i4 4 #a4 ,induction of electric currents #f 4 #b4 ,evolution of electricity from magnetism #bg 4 #c4 ,new electrical state or condition of matter #fj 4 #d4 ,explication of ,arago's magnetic phenomena #ha ,series ,,ii4 4 #e4 ,terrestrial magneto-electric induction #adj 4 #f4 ,force and direction of magneto-electric induction generally #aic ,series ,,iii4 4 #g4 ,identity of electricities from different sources #bfe ---- ---- i ,voltaic electricity #bfh ---- ---- ii ,ordinary electricity #bhd ---- ---- iii ,magneto-electricity #cdc ---- ---- iv ,thermo-electricity #cdi ---- ---- v ,animal electricity #cea 4 #h4 ,relation by measure of common and voltaic electricity #cfa ---- ,note respecting ,ampre's inductive results after #cgi ,series ,,iv4 4 #i4 ,new law of electric conduction #chj 4 #aj4 ,on conducting power generally #dah ,series ,v4 4 #aa4 ,electro-chemical decomposition #dej ---- #a4 ,new conditions of electro-chemical decomposition #dec ---- #b4 ,influence of water in such decomposition #dgb ---- #c4 ,theory of electro-chemical decomposition #dgg ,series ,,vi4 4 #ab4 ,power of platina1 c4 to induce combination #efd ,series ,,vii4 4 #aa499 ,electro-chemical decomposition continued 7nomenclature7 #ffa ---- #d4 ,some general conditions of ,electro-chemical decomposition #ffi ---- #e4 ,volta-electrometer #gjd ---- #f4 ,primary and secondary results #gdb ---- #g4 ,definite nature and extent of electro-chemical forces #ghc ---- ---- ,electro-chemical equivalents #hbb 4 #ac4 ,absolute quantity of ,electricity in the molecules of matter #heb ,series ,,viii4 4 #ad4 ,electricity of the voltaic pile #hge ---- #a4 ,simple voltaic circles #hge ---- #b4 ,electrolytic intensity #iff ---- #c4 ,associated voltaic circles2 or battery #ihi ---- #d4 ,resistance of an electrolyte to decomposition #ajjg ---- #e4 ,general remarks on the active battery #ajcd ,series ,,ix4 4 #ae4 ,induction of a current on itself #ajdh ---- ,inductive action of currents generally #aaja ,series ,x4 4 #af4 ,improved voltaic battery #aaai 4 #ag4 ,practical results with the voltaic battery #aacf ,series ,,xi4 4 #ah4 ,on static induction #aafa ---- #a4 ,induction an action of contiguous particles #aafa ---- #b4 ,absolute charge of matter #aafi ---- #c4 ,electrometer and inductive apparatus #aagi ---- #d4 ,induction in curved lines #abae ---- ---- ,conduction by glass1 lac1 sulphur1 c4 #abhc ---- #e4 ,specific inductive capacity #abeb ---- #f4 ,general results as to the nature of induction #abie ---- ---- ,differential inductometer #acjg ,series ,,xii4 ---- #g4 ,conduction or conductive discharge #acbj ---- #h4 ,electrolytic discharge #acdc ---- #i4 ,disruptive discharge #acei ---- ---- ---- ,insulation #acfb ---- ---- ---- as spark #adjf ---- ---- ---- as brush #adbe ---- ---- ---- positive and negative #adfe ,series ,,xiii4 ---- ---- ---- as glow #aebf ---- ---- ---- dark #aedd ---- #aj4 ,convection2 or carrying discharge #aefb ---- #aa4 ,relation of a vacuum to electrical phenomena #afac 4 #ai4 ,nature of the electric current #afag ---- ---- its transverse forces #afec ,series ,,xiv4 4 #bj4 ,nature of the electric force or forces #affg 4 #ba4 ,relation of the electric and magnetic forces #agji 4 #bb4 ,note on electrical excitation #agcg ,index ,notes ,,experimental ,,researches ,,in ,,electricity4 ,,first ,,series4 #a4 ,on the ,induction of ,electric ,currents4 #b4 ,on the ,evolution of ,electricity from ,magnetism4 #c4 ,on a new ,electrical ,condition of ,matter4 #d4 ,on ,arago's ,magnetic ,phenomena4 ,read ,november #bd1 #ahca4 #a4 ,the power which electricity of tension possesses of causing an opposite electrical state in its vicinity has been expressed by the general term ,induction2 which1 as it has been received into scientific language1 may also1 with propriety1 be used in the same general sense to express the power which electrical currents may possess of inducing any particular state upon matter in their immediate neighbourhood1 otherwise indifferent4 ,it is with this meaning that ,i purpose using it in the present paper4 #b4 ,certain effects of the induction of electrical currents have already been recognised and described3 as those of magnetization2 ,ampre's experiments of bringing a copper disc near to a flat spiral2 his repetition with electro-magnets of ,arago's extraordinary experiments1 and perhaps a few others4 ,still it appeared unlikely that these could be all the effects which induction by currents could produce2 especially as1 upon dispensing with iron1 almost the whole of them disappear1 whilst yet an infinity of bodies1 exhibiting definite phenomena of induction with electricity of tension1 still remain to be acted upon by the induction of electricity in motion4 #c4 ,further3 ,whether ,ampre's beautiful theory were adopted1 or any other1 or whatever reservation were mentally made1 still it appeared very extraordinary1 that as every electric current was accompanied by a corresponding intensity of magnetic action at right angles to the current1 good conductors of electricity1 when placed within the sphere of this action1 should not have any current induced through them1 or some sensible effect produced equivalent in force to such a current4 #d4 ,these considerations1 with their consequence1 the hope of obtaining electricity from ordinary magnetism1 have stimulated me at various times to investigate experimentally the inductive effect of electric currents4 ,i lately arrived at positive results2 and not only had my hopes fulfilled1 but obtained a key which appeared to me to open out a full explanation of ,arago's magnetic phenomena1 and also to discover a new state1 which may probably have great influence in some of the most important effects of electric currents4 #e4 ,these results ,i purpose describing1 not as they were obtained1 but in such a manner as to give the most concise view of the whole4 #a4 ,induction of ,electric ,currents4 #f4 ,about twenty-six feet of copper wire one twentieth of an inch in diameter were wound round a cylinder of wood as a helix1 the different spires of which were prevented from touching by a thin interposed twine4 ,this helix was covered with calico1 and then a second wire applied in the same manner4 ,in this way twelve helices were superposed1 each containing an average length of wire of twenty-seven feet1 and all in the same direction4 ,the first1 third1 fifth1 seventh1 ninth1 and eleventh of these helices were connected at their extremities end to end1 so as to form one helix2 the others were connected in a similar manner2 and thus two principal helices were produced1 closely interposed1 having the same direction1 not touching anywhere1 and each containing one hundred and fifty-five feet in length of wire4 #g4 ,one of these helices was connected with a galvanometer1 the other with a voltaic battery of ten pairs of plates four inches square1 with double coppers and well charged2 yet not the slightest sensible reflection of the galvanometer-needle could be observed4 #h4 ,a similar compound helix1 consisting of six lengths of copper and six of soft iron wire1 was constructed4 ,the resulting iron helix contained two hundred and fourteen feet of wire1 the resulting copper helix two hundred and eight feet2 but whether the current from the trough was passed through the copper or the iron helix1 no effect upon the other could be perceived at the galvanometer4 #i4 ,in these and many similar experiments no difference in action of any kind appeared between iron and other metals4 #aj4 ,two hundred and three feet of copper wire in one length were coiled round a large block of wood2 other two hundred and three feet of similar wire were interposed as a spiral between the turns of the first coil1 and metallic contact everywhere prevented by twine4 ,one of these helices was connected with a galvanometer1 and the other with a battery of one hundred pairs of plates four inches square1 with double coppers1 and well charged4 ,when the contact was made1 there was a sudden and very slight effect at the galvanometer1 and there was also a similar slight effect when the contact with the battery was broken4 ,but whilst the voltaic current was continuing to pass through the one helix1 no galvanometrical appearances nor any effect like induction upon the other helix could be perceived1 although the active power of the battery was proved to be great1 by its heating the whole of its own helix1 and by the brilliancy of the discharge when made through charcoal4 #aa4 ,repetition of the experiments with a battery of one hundred and twenty pairs of plates produced no other effects2 but it was ascertained1 both at this and the former time1 that the slight deflection of the needle occurring at the moment of completing the connexion1 was always in one direction1 and that the equally slight deflection produced when the contact was broken1 was in the other direction2 and also1 that these effects occurred when the first helices were used 7#f4 #h474 #ab4 ,the results which ,i had by this time obtained with magnets led me to believe that the battery current through one wire1 did1 in reality1 induce a similar current through the other wire1 but that it continued for an instant only1 and partook more of the nature of the electrical wave passed through from the shock of a common ,leyden jar than of the current from a voltaic battery1 and therefore might magnetise a steel needle1 although it scarcely affected the galvanometer4 #ac4 ,this expectation was confirmed2 for on substituting a small hollow helix1 formed round a glass tube1 for the galvanometer1 introducing a steel needle1 making contact as before between the battery and the inducing wire 7#g4 #aj471 and then removing the needle before the battery contact was broken1 it was found magnetised4 #ad4 ,when the battery contact was first made1 then an unmagnetised needle introduced into the small indicating helix 7#ac471 and lastly the battery contact broken1 the needle was found magnetised to an equal degree apparently as before2 but the poles were of the contrary kind4 #ae4 ,the same effects took place on using the large compound helices first described 7#f4 #h474 #af4 ,when the unmagnetised needle was put into the indicating helix1 before contact of the inducing wire with the battery1 and remained there until the contact was broken1 it exhibited little or no magnetism2 the first effect having been nearly neutralised by the second 7#ac4 #ad474 ,the force of the induced current upon making contact was found always to exceed that of the induced current at breaking of contact2 and if therefore the contact was made and broken many times in succession1 whilst the needle remained in the indicating helix1 it at last came out not unmagnetised1 but a needle magnetised as if the induced current upon making contact had acted alone on it4 ,this effect may be due to the accumulation 7as it is called7 at the poles of the unconnected pile1 rendering the current upon first making contact more powerful than what it is afterwards1 at the moment of breaking contact4 #ag4 ,if the circuit between the helix or wire under induction and the galvanometer or indicating spiral was not rendered complete before the connexion between the battery and the inducing wire was completed or broken1 then no effects were perceived at the galvanometer4 ,thus1 if the battery communications were first made1 and then the wire under induction connected with the indicating helix1 no magnetising power was there exhibited4 ,but still retaining the latter communications1 when those with the battery were broken1 a magnet was formed in the helix1 but of the second kind 7#ad471 i4e4 with poles indicating a current in the same direction to that belonging to the battery current1 or to that always induced by that current at its cessation4 #ah4 ,in the preceding experiments the wires were placed near to each other1 and the contact of the inducing one with the buttery made when the inductive effect was required2 but as the particular action might be supposed to be exerted only at the moments of making and breaking contact1 the induction was produced in another way4 ,several feet of copper wire were stretched in wide zigzag forms1 representing the letter ,w1 on one surface of a broad board2 a second wire was stretched in precisely similar forms on a second board1 so that when brought near the first1 the wires should everywhere touch1 except that a sheet of thick paper was interposed4 ,one of these wires was connected with the galvanometer1 and the other with a voltaic battery4 ,the first wire was then moved towards the second1 and as it approached1 the needle was deflected4 ,being then removed1 the needle was deflected in the opposite direction4 ,by first making the wires approach and then recede1 simultaneously with the vibrations of the needle1 the latter soon became very extensive2 but when the wires ceased to move from or towards each other1 the galvanometer-needle soon came to its usual position4 #ai4 ,as the wires approximated1 the induced current was in the contrary direction to the inducing current4 ,as the wires receded1 the induced current was in the same direction as the inducing current4 ,when the wires remained stationary1 there was no induced current 7#ed474 #bj4 ,when a small voltaic arrangement was introduced into the circuit between the galvanometer 7#aj47 and its helix or wire1 so as to cause a permanent deflection of #cj or #dj1 and then the battery of one hundred pairs of plates connected with the inducing wire1 there was an instantaneous action as before 7#aa472 but the galvanometer-needle immediately resumed and retained its place unaltered1 notwithstanding the continued contact of the inducing wire with the trough3 such was the case in whichever way the contacts were made 7#cc474 #ba4 ,hence it would appear that collateral currents1 either in the same or in opposite directions1 exert no permanent inducing power on each other1 affecting their quantity or tension4 #bb4 ,i could obtain no evidence by the tongue1 by spark1 or by heating fine wire or charcoal1 of the electricity passing through the wire under induction2 neither could ,i obtain any chemical effects1 though the contacts with metallic and other solutions were made and broken alternately with those of the battery1 so that the second effect of induction should not oppose or neutralise the first 7#ac4 #af474 #bc4 ,this deficiency of effect is not because the induced current of electricity cannot pass fluids1 but probably because of its brief duration and feeble intensity2 for on introducing two large copper plates into the circuit on the induced side 7#bj471 the plates being immersed in brine1 but prevented from touching each other by an interposed cloth1 the effect at the indicating galvanometer1 or helix1 occurred as before4 ,the induced electricity could also pass through a voltaic trough 7#bj474 ,when1 however1 the quantity of interposed fluid was reduced to a drop1 the galvanometer gave no indication4 #bd4 ,attempts to obtain similar effects by the use of wires conveying ordinary electricity were doubtful in the results4 ,a compound helix similar to that already described1 containing eight elementary helices 7#f471 was used4 ,four of the helices had their similar ends bound together by wire1 and the two general terminations thus produced connected with the small magnetising helix containing an unmagnetised needle 7#ac474 ,the other four helices were similarly arranged1 but their ends connected with a ,leyden jar4 ,on passing the discharge1 the needle was found to be a magnet2 but it appeared probable that a part of the electricity of the jar had passed off to the small helix1 and so magnetised the needle4 ,there was indeed no reason to expect that the electricity of a jar possessing as it does great tension1 would not diffuse itself through all the metallic matter interposed between the coatings4 #be4 ,still it does not follow that the discharge of ordinary electricity through a wire does not produce analogous phenomena to those arising from voltaic electricity2 but as it appears impossible to separate the effects produced at the moment when the discharge begins to pass1 from the equal and contrary effects produced when it ceases to pass 7#af471 inasmuch as with ordinary electricity these periods are simultaneous1 so there can be scarcely any hope that in this form of the experiment they can be perceived4 #bf4 ,hence it is evident that currents of voltaic electricity present phenomena of induction somewhat analogous to those produced by electricity of tension1 although1 as will be seen hereafter1 many differences exist between them4 ,the result is the production of other currents1 7but which are only momentary17 parallel1 or tending to parallelism1 with the inducing current4 ,by reference to the poles of the needle formed in the indicating helix 7#ac4 #ad47 and to the deflections of the galvanometer-needle 7#aa471 it was found in all cases that the induced current1 produced by the first action of the inducing current1 was in the contrary direction to the latter1 but that the current produced by the cessation of the inducing current was in the same direction 7#ai474 ,for the purpose of avoiding periphrasis1 ,i propose to call this action of the current from the voltaic battery1 volta-electric induction4 ,the properties of the second wire1 after induction has developed the first current1 and whilst the electricity from the battery continues to flow through its inducing neighbour 7#aj4 #ah471 constitute a peculiar electric condition1 the consideration of which will be resumed hereafter 7#fj474 ,all these results have been obtained with a voltaic apparatus consisting of a single pair of plates4 #b4 ,evolution of ,electricity from ,magnetism4 #bg4 ,a welded ring was made of soft round bar-iron1 the metal being seven-eighths of an inch in thickness1 and the ring six inches in external diameter4 ,three helices were put round one part of this ring1 each containing about twenty-four feet of copper wire one twentieth of an inch thick2 they were insulated from the iron and each other1 and superposed in the manner before described 7#f471 occupying about nine inches in length upon the ring4 ,they could be used separately or conjointly2 the group may be distinguished by the letter ,a 7,pl4 ,i4 fig4 #a474 ,on the other part of the ring about sixty feet of similar copper wire in two pieces were applied in the same manner1 forming a helix ,b1 which had the same common direction with the helices of ,a1 but being separated from it at each extremity by about half an inch of the uncovered iron4 #bh4 ,the helix ,b was connected by copper wires with a galvanometer three feet from the ring4 ,the helices of ,a were connected end to end so as to form one common helix1 the extremities of which were connected with a battery of ten pairs of plates four inches square4 ,the galvanometer was immediately affected1 and to a degree far beyond what has been described when with a battery of tenfold power helices without iron were used 7#aj472 but though the contact was continued1 the effect was not permanent1 for the needle soon came to rest in its natural position1 as if quite indifferent to the attached electro-magnetic arrangement4 ,upon breaking the contact with the batterry1 the needle was again powerfully deflected1 but in the contrary direction to that induced in the first instance4 #bi4 ,upon arranging the apparatus so that ,b should be out of use1 the galvanometer be connected with one of the three wires of ,a 7#bg471 and the other two made into a helix through which the current from the trough 7#bh47 was passed1 similar but rather more powerful effects were produced4 #cj4 ,when the battery contact was made in one direction1 the galvanometer-needle was deflected on the one side2 if made in the other direction1 the deflection was on the other side4 ,the deflection on breaking the battery contact was always the reverse of that produced by completing it4 ,the deflection on making a battery contact always indicated an induced current in the opposite direction to that from the battery2 but on breaking the contact the deflection indicated an induced current in the same direction as that of the battery4 ,no making or breaking of the contact at ,b side1 or in any part of the galvanometer circuit1 produced any effect at the galvanometer4 ,no continuance of the battery current caused any deflection of the galvanometer-needle4 ,as the above results are common to all these experiments1 and to similar ones with ordinary magnets to be hereafter detailed1 they need not be again particularly described4 #ca4 ,upon using the power of one hundred pairs of plates 7#aj47 with this ring1 the impulse at the galvanometer1 when contact was completed or broken1 was so great as to make the needle spin round rapidly four or five times1 before the air and terrestrial magnetism could reduce its motion to mere oscillation4 #cb4 ,by using charcoal at the ends of the ,b helix1 a minute spark could be perceived when the contact of the battery with ,a was completed4 ,this spark could not be due to any diversion of a part of the current of the battery through the iron to the helix ,b2 for when the battery contact was continued1 the galvanometer still resumed its perfectly indifferent state 7#bh474 ,the spark was rarely seen on breaking contact4 ,a small platina wire could not be ignited by this induced current2 but there seems every reason to believe that the effect would be obtained by using a stronger original current or a more powerful arrangement of helices4 #cc4 ,a feeble voltaic current was sent through the helix ,b and the galvanometer1 so as to deflect the needle of the latter #cj or #dj1 and then the battery of one hundred pairs of plates connected with ,a2 but after the first effect was over1 the galvanometer-needle resumed exactly the position due to the feeble current transmitted by its own wire4 ,this took place in whichever way the battery contacts were made1 and shows that here again 7#bj47 no permanent influence of the currents upon each other1 as to their quantity and tension1 exists4 #cd4 ,another arrangement was then employed connecting the former experiments on volta-electric induction 7#f-bf47 with the present4 ,a combination of helices like that already described 7#f47 was constructed upon a hollow cylinder of pasteboard3 there were eight lengths of copper wire1 containing altogether #bbj feet2 four of these helices were connected end to end1 and then with the galvanometer 7#g472 the other intervening four were also connected end to end1 and the battery of one hundred pairs discharged through them4 ,in this form the effect on the galvanometer was hardly sensible 7#aa471 though magnets could be made by the induced current 7#ac474 ,but when a soft iron cylinder seven eighths of an inch thick1 and twelve inches long1 was introduced into the pasteboard tube1 surrounded by the helices1 then the induced current affected the galvanometer powerfully and with all the phenomena just described 7#cj474 ,it possessed also the power of making magnets with more energy1 apparently1 than when no iron cylinder was present4 #ce4 ,when the iron cylinder was replaced by an equal cylinder of copper1 no effect beyond that of the helices alone was produced4 ,the iron cylinder arrangement was not so powerful as the ring arrangement already described 7#bg474 #cf4 ,similar effects were then produced by ordinary magnets3 thus the hollow helix just described 7#cd47 had all its elementary helices connected with the galvanometer by two copper wires1 each five feet in length2 the soft iron cylinder was introduced into its axis2 a couple of bar magnets1 each twenty-four inches long1 were arranged with their opposite poles at one end in contact1 so as to resemble a horse-shoe magnet1 and then contact made between the other poles and the ends of the iron cylinder1 so as to convert it for the time into a magnet 7fig4 #b473 by breaking the magnetic contacts1 or reversing them1 the magnetism of the iron cylinder could be destroyed or reversed at pleasure4 #cg4 ,upon making magnetic contact1 the needle was deflected2 continuing the contact1 the needle became indifferent1 and resumed its first position2 on breaking the contact1 it was again deflected1 but in the opposite direction to the first effect1 and then it again became indifferent4 ,when the magnetic contacts were reversed the deflections were reversed4 #ch4 ,when the magnetic contact was made1 the deflection was such as to indicate an induced current of electricity in the opposite direction to that fitted to form a magnet1 having the same polarity as that really produced by contact with the bar magnets4 ,thus when the marked and unmarked poles were placed as in fig4 #c1 the current in the helix was in the direction represented1 ,p being supposed to be the end of the wire going to the positive pole of the battery1 or that end towards which the zinc plates face1 and ,n the negative wire4 ,such a current would have converted the cylinder into a magnet of the opposite kind to that formed by contact with the poles ,a and ,b2 and such a current moves in the opposite direction to the currents which in ,m4 ,ampre's beautiful theory are considered as constituting a magnet in the position figured,a4 ,a ,the relative position of an electric current and a magnet is by most persons found very difficult to remember1 and three or four helps to the memory have been devised by ,m4 ,ampre and others4 ,i venture to suggest the following as a very simple and effectual assistance in these and similar latitudes4 ,let the experimenter think he is looking down upon a dipping needle1 or upon the pole of the north1 and then let him think upon the direction of the motion of the hands of a watch1 or of a screw moving direct2 currents in that direction round a needle would make it into such a magnet as the dipping needle1 or would themselves constitute an electro-magnet of similar qualities2 or if brought near a magnet would tend to make it take that direction2 or would themselves be moved into that position by a magnet so placed2 or in ,m4 ,ampre's theory are considered as moving in that direction in the magnet4 ,these two points of the position of the dipping-needle and the motion of the watch hands being remembered1 any other relation of the current and magnet can be at once deduced from it4 #ci4 ,but as it might be supposed that in all the preceding experiments of this section1 it was by some peculiar effect taking place during the formation of the magnet1 and not by its mere virtual approximation1 that the momentary induced current was excited1 the following experiment was made4 ,all the similar ends of the compound hollow helix 7#cd47 were bound together by copper wire1 forming two general terminations1 and these were connected with the galvanometer4 ,the soft iron cylinder 7#cd47 was removed1 and a cylindrical magnet1 three quarters of an inch in diameter and eight inches and a half in length1 used instead4 ,one end of this magnet was introduced into the axis of the helix 7fig4 #d471 and then1 the galvanometer-needle being stationary1 the magnet was suddenly thrust in2 immediately the needle was deflected in the same direction as if the magnet had been formed by either of the two preceding processes 7#cd4 #cf474 ,being left in1 the needle resumed its first position1 and then the magnet being withdrawn the needle was deflected in the opposite direction4 ,these effects were not great2 but by introducing and withdrawing the magnet1 so that the impulse each time should be added to those previously communicated to the needle1 the latter could be made to vibrate through an arc of #ahj or more4 #dj4 ,in this experiment the magnet must not be passed entirely through the helix1 for then a second action occurs4 ,when the magnet is introduced1 the needle at the galvanometer is deflected in a certain direction2 but being in1 whether it be pushed quite through or withdrawn1 the needle is deflected in a direction the reverse of that previously produced4 ,when the magnet is passed in and through at one continuous motion1 the needle moves one way1 is then suddenly stopped1 and finally moves the other way4 #da4 ,if such a hollow helix as that described 7#cd47 be laid east and west 7or in any other constant position71 and a magnet be retained east and west1 its marked pole always being one way2 then whichever end of the helix the magnet goes in at1 and consequently whichever pole of the magnet enters first1 still the needle is deflected the same way3 on the other hand1 whichever direction is followed in withdrawing the magnet1 the deflection is constant1 but contrary to that due to its entrance4 #db4 ,these effects are simple consequences of the law hereafter to be described 7#aad74 #dc4 ,when the eight elementary helices were made one long helix1 the effect was not so great as in the arrangement described4 ,when only one of the eight helices was used1 the effect was also much diminished4 ,all care was taken to guard against tiny direct action of the inducing magnet upon the galvanometer1 and it was found that by moving the magnet in the same direction1 and to the same degree on the outside of the helix1 no effect on the needle was produced4 #dd4 ,the ,royal ,society are in possession of a large compound magnet formerly belonging to ,dr4 ,gowin ,knight1 which1 by permission of the ,president and ,council1 ,i was allowed to use in the prosecution of these experiments3 it is at present in the charge of ,mr4 ,christie1 at his house at ,woolwich1 where1 by ,mr4 ,christie's kindness1 ,i was at liberty to work2 and ,i have to acknowledge my obligations to him for his assistance in all the experiments and observations made with it4 ,this magnet is composed of about #dej bar magnets1 each fifteen inches long1 one inch wide1 and half an inch thick1 arranged in a box so as to present at one of its extremities two external poles 7fig4 #e474 ,these poles projected horizontally six inches from the box1 were each twelve inches high and three inches wide4 ,they were nine inches apart2 and when a soft iron cylinder1 three quarters of an inch in diameter and twelve inches long1 was put across from one to the other1 it required a force of nearly one hundred pounds to break the contact4 ,the pole to the left in the figure is the marked pole,a4 ,a ,to avoid any confusion as to the poles of the magnet1 ,i shall designate the pole pointing to the north as the marked pole2 ,i may occasionally speak of the north and south ends of the needle1 but do not mean thereby north and south poles4 ,that is by many considered the true north pole of a needle which points to the south2 but in this country it in often called the south pole4 #de4 ,the indicating galvanometer1 in all experiments made with this magnet1 was about eight feet from it1 not directly in front of the poles1 but about #af or #ag on one side4 ,it was found that on making or breaking the connexion of the poles by soft iron1 the instrument was slightly affected2 but all error of observation arising from this cause was easily and carefully avoided4 #df4 ,the electrical effects exhibited by this magnet were very striking4 ,when a soft iron cylinder thirteen inches long was put through the compound hollow helix1 with its ends arranged as two general terminations 7#ci471 these connected with the galvanometer1 and the iron cylinder brought in contact with the two poles of the magnet 7fig4 #e471 so powerful a rush of electricity took place that the needle whirled round many times in succession,a4 ,a ,a soft iron bar in the form of a lifter to a horse-shoe magnet1 when supplied with a coil of this kind round the middle of it1 becomes1 by juxta-position with a magnet1 a ready source of a brief but determinate current of electricity4 #dg4 ,notwithstanding this great power1 if the contact was continued1 the needle resumed its natural position1 being entirely uninfluenced by the position of the helix 7#cj474 ,but on breaking the magnetic contact1 the needle was whirled round in the opposite direction with a force equal to the former4 #dh4 ,a piece of copper plate wrapped once round the iron cylinder like a socket1 but with interposed paper to prevent contact1 had its edges connected with the wires of the galvanometer4 ,when the iron was brought in contact with the poles the galvanometer was strongly affected4 #di4 ,dismissing the helices and sockets1 the galvanometer wire was passed over1 and consequently only half round the iron cylinder 7fig4 #f472 but even then a strong effect upon the needle was exhibited1 when the magnetic contact was made or broken4 #ej4 ,as the helix with its iron cylinder was brought towards the magnetic poles1 but without making contact1 still powerful effects were produced4 ,when the helix1 without the iron cylinder1 and consequently containing no metal but copper1 was approached to1 or placed between the poles 7#dd471 the needle was thrown #hj1 #ij1 or more1 from its natural position4 ,the inductive force was of course greater1 the nearer the helix1 either with or without its iron cylinder1 was brought to the poles2 but otherwise the same effects were produced1 whether the helix1 c4 was or was not brought into contact with the magnet2 i4e4 no permanent effect on the galvanometer was produced2 and the effects of approximation and removal were the reverse of each other 7#cj474 #ea4 ,when a bolt of copper corresponding to the iron cylinder was introduced1 no greater effect was produced by the helix than without it4 ,but when a thick iron wire was substituted1 the magneto-electric induction was rendered sensibly greater4 #eb4 ,the direction of the electric current produced in all these experiments with the helix1 was the same as that already described 7#ch47 as obtained with the weaker bar magnets4 #ec4 ,a spiral containing fourteen feet of copper wire1 being connected with the galvanometer1 and approximated directly towards the marked pole in the line of its axis1 affected the instrument strongly2 the current induced in it was in the reverse direction to the current theoretically considered by ,m4 ,ampre as existing in the magnet 7#ch471 or as the current in an electro-magnet of similar polarity4 ,as the spiral was withdrawn1 the induced current was reversed4 #ed4 ,a similar spiral had the current of eighty pairs of #d-;inch plates sent through it so as to form an electro-magnet1 and then the other spiral connected with the galvanometer 7#eh47 approximated to it2 the needle vibrated1 indicating a current in the galvanometer spiral the reverse of that in the battery spiral 7#ah4 #bf474 ,on withdrawing the latter spiral1 the needle passed in the opposite direction4 #ee4 ,single wires1 approximated in certain directions towards the magnetic pole1 had currents induced in them4 ,on their removal1 the currents were inverted4 ,in such experiments the wires should not be removed in directions different to those in which they were approximated2 for then occasionally complicated and irregular effects are produced1 the causes of which will be very evident in the fourth part of this paper4 #ef4 ,all attempts to obtain chemical effects by the induced current of electricity failed1 though the precautions before described 7#bb471 and all others that could be thought of1 were employed4 ,neither was any sensation on the tongue1 or any convulsive effect upon the limbs of a frog1 produced4 ,nor could charcoal or fine wire be ignited 7#acc474 ,but upon repeating the experiments more at leisure at the ,royal ,institution1 with an armed loadstone belonging to ,professor ,daniell and capable of lifting about thirty pounds1 a frog was very powerfully convulsed each time magnetic contact was made4 ,at first the convulsions could not be obtained on breaking magnetic contact2 but conceiving the deficiency of effect was because of the comparative slowness of separation1 the latter act was effected by a blow1 and then the frog was convulsed strongly4 ,the more instantaneous the union or disunion is effected1 the more powerful the convulsion4 ,i thought also ,i could perceive the sensation upon the tongue and the flash before the eyes2 but ,i could obtain no evidence of chemical decomposition4 #eg4 ,the various experiments of this section prove1 ,i think1 most completely the production of electricity from ordinary magnetism4 ,that its intensity should be very feeble and quantity small1 cannot be considered wonderful1 when it is remembered that like thermo-electricity it is evolved entirely within the substance of metals retaining all their conducting power4 ,but an agent which is conducted along metallic wires in the manner described2 which whilst so passing possesses the peculiar magnetic actions and force of a current of electricity2 which can agitate and convulse the limbs of a frog2 and which1 finally1 can produce a spark,a by its discharge through charcoal 7#cb471 can only be electricity4 ,as all the effects can be produced by ferruginous electro-magnets 7#cd471 there is no doubt that arrangements like the magnets of ,professors ,moll1 ,henry1 ,ten ,eyke1 and others1 in which as many as two thousand pounds have been lifted1 may be used for these experiments2 in which case not only a brighter spark may be obtained1 but wires also ignited1 and1 as the current can pass liquids 7#bc471 chemical action be produced4 ,these effects are still more likely to be obtained when the magneto-electric arrangements to be explained in the fourth section are excited by the powers of such apparatus4 ,a ,for a mode of obtaining the spark from the common magnet which ,i have found effectual1 see the ,philosophical ,magazine for ,june #ahcb1 p4 #e4 ,in the same ,journal for ,november #ahcd1 vol4 v4 p4 #cdi1 will be found a method of obtaining the magneto-electric spark1 still simpler in its principle1 the use of soft iron being dispensed with altogether4--,dec4 #ahch4 #eh4 ,the similarity of action1 almost amounting to identity1 between common magnets and either electro-magnets or volta-electric currents1 is strikingly in accordance with and confirmatory of ,m4 ,ampre's theory1 and furnishes powerful reasons for believing that the action is the same in both cases2 but1 as a distinction in language is still necessary1 ,i propose to call the agency thus exerted by ordinary magnets1 magneto-electric or magnelectric induction 7#bf74 #ei4 ,the only difference which powerfully strikes the attention as existing between volta-electric and magneto-electric induction1 is the suddenness of the former1 and the sensible time required by the latter2 but even in this early state of investigation there are circumstances which seem to indicate1 that upon further inquiry this difference will1 as a philosophical distinction1 disappear 7#fh74;,a ,a ,for important additional phenomena and developments of the induction of electrical currents1 see now the ninth series1 #ajdh-aaah4--;,dec4 #ahch4 #c4 ,new ,electrical ,state or ,condition of ,matter4,a ,a ,this section having been read at the ,royal ,society and reported upon1 and having also1 in consequence of a letter from myself to ,m4 ,hachette1 been noticed at the ,french ,institute1 ,i feel bound to let it stand as part of the paper2 but later investigations 7intimated #gc4 #gf4 #gg47 of the laws governing those phenomena1 induce me to think that the latter can be fully explained without admitting the electro-tonic state4 ,my views on this point will appear in the second series of these researches4--,m4,f4 #fj4 ,whilst the wire is subject to either volta-electric or magneto-electric induction1 it appears to be in a peculiar state2 for it resists the formation of an electrical current in it1 whereas1 if in its common condition1 such a current would be produced2 and when left uninfluenced it has the power of originating a current1 a power which the wire does not possess under common circumstances4 ,this electrical condition of matter has not hitherto been recognised1 but it probably exerts a very important influence in many if not most of the phenomena produced by currents of electricity4 ,for reasons which will immediately appear 7#ga471 ,i have1 after advising with several learned friends1 ventured to designate it as the electro-ionic state4 #fa4 ,this peculiar condition shows no known electrical effects whilst it continues2 nor have ,i yet been able to discover any peculiar powers exerted1 or properties possessed1 by matter whilst retained in this state4 #fb4 ,it shows no reaction by attractive or repulsive powers4 ,the various experiments which have been made with powerful magnets upon such metals1 as copper1 silver1 and generally those substances not magnetic1 prove this point2 for the substances experimented upon1 if electrical conductors1 must have acquired this state2 and yet no evidence of attractive or repulsive powers has been observed4 ,i have placed copper and silver discs1 very delicately suspended on torsion balances in vacuo near to the poles of very powerful magnets1 yet have not been able to observe the least attractive or repulsive force4 #fc4 ,i have also arranged a fine slip of gold-leaf very near to a bar of copper1 the two being in metallic contact by mercury at their extremities4 ,these have been placed in vacuo1 so that metal rods connected with the extremities of the arrangement should pass through the sides of the vessel into the air4 ,i have then moved powerful magnetic poles1 about this arrangement1 in various directions1 the metallic circuit on the outside being sometimes completed by wires1 and sometimes broken4 ,but ,i never could obtain any sensible motion of the gold-leaf1 either directed to the magnet or towards the collateral bar of copper1 which must have been1 as far as induction was concerned1 in a similar state to itself4 #fd4 ,in some cases it has been supposed that1 under such circumstances1 attractive and repulsive forces have been exhibited1 i4e4 that such bodies have become slightly magnetic4 ,but the phenomena now described1 in conjunction with the confidence we may reasonably repose in ,m4 ,ampre's theory of magnetism1 tend to throw doubt on such cases2 for if magnetism depend upon the attraction of electrical currents1 and if the powerful currents at first excited1 both by volta-electric and magneto-electric induction1 instantly and naturally cease 7#ab4 #bh4 #dg471 causing at the same time an entire cessation of magnetic effects at the galvanometer needle1 then there can be little or no expectation that any substances not partaking of the peculiar relation in which iron1 nickel1 and one or two other bodies1 stand1 should exhibit magneto-attractive powers4 ,it seems far more probable1 that the extremely feeble permanent effects observed have been due to traces of iron1 or perhaps some other unrecognised cause not magnetic4 #fe4 ,this peculiar condition exerts no retarding or accelerating power upon electrical currents passing through metal thus circumstanced 7#bj4 #cc474 ,neither could any such power upon the inducing current itself be detected2 for when masses of metal1 wires1 helices1 c4 were arranged in all possible ways by the side of a wire or helix1 carrying a current measured by the galvanometer 7#bj471 not the slightest permanent change in the indication of the instrument could be perceived4 ,metal in the supposed peculiar state1 therefore1 conducts electricity in all directions with its ordinary facility1 or1 in other words1 its conducting power is not sensibly altered by it4 #ff4 ,all metals take on the peculiar state4 ,this is proved in the preceding experiments with copper and iron 7#i471 and with gold1 silver1 tin1 lead1 zinc1 antimony1 bismuth1 mercury1 c4 by experiments to be described in the fourth part 7#acb471 admitting of easy application4 ,with regard to iron1 the experiments prove the thorough and remarkable independence of these phenomena of induction1 and the ordinary magnetical appearances of that metal4 #fg4 ,this state is altogether the effect of the induction exerted1 and ceases as soon as the inductive force is removed4 ,it is the same state1 whether produced by the collateral passage of voltaic currents 7#bf471 or the formation of a magnet 7#cd4 #cf471 or the mere approximation of a magnet 7#ci4 #ej472 and is a strong proof in addition to those advanced by ,m4 ,ampre1 of the identity of the agents concerned in these several operations4 ,it probably occurs1 momentarily1 during the passage of the common electric spark 7#bd471 and may perhaps be obtained hereafter in bad conductors by weak electrical currents or other means 7#gd4 #gf74 #fh4 ,the state appears to be instantly assumed 7#ab471 requiring hardly a sensible portion of time for that purpose4 ,the difference of time between volta-electric and magneto-electric induction1 rendered evident by the galvanometer 7#ei471 may probably be thus explained4 ,when a voltaic current is sent through one of two parallel wires1 as those of the hollow helix 7#cd471 a current is produced in the other wire1 as brief in its continuance as the time required for a single action of this kind1 and which1 by experiment1 is found to be inappreciably small4 ,the action will seem still more instantaneous1 because1 as there is an accumulation of power in the poles of the battery before contact1 the first rush of electricity in the wire of communication is greater than that sustained after the contact is completed2 the wire of induction becomes at the moment electro-tonic to an equivalent degree1 which the moment after sinks to the state in which the continuous current can sustain it1 but in sinking1 causes an opposite induced current to that at first produced4 ,the consequence is1 that the first induced wave of electricity more resembles that from the discharge of an electric jar1 than it otherwise would do4 #fi4 ,but when the iron cylinder is put into the same helix 7#ca471 previous to the connexion being made with the battery1 then the current from the latter may be considered as active in inducing innumerable currents of a similar kind to itself in the iron1 rendering it a magnet4 ,this is known by experiment to occupy time2 for a magnet so formed1 even of soft iron1 does not rise to its fullest intensity in an instant1 and it may be because the currents within the iron are successive in their formation or arrangement4 ,but as the magnet can induce1 as well as the battery current1 the combined action of the two continues to evolve induced electricity1 until their joint effect is at a maximum1 and thus the existence of the deflecting force is prolonged sufficiently to overcome the inertia of the galvanometer needle4 #gj4 ,in all those cases where the helices or wires are advanced towards or taken from the magnet 7#ej4 #ee471 the direct or inverted current of induced electricity continues for the time occupied in the advance or recession2 for the electro-tonic state is rising to a higher or falling to a lower degree during that time1 and the change is accompanied by its corresponding evolution of electricity2 but these form no objections to the opinion that the electro-tonic state is instantly assumed4 #ga4 ,this peculiar state appears to be a state of tension1 and may be considered as equivalent to a current of electricity1 at least equal to that produced either when the condition is induced or destroyed4 ,the current evolved1 however1 first or last1 is not to be considered a measure of the degree of tension to which the electro-tonic state has risen2 for as the metal retains its conducting powers unimpaired 7#fe471 and as the electricity evolved is but for a moment1 7the peculiar state being instantly assumed and lost 7#fh4717 the electricity which may be led away by long wire conductors1 offering obstruction in their substance proportionate to their small lateral and extensive linear dimensions1 can be but a very small portion of that really evolved within the mass at the moment it assumes this condition4 ,insulated helices and portions of metal instantly assumed the state2 and no traces of electricity could be discovered in them1 however quickly the contact with the electrometer was made1 after they were put under induction1 either by the current from the battery or the magnet4 ,a single drop of water or a small piece of moistened paper 7#bc4 #ef47 was obstacle sufficient to stop the current through the conductors1 the electricity evolved returning to a state of equilibrium through the metal itself1 and consequently in an unobserved manner4 #gb4 ,the tension of this state may therefore be comparatively very great4 ,but whether great or small1 it is hardly conceivable that it should exist without exerting a reaction upon the original inducing current1 and producing equilibrium of some kind4 ,it might be anticipated that this would give rise to a retardation of the original current2 but ,i have not been able to ascertain that this is the case4 ,neither have ,i in any other way as yet been able to distinguish effects attributable to such a reaction4 #gc4 ,all the results favour the notion that the electro-tonic state relates to the particles1 and not to the mass1 of the wire or substance under induction1 being in that respect different to the induction exerted by electricity of tension4 ,if so1 the state may be assumed in liquids when no electrical current is sensible1 and even in non-conductors2 the current itself1 when it occurs1 being as it were a contingency due to the existence of conducting power1 and the momentary propulsive force exerted by the particles during their arrangement4 ,even when conducting power is equal1 the currents of electricity1 which as yet are the only indicators of this state1 may be unequal1 because of differences as to numbers1 size1 electrical condition1 c4 c4 in the particles themselves4 ,it will only be after the laws which govern this new state are ascertained1 that we shall be able to predict what is the true condition of1 and what are the electrical results obtainable from1 any particular substance4 #gd4 ,the current of electricity which induces the electro-tonic state in a neighbouring wire1 probably induces that state also in its own wire2 for when by a current in one wire a collateral wire is made electro-tonic1 the latter state is not rendered any way incompatible or interfering with a current of electricity passing through it 7#fb474 ,if1 therefore1 the current were sent through the second wire instead of the first1 it does not seem probable that its inducing action upon the second would be less1 but on the contrary more1 because the distance between the agent and the matter acted upon would be very greatly diminished4 ,a copper bolt had its extremities connected with a galvanometer1 and then the poles of a battery of one hundred pairs of plates connected with the bolt1 so as to send the current through it2 the voltaic circuit was then suddenly broken1 and the galvanometer observed for any indications of a return current through the copper bolt due to the discharge of its supposed electro-tonic state4 ,no effect of the kind was obtained1 nor indeed1 for two reasons1 ought it to be expected2 for first1 as the cessation of induction and the discharge of the electro-tonic condition are simultaneous1 and not successive1 the return current would only be equivalent to the neutralization of the last portion of the inducing current1 and would not therefore show any alteration of direction2 or assuming that time did intervene1 and that the latter current was really distinct from the former1 its short1 sudden character 7#ab4 #bf47 would prevent it from being thus recognised4 #ge4 ,no difficulty arises1 ,i think1 in considering the wire thus rendered electro-tonic by its own current more than by any external current1 especially when the apparent non-interference of that state with currents is considered 7#fb4 #ga474 ,the simultaneous existence of the conducting and electro-tonic states finds an analogy in the manner in which electrical currents can be passed through magnets1 where it is found that both the currents passed1 and those of the magnets1 preserve all their properties distinct from each other1 and exert their mutual actions4 #gf4 ,the reason given with regard to metals extends also to fluids and all other conductors1 and leads to the conclusion that when electric currents are passed through them they also assume the electro-tonic state4 ,should that prove to be the case1 its influence in voltaic decomposition1 and the transference of the elements to the poles1 can hardly be doubted4 ,in the electro-tonic state the homogeneous particles of matter appear to have assumed a regular but forced electrical arrangement in the direction of the current1 which if the matter be undecomposable1 produces1 when relieved1 a return current2 but in decomposable matter this forced state may be sufficient to make an elementary particle leave its companion1 with which it is in a constrained condition1 and associate with the neighbouring similar particle1 in relation to which it is in a more natural condition1 the forced electrical arrangement being itself discharged or relieved1 at the same time1 as effectually as if it had been freed from induction4 ,but as the original voltaic current is continued1 the electro-tonic state may be instantly renewed1 producing the forced arrangement of the compound particles1 to be as instantly discharged by a transference of the elementary particles of the opposite kind in opposite directions1 but parallel to the current4 ,even the differences between common and voltaic electricity1 when applied to effect chemical decomposition1 which ,dr4 ,wollaston has pointed out,a1 seem explicable by the circumstances connected with the induction of electricity from these two sources 7#be474 ,but as ,i have reserved this branch of the inquiry1 that ,i might follow out the investigations contained in the present paper1 ,i refrain 7though much tempted7 from offering further speculations4 ,a ,philosophical ,transactions1 #ahja1 p4 #bdg4 #gg4 ,marianini has discovered and described a peculiar affection of the surfaces of metallic discs1 when1 being in contact with humid conductors1 a current of electricity is passed through them2 they are then capable of producing a reverse current of electricity1 and ,marianini has well applied the effect in explanation of the phenomena of ,ritter's piles,a4 ,m4,a4 de la ,rive has described a peculiar property acquired by metallic conductors1 when being immersed in a liquid as poles1 they have completed1 for some time1 the voltaic circuit1 in consequence of which1 when separated from the battery and plunged into the same fluid1 they by themselves produce an electric current,b4 ,m4,a4 ,van ,beek has detailed cases in which the electrical relation of one metal in contact with another has been preserved after separation1 and accompanied by its corresponding chemical effects,c4 ,these states and results appear to differ from the electro-tonic state and its phenomena2 but the true relation of the former to the latter can only be decided when our knowledge of all these phenomena has been enlarged4 ,a ,annales de ,chimie1 xxxviii4 #e4 ,b ,ibid4 xxviii4 #aij4 ,c ,ibid4 xxxviii4 #di4 #gh4 ,i had occasion in the commencement of this paper 7#b47 to refer to an experiment by ,ampre1 as one of those dependent upon the electrical induction of currents made prior to the present investigation1 and have arrived at conclusions which seem to imply doubts of the accuracy of the experiment 7#fb4 c472 it is therefore due to ,m4 ,ampre that ,i should attend to it more distinctly4 ,when a disc of copper 7says ,m4 ,ampre7 was suspended by a silk thread and surrounded by a helix or spiral1 and when the charge of a powerful voltaic battery was sent through the spiral1 a strong magnet at the same time being presented to the copper disc1 the latter turned at the moment to take a position of equilibrium1 exactly as the spiral itself would have turned had it been free to move4 ,i have not been able to obtain this effect1 nor indeed any motion2 but the cause of my failure in the latter point may be due to the momentary existence of the current not allowing time for the inertia of the plate to be overcome 7#aa4 #ab474 ,m4 ,ampre has perhaps succeeded in obtaining motion from the superior delicacy and power of his electro-magnetical apparatus1 or he may have obtained only the motion due to cessation of action4 ,but all my results tend to invert the sense of the proposition stated by ,m4 ,ampre1 that a current of electricity tends to put the electricity of conductors near which it passes in motion in the same direction1 for they indicate an opposite direction for the produced current 7#bf4 #ec472 and they show that the effect is momentary1 and that it is also produced by magnetic induction1 and that certain other extraordinary effects follow thereupon4 #gi4 ,the momentary existence of the phenomena of induction now described is sufficient to furnish abundant reasons for the uncertainty or failure of the experiments1 hitherto made to obtain electricity from magnets1 or to effect chemical decomposition or arrangement by their means,a4 ,a ,the ,lyce1 ,no4 #cf1 for ,january #ast1 has a long and rather premature article1 in which it endeavours to show anticipations by ,french philosophers of my researches4 ,it however mistakes the erroneous results of ,,mm4 ,fresnel and ,ampre for true ones1 and then imagines my true results are like those erroneous ones4 ,i notice it here1 however1 for the purpose of doing honour to ,fresnel in a much higher degree than would have been merited by a feeble anticipation of the present investigations4 ,that great philosopher1 at the same time with myself and fifty other persons1 made experiments which the present paper proves could give no expected result4 ,he was deceived for the moment1 and published his imaginary success2 but on more carefully repeating his trials1 he could find no proof of their accuracy2 and1 in the high and pure philosophic desire to remove error as well as discover truth1 he recanted his first statement4 ,the example of ,berzelius regarding the first ,thorina is another instance of this fine feeling2 and as occasions are not rare1 it would be to the dignity of science if such examples were more frequently followed4--,february #ajth1 #ahcb4 #hj4 ,it also appears capable of explaining fully the remarkable phenomena observed by ,m4 ,arago between metals and magnets when neither are moving 7#abj471 as well as most of the results obtained by ,sir ,john ,herschel1 ,messrs4 ,babbage1 ,harris1 and others1 in repeating his experiments2 accounting at the same time perfectly for what at first appeared inexplicable2 namely1 the non-action of the same metals and magnets when at rest4 ,these results1 which also afford the readiest means of obtaining electricity from magnetism1 ,i shall now proceed to describe4 #d4 ,explication of ,arago's ,magnetic ,phenomena4 #ha4 ,if a plate of copper be revolved close to a magnetic needle1 or magnet1 suspended in such a way that the latter may rotate in a plane parallel to that of the former1 the magnet tends to follow the motion of the plate2 or if the magnet be revolved1 the plate tends to follow its motion2 and the effect is so powerful1 that magnets or plates of many pounds weight may be thus carried round4 ,if the magnet and plate be at rest relative to each other1 not the slightest effect1 attractive or repulsive1 or of any kind1 can be observed between them 7#fb474 ,this is the phenomenon discovered by ,m4 ,arago2 and he states that the effect takes place not only with all metals1 but with solids1 liquids1 and even gases1 i4e4 with all substances 7#acj474 #hb4 ,mr4 ,babbage and ,sir ,john ,herschel1 on conjointly repeating the experiments in this country,a1 could obtain the effects only with the metals1 and with carbon in a peculiar state 7from gas retorts71 i4e4 only with excellent conductors of electricity4 ,they refer the effect to magnetism induced in the plate by the magnet2 the pole of the latter causing an opposite pole in the nearest part of the plate1 and round this a more diffuse polarity of its own kind 7#abj474 ,the essential circumstance in producing the rotation of the suspended magnet is1 that the substance revolving below it shall acquire and lose its magnetism in sensible time1 and not instantly 7#abd474 ,this theory refers the effect to an attractive force1 and is not agreed to by the discoverer1 ,m4 ,arago1 nor by ,m4 ,ampre1 who quote against it the absence of all attraction when the magnet and metal are at rest 7#fb4 #abf471 although the induced magnetism should still remain2 and who1 from experiments made with a long dipping needle1 conceive the action to be always repulsive 7#abe474 ,a ,philosophical ,transactions1 #ahbe1 p4 #dfg4 #hc4 ,upon obtaining electricity from magnets by the means already described 7#cf #df471 ,i hoped to make the experiment of ,m4 ,arago a new source of electricity2 and did not despair1 by reference to terrestrial magneto-electric induction1 of being able to construct a new electrical machine4 ,thus stimulated1 numerous experiments were made with the magnet of the ,royal ,society at ,mr4 ,christie's house1 in all of which ,i had the advantage of his assistance4 ,as many of these were in the course of the superseded by more perfect arrangements1 ,i shall consider myself at liberty investigation to rearrange them in a manner calculated to convey most readily what appears to me to be a correct view of the nature of the phenomena4 #hd4 ,the magnet has been already described 7#dd474 ,to concentrate the poles1 and bring them nearer to each other1 two iron or steel bars1 each about six or seven inches long1 one inch wide1 and half an inch thick1 were put across the poles as in fig4 #g1 and being supported by twine from slipping1 could be placed as near to or far from each other as was required4 ,occasionally two bars of soft iron were employed1 so bent that when applied1 one to each pole1 the two smaller resulting poles were vertically over each other1 either being uppermost at pleasure4 #he4 ,a disc of copper1 twelve inches in diameter1 and about one fifth of an inch in thickness1 fixed upon a brass axis1 was mounted in frames so as to allow of revolution either vertically or horizontally1 its edge being at the same time introduced more or less between the magnetic poles 7fig4 #g474 ,the edge of the plate was well amalgamated for the purpose of obtaining a good but moveable contact1 and a part round the axis was also prepared in a similar manner4 #hf4 ,conductors or electric collectors of copper and lead were constructed so as to come in contact with the edge of the copper disc 7#he471 or with other forms of plates hereafter to be described 7#aja474 ,these conductors were about four inches long1 one third of an inch wide1 and one fifth of an inch thick2 one end of each was slightly grooved1 to allow of more exact adaptation to the somewhat convex edge of the plates1 and then amalgamated4 ,copper wires1 one sixteenth of an inch in thickness1 attached1 in the ordinary manner1 by convolutions to the other ends of these conductors1 passed away to the galvanometer4 #hg4 ,the galvanometer was roughly made1 yet sufficiently delicate in its indications4 ,the wire was of copper covered with silk1 and made sixteen or eighteen convolutions4 ,two sewing-needles were magnetized and fixed on to a stem of dried grass parallel to each other1 but in opposite directions1 and about half an inch apart2 this system was suspended by a fibre of unspun silk1 so that the lower needle should be between the convolutions of the multiplier1 and the upper above them4 ,the latter was by much the most powerful magnet1 and gave terrestrial direction to the whole2 fig4 #h4 represents the direction of the wire and of the needles when the instrument was placed in the magnetic meridian3 the ends of the wires are marked ,a and ,b for convenient reference hereafter4 ,the letters ,s and ,n designate the south and north ends of the needle when affected merely by terrestrial magnetism2 the end ,n is therefore the marked pole 7#dd474 ,the whole instrument was protected by a glass jar1 and stood1 as to position and distance relative to the large magnet1 under the same circumstances as before 7#de474 #hh4 ,all these arrangements being made1 the copper disc was adjusted as in fig4 #g1 the small magnetic poles being about half an inch apart1 and the edge of the plate inserted about half their width between them4 ,one of the galvanometer wires was passed twice or thrice loosely round the brass axis of the plate1 and the other attached to a conductor 7#hf471 which itself was retained by the hand in contact with the amalgamated edge of the disc at the part immediately between the magnetic poles4 ,under these circumstances all was quiescent1 and the galvanometer exhibited no effect4 ,but the instant the plate moved1 the galvanometer was influenced1 and by revolving the plate quickly the needle could be deflected #ij or more4 #hi4 ,it was difficult under the circumstances to make the contact between the conductor and the edge of the revolving disc uniformly good and extensive2 it was also difficult in the first experiments to obtain a regular velocity of rotation3 both these causes tended to retain the needle in a continual state of vibration2 but no difficulty existed in ascertaining to which side it was deflected1 or generally1 about what line it vibrated4 ,afterwards1 when the experiments were made more carefully1 a permanent deflection of the needle of nearly #de could be sustained4 #ij4 ,here therefore was demonstrated the production of a permanent current of electricity by ordinary magnets 7#eg474 #ia4 ,when the motion of the disc was reversed1 every other circumstance remaining the same1 the galvanometer needle was deflected with equal power as before2 but the deflection was on the opposite side1 and the current of electricity evolved1 therefore1 the reverse of the former4 #ib4 ,when the conductor was placed on the edge of the disc a little to the right or left1 as in the dotted positions fig4 #i1 the current of electricity was still evolved1 and in the same direction as at first 7#hh4 #ia474 ,this occurred to a considerable distance1 i4e4 #ej or #fj on each side of the place of the magnetic poles4 ,the current gathered by the conductor and conveyed to the galvanometer was of the same kind on both sides of the place of greatest intensity1 but gradually diminished in force from that place4 ,it appeared to be equally powerful at equal distances from the place of the magnetic poles1 not being affected in that respect by the direction of the rotation4 ,when the rotation of the disc was reversed1 the direction of the current of electricity was reversed also2 but the other circumstances were not affected4 #ic4 ,on raising the plate1 so that the magnetic poles were entirely hidden from each other by its intervention1 7a4 fig4 #aj17 the same effects were produced in the same order1 and with equal intensity as before4 ,on raising it still higher1 so as to bring the place of the poles to c1 still the effects were produced1 and apparently with as much power as at first4 #id4 ,when the conductor was held against the edge as if fixed to it1 and with it moved between the poles1 even though but for a few degrees1 the galvanometer needle moved and indicated a current of electricity1 the same as that which would have been produced if the wheel had revolved in the same direction1 the conductor remaining stationary4 #ie4 ,when the galvanometer connexion with the axis was broken1 and its wires made fast to two conductors1 both applied to the edge of the copper disc1 then currents of electricity were produced1 presenting more complicated appearances1 but in perfect harmony with the above results4 ,thus1 if applied as in fig4 #aa1 a current of electricity through the galvanometer was produced2 but if their place was a little shifted1 as in fig4 #ab1 a current in the contrary direction resulted2 the fact being1 that in the first instance the galvanometer indicated the difference between a strong current through ,a and a weak one through ,b1 and in the second1 of a weak current through ,a and a strong one through ,b 7#ib471 and therefore produced opposite deflections4 #if4 ,so also when the two conductors were equidistant from the magnetic poles1 as in fig4 #ac1 no current at the galvanometer was perceived1 whichever way the disc was rotated1 beyond what was momentarily produced by irregularity of contact2 because equal currents in the same direction tended to pass into both4 ,but when the two conductors were connected with one wire1 and the axis with the other wire1 7fig4 #ad17 then the galvanometer showed a current according with the direction of rotation 7#ia472 both conductors now acting consentaneously1 and as a single conductor did before 7#hh474 #ig4 ,all these effects could be obtained when only one of the poles of the magnet was brought near to the plate2 they were of the same kind as to direction1 c41 but by no means so powerful4 #ih4 ,all care was taken to render these results independent of the earth's magnetism1 or of the mutual magnetism of the magnet and galvanometer needles4 ,the contacts were made in the magnetic equator of the plate1 and at other parts2 the plate was placed horizontally1 and the poles vertically2 and other precautions were taken4 ,but the absence of any interference of the kind referred to1 was readily shown by the want of all effect when the disc was removed from the poles1 or the poles from the disc2 every other circumstance remaining the same4 #ii4 ,the relation of the current of electricity produced1 to the magnetic pole1 to the direction of rotation of the plate1 c4 c41 may be expressed by saying1 that when the unmarked pole 7#dd4 #hd47 is beneath the edge of the plate1 and the latter revolves horizontally1 screw-fashion1 the electricity which can be collected at the edge of the plate nearest to the pole is positive4 ,as the pole of the earth may mentally be considered the unmarked pole1 this relation of the rotation1 the pole1 and the electricity evolved1 is not difficult to remember4 ,or if1 in fig4 #ae1 the circle represent the copper disc revolving in the direction of the arrows1 and a the outline of the unmarked pole placed beneath the plate1 then the electricity collected at b and the neighbouring parts is positive1 whilst that collected at the centre c and other parts is negative 7#hh474 ,the currents in the plate are therefore from the centre by the magnetic poles towards the circumference4 #ajj4 ,if the marked pole be placed above1 all other things remaining the same1 the electricity at b1 fig4 #ae1 is still positive4 ,if the marked pole be placed below1 or the unmarked pole above1 the electricity is reversed4 ,if the direction of revolution in any case is reversed1 the electricity is also reversed4 #aja4 ,it is now evident that the rotating plate is merely another form of the simpler experiment of passing a piece of metal between the magnetic poles in a rectilinear direction1 and that in such cases currents of electricity are produced at right angles to the direction of the motion1 and crossing it at the place of the magnetic pole or poles4 ,this was sufficiently shown by the following simple experiment3 ,a piece of copper plate one fifth of an inch thick1 one inch and a half wide1 and twelve inches long1 being amalgamated at the edges1 was placed between the magnetic poles1 whilst the two conductors from the galvanometer were held in contact with its edges2 it was then drawn through between the poles of the conductors in the direction of the arrow1 fig4 #af2 immediately the galvanometer needle was deflected1 its north or marked end passed eastward1 indicating that the wire ,a received negative and the wire ,b positive electricity2 and as the marked pole was above1 the result is in perfect accordance with the effect obtained by the rotatory plate 7#ii474 #ajb4 ,on reversing the motion of the plate1 the needle at the galvanometer was deflected in the opposite direction1 showing an opposite current4 #ajc4 ,to render evident the character of the electrical current existing in various parts of the moving copper plate1 differing in their relation to the inducing poles1 one collector 7#hf47 only was applied at the part to be examined near to the pole1 the other being connected with the end of the plate as the most neutral place3 the results are given at fig4 #ag-bj1 the marked pole being above the plate4 ,in fig4 #ag1 ,b received positive electricity2 but the plate moving in the same direction1 it received on the opposite side1 fig4 #ah1 negative electricity3 reversing the motion of the latter1 as in fig4 #bj1 ,b received positive electricity2 or reversing the motion of the first arrangement1 that of fig4 #ag to fig4 #ai1 ,b received negative electricity4 #ajd4 ,when the plates were previously removed sideways from between the magnets1 as in fig4 #ba1 so as to be quite out of the polar axis1 still the same effects were produced1 though not so strongly4 #aje4 ,when the magnetic poles were in contact1 and the copper plate was drawn between the conductors near to the place1 there was but very little effect produced4 ,when the poles were opened by the width of a card1 the effect was somewhat more1 but still very small4 #ajf4 ,when an amalgamated copper wire1 one eighth of an inch thick1 was drawn through between the conductors and poles 7#aja471 it produced a very considerable effect1 though not so much as the plates4 #ajg4 ,if the conductors were held permanently against any particular parts of the copper plates1 and carried between the magnetic poles with them1 effects the same as those described were produced1 in accordance with the results obtained with the revolving disc 7#id474 #ajh4 ,on the conductors being held against the ends of the plates1 and the latter then passed between the magnetic poles1 in a direction transverse to their length1 the same effects were produced 7fig4 #bb474 ,the parts of the plates towards the end may be considered either as mere conductors1 or as portions of metal in which the electrical current is excited1 according to their distance and the strength of the magnet2 but the results were in perfect harmony with those before obtained4 ,the effect was as strong as when the conductors were held against the sides of the plate 7#aja474 #aji4 ,when a mere wire1 connected with the galvanometer so as to form a complete circuit1 was passed through between the poles1 the galvanometer was affected2 and upon moving the wire to and fro1 so as to make the alternate impulses produced correspond with the vibrations of the needle1 the latter could be increased to #bj or #cj on each side the magnetic meridian4 #aaj4 ,upon connecting the ends of a plate of metal with the galvanometer wires1 and then carrying it between the poles from end to end 7as in fig4 #bc471 in either direction1 no effect whatever was produced upon the galvanometer4 ,but the moment the motion became transverse1 the needle was deflected4 #aaa4 ,these effects were also obtained from electro-magnetic poles1 resulting from the use of copper helices or spirals1 either alone or with iron cores 7#cd4 #ed474 ,the directions of the motions were precisely the same2 but the action was much greater when the iron cores were used1 than without4 #aab4 ,when a flat spiral was passed through edgewise between the poles1 a curious action at the galvanometer resulted2 the needle first went strongly one way1 but then suddenly stopped1 as if it struck against some solid obstacle1 and immediately returned4 ,if the spiral were passed through from above downwards1 or from below upwards1 still the motion of the needle was in the same direction1 then suddenly stopped1 and then was reversed4 ,but on turning the spiral half-way round1 i4e4 edge for edge1 then the directions of the motions were reversed1 but still were suddenly interrupted and inverted as before4 ,this double action depends upon the halves of the spiral 7divided by a line passing through its centre perpendicular to the direction of its motion7 acting in opposite directions2 and the reason why the needle went to the same side1 whether the spiral passed by the poles in the one or the other direction1 was the circumstance1 that upon changing the motion1 the direction of the wires in the approaching half of the spiral was changed also4 ,the effects1 curious as they appear when witnessed1 are immediately referable to the action of single wires 7#dj4 #aji474 #aac4 ,although the experiments with the revolving plate1 wires1 and plates of metal1 were first successfully made with the large magnet belonging to the ,royal ,society1 yet they were all ultimately repeated with a couple of bar magnets two feet long1 one inch and a half wide1 and half an inch thick2 and1 by rendering the galvanometer 7#hg47 a little more delicate1 with the most striking results4 ,ferro-electro-magnets1 as those of ,moll1 ,henry1 c4 7#eg471 are very powerful4 ,it is very essential1 when making experiments on different substances1 that thermo-electric effects 7produced by contact of the fingers1 c47 be avoided1 or at least appreciated and accounted for2 they are easily distinguished by their permanency1 and their independence of the magnets1 or of the direction of the motion4 #aad4 ,the relation which holds between the magnetic pole1 the moving wire or metal1 and the direction of the current evolved1 i4e4 the law which governs the evolution of electricity by magneto-electric induction1 is very simple1 although rather difficult to express4 ,if in fig4 #bd1 ,,pn represent a horizontal wire passing by a marked magnetic pole1 so that the direction of its motion shall coincide with the curved line proceeding from below upwards2 or if its motion parallel to itself be in a line tangential to the curved line1 but in the general direction of the arrows2 or if it pass the pole in other directions1 but so as to cut the magnetic curves,a in the same general direction1 or on the same side as they would be cut by the wire if moving along the dotted curved line2--then the current of electricity in the wire is from ,p to ,n4 ,if it be carried in the reverse directions1 the electric current will be from ,n to ,p4 ,or if the wire be in the vertical position1 figured ,p' ,n'1 and it be carried in similar directions1 coinciding with the dotted horizontal curve so far1 as to cut the magnetic curves on the same side with it1 the current will be from ,p' to ,n'4 ,if the wire be considered a tangent to the curved surface of the cylindrical magnet1 and it be carried round that surface into any other position1 or if the magnet itself be revolved on its axis1 so as to bring any part opposite to the tangential wire1--still1 if afterwards the wire be moved in the directions indicated1 the current of electricity will be from ,p to ,n2 or if it be moved in the opposite direction1 from ,n to ,p2 so that as regards the motions of the wire past the pole1 they may be reduced to two1 directly opposite to each other1 one of which produces a current from ,p to ,n1 and the other from ,n to ,p4 ,a ,by magnetic curves1 ,i mean the lines of magnetic forces1 however modified by the juxtaposition of poles1 which would be depicted by iron filings2 or those to which a very small magnetic needle would form a tangent4 #aae4 ,the same holds true of the unmarked pole of the magnet1 except that if it be substituted for the one in the figure1 then1 as the wires are moved in the direction of the arrows1 the current of electricity would be from ,n to ,p1 and when they move in the reverse direction1 from ,p to ,n4 #aaf4 ,hence the current of electricity which is excited in metal when moving in the neighbourhood of a magnet1 depends for its direction altogether upon the relation of the metal to the resultant of magnetic action1 or to the magnetic curves1 and may be expressed in a popular way thus2 ,let ,,ab 7fig4 #be47 represent a cylinder magnet1 ,a being the marked pole1 and ,b the unmarked pole2 let ,,pn be a silver knife-blade1 resting across the magnet with its edge upward1 and with its marked or notched side towards the pole ,a2 then in whatever direction or position this knife be moved edge foremost1 either about the marked or the unmarked pole1 the current of electricity produced will be from ,p to ,n1 provided the intersected curves proceeding from ,a abut upon the notched surface of the knife1 and those from ,b upon the unnotched side4 ,or if the knife be moved with its back foremost1 the current will be from ,n to ,p in every possible position and direction1 provided the intersected curves abut on the same surfaces as before4 ,a little model is easily constructed1 by using a cylinder of wood for a magnet1 a flat piece for the blade1 and a piece of thread connecting one end of the cylinder with the other1 and passing through a hole in the blade1 for the magnetic curves3 this readily gives the result of any possible direction4 #aag4 ,when the wire under induction is passing by an electromagnetic pole1 as for instance one end of a copper helix traversed by the electric current 7#cd471 the direction of the current in the approaching wire is the same with that of the current in the parts or sides of the spirals nearest to it1 and in the receding wire the reverse of that in the parts nearest to it4 #aah4 ,all these results show that the power of inducing electric currents is circumferentially exerted by a magnetic resultant or axis of power1 just as circumferential magnetism is dependent upon and is exhibited by an electric current4 #aai4 ,the experiments described combine to prove that when a piece of metal 7and the same may be true of all conducting matter 7#bac47 7 is passed either before a single pole1 or between the opposite poles of a magnet1 or near electro-magnetic poles1 whether ferruginous or not1 electrical currents are produced across the metal transverse to the direction of motion2 and which therefore1 in ,arago's experiments1 will approximate towards the direction of radii4 ,if a single wire be moved like the spoke of a wheel near a magnetic pole1 a current of electricity is determined through it from one end towards the other4 ,if a wheel be imagined1 constructed of a great number of these radii1 and this revolved near the pole1 in the manner of the copper disc 7#he471 each radius will have a current produced in it as it passes by the pole4 ,if the radii be supposed to be in contact laterally1 a copper disc results1 in which the directions of the currents will be generally the same1 being modified only by the coaction which can take place between the particles1 now that they are in metallic contact4 #abj4 ,now that the existence of these currents is known1 ,arago's phenomena may be accounted for without considering them as due to the formation in the copper1 of a pole of the opposite kind to that approximated1 surrounded by a diffuse polarity of the same kind 7#hb472 neither is it essential that the plate should acquire and lose its state in a finite time2 nor on the other hand does it seem necessary that any repulsive force should be admitted as the cause of the rotation 7#hb474 #aba4 ,the effect is precisely of the same kind as the electromagnetic rotations which ,i had the good fortune to discover some years ago,a4 ,according to the experiments then made which have since been abundantly confirmed1 if a wire 7,,pn fig4 #bf47 be connected with the positive and negative ends of a voltaic buttery1 so that the positive electricity shall pass from ,p to ,n1 and a marked magnetic pole ,n be placed near the wire between it and the spectator1 the pole will move in a direction tangential to the wire1 i4e4 towards the right1 and the wire will move tangentially towards the left1 according to the directions of the arrows4 ,this is exactly what takes place in the rotation of a plate beneath a magnetic pole2 for let ,n 7fig4 #bg47 be a marked pole above the circular plate1 the latter being rotated in the direction of the arrow3 immediately currents of positive electricity set from the central parts in the general direction of the radii by the pole to the parts of the circumference a on the other side of that pole 7#ii4 #aai471 and are therefore exactly in the same relation to it as the current in the wire 7,,pn1 fig4 #bf471 and therefore the pole in the same manner moves to the right hand4 ,a ,quarterly ,journal of ,science1 vol4 xii4 pp4 #gd4 #ahf4 #daf4 #bhc4 #abb4 ,if the rotation of the disc be reversed1 the electric currents are reversed 7#ia471 and the pole therefore moves to the left hand4 ,if the contrary pole be employed1 the effects are the same1 i4e4 in the same direction1 because currents of electricity1 the reverse of those described1 are produced1 and by reversing both poles and currents1 the visible effects remain unchanged4 ,in whatever position the axis of the magnet be placed1 provided the same pole be applied to the same side of the plate1 the electric current produced is in the same direction1 in consistency with the law already stated 7#aad1 c472 and thus every circumstance regarding the direction of the motion may be explained4 #abc4 ,these currents are discharged or return in the parts of the plate on each side of and more distant from the place of the pole1 where1 of course1 the magnetic induction is weaker2 and when the collectors are applied1 and a current of electricity is carried away to the galvanometer 7#hh471 the deflection there is merely a repetition1 by the same current or part of it1 of the effect of rotation in the magnet over the plate itself4 #abd4 ,it is under the point of view just put forth that ,i have ventured to say it is not necessary that the plate should acquire and lose its state in a finite time 7#abj472 for if it were possible for the current to be fully developed the instant before it arrived at its state of nearest approximation to the vertical pole of the magnet1 instead of opposite to or a little beyond it1 still the relative motion of the pole and plate would be the same1 the resulting force being in fact tangential instead of direct4 #abe4 ,but it is possible 7though not necessary for the rotation7 that time may be required for the development of the maximum current in the plate1 in which case the resultant of all the forces would be in advance of the magnet when the plate is rotated1 or in the rear of the magnet when the latter is rotated1 and many of the effects with pure electro-magnetic poles tend to prove this is the case4 ,then1 the tangential force may be resolved into two others1 one parallel to the plane of rotation1 and the other perpendicular to it2 the former would be the force exerted in making the plate revolve with the magnet1 or the magnet with the plate2 the latter would be a repulsive force1 and is probably that1 the effects of which ,m4 ,arago has also discovered 7#hb474 #abf4 ,the extraordinary circumstance accompanying this action1 which has seemed so inexplicable1 namely1 the cessation of all phenomena when the magnet and metal are brought to rest1 now receives a full explanation 7#hb472 for then the electrical currents which cause the motion cease altogether4 #abg4 ,all the effects of solution of metallic continuity1 and the consequent diminution of power described by ,messrs4 ,babbage and ,herschel,a1 now receive their natural explanation1 as well also as the resumption of power when the cuts were filled up by metallic substances1 which1 though conductors of electricity1 were themselves very deficient in the power of influencing magnets4 ,and new modes of cutting the plate may be devised1 which shall almost entirely destroy its power4 ,thus1 if a copper plate 7#ha47 be cut through at about a fifth or sixth of its diameter from the edge1 so as to separate a ring from it1 and this ring be again fastened on1 but with a thickness of paper intervening 7fig4 #bi471 and if ,arago's experiment be made with this compound plate so adjusted that the section shall continually travel opposite the pole1 it is evident that the magnetic currents will be greatly interfered with1 and the plate probably lose much of its effect,b4 ,a ,philosophical ,transactions1 #ahbe1 p4 #dha4 ,b ,this experiment has actually been made by ,mr4 ,christie1 with the results here described1 and is recorded in the ,philosophical ,transactions for #ahbg1 p4 #hb4 ,an elementary result of this kind was obtained by using two pieces of thick copper1 shaped as in fig4 #bh4 ,when the two neighbouring edges were amalgamated and put together1 and the arrangement passed between the poles of the magnet1 in the direction parallel to these edges1 a current was urged through the wires attached to the outer angles1 and the galvanometer became strongly affected2 but when a single film of paper was interposed1 and the experiment repeated1 no sensible effect could be produced4 #abh4 ,a section of this kind could not interfere much with the induction of magnetism1 supposed to be of the nature ordinarily received by iron4 #abi4 ,the effect of rotation or deflection of the needle1 which ,m4 ,arago obtained by ordinary magnets1 ,m4 ,ampre succeeded in procuring by electro-magnets4 ,this is perfectly in harmony with the results relative to volta-electric and magneto-electric induction described in this paper4 ,and by using flat spirals of copper wire1 through which electric currents were sent1 in place of ordinary magnetic poles 7,ill471 sometimes applying a single one to one side of the rotating plate1 and sometimes two to opposite sides1 ,i obtained the induced currents of electricity from the plate itself1 and could lead them away to1 and ascertain their existence by1 the galvanometer4 #acj4 ,the cause which has now been assigned for the rotation in ,arago's experiment1 namely1 the production of electrical currents1 seems abundantly sufficient in all cases where the metals1 or perhaps even other conductors1 are concerned2 but with regard to such bodies as glass1 resins1 and1 above all1 gases1 it seems impossible that currents of electricity1 capable of producing these effects1 should be generated in them4 ,yet ,arago found that the effects in question were produced by these and by all bodies tried 7#ha474 ,messrs4 ,babbage and ,herschel1 it is true1 did not observe them with any substance not metallic1 except carbon1 in a highly conducting state 7#hb474 ,mr4 ,harris has ascertained their occurrence with wood1 marble1 freestone and annealed glass1 but obtained no effect with sulphuric acid and saturated solution of sulphate of iron1 although these are better conductors of electricity than the former substances4 #aca4 ,future investigations will no doubt explain these difficulties1 and decide the point whether the retarding or dragging action spoken of is always simultaneous with electric currents4,a ,the existence of the action in metals1 only whilst the currents exist1 i4e4 whilst motion is given 7#hb4 #hh471 and the explication of the repulsive action observed by ,m4 ,arago 7#hb4 #abe471 are powerful reasons for referring it to this cause2 but it may be combined with others which occasionally act alone4 ,a ,experiments which ,i have since made convince me that this particular action is always due to the electrical currents formed2 and they supply a test by which it may be distinguished from the action of ordinary magnetism1 or any other cause1 including those which are mechanical or irregular1 producing similar effects 7#bed47 #acb4 ,copper1 iron1 tin1 zinc1 lead1 mercury1 and all the metals tried1 produced electrical currents when passed between the magnetic poles3 the mercury was put into a glass tube for the purpose4 ,the dense carbon deposited in coal gas retorts1 also produced the current1 but ordinary charcoal did not4 ,neither could ,i obtain any sensible effects with brine1 sulphuric acid1 saline solutions1 c41 whether rotated in basins1 or inclosed in tubes and passed between the poles4 #acc4 ,i have never been able to produce any sensation upon the tongue by the wires connected with the conductors applied to the edges of the revolving plate 7#hh47 or slips of metal 7#aja474 ,nor have ,i been able to heat a fine platina wire1 or produce a spark1 or convulse the limbs of a frog4 ,i have failed also to produce any chemical effects by electricity thus evolved 7#bb4 #ef74 #acd4 ,as the electric current in the revolving copper plate occupies but a small space1 proceeding by the poles and being discharged right and left at very small distances comparatively 7#abc472 and as it exists in a thick mass of metal possessing almost the highest conducting power of any1 and consequently offering extraordinary facility for its production and discharge2 and as1 notwithstanding this1 considerable currents may be drawn off which can pass through narrow wires1 forty1 fifty1 sixty1 or even one hundred feet long2 it is evident that the current existing in the plate itself must be a very powerful one1 when the rotation is rapid and the magnet strong4 ,this is also abundantly proved by the obedience and readiness with which a magnet ten or twelve pounds in weight follows the motion of the plate and will strongly twist up the cord by which it is suspended4 #ace4 ,two rough trials were made with the intention of constructing magneto-electric machines4 ,in one1 a ring one inch and a half broad and twelve inches external diameter1 cut from a thick copper plate1 was mounted so as to revolve between the poles of the magnet and represent a plate similar to those formerly used 7#aja471 but of interminable length2 the inner and outer edges were amalgamated1 and the conductors applied one to each edge1 at the place of the magnetic poles4 ,the current of electricity evolved did not appear by the galvanometer to be stronger1 if so strong1 as that from the circular plate 7#hh474 #acf4 ,in the other1 small thick discs of copper or other metal1 half an inch in diameter1 were revolved rapidly near to the poles1 but with the axis of rotation out of the polar axis2 the electricity evolved was collected by conductors applied as before to the edges 7#hf474 ,currents were procured1 but of strength much inferior to that produced by the circular plate4 #acg4 ,the latter experiment is analogous to those made by ,mr4 ,barlow with a rotating iron shell1 subject to the influence of the earth,a4 ,the effects obtained by him have been referred by ,messrs4 ,babbage and ,herschel to the same cause as that considered as influential in ,arago's experiment,b2 but it would be interesting to know how far the electric current which might be produced in the experiment would account for the deflexion of the needle4 ,the mere inversion of a copper wire six or seven times near the poles of the magnet1 and isochronously with the vibrations of the galvanometer needle connected with it1 was sufficient to make the needle vibrate through an arc of #fj or #gj4 ,the rotation of a copper shell would perhaps decide the point1 and might even throw light upon the more permanent1 though somewhat analogous effects obtained by ,mr4 ,christie4 ,a ,philosophical ,transactions1 #ahbe4 p4 #cag4 ,b ,ibid4 #ahbe4 p4 #dhe4 #ach4 ,the remark which has already been made respecting iron 7#ff471 and the independence of the ordinary magnetical phenomena of that substance and the phenomena now described of magneto-electric induction in that and other metals1 was fully confirmed by many results of the kind detailed in this section4 ,when an iron plate similar to the copper one formerly described 7#aja47 was passed between the magnetic poles1 it gave a current of electricity like the copper plate1 but decidedly of less power2 and in the experiments upon the induction of electric currents 7#i471 no difference in the kind of action between iron and other metals could be perceived4 ,the power therefore of an iron plate to drag a magnet after it1 or to intercept magnetic action1 should be carefully distinguished from the similar power of such metals as silver1 copper1 c4 c41 inasmuch as in the iron by far the greater part of the effect is due to what may be called ordinary magnetic action4 ,there can be no doubt that the cause assigned by ,messrs4 ,babbage and ,herschel in explication of ,arago's phenomena is the true one1 when iron is the metal used4 #aci4 ,the very feeble powers which were found by those philosophers to belong to bismuth and antimony1 when moving1 of affecting the suspended magnet1 and which has been confirmed by ,mr4 ,harris1 seem at first disproportionate to their conducting powers2 whether it be so or not must be decided by future experiment 7#gc47;,a4 ,these metals are highly crystalline1 and probably conduct electricity with different degrees of facility in different directions2 and it is not unlikely that where a mass is made up of a number of crystals heterogeneously associated1 an effect approaching to that of actual division may occur 7#abg472 or the currents of electricity may become more suddenly deflected at the confines of similar crystalline arrangements1 and so be more readily and completely discharged within the mass4 ,a ,i have since been able to explain these differences1 and prove1 with several metals1 that the effect is in the order of the conducting power2 for ,i have been able to obtain1 by magneto-electric induction1 currents of electricity which are proportionate in strength to the conducting power of the bodies experimented with 7#baa474 4 ,royal ,institution1 ,november #ahca4 ,note4--,in consequence of the long period which has intervened between the reading and printing of the foregoing paper1 accounts of the experiments have been dispersed1 and1 through a letter of my own to ,m4 ,hachette1 have reached ,france and ,italy4 ,that letter was translated 7with some errors71 and read to the ,academy of ,sciences at ,paris1 #bfth ,december1 #ahca4 ,a copy of it in ,le ,temps of the #bhth ,december quickly reached ,signor ,nobili1 who1 with ,signor ,antinori1 immediately experimented upon the subject1 and obtained many of the results mentioned in my letter2 others they could not obtain or understand1 because of the brevity of my account4 ,these results by ,signori ,nobili and ,antinori have been embodied in a paper dated #cast ,january #ahcb1 and printed and published in the number of the ,antologia dated ,november #ahca 7according at least to the copy of the paper kindly sent me by ,signor ,nobili74 ,it is evident the work could not have been then printed2 and though ,signor ,nobili1 in his paper1 has inserted my letter as the text of his experiments1 yet the circumstance of back date has caused many here1 who have heard of ,nobili's experiments by report only1 to imagine his results were anterior to1 instead of being dependent upon1 mine4 ,i may be allowed under these circumstances to remark1 that ,i experimented on this subject several years ago1 and have published results4 7,see ,quarterly ,journal of ,science for ,july #ahbe1 p4 #cch47 ,the following also is an extract from my note-book1 dated ,november #bh1 #ahbe3 ,experiments on induction by connecting wire of voltaic battery3--a battery of four troughs1 ten pairs of plates1 each arranged side by side--the poles connected by a wire about four feet long1 parallel to which was another similar wire separated from it only by two thicknesses of paper1 the ends of the latter were attached to a galvanometer3--exhibited no action1 c4 c4 c4--,could not in any way render any induction evident from the connecting wire4 ,the cause of failure at that time is now evident 7#gi474--,m4,f4 ,april1 #ahcb4 ,,second ,,series4 ,,the ,,bakerian ,,lecture4 #e4 ,terrestrial ,magneto-electric ,induction4 #f4 ,force and ,direction of ,magneto-electric ,induction generally4 ,read ,january #ab1 #ahcb4 #e4 ,terrestrial ,magneto-electric ,induction4 #adj4 ,when the general facts described in the former paper were discovered1 and the law of magneto-electric induction relative to direction was ascertained 7#aad471 it was not difficult to perceive that the earth would produce the same effect as a magnet1 and to an extent that would1 perhaps1 render it available in the construction of new electrical machines4 ,the following are some of the results obtained in pursuance of this view4 #ada4 ,the hollow helix already described 7#f47 was connected with a galvanometer by wires eight feet long2 and the soft iron cylinder 7#cd47 after being heated red-hot and slowly cooled1 to remove all traces of magnetism1 was put into the helix so as to project equally at both ends1 and fixed there4 ,the combined helix and bar were held in the magnetic direction or line of dip1 and 7the galvanometer needle being motionless7 were then inverted1 so that the lower end should become the upper1 but the whole still correspond to the magnetic direction2 the needle was immediately deflected4 ,as the latter returned to its first position1 the helix and bar were again inverted2 and by doing this two or three times1 making the inversions and vibrations to coincide1 the needle swung through an arc of #aej or #afj4 #adb4 ,when one end of the helix1 which may be called ,a1 was uppermost at first 7,b end consequently being below71 then it mattered not in which direction it proceeded during the inversion1 whether to the right hand or left hand1 or through any other course2 still the galvanometer needle passed in the same direction4 ,again1 when ,b end was uppermost1 the inversion of the helix and bar in any direction always caused the needle to be deflected one way2 that way being the opposite to the course of the deflection in the former case4 #adc4 ,when the helix with its iron core in any given position was inverted1 the effect was as if a magnet with its marked pole downwards had been introduced from above into the inverted helix4 ,thus1 if the end ,b were upwards1 such a magnet introduced from above would make the marked end of the galvanometer needle pass west4 ,or the end ,b being downwards1 and the soft iron in its place1 inversion of the whole produced the same effect4 #add4 ,when the soft iron bar was taken out of the helix and inverted in various directions within four feet of the galvanometer1 not the slightest effect upon it was produced4 #ade4 ,these phenomena are the necessary consequence of the inductive magnetic power of the earth1 rendering the soft iron cylinder a magnet with its marked pole downwards4 ,the experiment is analogous to that in which two bar magnets were used to magnetize the same cylinder in the same helix 7#cf471 and the inversion of position in the present experiment is equivalent to a change of the poles in that arrangement4 ,but the result is not less an instance of the evolution of electricity by means of the magnetism of the globe4 #adf4 ,the helix alone was then held permanently in the magnetic direction1 and the soft iron cylinder afterwards introduced2 the galvanometer needle was instantly deflected2 by withdrawing the cylinder as the needle returned1 and continuing the two actions simultaneously1 the vibrations soon extended through an arc of #ahj4 ,the effect was precisely the same as that obtained by using a cylinder magnet with its marked pole downwards2 and the direction of motion1 c4 was perfectly in accordance with the results of former experiments obtained with such a magnet 7#ci474 ,a magnet in that position being used1 gave the same deflections1 but stronger4 ,when the helix was put at right angles to the magnetic direction or dip1 then the introduction or removal of the soft iron cylinder produced no effect at the needle4 ,any inclination to the dip gave results of the same kind as those already described1 but increasing in strength as the helix approximated to the direction of the dip4 #adg4 ,a cylinder magnet1 although it has great power of affecting the galvanometer when moving into or out of the helix1 has no power of continuing the deflection 7#ci472 and therefore1 though left in1 still the magnetic needle comes to its usual place of rest4 ,but upon repeating 7with the magnet7 the experiment of inversion in the direction of the dip 7#ada71 the needle was affected as powerfully as before2 the disturbance of the magnetism in the steel magnet1 by the earth's inductive force upon it1 being thus shown to be nearly1 if not quite1 equal in amount and rapidity to that occurring in soft iron4 ,it is probable that in this way magneto-electrical arrangements may become very useful in indicating the disturbance of magnetic forces1 where other means will not apply2 for it is not the whole magnetic power which produces the visible effect1 but only the difference due to the disturbing causes4 #adh4 ,these favourable results led me to hope that the direct magneto-electric induction of the earth might be rendered sensible2 and ,i ultimately succeeded in obtaining the effect in several ways4 ,when the helix just referred to 7#ada4 #f47 was placed in the magnetic dip1 but without any cylinder of iron or steel1 and was then inverted1 a feeble action at the needle was observed4 ,inverting the helix ten or twelve times1 and at such periods that the deflecting forces exerted by the currents of electricity produced in it should be added to the momentum of the needle 7#ci471 the latter was soon made to vibrate through an arc of #hj or #ij4 ,here1 therefore1 currents of electricity were produced by the direct inductive power of the earth's magnetism1 without the use of any ferruginous matter1 and upon a metal not capable of exhibiting any of the ordinary magnetic phenomena4 ,the experiment in everything represents the effects produced by bringing the same helix to one or both poles of any powerful magnet 7#ej474 #adi4 ,guided by the law already expressed 7#aad471 ,i expected that all the electric phenomena of the revolving metal plate could now be produced without any other magnet than the earth4 ,the plate so often referred to 7#he47 was therefore fixed so as to rotate in a horizontal plane4 ,the magnetic curves of the earth 7#aad4 note71 i4e4 the dip1 passes through this plane at angles of about #gj1 which it was expected would be an approximation to perpendicularity1 quite enough to allow of magneto-electric induction sufficiently powerful to produce a current of electricity4 #aej4 ,upon rotation of the plate1 the currents ought1 according to the law 7#aad4 #aba471 to tend to pass in the direction of the radii1 through all parts of the plate1 either from the centre to the circumference1 or from the circumference to the centre1 as the direction of the rotation of the plate was one way or the other4 ,one of the wires of the galvanometer was therefore brought in contact with the axis of the plate1 and the other attached to a leaden collector or conductor 7#hf471 which itself was placed against the amalgamated edge of the disc4 ,on rotating the plate there was a distinct effect at the galvanometer needle2 on reversing the rotation1 the needle went in the opposite direction2 and by making the action of the plate coincide with the vibrations of the needle1 the arc through which the latter passed soon extended to half a circle4 #aea4 ,whatever part of the edge of the plate was touched by the conductor1 the electricity was the same1 provided the direction of rotation continued unaltered4 #aeb4 ,when the plate revolved screw-fashion1 or as the hands of a watch1 the current of electricity 7#aej47 was from the centre to the circumference2 when the direction of rotation was unscrew1 the current was from the circumference to the centre4 ,these directions are the same with those obtained when the unmarked pole of a magnet was placed beneath the revolving plate 7#ii474 #aec4 ,when the plate was in the magnetic meridian1 or in any other plane coinciding with the magnetic dip1 then its rotation produced no effect upon the galvanometer4 ,when inclined to the dip but a few degrees1 electricity began to appear upon rotation4 ,thus when standing upright in a plane perpendicular to the magnetic meridian1 and when consequently its own plane was inclined only about #bj to the dip1 revolution of the plate evolved electricity4 ,as the inclination was increased1 the electricity became more powerful until the angle formed by the plane of the plate with the dip was #ij1 when the electricity for a given velocity of the plate was a maximum4 #aed4 ,it is a striking thing to observe the revolving copper plate become thus a new electrical machine2 and curious results arise on comparing it with the common machine4 ,in the one1 the plate is of the best non-conducting substance that can be applied2 in the other1 it is the most perfect conductor3 in the one1 insulation is essential2 in the other1 it is fatal4 ,in comparison of the quantities of electricity produced1 the metal machine does not at all fall below the glass one2 for it can produce a constant current capable of deflecting the galvanometer needle1 whereas the latter cannot4 ,it is quite true that the force of the current thus evolved has not as yet been increased so as to render it available in any of our ordinary applications of this power2 but there appears every reasonable expectation that this may hereafter be effected2 and probably by several arrangements4 ,weak as the current may seem to be1 it is as strong as1 if not stronger than1 any thermo-electric current2 for it can pass fluids 7#bc471 agitate the animal system1 and in the case of an electro-magnet has produced sparks 7#cb474 #aee4 ,a disc of copper1 one fifth of an inch thick and only one inch and a half in diameter1 was amalgamated at the edge2 a square piece of sheet lead 7copper would have been better7 of equal thickness had a circular hole cut in it1 into which the disc loosely fitted2 a little mercury completed the metallic communication of the disc and its surrounding ring2 the latter was attached to one of the galvanometer wires1 and the other wire dipped into a little metallic cup containing mercury1 fixed upon the top of the copper axis of the small disc4 ,upon rotating the disc in a horizontal plane1 the galvanometer needle could be affected1 although the earth was the only magnet employed1 and the radius of the disc but three quarters of an inch2 in which space only the current was excited4 #aef4 ,on putting the pole of a magnet under the revolving disc1 the galvanometer needle could be permanently deflected4 #aeg4 ,on using copper wires one sixth of an inch in thickness instead of the smaller wires 7#hf47 hitherto constantly employed1 far more powerful effects were obtained4 ,perhaps if the galvanometer had consisted of fewer turns of thick wire instead of many convolutions of thinner1 more striking effects would have been produced4 #aeh4 ,one form of apparatus which ,i purpose having arranged1 is to have several discs superposed2 the discs are to be metallically connected1 alternately at the edges and at the centres1 by means of mercury2 and are then to be revolved alternately in opposite directions1 i4e4 the first1 third1 fifth1 c4 to the right hand1 and the second1 fourth1 sixth1 c4 to the left hand2 the whole being placed so that the discs are perpendicular to the dip1 or intersect most directly the magnetic curves of powerful magnets4 ,the electricity will be from the centre to the circumference in one set of discs1 and from the circumference to the centre in those on each side of them2 thus the action of the whole will conjoin to produce one combined and more powerful current4 #aei4 ,i have rather1 however1 been desirous of discovering new facts and new relations dependent on magneto-electric induction1 than of exalting the force of those already obtained2 being assured that the latter would find their full development hereafter4 99 99 99 99 99 #afj4 ,i referred in my former paper to the probable influence of terrestrial magneto-electric induction 7#acg47 in producing1 either altogether or in part1 the phenomena observed by ,messrs4 ,christie and ,barlow,a1 whilst revolving ferruginous bodies2 and especially those observed by the latter when rapidly rotating an iron shell1 which were by that philosopher referred to a change in the ordinary disposition of the magnetism of the ball4 ,i suggested also that the rotation of a copper globe would probably insulate the effects due to electric currents from those due to mere derangement of magnetism1 and throw light upon the true nature of the phenomena4 ,a ,christie1 ,phil4 ,trans4 #ahbe1 pp4 #eh1 #cdg1 c4 ,barlow1 ,phil4 ,trans4 #ahbe1 p4 #cag4 #afa4 ,upon considering the law already referred to 7#aad471 it appeared impossible that a metallic globe could revolve under natural circumstances1 without having electric currents produced within it1 circulating round the revolving globe in a plane at right angles to the plane of revolution1 provided its axis of rotation did not coincide with the dip2 and it appeared that the current would be most powerful when the axis of revolution was perpendicular to the dip of the needle3 for then all those parts of the ball below a plane passing through its centre and perpendicular to the dip1 would in moving cut the magnetic curves in one direction1 whilst all those parts above that plane would intersect them in the other direction3 currents therefore would exist in these moving parts1 proceeding from one pole of rotation to the other2 but the currents above would be in the reverse direction to those below1 and in conjunction with them would produce a continued circulation of electricity4 #afb4 ,as the electric currents are nowhere interrupted in the ball1 powerful effects were expected1 and ,i endeavoured to obtain them with simple apparatus4 ,the ball ,i used was of brass2 it had belonged to an old electrical machine1 was hollow1 thin 7too thin71 and four inches in diameter2 a brass wire was screwed into it1 and the ball either turned in the hand by the wire1 or sometimes1 to render it more steady1 supported by its wire in a notched piece of wood1 and motion again given by the hand4 ,the ball gave no signs of magnetism when at rest4 #afc4 ,a compound magnetic needle was used to detect the currents4 ,it was arranged thus3 a sewing-needle had the head and point broken off1 and was then magnetised2 being broken in halves1 the two magnets thus produced were fixed on a stem of dried grass1 so as to be perpendicular to it1 and about four inches asunder2 they were both in one plane1 but their similar poles in contrary directions4 ,the grass was attached to a piece of unspun silk about six inches long1 the latter to a stick passing through a cork in the mouth of a cylindrical jar2 and thus a compound arrangement was obtained1 perfectly sheltered from the motion of the air1 but little influenced by the magnetism of the earth1 and yet highly sensible to magnetic and electric forces1 when the latter were brought into the vicinity of the one or the other needle4 #afd4 ,upon adjusting the needles to the plane of the magnetic meridian2 arranging the ball on the outside of the glass jar to the west of the needles1 and at such a height that its centre should correspond horizontally with the upper needle1 whilst its axis was in the plane of the magnetic meridian1 but perpendicular to the dip2 and then rotating the ball1 the needle was immediately affected4 ,upon inverting the direction of rotation1 the needle was again affected1 but in the opposite direction4 ,when the ball revolved from east over to west1 the marked pole went eastward2 when the ball revolved in the opposite direction1 the marked pole went westward or towards the ball4 ,upon placing the ball to the east of the needles1 still the needle was deflected in the same way2 i4e4 when the ball revolved from east over to west1 the marked pole wont eastward 7or towards the ball72 when the rotation was in the opposite direction1 the marked pole went westward4 #afe4 ,by twisting the silk of the needles1 the latter were brought into a position perpendicular to the plane of the magnetic meridian2 the ball was again revolved1 with its axis parallel to the needles2 the upper was affected as before1 and the deflection was such as to show that both here and in the former case the needle was influenced solely by currents of electricity existing in the brass globe4 #aff4 ,if the upper part of the revolving ball be considered as a wire moving from east to west1 over the unmarked pole of the earth1 the current of electricity in it should be from north to south 7#ii4 #aad4 #aej472 if the under part be considered as a similar wire1 moving from west to east over the same pole1 the electric current should be from south to north2 and the circulation of electricity should therefore be from north above to south1 and below back to north1 in a metal ball revolving from east above to west in these latitudes4 ,now these currents are exactly those required to give the directions of the needle in the experiments just described2 so that the coincidence of the theory from which the experiments were deduced with the experiments themselves1 is perfect4 #afg4 ,upon inclining the axis of rotation considerably1 the revolving ball was still found to affect the magnetic needle2 and it was not until the angle which it formed with the magnetic dip was rendered small1 that its effects1 even upon this apparatus1 were lost 7#aec474 ,when revolving with its axis parallel to the dip1 it is evident that the globe becomes analogous to the copper plate2 electricity of one kind might be collected at its equator1 and of the other kind at its poles4 #afh4 ,a current in the ball1 such as that described above 7#afa471 although it ought to deflect a needle the same way whether it be to the right or the left of the ball and of the axis of rotation1 ought to deflect it the contrary way when above or below the ball2 for then the needle is1 or ought to be1 acted upon in a contrary direction by the current4 ,this expectation was fulfilled by revolving the ball beneath the magnetic needle1 the latter being still inclosed in its jar4 ,when the ball was revolved from east over to west1 the marked pole of the needle1 instead of passing eastward1 went westward2 and when revolved from west over to east1 the marked pole went eastward4 #afi4 ,the deflections of the magnetic needle thus obtained with a brass ball are exactly in the same direction as those observed by ,mr4 ,barlow in the revolution of the iron shell2 and from the manner in which iron exhibits the phenomena of magneto-electric induction like any other metal1 and distinct from its peculiar magnetic phenomena 7#acb471 it is impossible but that electric currents must have been excited1 and become active in those experiments4 ,what proportion of the whole effect obtained is due to this cause1 must be decided by a more elaborate investigation of all the phenomena4 #agj4 ,these results1 in conjunction with the general law before stated 7#aad471 suggested an experiment of extreme simplicity1 which yet1 on trial1 was found to answer perfectly4 ,the exclusion of all extraneous circumstances and complexity of arrangement1 and the distinct character of the indications afforded1 render this single experiment an epitome of nearly all the facts of magneto-electric induction4 #aga4 ,a piece of common copper wire1 about eight feet long and one twentieth of an inch in thickness1 had one of its ends fastened to one of the terminations of the galvanometer wire1 and the other end to the other termination2 thus it formed an endless continuation of the galvanometer wire3 it was then roughly adjusted into the shape of a rectangle1 or rather of a loop1 the upper part of which could be carried to and fro over the galvanometer1 whilst the lower part1 and the galvanometer attached to it1 remained steady 7,plate ,,ii4 fig4 #cj474 ,upon moving this loop over the galvanometer from right to left1 the magnetic needle was immediately deflected2 upon passing the loop back again1 the needle passed in the contrary direction to what it did before2 upon repeating these motions of the loop in accordance with the vibrations of the needle 7#ci471 the latter soon swung through #ij or more4 #agb4 ,the relation of the current of electricity produced in the wire1 to its motion1 may be understood by supposing the convolutions at the galvanometer away1 and the wire arranged as a rectangle1 with its lower edge horizontal and in the plane of the magnetic meridian1 and a magnetic needle suspended above and over the middle part of this edge1 and directed by the earth 7fig4 #cj474 ,on passing the upper part of the rectangle from west to east into the position represented by the dotted line1 the marked pole of the magnetic needle went west2 the electric current was therefore from north to south in the part of the wire passing under the needle1 and from south to north in the moving or upper part of the parallelogram4 ,on passing the upper part of the rectangle from east to west over the galvanometer1 the marked pole of the needle went east1 and the current of electricity was therefore the reverse of the former4 #agc4 ,when the rectangle was arranged in a plane east and west1 and the magnetic needle made parallel to it1 either by the torsion of its suspension thread or the action of a magnet1 still the general effects were the same4 ,on moving the upper part of the rectangle from north to south1 the marked pole of the needle went north2 when the wire was moved in the opposite direction1 the marked pole went south4 ,the same effect took place when the motion of the wire was in any other azimuth of the line of dip2 the direction of the current always being conformable to the law formerly expressed 7#aad471 and also to the directions obtained with the rotating ball 7#aja474 #agd4 ,in these experiments it is not necessary to move the galvanometer or needle from its first position4 ,it is quite sufficient if the wire of the rectangle is distorted where it leaves the instrument1 and bent so as to allow the moving upper part to travel in the desired direction4 #age4 ,the moveable part of the wire was then arranged below the galvanometer1 but so as to be carried across the dip4 ,it affected the instrument as before1 and in the same direction2 i4e4 when carried from west to east under the instrument1 the marked end of the needle went west1 as before4 ,this should1 of course1 be the case2 for when the wire is cutting the magnetic dip in a certain direction1 an electric current also in a certain direction should be induced in it4 #agf4 ,if in fig4 #ca dp be parallel to the dip1 and ,,ba be considered as the upper part of the rectangle 7#aga471 with an arrow c attached to it1 both these being retained in a plane perpendicular to the dip1--then1 however ,,ba with its attached arrow is moved upon dp as an axis1 if it afterwards proceed in the direction of the arrow1 a current of electricity will move along it from ,b towards ,a4 #agg4 ,when the moving part of the wire was carried up or down parallel to the dip1 no effect was produced on the galvanometer4 ,when the direction of motion was a little inclined to the dip1 electricity manifested itself2 and was at a maximum when the motion was perpendicular to the magnetic direction4 #agh4 ,when the wire was bent into other forms and moved1 equally strong effects were obtained1 especially when instead of a rectangle a double catenarian curve was formed of it on one side of the galvanometer1 and the two single curves or halves were swung in opposite directions at the same time2 their action then combined to affect the galvanometer3 but all the results were reducible to those above described4 #agi4 ,the longer the extent of the moving wire1 and the greater the space through which it moves1 the greater is the effect upon the galvanometer4 #ahj4 ,the facility with which electric currents are produced in metals when moving under the influence of magnets1 suggests that henceforth precautions should always be taken1 in experiments upon metals and magnets1 to guard against such effects4 ,considering the universality of the magnetic influence of the earth1 it is a consequence which appears very extraordinary to the mind1 that scarcely any piece of metal can be moved in contact with others1 either at rest1 or in motion with different velocities or in varying directions1 without an electric current existing within them4 ,it is probable that amongst arrangements of steam-engines and metal machinery1 some curious accidental magneto-electric combinations may be found1 producing effects which have never been observed1 or1 if noticed1 have never as yet been understood4 99 99 99 99 99 #aha4 ,upon considering the effects of terrestrial magneto-electric induction which have now been described1 it is almost impossible to resist the impression that similar effects1 but infinitely greater in force1 may be produced by the action of the globe1 as a magnet1 upon its own mass1 in consequence of its diurnal rotation4 ,it would seem that if a bar of metal be laid in these latitudes on the surface of the earth parallel to the magnetic meridian1 a current of electricity tends to pass through it from south to north1 in consequence of the travelling of the bar from west to east 7#agb471 by the rotation of the earth2 that if another bar in the same direction be connected with the first by wires1 it cannot discharge the current of the first1 because it has an equal tendency to have a current in the same direction induced within itself3 but that if the latter be carried from east to west1 which is equivalent to a diminution of the motion communicated to it from the earth 7#agb471 then the electric current from south to north is rendered evident in the first bar1 in consequence of its discharge1 at the same time1 by means of the second4 #ahb4 ,upon the supposition that the rotation of the earth tended1 by magneto-electric induction1 to cause currents in its own mass1 these would1 according to the law 7#aad47 and the experiments1 be1 upon the surface at least1 from the parts in the neighbourhood of or towards the plane of the equator1 in opposite directions to the poles2 and if collectors could be applied at the equator and at the poles of the globe1 as has been done with the revolving copper plate 7#aej471 and also with magnets 7#bbj471 then negative electricity would be collected at the equator1 and positive electricity at both poles 7#bbb474 ,but without the conductors1 or something equivalent to them1 it is evident these currents could not exist1 as they could not be discharged4 #ahc4 ,i did not think it impossible that some natural difference might occur between bodies1 relative to the intensity of the current produced or tending to be produced in them by magneto-electric induction1 which might be shown by opposing them to each other2 especially as ,messrs4 ,arago1 ,babbage1 ,herschel1 and ,harris1 have all found great differences1 not only between the metals and other substances1 but between the metals themselves1 in their power of receiving motion from or giving it to a magnet in trials by revolution 7#acj474 ,i therefore took two wires1 each one hundred and twenty feet long1 one of iron and the other of copper4 ,these were connected with each other at their ends1 and then extended in the direction of the magnetic meridian1 so as to form two nearly parallel lines1 nowhere in contact except at the extremities4 ,the copper wire was then divided in the middle1 and examined by a delicate galvanometer1 but no evidence of an electrical current was obtained4 #ahd4 ,by favour of ,his ,royal ,highness the ,president of the ,society1 ,i obtained the permission of ,his ,majesty to make experiments at the lake in the gardens of ,kensington-palace1 for the purpose of comparing1 in a similar manner1 water and metal4 ,the basin of this lake is artificial2 the water is supplied by the ,chelsea ,company2 no springs run into it1 and it presented what ,i required1 namely1 a uniform mass of still pure water1 with banks ranging nearly from east to west1 and from north to south4 #ahe4 ,two perfectly clean bright copper plates1 each exposing four square feet of surface1 were soldered to the extremities of a copper wire2 the plates were immersed in the water1 north and south of each other1 the wire which connected them being arranged upon the grass of the bank4 ,the plates were about four hundred and eighty feet from each other1 in a right line2 the wire was probably six hundred feet long4 ,this wire was then divided in the middle1 and connected by two cups of mercury with a delicate galvanometer4 #ahf4 ,at first1 indications of electric currents were obtained2 but when these were tested by inverting the direction of contact1 and in other ways1 they were found to be due to other causes than the one sought for4 ,a little difference in temperature2 a minute portion of the nitrate of mercury used to amalgamate the wires1 entering into the water employed to reduce the two cups of mercury to the same temperature2 was sufficient to produce currents of electricity1 which affected the galvanometer1 notwithstanding they had to pass through nearly five hundred feet of water4 ,when these and other interfering causes were guarded against1 no effect was obtained2 and it appeared that even such dissimilar substances as water and copper1 when cutting the magnetic curves of the earth with equal velocity1 perfectly neutralized each other's action4 #ahg4 ,mr4 ,fox of ,falmouth has obtained some highly important results respecting the electricity of metalliferous veins in the mines of ,cornwall1 which have been published in the ,philosophical ,transactions,a4 ,i have examined the paper with a view to ascertain whether any of the effects were probably referable to magneto-electric induction2 but1 though unable to form a very strong opinion1 believe they are not4 ,when parallel veins running east and west were compared1 the general tendency of the electricity in the wires was from north to south2 when the comparison was made between parts towards the surface and at some depth1 the current of electricity in the wires was from above downwards4 ,if there should be any natural difference in the force of the electric currents produced by magneto-electric induction in different substances1 or substances in different positions moving with the earth1 and which might be rendered evident by increasing the masses acted upon1 then the wires and veins experimented with by ,mr4 ,fox might perhaps have acted as dischargers to the electricity of the mass of strata included between them1 and the directions of the currents would agree with those observed as above4 ,a #ahcj4 p4 #cii4 #ahh4 ,although the electricity obtained by magneto-electric induction in a few feet of wire is of but small intensity1 and has not yet been observed except in metals1 and carbon in a particular state1 still it has power to pass through brine 7#bc472 and1 as increased length in the substance acted upon produces increase of intensity1 ,i hoped to obtain effects from extensive moving masses of water1 though quiescent water gave none4 ,i made experiments therefore 7by favour7 at ,waterloo ,bridge1 extending a copper wire nine hundred and sixty feet in length upon the parapet of the bridge1 and dropping from its extremities other wires with extensive plates of metal attached to them to complete contact with the water4 ,thus the wire and the water made one conducting circuit2 and as the water ebbed or flowed with the tide1 ,i hoped to obtain currents analogous to those of the brass ball 7#afa474 #ahi4 ,i constantly obtained deflections at the galvanometer1 but they were very irregular1 and were1 in succession1 referred to other causes than that sought for4 ,the different condition of the water as to purity on the two sides of the river2 the difference in temperature2 slight differences in the plates1 in the solder used1 in the more or less perfect contact made by twisting or otherwise2 all produced effects in turn3 and though ,i experimented on the water passing through the middle arches only2 used platina plates instead of copper2 and took every other precaution1 ,i could not after three days obtain any satisfactory results4 #aij4 ,theoretically1 it seems a necessary consequence1 that where water is flowing1 there electric currents should be formed2 thus1 if a line be imagined passing from ,dover to ,calais through the sea1 and returning through the land beneath the water to ,dover1 it traces out a circuit of conducting matter1 one part of which1 when the water moves up or down the channel1 is cutting the magnetic curves of the earth1 whilst the other is relatively at rest4 ,this is a repetition of the wire experiment 7#aga471 but with worse conductors4 ,still there is every reason to believe that electric currents do run in the general direction of the circuit described1 either one way or the other1 according as the passage of the waters is up or down the channel4 ,where the lateral extent of the moving water is enormously increased1 it does not seem improbable that the effect should become sensible2 and the gulf stream may thus1 perhaps1 from electric currents moving across it1 by magneto-electric induction from the earth1 exert a sensible influence upon the forms of the lines of magnetic variation,a4 ,a ,theoretically1 even a ship or a boat when passing on the surface of the water1 in northern or southern latitudes1 should have currents of electricity running through it directly across the line of her motion2 or if the water is flowing past the ship at anchor1 similar currents should occur4 #aia4 ,though positive results have not yet been obtained by the action of the earth upon water and aqueous fluids1 yet1 as the experiments are very limited in their extent1 and as such fluids do yield the current by artificial magnets 7#bc471 7for transference of the current is proof that it may be produced 7#bac4717 the supposition made1 that the earth produces these induced currents within itself 7#aha47 in consequence of its diurnal rotation1 is still highly probable 7#bbb1 #bbc472 and when it is considered that the moving masses extend for thousands of miles across the magnetic curves1 cutting them in various directions within its mass1 as well as at the surface1 it is possible the electricity may rise to considerable intensity4 #aib4 ,i hardly dare venture1 even in the most hypothetical form1 to ask whether the ,aurora ,borealis and ,australia may not be the discharge of electricity1 thus urged towards the poles of the earth1 from whence it is endeavouring to return by natural and appointed means above the earth to the equatorial regions4 ,the non-occurrence of it in very high latitudes is not at all against the supposition2 and it is remarkable that ,mr4 ,fox1 who observed the deflections of the magnetic needle at ,falmouth1 by the ,aurora ,borealis1 gives that direction of it which perfectly agrees with the present view4 ,he states that all the variations at night were towards the east,a1 and this is what would happen if electric currents were setting from south to north in the earth under the needle1 or from north to south in space above it4 ,a ,philosophical ,transactions1 #ahca1 p4 #bjb4 #f4 ,general remarks and illustrations of the ,force and ,direction of ,magneto-electric ,induction4 #aic4 ,in the repetition and variation of ,arago's experiment by ,messrs4 ,babbage1 ,herschel1 and ,harris1 these philosophers directed their attention to the differences of force observed amongst the metals and other substances in their action on the magnet4 ,these differences were very great,a1 and led me to hope that by mechanical combinations of various metals important results might be obtained 7#ahc474 ,the following experiments were therefore made1 with a view to obtain1 if possible1 any such difference of the action of two metals1 ,b ,philosophical ,transactions1 #ahbe1 p4 #dgb2 #ahca1 p4#gh4 #aid4 ,a piece of soft iron bonnet-wire covered with cotton was laid bare and cleaned at one extremity1 and there fastened by metallic contact with the clean end of a copper wire4 ,both wires were then twisted together like the strands of a rope1 for eighteen or twenty inches2 and the remaining parts being made to diverge1 their extremities were connected with the wires of the galvanometer4 ,the iron wire was about two feet long1 the continuation to the galvanometer being copper4 #aie4 ,the twisted copper and iron 7touching each other nowhere but at the extremity7 were then passed between the poles of a powerful magnet arranged horse-shoe fashion 7fig4 #cb472 but not the slightest effect was observed at the galvanometer1 although the arrangement seemed fitted to show any electrical difference between the two metals relative to the action of the magnet1 #aif4 ,a soft iron cylinder was then covered with paper at the middle part1 and the twisted portion of the above compound wire coiled as a spiral around it1 the connexion with the galvanometer still being made at the ends ,a and ,b4 ,the iron cylinder was then brought in contact with the poles of a powerful magnet capable of raising thirty pounds2 yet no signs of electricity appeared at the galvanometer4 ,every precaution was applied in making and breaking contact to accumulate effect1 but no indications of a current could be obtained4 #aig4 ,copper and tin1 copper and zinc1 tin and zinc1 tin and iron1 and zinc and iron1 were tried against each other in a similar manner 7#aid71 but not the slightest sign of electric currents could be procured4 #aih4 ,two flat spirals1 one of copper and the other of iron1 containing each eighteen inches of wire1 were connected with each other and with the galvanometer1 and then put face to face so as to be in contrary directions4 ,when brought up to the magnetic pole 7#ec474 ,no electrical indications at the galvanometer were observed4 ,when one was turned round so that both were in the same direction1 the effect at the galvanometer was very powerful4 #aii4 ,the compound helix of copper and iron wire formerly described 7#h47 was arranged as a double helix1 one of the helices being all iron and containing two hundred and fourteen feet1 the other all copper and continuing two hundred and eight feet4 ,the two similar ends ,,aa of the copper and iron helix were connected together1 and the other ends ,,bb of each helix connected with the galvanometer2 so that when a magnet was introduced into the centre of the arrangement1 the induced currents in the iron and copper would tend to proceed in contrary directions4 ,yet when a magnet was inserted1 or a soft iron bar within made a magnet by contact with poles1 no effect at the needle was produced4 #bjj4 ,a glass tube about fourteen inches long was filled with strong sulphuric acid4 ,twelve inches of the end of a clean copper wire were bent up into a bundle and inserted into the tube1 so as to make good superficial contact with the acid1 and the rest of the wire passed along the outside of the tube and away to the galvanometer4 ,a wire similarly bent up at the extremity was immersed in the other end of the sulphuric acid1 and also connected with the galvanometer1 so that the acid and copper wire were in the same parallel relation to each other in this experiment as iron and copper were in the first 7#aid74 ,when this arrangement was passed in a similar manner between the poles of the magnet1 not the slightest effect at the galvanometer could be perceived4 #bja4 ,from these experiments it would appear1 that when metals of different kinds connected in one circuit are equally subject in every circumstance to magneto-electric induction1 they exhibit exactly equal powers with respect to the currents which either are formed1 or tend to form1 in them4 ,the same even appears to be the case with regard to fluids1 and probably all other substances4 #bjb4 ,still it seemed impossible that these results could indicate the relative inductive power of the magnet upon the different metals2 for that the effect should be in some relation to the conducting power seemed a necessary consequence 7#aci471 and the influence of rotating plates upon magnets had been found to bear a general relation to the conducting power of the substance used4 #bjc4 ,in the experiments of rotation 7#ha471 the electric current is excited and discharged in the same substance1 be it a good or bad conductor2 but in the experiments just described the current excited in iron could not be transmitted but through the copper1 and that excited in copper had to pass through iron3 i4e4 supposing currents of dissimilar strength to be formed in the metals proportionate to their conducting power1 the stronger current had to pass through the worst conductor1 and the weaker current through the best4 #bjd4 ,experiments were therefore made in which different metals insulated from each other were passed between the poles of the magnet1 their opposite ends being connected with the same end of the galvanometer wire1 so that the currents formed and led away to the galvanometer should oppose each other2 and when considerable lengths of different wires were used1 feeble deflections were obtained4 #bje4 ,to obtain perfectly satisfactory results a new galvanometer was constructed1 consisting of two independent coils1 each containing eighteen feet of silked copper wire4 ,these coils were exactly alike in shape and number of turns1 and were fixed side by side with a small interval between them1 in which a double needle could be hung by a fibre of silk exactly as in the former instrument 7#hg474 ,the coils may be distinguished by the letters ,,kl1 and when electrical currents were sent through them in the same direction1 acted upon the needle with the sum of their powers2 when in opposite directions1 with the difference of their powers4 #bjf4 ,the compound helix 7#aii4 #h47 was now connected1 the ends ,a and ,b of the iron with ,a and ,b ends of galvanometer coil ,k1 and the ends ,a and ,b of the copper with ,b and ,a ends of galvanometer coil ,l1 so that the currents excited in the two helices should pass in opposite directions through the coils ,k and ,l4 ,on introducing a small cylinder magnet within the helices1 the galvanometer needle was powerfully deflected4 ,on disuniting the iron helix1 the magnet caused with the copper helix alone still stronger deflection in the same direction4 ,on reuniting the iron helix1 and unconnecting the copper helix1 the magnet caused a moderate deflection in the contrary direction4 ,thus it was evident that the electric current induced by a magnet in a copper wire was far more powerful than the current induced by the same magnet in an equal iron wire4 #bjg4 ,to prevent any error that might arise from the greater influence1 from vicinity or other circumstances1 of one coil on the needle beyond that of the other1 the iron and copper terminations were changed relative to the galvanometer coils ,,kl1 so that the one which before carried the current from the copper now conveyed that from the iron1 and vice versa4 ,but the same striking superiority of the copper was manifested as before4 ,this precaution was taken in the rest of the experiments with other metals to be described4 #bjh4 ,i then had wires of iron1 zinc1 copper1 tin1 and lead1 drawn to the same diameter 7very nearly one twentieth of an inch71 and ,i compared exactly equal lengths1 namely sixteen feet1 of each in pairs in the following manner3 ,the ends of the copper wire were connected with the ends ,a and ,b of galvanometer coil ,k1 and the ends of the zinc wire with the terminations ,a and ,b of the galvanometer coil ,l4 ,the middle part of each wire was then coiled six times round a cylinder of soft iron covered with paper1 long enough to connect the poles of ,daniell's horse-shoe magnet 7#ef47 7fig4 #cc471 so that similar helices of copper and zinc1 each of six turns1 surrounded the bar at two places equidistant from each other and from the poles of the magnet2 but these helices were purposely arranged so as to be in contrary directions1 and therefore send contrary currents through the galvanometer coils ,k and ,l1 #bji4 ,on making and breaking contact between the soft iron bar and the poles of the magnet1 the galvanometer was strongly affected2 on detaching the zinc it was still more strongly affected in the same direction4 ,on taking all the precautions before alluded to 7#bjg471 with others1 it was abundantly proved that the current induced by the magnet in copper was far more powerful than in zinc4 #baj4 ,the copper was then compared in a similar manner with tin1 lead1 and iron1 and surpassed them all1 even more than it did zinc4 ,the zinc was then compared experimentally with the tin1 lead1 and iron1 and found to produce a more powerful current than any of them4 ,iron in the same manner proved superior to tin and lead4 ,tin came next1 and lead the last4 #baa4 ,thus the order of these metals is copper1 zinc1 iron1 tin1 and lead4 ,it is exactly their order with respect to conducting power for electricity1 and1 with the exception of iron1 is the order presented by the magneto-rotation experiments of ,messrs4 ,babbage1 ,herschel1 ,harris1 c4 ,the iron has additional power in the latter kind of experiments1 because of its ordinary magnetic relations1 and its place relative to magneto-electric action of the kind now under investigation cannot be ascertained by such trials4 ,in the manner above described it may be correctly ascertained,a4 ,a ,mr4 ,christie1 who being appointed reporter upon this paper1 had it in his hands before it was complete1 felt the difficulty 7#bjb472 and to satisfy his mind1 made experiments upon iron and copper with the large magnet7#dd471 and came to the same conclusions as ,i have arrived at4 ,the two sets of experiments were perfectly independent of each other1 neither of us being aware of the other's proceedings4 #bab4 ,it must still be observed that in these experiments the whole effect between different metals is not obtained2 for of the thirty-four feet of wire included in each circuit1 eighteen feet are copper in both1 being the wire of the galvanometer coils2 and as the whole circuit is concerned in the resulting force of the current1 tin's circumstance must tend to diminish the difference which would appear between the metals if the circuits were of the same substances throughout4 ,in the present case the difference obtained is probably not more than a half of that which would be given if the whole of each circuit were of one metal4 #bac4 ,these results tend to prove that the currents produced by magneto-electric induction in bodies is proportional to their conducting power4 ,that they are exactly proportional to and altogether dependent upon the conducting power1 is1 ,i think1 proved by the perfect neutrality displayed when two metals or other substances1 as acid1 water1 c4 c4 7#bja4 #ahf471 are opposed to each other in their action4 ,the feeble current which tends to be produced in the worse conductor1 has its transmission favoured in the better conductor1 and the stronger current which tends to form in the latter has its intensity diminished by the obstruction of the former2 and the forces of generation and obstruction are so perfectly neutralize each other exactly4 ,now as the obstruction is inversely as the balanced as to conducting power1 the tendency to generate a current must be directly as that power to produce this perfect equilibrium4 #bad4 ,the cause of the equality of action under the various circumstances described1 where great extent of wire 7#ahc47 or wire and water 7#aha47 were connected together1 which yet produced such different effects upon the magnet1 is now evident and simple4 #bae4 ,the effects of a rotating substance upon a needle or magnet ought1 where ordinary magnetism has no influence1 to be directly as the conducting power of the substance2 and ,i venture now to predict that such will be found to be the case2 and that in all those instances where non-conductors have been supposed to exhibit this peculiar influence1 the motion has been due to some interfering cause of an ordinary kind2 as mechanical communication of motion through the parts of the apparatus1 or otherwise 7as in the case ,mr4 ,harris has pointed out,a72 or else to ordinary magnetic attractions4 ,to distinguish the effects of the latter from those of the induced electric currents1 ,i have been able to devise a most perfect test1 which shall be almost immediately described 7#bdc474 ,a ,philosophical ,transactions1 #ahca4 p4 #fh4 #baf4 ,there is every reason to believe that the magnet or magnetic needle will become an excellent measurer of the conducting power of substances rotated near it2 for ,i have found by careful experiment1 that when a constant current of electricity was sent successively through a series of wires of copper1 platina1 zinc1 silver1 lead1 and tin1 drawn to the same diameter2 the deflection of the needle was exactly equal by them all4 ,it must be remembered that when bodies are rotated in a horizontal plane1 the magnetism of the earth is active upon them4 ,as the effect is general to the whole of the plate1 it may not interfere in these cases2 but in some experiments and calculations may be of important consequence4 #bag4 ,another point which ,i endeavoured to ascertain1 was1 whether it was essential or not that the moving part of the wire should1 in cutting the magnetic curves1 pass into positions of greater or lesser magnetic force2 or whether1 always intersecting curves of equal magnetic intensity1 the mere motion was sufficient for the production of the current4 ,that the latter is true1 has been proved already in several of the experiments on terrestrial magneto-electric induction4 ,thus the electricity evolved from the copper plate 7#adi471 the currents produced in the rotating globe 7#afa1 c471 and those passing through the moving wire 7#aga471 are all produced under circumstances in which the magnetic force could not but be the same during the whole experiments4 #bah4 ,to prove the point with an ordinary magnet1 a copper disc was cemented upon the end of a cylinder magnet1 with paper intervening2 the magnet and disc were rotated together1 and collectors 7attached to the galvanometer7 brought in contact with the circumference and the central part of the copper plate4 ,the galvanometer needle moved as in former cases1 and the direction of motion was the same as that which would have resulted1 if the copper only had revolved1 and the magnet been fixed4 ,neither was there any apparent difference in the quantity of deflection4 ,hence1 rotating the magnet causes no difference in the results2 for a rotatory and a stationary magnet produce the same effect upon the moving copper4 #bai4 ,a copper cylinder1 closed at one extremity1 was then put over the magnet1 one half of which it inclosed like a cap2 it was firmly fixed1 and prevented from touching the magnet anywhere by interposed paper4 ,the arrangement was then floated in a narrow jar of mercury1 so that the lower edge of the copper cylinder touched the fluid metal2 one wire of the galvanometer dipped into this mercury1 and the other into a little cavity in the centre of the end of the copper cap4 ,upon rotating the magnet and its attached cylinder1 abundance of electricity passed through the galvanometer1 and in the same direction as if the cylinder had rotated only1 the magnet being still4 ,the results therefore were the same as those with the disc 7#bah474 #bbj4 ,that the metal of the magnet itself might be substituted for the moving cylinder1 disc1 or wire1 seemed an inevitable consequence1 and yet one which would exhibit the effects of magneto-electric induction in a striking form4 ,a cylinder magnet had therefore a little hole made in the centre of each end to receive a drop of mercury1 and was then floated pole upwards in the same metal contained in a narrow jar4 ,one wire from the galvanometer dipped into the mercury of the jar1 and the other into the drop contained in the hole at the upper extremity of the axis4 ,the magnet was then revolved by a piece of string passed round it1 and the galvanometer-needle immediately indicated a powerful current of electricity4 ,on reversing the order of rotation1 the electrical current was reversed4 ,the direction of the electricity was the same as if the copper cylinder 7#bai47 or a copper wire had revolved round the fixed magnet in the same direction as that which the magnet itself had followed4 ,thus a singular independence of the magnetism and the bar in which it resides is rendered evident4 #bba4 ,in the above experiment the mercury reached about halfway up the magnet2 but when its quantity was increased until within one eighth of an inch of the top1 or diminished until equally near the bottom1 still the same effects and the same direction of electrical current was obtained4 ,but in those extreme proportions the effects did not appear so strong as when the surface of the mercury was about the middle1 or between that and an inch from each end4 ,the magnet was eight inches and a half long1 and three quarters of an inch in diameter4 #bbb4 ,upon inversion of the magnet1 and causing rotation in the same direction1 i4e4 always screw or always unscrew1 then a contrary current of electricity was produced4 ,but when the motion of the magnet was continued in a direction constant in relation to its own axis1 then electricity of the same kind was collected at both poles1 and the opposite electricity at the equator1 or in its neighbourhood1 or in the parts corresponding to it4 ,if the magnet be held parallel to the axis of the earth1 with its unmarked pole directed to the pole star1 and then rotated so that the parts at its southern side pass from west to east in conformity to the motion of the earth2 then positive electricity may be collected at the extremities of the magnet1 and negative electricity at or about the middle of its mass4 #bbc4 ,when the galvanometer was very sensible1 the mere spinning of the magnet in the air1 whilst one of the galvanometer wires touched the extremity1 and the other the equatorial parts1 was sufficient to evolve a current of electricity and deflect the needle4 #bbd4 ,experiments were then made with a similar magnet1 for the purpose of ascertaining whether any return of the electric current could occur at the central or axial parts1 they having the same angular velocity of rotation as the other parts 7#bei47 the belief being that it could not4 #bbe4 ,a cylinder magnet1 seven inches in length1 and three quarters of an inch in diameter1 had a hole pierced in the direction of its axis from one extremity1 a quarter of an inch in diameter1 and three inches deep4 ,a copper cylinder1 surrounded by paper and amalgamated at both extremities1 was introduced so as to be in metallic contact at the bottom of the hole1 by a little mercury1 with the middle of the magnet2 insulated at the sides by the paper2 and projecting about a quarter of an inch above the end of the steel4 ,a quill was put over the copper rod1 which reached to the paper1 and formed a cup to receive mercury for the completion of the circuit4 ,a high paper edge was also raised round that end of the magnet and mercury put within it1 which however had no metallic connexion with that in the quill1 except through the magnet itself and the copper rod 7fig4 #cd474 ,the wires ,a and ,b from the galvanometer were dipped into these two portions of mercury2 any current through them could1 therefore1 only pass down the magnet towards its equatorial parts1 and then up the copper rod2 or vice versa4 #bbf4 ,when thus arranged and rotated screw fashion1 the marked end of the galvanometer needle went west1 indicating that there was a current through the instrument from ,a to ,b and consequently from ,b through the magnet and copper rod to ,a 7fig4 #cd474 #bbg4 ,the magnet was then put into a jar of mercury 7fig4 #ce47 as before 7#bai472 the wire ,a left in contact with the copper axis1 but the wire ,b dipped in the mercury of the jar1 and therefore in metallic communication with the equatorial parts of the magnet instead of its polar extremity4 ,on revolving the magnet screw fashion1 the galvanometer needle was deflected in the same direction as before1 but far more powerfully4 ,yet it is evident that the parts of the magnet from the equator to the pole were out of the electric circuit4 #bbh4 ,then the wire ,a was connected with the mercury on the extremity of the magnet1 the wire ,b still remaining in contact with that in the jar 7fig4 #cf471 so that the copper axis was altogether out of the circuit4 ,the magnet was again revolved screw fashion1 and again caused the same deflection of the needle1 the current being as strong as it was in the last trial 7#bbg471 and much stronger than at first 7#bbf474 #bbi4 ,hence it is evident that there is no discharge of the current at the centre of the magnet1 for the current1 now freely evolved1 is up through the magnet2 but in the first experiment 7#bbf47 it was down4 ,in fact1 at that time1 it was only the part of the moving metal equal to a little disc extending from the end of the wire ,b in the mercury to the wire ,a that was efficient1 i4e4 moving with a different angular velocity to the rest of the circuit 7#beh472 and for that portion the direction of the current is consistent with the other results4 #bcj4 ,in the two after experiments1 the lateral parts of the magnet or of the copper rod are those which move relative to the other parts of the circuit1 i4e4 the galvanometer wires2 and being more extensive1 intersecting more curves1 or moving with more velocity1 produce the greater effect4 ,for the discal part1 the direction of the induced electric current is the same in all1 namely1 from the circumference towards the centre4 99 99 99 99 99 #bca4 ,the law under which the induced electric current excited in bodies moving relatively to magnets1 is made dependent on the intersection of the magnetic curves by the metal 7#aad47 being thus rendered more precise and definite 7#bag4 #bbj4 #bbd471 seem now even to apply to the cause in the first section of the former paper 7#bf472 and by rendering a perfect reason for the effects produced1 take away any for supposing that peculiar condition1 which ,i ventured to call the electro-tonic state 7#fj474 #bcb4 ,when an electrical current is passed through a wire1 that wire is surrounded at every part by magnetic curves1 diminishing in intensity according to their distance from the wire1 and which in idea may be likened to rings situated in planes perpendicular to the wire or rather to the electric current within it4 ,these curves1 although different in form1 are perfectly analogous to those existing between two contrary magnetic poles opposed to each other2 and when a second wire1 parallel to that which carries the current1 is made to approach the latter 7#ah471 it passes through magnetic curves exactly of the same kind as those it would intersect when carried between opposite magnetic poles 7#aji47 in one direction2 and as it recedes from the inducing wire1 it cuts the curves around it in the same manner that it would do those between the same poles if moved in the other direction4 #bcc4 ,if the wire ,,np 7fig4 #dj47 have an electric current passed through it in the direction from ,p to ,n1 then the dotted ring may represent a magnetic curve round it1 and it is in such a direction that if small magnetic needles lie placed as tangents to it1 they will become arranged as in the figure1 n and s indicating north and south ends 7#ad4 note474 #bcd4 ,but if the current of electricity were made to cease for a while1 and magnetic poles were used instead to give direction to the needles1 and make them take the same position as when under the influence of the current1 then they must be arranged as at fig4 #da2 the marked and unmarked poles ab above the wire1 being in opposite directions to those a'b' below4 ,in such a position therefore the magnetic curves between the poles ab and a'b' have the same general direction with the corresponding parts of the ring magnetic curve surrounding the wire ,,np carrying an electric current4 #bce4 ,if the second wire pn 7fig4 #dj47 be now brought towards the principal wire1 carrying a current1 it will cut an infinity of magnetic curves1 similar in direction to that figured1 and consequently similar in direction to those between the poles ab of the magnets 7fig4 #da471 and it will intersect these current curves in the same manner as it would the magnet curves1 if it passed from above between the poles downwards4 ,now1 such an intersection would1 with the magnets1 induce an electric current in the wire from p to n 7#aad472 and therefore as the curves are alike in arrangement1 the same effect ought to result from the intersection of the magnetic curves dependent on the current in the wire ,,np2 and such is the case1 for on approximation the induced current is in the opposite direction to the principal current 7#ai474 #bcf4 ,if the wire p'n' be carried up from below1 it will pass in the opposite direction between the magnetic poles2 but then also the magnetic poles themselves are reversed 7fig4 #da471 and the induced current is therefore 7#aad47 still in the same direction as before4 ,it is also1 for equally sufficient and evident reasons1 in the same direction1 if produced by the influence of the curves dependent upon the wire4 #bcg4 ,when the second wire is retained at rest in the vicinity the principal wire1 no current is induced through it1 for it is intersecting no magnetic curves4 ,when it is removed from the principal wire1 it intersects the curves in the opposite direction to what it did before 7#bce472 and a current in the opposite direction is induced1 which therefore corresponds with the direction of the principal current 7#ai474 ,the same effect would take place if by inverting the direction of motion of the wire in passing between either set of poles 7fig4 #da471 it were made to intersect the curves there existing in the opposite direction to what it did before4 #bch4 ,in the first experiments 7#aj4 #ac471 the inducing wire and that under induction were arranged at a fixed distance from each other1 and then an electric current sent through the former4 ,in such cases the magnetic curves themselves must be considered as moving 7if ,i may use the expression7 across the wire under induction1 from the moment at which they begin to be developed until the magnetic force of the current is at its utmost2 expanding as it were from the wire outwards1 and consequently being in the same relation to the fixed wire under induction as if it had moved in the opposite direction across them1 or towards the wire carrying the current4 ,hence the first current induced in such cases was in the contrary direction to the principal current 7#ag4 #bce474 ,on breaking the battery contact1 the magnetic curves 7which are mere expressions for arranged magnetic forces7 may be conceived as contracting upon and returning towards the failing electrical current1 and therefore move in the opposite direction across the wire1 and cause an opposite induced current to the first4 #bci4 ,when1 in experiments with ordinary magnets1 the latter1 in place of being moved past the wires1 were actually made near them 7#bg4 #cf471 then a similar progressive development of the magnetic curves may be considered as having taken place1 producing the effects which would have occurred by motion of the wires in one direction2 the destruction of the magnetic power corresponds to the motion of the wire in the opposite direction4 #bdj4 ,if1 instead of intersecting the magnetic curves of a straight wire carrying a current1 by approximating or removing a second wire 7#bce471 a revolving plate be used1 being placed for that purpose near the wire1 and1 as it were1 amongst the magnetic curves1 then it ought to have continuous electric currents induced within it2 and if a line joining the wire with the centre of the plate were perpendicular to both1 then the induced current ought to be1 according to the law 7#aad471 directly across the plate1 from one side to the other1 and at right angles to the direction of the inducing current4 #bda4 ,a single metallic wire one twentieth of an inch in diameter had an electric current passed through it1 and a small copper disc one inch and a half in diameter revolved near to and under1 but not in actual contact with it 7fig4 #ci74 ,collectors were then applied at the opposite edges of the disc1 and wires from them connected with the galvanometer4 ,as the disc revolved in one direction1 the needle was deflected on one side3 and when the direction of revolution was reversed1 the needle was inclined on the other side1 in accordance with the results anticipated4 #bdb4 ,thus the reasons which induce me to suppose a particular state in the wire 7#fj47 have disappeared2 and though it still seems to me unlikely that a wire at rest in the neighbourhood of another carrying a powerful electric current is entirely indifferent to it1 yet ,i am not aware of any distinct facts which authorize the conclusion that it is in a particular state4 99 99 99 99 99 #bdc4 ,in considering the nature of the cause assigned in these papers to account for the mutual influence of magnets and moving metals 7#abj471 and comparing it with that heretofore admitted1 namely1 the induction of a feeble magnetism like that produced in iron1 it occurred to me that a most decisive experimental test of the two views could be applied 7#bae474 #bdd4 ,no other known power has like direction with that exerted between an electric current and a magnetic pole2 it is tangential1 while all other forces1 acting at a distance1 are direct4 ,hence1 if a magnetic pole on one side of a revolving plate follow its course by reason of its obedience to the tangential force exerted upon it by the very current of electricity which it has itself caused1 a similar pole on the opposite side of the plate should immediately set it free from this force2 for the currents which tend to be formed by the action of the two poles are in opposite directions2 or rather no current tends to be formed1 or no magnetic curves are intersected 7#aad472 and therefore the magnet should remain at rest4 ,on the contrary1 if the action of a north magnetic pole were to produce a southness in the nearest part of the copper plate1 and a diffuse northness elsewhere 7#hb471 as is really the case with iron2 then the use of another north pole on the opposite side of the same part of the plate should double the effect instead of destroying it1 and double the tendency of the first magnet to move with the plate4 #bde4 ,a thick copper plate 7#he47 was therefore fixed on a vertical axis1 a bar magnet was suspended by a plaited silk cord1 so that its marked pole hung over the edge of the plate1 and a sheet of paper being interposed1 the plate was revolved2 immediately the magnetic pole obeyed its motion and passed off in the same direction4 ,a second magnet of equal size and strength was then attached to the first1 so that its marked pole should hang beneath the edge of the copper plate in a corresponding position to that above1 and at an equal distance 7fig4 #cg474 ,then a paper sheath or screen being interposed as before1 and the plate revolved1 the poles were found entirely indifferent to its motion1 although either of them alone would have followed the course of rotation4 #bdf4 ,on turning one magnet round1 so that opposite poles were on each side of the plate1 then the mutual action of the poles and the moving metal was a maximum4 #bdg4 ,on suspending one magnet so that its axis was level with the plate1 and either pole opposite its edge1 the revolution of the plate caused no motion of the magnet4 ,the electrical currents dependent upon induction would now tend to be produced in a vertical direction across the thickness of the plate1 but could not be so discharged1 or at least only to so slight a degree as to leave all effects insensible2 but ordinary magnetic induction1 or that on an iron plate1 would be equally if not more powerfully developed in such a position 7#bea474 #bdh4 ,then1 with regard to the production of electricity in these cases3--whenever motion was communicated by the plate to the magnets1 currents existed2 when it was not communicated1 they ceased4 ,a marked pole of a large bar magnet was put under the edge of the plate2 collectors 7#hf47 applied at the axis and edge of the plate as on former occasions 7fig4 #ch471 and these connected with the galvanometer2 when the plate was revolved1 abundance of electricity passed to the instrument4 ,the unmarked pole of a similar magnet was then put over the place of the former pole1 so that contrary poles were above and below2 on revolving the plate1 the electricity was more powerful than before4 ,the latter magnet was then turned end for end1 so that marked poles were both above and below the plate1 and then1 upon revolving it1 scarcely any electricity was procured4 ,by adjusting the distance of the poles so as to correspond with their relative force1 they at last were brought so perfectly to neutralize each other's inductive action upon the plate1 that no electricity could be obtained with the most rapid motion4 #bdi4 ,i now proceeded to compare the effect of similar and dissimilar poles upon iron and copper1 adopting for the purpose ,mr4 ,sturgeon's very useful form of ,arago's experiment4 ,this consists in a circular plate of metal supported in a vertical plane by a horizontal axis1 and weighted a little at one edge or rendered excentric so as to vibrate like a pendulum4 ,the poles of the magnets are applied near the side and edges of these plates1 and then the number of vibrations1 required to reduce the vibrating arc a certain constant quantity1 noted4 ,in the first description of this instrument,a it is said that opposite poles produced the greatest retarding effect1 and similar poles none2 and yet within a page of the place the effect is considered as of the same kind with that produced in iron4 ,a ,edin4 ,phil4 ,journal1 #ahbe1 p4 #abd4 #bej4 ,i had two such plates mounted1 one of copper1 one of iron4 ,the copper plate alone gave sixty vibrations1 in the average of several experiments1 before the arc of vibration was reduced from one constant mark to another4 ,on placing opposite magnetic poles near to1 and on each side of1 the same place1 the vibrations were reduced to fifteen4 ,on putting similar poles on each side of it1 they rose to fifty2 and on placing two pieces of wood of equal size with the poles equally near1 they became fifty-two4 ,so that1 when similar poles were used1 the magnetic effect was little or none1 7the obstruction being due to the confinement of the air1 rather17 whilst with opposite poles it was the greatest possible4 ,when a pole was presented to the edge of the plate1 no retardation occurred4 #bea4 ,the iron plate alone made thirty-two vibrations1 whilst the arc of vibration diminished a certain quantity4 ,on presenting a magnetic pole to the edge of the plate 7#bdg471 the vibrations were diminished to eleven2 and when the pole was about half an inch from the edge1 to five4 #beb4 ,when the marked pole was put at the side of the iron plate at a certain distance1 the number of vibrations was only five4 ,when the marked pole of the second bar was put on the opposite side of the plate at the same distance 7#bej471 the vibrations were reduced to two4 ,but when the second pole was an unmarked one1 yet occupying exactly the same position1 the vibrations rose to twenty-two4 ,by removing the stronger of these two opposite poles a little way from the plate1 the vibrations increased to thirty-one1 or nearly the original number4 ,but on removing it altogether1 they fell to between five and six4 #bec4 ,nothing can be more clear1 therefore1 than that with iron1 and bodies admitting of ordinary magnetic induction1 opposite poles on opposite sides of the edge of the plate neutralize each other's effect1 whilst similar poles exalt the action2 a single pole end on is also sufficient4 ,but with copper1 and substances not sensible to ordinary magnetic impressions1 similar poles on opposite sides of the plate neutralize each other2 opposite poles exalt the action2 and a single pole at the edge or end on does nothing4 #bed4 ,nothing can more completely show the thorough independence of the effects obtained with the metals by ,arago1 and those due to ordinary magnetic forces2 and henceforth1 therefore1 the application of two poles to various moving substances will1 if they appear at all magnetically affected1 afford a proof of the nature of that affection4 ,if opposite poles produce a greater effect than one pole1 the result will be due to electric currents4 ,if similar poles produce more effect than one1 then the power is not electrical2 it is not like that active in the metals and carbon when they are moving1 and in most cases will probably be found to be not even magnetical1 but the result of irregular causes not anticipated and consequently not guarded against4 #bee4 ,the result of these investigations tends to show that there are really but very few bodies that are magnetic in the manner of iron4 ,i have often sought for indications of this power in the common metals and other substances2 and once in illustration of ,arago's objection 7#hb471 and in hopes of ascertaining the existence of currents in metals by the momentary approach of a magnet1 suspended a disc of copper by a single fibre of silk in an excellent vacuum1 and approximated powerful magnets on the outside of the jar1 making them approach and recede in unison with a pendulum that vibrated as the disc would do3 but no motion could be obtained2 not merely1 no indication of ordinary magnetic powers1 but none or any electric current occasioned in the metal by the approximation and recession of the magnet4 ,i therefore venture to arrange substances in three classes as regards their relation to magnets2 first1 those which are affected when at rest1 like iron1 nickel1 c41 being such as possess ordinary magnetic properties2 then1 those which are affected when in motion1 being conductors of electricity in which are produced electric currents by the inductive force of the magnet2 and1 lastly1 those which are perfectly indifferent to the magnet1 whether at rest or in motion4 #bef4 ,although it will require further research1 and probably close investigation1 both experimental and mathematical1 before the exact mode of action between a magnet and metal moving relatively to each other is ascertained2 yet many of the results appear sufficiently clear and simple to allow of expression in a somewhat general manner4--,if a terminated wire move so as to cut a magnetic curve1 a power is called into action which tends to urge an electric current through it2 but this current cannot be brought into existence unless provision be made at the ends of the wire for its discharge and renewal4 #beg4 ,if a second wire move in the same direction as the first1 the same power is exerted upon it1 and it is therefore unable to alter the condition of the first3 for there appear to be no natural differences among substances when connected in a series1 by which1 when moving under the same circumstances relative to the magnet1 one tends to produce a more powerful electric current in the whole circuit than another 7#bja4 #bad474 #beh4 ,but if the second wire move with a different velocity1 or in some other direction1 then variations in the force exerted take place2 and if connected at their extremities1 an electric current passes through them4 #bei4 ,taking1 then1 a mass of metal or an endless wire1 and referring to the pole of the magnet as a centre of action1 7which though perhaps not strictly correct may be allowed for facility of expression1 at present17 if all parts move in the same direction1 and with the same angular velocity1 and through magnetic curves of constant intensity1 then no electric currents are produced4 ,this point is easily observed with masses subject to the earth's magnetism1 and may be proved with regard to small magnets2 by rotating them1 and leaving the metallic arrangements stationary1 no current is produced4 #bfj4 ,if one part of the wire or metal cut the magnetic curves1 whilst the other is stationary1 then currents are produced4 ,all the results obtained with the galvanometer are more or less of this nature1 the galvanometer extremity being the fixed part4 ,even those with the wire1 galvanometer1 and earth 7#agj471 may be considered so without any error in the result4 #bfa4 ,if the motion of the metal be in the same direction1 but the angular velocity of its parts relative to the pole of the magnet different1 then currents are produced4 ,this is the case in ,arago's experiment1 and also in the wire subject to the earth's induction 7#agb471 when it was moved from west to east4 #bfb4 ,if the magnet moves not directly to or from the arrangement1 but laterally1 then the case is similar to the last4 #bfc4 ,if different parts move in opposite directions across the magnetic curves1 then the effect is a maximum for equal velocities4 #bfd4 ,all these in fact are variations of one simple condition1 namely1 that all parts of the mass shall not move in the same direction across the curves1 and with the same angular velocity4 ,but they are forms of expression which1 being retained in the mind1 ,i have found useful when comparing the consistency of particular phenomena with general results4 ,royal ,institution1 ,december #ba1 #ahca4 ,,third ,,series4 #g4 ,identity of ,electricities derived from different sources4 #h4 ,relation by measure of common and voltaic ,electricity4 ,read ,january #ajth and #agth1 #ahcc4 #g4 ,identity of ,electricities derived from different sources4 #bfe4 ,the progress of the electrical researches which ,i have had the honour to present to the ,royal ,society1 brought me to a point at which it was essential for the further prosecution of my inquiries that no doubt should remain of the identity or distinction of electricities excited by different means4 ,it is perfectly true that ,cavendish,a1 ,wollaston,b1 ,colladon,c1 and others1 have in succession removed some of the greatest objections to the acknowledgement of the identity of common1 animal and voltaic electricity1 and ,i believe that most philosophers consider these electricities as really the same4 ,but on the other hand it is also true1 that the accuracy of ,wollaston's experiments has been denied,d2 and also that one of them1 which really is no proper proof of chemical decomposition by common electricity 7#cji4 #cbg471 has been that selected by several experimenters as the test of chemical action 7#ccf4 #cdf474 ,it is a fact1 too1 that many philosophers are still drawing distinctions between the electricities from different sources2 or at least doubting whether their identity is proved4 ,sir ,humphry ,davy1 for instance1 in his paper on the ,torpedo,e1 thought it probable that animal electricity would be found of a peculiar kind2 and referring to it1 to common electricity1 voltaic electricity and magnetism1 has said1 ,distinctions might be established in pursuing the various modifications or properties of electricity in those different forms1 c4 ,indeed ,i need only refer to the last volume of the ,philosophical ,transactions to show that the question is by no means considered as settled,f4 ,a ,phil4 ,trans4 #aggi1 p4 #aif4 ,b ,ibid4 #ahja1 p4 #dcd4 ,c ,annnles de ,chimie1 #ahbf1 p4 #fb1 c4 ,d ,phil4 ,trans4 #ahcb1 p4 #bhb1 note4 ,e ,phil4 ,trans4 #ahib1 p4 #ag4 ,common electricity is excited upon non-conductors1 and is readily carried off by conductors and imperfect conductors4 ,voltaic electricity is excited upon combinations of perfect and imperfect conductors1 and is only transmitted by perfect conductors or imperfect conductors of the best kind4 ,magnetism1 if it be a form of electricity1 belongs only to perfect conductors2 and1 in its modifications1 to a peculiar class of them#a4 ,animal electricity resides only in the imperfect conductors forming the organs of living animals1 c4 #a ,dr4 ,ritchie has shown this is not the case4 ,phil4 ,trans4 #ahcb1 p4 #bid4 ,f ,phil4 ,trans4 #ahcb1 p4 #bei4 ,dr4 ,davy1 in making experiments on the torpedo1 obtains effects the same as those produced by common and voltaic electricity1 and says that in its magnetic and chemical power it does not seem to be essentially peculiar1--p4 #bgd2 but he then says1 p4 #bge1 there are other points of difference2 and after referring to them1 adds1 ,how are these differences to be explained8 ,do they admit of explanation similar to that advanced by ,mr4 ,cavendish in his theory of the torpedo2 or may we suppose1 according to the analogy of the solar ray1 that the electrical power1 whether excited by the common machine1 or by the voltaic battery1 or by the torpedo1 is not a simple power1 but a combination of powers1 which may occur variously associated1 and produce all the varieties of electricity with which we are acquainted8 ,at p4 #bgi of the same volume of ,transactions is ,dr4 ,ritchie's paper1 from which the following are extracts3 ,common electricity is diffused over the surface of the metal2--voltaic electricity exists within the metal4 ,free electricity is conducted over the surface of the thinnest gold leaf as effectually as over a mass of metal having the same surface2--voltaic electricity requires thickness of metal for its conduction1 p4 #bhj3 and again1 ,the supposed analogy between common and voltaic electricity1 which was so eagerly traced after the invention of the pile1 completely fails in this case1 which was thought to afford the most striking resemblance4 p4 #bia4 #bff4 ,notwithstanding1 therefore1 the general impression of the identity of electricities1 it is evident that the proofs have not been sufficiently clear and distinct to obtain the assent of all those who were competent to consider the subject2 and the question seemed to me very much in the condition of that which ,sir ,h4 ,davy solved so beautifully1--namely1 whether voltaic electricity in all cases merely eliminated1 or did not in some actually produce1 the acid and alkali found after its action upon water4 ,the same necessity that urged him to decide the doubtful point1 which interfered with the extension of his views1 and destroyed the strictness of his reasoning1 has obliged me to ascertain the identity or difference of common and voltaic electricity4 ,i have satisfied myself that they are identical1 and ,i hope the experiments which ,i have to offer and the proofs flowing from them1 will be found worthy the attention of the ,royal ,society4 #bfg4 ,the various phenomena exhibited by electricity may1 for the purposes of comparison1 be arranged under two heads2 namely1 those connected with electricity of tension1 and those belonging to electricity in motion4 ,this distinction is taken at present not as philosophical1 but merely as convenient4 ,the effect of electricity of tension1 at rest1 is either attraction or repulsion at sensible distances4 ,the effects of electricity in motion or electrical currents may be considered as #ast1 ,evolution of heat2 #bnd1 ,magnetism2 #crd1 ,chemical decomposition2 #dth1 ,physiological phenomena2 #eth1 ,spark4 ,it will be my object to compare electricities from different sources1 and especially common and voltaic electricities1 by their power of producing these effects4 ,i4 ,voltaic ,electricity4 #bfh4 ,tension4--,when a voltaic battery of #ajj pairs of plates has its extremities examined by the ordinary electrometer1 it is well known that they are found positive and negative1 the gold leaves at the same extremity repelling each other1 the gold leaves at different extremities attracting each other1 even when half an inch or more of air intervenes4 #bfi4 ,that ordinary electricity is discharged by points with facility through air2 that it is readily transmitted through highly rarefied air2 and also through heated air1 as for instance a flame2 is due to its high tension4 ,i sought1 therefore1 for similar effects in the discharge of voltaic electricity1 using as a test of the passage of the electricity either the galvanometer or chemical action produced by the arrangement hereafter to be described 7#cab4 #caf474 #bgj4 ,the voltaic battery ,i had at my disposal consisted of #adj pairs of plates four inches square1 with double coppers4 ,it was insulated throughout1 and diverged a gold leaf electrometer about one third of an inch4 ,on endeavouring to discharge this battery by delicate points very nicely arranged and approximated1 either in the air or in an exhausted receiver1 ,i could obtain no indications of a current1 either by magnetic or chemical action4 ,in this1 however1 was found no point of discordance between voltaic and common electricity2 for when a ,leyden battery 7#bia47 was charged so as to deflect the gold leaf electrometer to the same degree1 the points were found equally unable to discharge it with such effect as to produce either magnetic or chemical action4 ,this was not because common electricity could not produce both these effects 7#cjg4 #caj472 but because when of such low intensity the quantity required to make the effects visible 7being enormously great 7#cga4 #cge4717 could not be transmitted in any reasonable time4 ,in conjunction with the other proofs of identity hereafter to be given1 these effects of points also prove identity instead of difference between voltaic and common electricity4 #bga4 ,as heated air discharges common electricity with far greater facility than points1 ,i hoped that voltaic electricity might in this way also be discharged4 ,an apparatus was therefore constructed 7,plate ,,iii4 fig4 #df471 in which ,,ab is an insulated glass rod upon which two copper wires1 ,c1 ,d1 are fixed firmly2 to these wires are soldered two pieces of fine platina wire1 the ends of which are brought very close to each other at e1 but without touching2 the copper wire ,c was connected with the positive pole of a voltaic battery1 and the wire ,d with a decomposing apparatus 7#cab4 #caf471 from which the communication was completed to the negative pole of the battery4 ,in these experiments only two troughs1 or twenty pairs of plates1 were used4 #bgb4 ,whilst in the state described1 no decomposition took place at the point a1 but when the side of a spirit-lamp flame was applied to the two platina extremities at e1 so as to make them bright red-hot1 decomposition occurred2 iodine soon appeared at the point a1 and the transference of electricity through the heated air was established4 ,on raising the temperature of the points e by a blowpipe1 the discharge was rendered still more free1 and decomposition took place instantly4 ,on removing the source of heat1 the current immediately ceased4 ,on putting the ends of the wires very close by the side of and parallel to each other1 but not touching1 the effects were perhaps more readily obtained than before4 ,on using a larger voltaic battery 7#bgj471 they were also more freely obtained4 #bgc4 ,on removing the decomposing apparatus and interposing a galvanometer instead1 heating the points e as the needle would swing one way1 and removing the heat during the time of its return 7#cjb471 feeble deflections were soon obtained3 thus also proving the current through heated air2 but the instrument used was not so sensible under the circumstances as chemical action4 #bgd4 ,these effects1 not hitherto known or expected under this form1 are only cases of the discharge which takes place through air between the charcoal terminations of the poles of a powerful battery1 when they are gradually separated after contact4 ,then the passage is through heated air exactly as with common electricity1 and ,sir ,h4 ,davy has recorded that with the original battery of the ,royal ,institution this discharge passed through a space of at least four inches,a4 ,in the exhausted receiver the electricity would strike through nearly half an inch of space1 and the combined effects of rarefaction and heat were such upon the inclosed air us to enable it to conduct the electricity through a space of six or seven inches4 ,a ,elements of ,chemical ,philosophy1 p4 #aec #bge4 ,the instantaneous charge of a ,leyden battery by the poles of a voltaic apparatus is another proof of the tension1 and also the quantity1 of electricity evolved by the latter4 ,sir ,h4 ,davy says,a1 ,when the two conductors from the ends of the combination were connected with a ,leyden battery1 one with the internal1 the other with the external coating1 the battery instantly became charged2 and on removing the wires and making the proper connexions1 either a shock or a spark could be perceived3 and the least possible time of contact was sufficient to renew the charge to its full intensity4 ,a ,elements of ,chemical ,philosophy1 p4 #aed4 #bgf4 ,in motion3 i4 ,evolution of ,heat4--,the evolution of heat in wires and fluids by the voltaic current is matter of general notoriety4 #bgg4 ii4 ,magnetism4--,no fact is better known to philosophers than the power of the voltaic current to deflect the magnetic needle1 and to make magnets according to certain laws2 and no effect can be more distinctive of an electrical current4 #bgh4 iii4 ,chemical decomposition4--,the chemical powers of the voltaic current1 and their subjection to certain laws1 are also perfectly well known4 #bgi4 iv4 ,physiological effects4--,the power of the voltaic current1 when strong1 to shock and convulse the whole animal system1 and when weak to affect the tongue and the eyes1 is very characteristic4 #bhj4 v4 ,spark4--,the brilliant star of light produced by the discharge of a voltaic battery is known to all as the most beautiful light that man can produce by art4 99 99 99 99 99 #bha4 ,that these effects may be almost infinitely varied1 some being exalted whilst others are diminished1 is universally acknowledged2 and yet without any doubt of the identity of character of the voltaic currents thus made to differ in their effect4 ,the beautiful explication of these variations afforded by ,cavendish's theory of quantity and intensity requires no support at present1 as it is not supposed to be doubted4 #bhb4 ,in consequence of the comparisons that will hereafter arise between wires carrying voltaic and ordinary electricities1 and also because of certain views of the condition of a wire or any other conducting substance connecting the poles of a voltaic apparatus1 it will be necessary to give some definite expression of what is called the voltaic current1 in contradistinction to any supposed peculiar state of arrangement1 not progressive1 which the wire or the electricity within it may be supposed to assume4 ,if two voltaic troughs ,,pn1 ,p',n'1 fig4 #db1 be symmetrically arranged and insulated1 and the ends ,,np' connected by a wire1 over which a magnetic needle is suspended1 the wire will exert no effect over the needle2 but immediately that the ends ,,pn' are connected by another wire1 the needle will be deflected1 and will remain so as long as the circuit is complete4 ,now if the troughs merely act by causing a peculiar arrangement in the wire either of its particles or its electricity1 that arrangement constituting its electrical and magnetic state1 then the wire ,,np' should be in a similar state of arrangement before ,p and ,n' were connected1 to what it is afterwards1 and should have deflected the needle1 although less powerfully1 perhaps to one half the extent which would result when the communication is complete throughout4 ,but if the magnetic effects depend upon a current1 then it is evident why they could not be produced in any degree before the circuit was complete2 because prior to that no current could exist4 #bhc4 ,by current1 ,i mean anything progressive1 whether it be a fluid of electricity1 or two fluids moving in opposite directions1 or merely vibrations1 or1 speaking still more generally1 progressive forces4 ,by arrangement1 ,i understand a local adjustment of particles1 or fluids1 or forces1 not progressive4 ,many other reasons might be urged in support of the view of a current rather than an arrangement1 but ,i am anxious to avoid stating unnecessarily what will occur to others at the moment4 ,,ii4 ,ordinary ,electricity4 #bhd4 ,by ordinary electricity ,i understand that which can be obtained from the common machine1 or from the atmosphere1 or by pressure1 or cleavage of crystals1 or by a multitude of other operations2 its distinctive character being that of great intensity1 and the exertion of attractive and repulsive powers1 not merely at sensible but at considerable distances4 #bhe4 ,tension4 ,the attractions and repulsions at sensible distances1 caused by ordinary electricity1 are well known to be so powerful in certain cases1 as to surpass1 almost infinitely1 the similar phenomena produced by electricity1 otherwise excited4 ,but still those attractions and repulsions are exactly of the same nature as those already referred to under the head ,tension1 ,voltaic electricity 7#bfh472 and the difference in degree between them is not greater than often occurs between cases of ordinary electricity only4 ,i think it will be unnecessary to enter minutely into the proofs of the identity of this character in the two instances4 ,they are abundant2 are generally admitted as good2 and lie upon the surface of the subject3 and whenever in other parts of the comparison ,i am about to draw1 a similar case occurs1 ,i shall content myself with a mere announcement of the similarity1 enlarging only upon those parts where the great question of distinction or identity still exists4 #bhf4 ,the discharge of common electricity through heated air is a well-known fact4 ,the parallel case of voltaic electricity has already been described 7#bgb1 c474 #bhg4 ,in motion4 i4 ,evolution of heat4--,the heating power of common electricity1 when passed through wires or other substances1 is perfectly well known4 ,the accordance between it and voltaic electricity is in this respect complete4 ,mr4 ,harris has constructed and described,a a very beautiful and sensible instrument on this principle1 in which the heat produced in a wire by the discharge of a small portion of common electricity is readily shown1 and to which ,i shall have occasion to refer for experimental proof in a future part of this paper 7#cdd474 ,a ,philosophical ,transactions1 #ahbg1 p4 #ah4 ,edinburgh ,transactions1 #ahca4 ,harris on a ,new ,electrometer1 c4 c4 #bhh4 ii4 ,magnetism4--,voltaic electricity has most extraordinary and exalted magnetic powers4 ,if common electricity be identical with it1 it ought to have the same powers4 ,in rendering needles or bars magnetic1 it is found to agree with voltaic electricity1 and the direction of the magnetism1 in both cases1 is the same2 but in deflecting the magnetic needle1 common electricity has been found deficient1 so that sometimes its power has been denied altogether1 and at other times distinctions have been hypothetically assumed for the purpose of avoiding the difficulty,a4 ,a ,demonferrand's ,manuel d',electricit dynamique1 p4 #aba4 #bhi4 ,m4 ,colladon1 of ,geneva1 considered that the difference might be due to the use of insufficient quantities of common electricity in all the experiments before made on this head2 and in a memoir read to the ,academie des ,sciences in #ahbf;,a1 describes experiments1 in which1 by the use of a battery1 points1 and a delicate galvanometer1 he succeeded in obtaining deflections1 and thus establishing identity in that respect4 ,,mm4 ,arago1 ,ampre1 and ,savary1 are mentioned in the paper as having witnessed a successful repetition of the experiments4 ,but as no other one has come forward in confirmation1 ,,mm4 ,arago1 ,ampre1 and ,savary1 not having themselves published 7that ,i am aware of7 their admission of the results1 and as some have not been able to obtain them1 ,m4 ,colladon's conclusions have been occasionally doubted or denied2 and an important point with me was to establish their accuracy1 or remove them entirely from the body of received experimental research4 ,i am happy to say that my results fully confirm those by ,m4 ,colladon1 and ,i should have had no occasion to describe them1 but that they are essential as proofs of the accuracy of the final and general conclusions ,i am enabled to draw respecting the magnetic and chemical action of electricity 7#cfj4 #cff4 #cfg4 #cgg4 c474 ,a ,annales de ,chimie1 xxxiii4 p4 #fb4 #bij4 ,the plate electrical machine ,i have used is fifty inches in diameter2 it has two sets of rubbers2 its prime conductor consists of two brass cylinders connected by a third1 the whole length being twelve feet1 and the surface in contact with air about #adbb square inches4 ,when in good excitation1 one revolution of the plate will give ten or twelve sparks from the conductors1 each an inch in length4 ,sparks or flashes from ten to fourteen inches in length may easily be drawn from the conductors4 ,each turn of the machine1 when worked moderately1 occupies about #d_/eths of a second4 #bia4 ,the electric battery consisted of fifteen equal jars4 ,they are coated eight inches upwards from the bottom1 and are twenty-three inches in circumference1 so that each contains one hundred and eighty-four square inches of glass1 coated on both sides2 this is independent of the bottoms1 which are of thicker glass1 and contain each about fifty square inches4 #bib4 ,a good discharging train was arranged by connecting metallically a sufficiently thick wire with the metallic gas pipes of the house1 with the metallic gas pipes belonging to the public gas works of ,london2 and also with the metallic water pipes of ,london4 ,it was so effectual in its office as to carry off instantaneously electricity of the feeblest tension1 even that of a single voltaic trough1 and was essential to many of the experiments4 #bic4 ,the galvanometer was one or the other of those formerly described 7#hg4 #bje471 but the glass jar covering it and supporting the needle was coated inside and outside with tinfoil1 and the upper part 7left uncoated1 that the motions of the needle might be examined17 was covered with a frame of wire-work1 having numerous sharp points projecting from it4 ,when this frame and the two coatings were connected with the discharging train 7#bib471 an insulated point or ball1 connected with the machine when most active1 might be brought within an inch of any part of the galvanometer1 yet without affecting the needle within by ordinary electrical attraction or repulsion4 #bid4 ,in connexion with these precautions1 it may be necessary to state that the needle of the galvanometer is very liable to have its magnetic power deranged1 diminished1 or even inverted by the passage of a shock through the instrument4 ,if the needle be at all oblique1 in the wrong direction1 to the coils of the galvanometer when the shock passes1 effects of this kind are sure to happen4 #bie4 ,it was to the retarding power of bad conductors1 with the intention of diminishing its intensity without altering its quantity1 that ,i first looked with the hope of being able to make common electricity assume more of the characters and power of voltaic electricity1 than it is usually supposed to have4 #bif1 ,the coating and armour of the galvanometer were first connected with the discharging train 7#bib472 the end ,b 7#hg47 of the galvanometer wire was connected with the outside coating of the battery1 and then both these with the discharging train2 the end ,a of the galvanometer wire was connected with a discharging rod by a wet thread four feet long2 and finally1 when the battery 7#bia47 had been positively charged by about forty turns of the machine1 it was discharged by the rod and the thread through the galvanometer4 ,the needle immediately moved4 #big4 ,during the time that the needle completed its vibration in the first direction and returned1 the machine was worked1 and the battery recharged2 and when the needle in vibrating resumed its first direction1 the discharge was again made through the galvanometer4 ,by repeating this action a few times1 the vibrations soon extended to above #dj on each side of the line of rest4 #bih4 ,this effect could be obtained at pleasure4 ,nor was it varied1 apparently1 either in direction or degree1 by using a short thick string1 or even four short thick strings in place of the long fine thread4 ,with a more delicate galvanometer1 an excellent swing of the needle could be obtained by one discharge of the battery4 #bii4 ,on reversing the galvanometer communications so as to pass the discharge through from ,b to ,a1 the needle was equally well deflected1 but in the opposite direction4 #cjj4 ,the deflections were in the same direction as if a voltaic current had been passed through the galvanometer1 i4e4 the positively charged surface of the electric battery coincided with the positive end of the voltaic apparatus 7#bfh47 and the negative surface of the former with the negative end of the latter4 #cja4 ,the battery was then thrown out of use1 and the communications so arranged that the current could be passed from the prime conductor1 by the discharging rod held against it1 through the wet string1 through the galvanometer coil1 and into the discharging train 7#bib71 by which it was finally dispersed4 ,this current could be stopped at any moment1 by removing the discharging rod1 and either stopping the machine or connecting the prime conductor by another rod with the discharging train2 and could be as instantly renewed4 ,the needle was so adjusted1 that whilst vibrating in moderate and small arcs1 it required time equal to twenty-five beats of a watch to pass in one direction through the arc1 and of course an equal time to pass in the other direction4 #cjb4 ,thus arranged1 and the needle being stationary1 the current1 direct from the machine1 was sent through the galvanometer for twenty-five beats1 then interrupted for other twenty-five beats1 renewed for twenty-five beats more1 again interrupted for an equal time1 and so on continually4 ,the needle soon began to vibrate visibly1 and after several alternations of this kind1 the vibration increased to #dj or more4 #cjc4 ,on changing the direction of the current through the galvanometer1 the direction of the deflection of the needle was also changed4 ,in all cases the motion of the needle was in direction the same as that caused either by the use of the electric battery or a voltaic trough 7#cjj74 #cjd4 ,i now rejected the wet string1 and substituted a copper wire1 so that the electricity of the machine passed at once into wires communicating directly with the discharging train1 the galvanometer coil being one of the wires used for the discharge4 ,the effects were exactly those obtained above 7#cjb74 #cje4 ,instead of passing the electricity through the system1 by bringing the discharging rod at the end of it into contact with the conductor1 four points were fixed on to the rod2 when the current was to pass1 they were held about twelve inches from the conductor1 and when it was not to pass1 they were turned away4 ,then operating as before 7#cjb471 except with this variation1 the needle was soon powerfully deflected1 and in perfect consistency with the former results4 ,points afforded the means by which ,colladon1 in all cases1 made his discharges4 #cjf4 ,finally1 ,i passed the electricity first through an exhausted receiver1 so as to make it there resemble the aurora borealis1 and then through the galvanometer to the earth2 and it was found still effective in deflecting the needle1 and apparently with the same force as before4 #cjg4 ,from all these experiments1 it appears that a current of common electricity1 whether transmitted through water or metal1 or rarefied air1 or by means of points in common air1 is still able to deflect the needle2 the only requisite being1 apparently1 to allow time for its action3 that it is1 in fact1 just as magnetic in every respect as a voltaic current1 and that in this character therefore no distinction exists4 #cjh4 ,imperfect conductors1 as water1 brine1 acids1 c4 c4 will be found far more convenient for exhibiting these effects than other modes of discharge1 as by points or balls2 for the former convert at once the charge of a powerful battery into a feeble spark discharge1 or rather continuous current1 and involve little or no risk of deranging the magnetism of the needles 7#bid474 #cji4 iii4 ,chemical decomposition4--,the chemical action of voltaic electricity is characteristic of that agent1 but not more characteristic than are the laws under which the bodies evolved by decomposition arrange themselves at the poles4 ,dr4 ,wollaston showed,a that common electricity resembled it in these effects1 and that they are both essentially the same2 but he mingled with his proofs an experiment having a resemblance1 and nothing more1 to a case of voltaic decomposition1 which however he himself partly distinguished2 and this has been more frequently referred to by some1 on the one hand1 to prove the occurrence of electro-chemical decomposition1 like that of the pile1 and by others to throw doubt upon the whole paper1 than the more numerous and decisive experiments which he has detailed4 ,a ,philosophical ,transactions1 #ahja1 pp4 #dbg1 #dcd4 #caj4 ,i take the liberty of describing briefly my results1 and of thus adding my testimony to that of ,dr4 ,wollaston on the identity of voltaic and common electricity as to chemical action1 not only that ,i may facilitate the repetition of the experiments1 but also lead to some new consequences respecting electrochemical decomposition 7#cgf4 #cgg474 #caa4 ,i first repeated ,wollaston's fourth experiment,a1 in which the ends of coated silver wires are immersed in a drop of sulphate of copper4 ,by passing the electricity of the machine through such an arrangement1 that end in the drop which received the electricity became coated with metallic copper4 ,one hundred turns of the machine produced an evident effect2 two hundred turns a very sensible one4 ,the decomposing action was however very feeble4 ,very little copper was precipitated1 and no sensible trace of silver from the other pole appeared in the solution4 ,a ,philosophical ,transactions1 #ahja1 p4 #dbi4 #cab4 ,a much more convenient and effectual arrangement for chemical decompositions by common electricity1 is the following4 ,upon a glass plate1 fig4 #dc1 placed over1 but raised above a piece of white paper1 so that shadows may not interfere1 put two pieces of tinfoil a1 b2 connect one of these by an insulated wire c1 or wire and string 7#cja47 with the machine1 and the other g1 with the discharging train 7#bib47 or the negative conductor2 provide two pieces of fine platina wire1 bent as in fig4 #dd1 so that the part d1 f shall be nearly upright1 whilst the whole is resting on the three bearing points p1 e1 f place these as in fig4 #dc2 the points p1 n then become the decomposing poles4 ,in this way surfaces of contact1 as minute as possible1 can be obtained at pleasure1 and the connexion can be broken or renewed in a moment1 and the substances acted upon examined with the utmost facility4 #cac4 ,a coarse line was made on the glass with solution of sulphate of copper1 and the terminations p and n put into it2 the foil a was connected with the positive conductor of the machine by wire and wet string1 so that no sparks passed3 twenty turns of the machine caused the precipitation of so much copper on the end n1 that it looked like copper wire2 no apparent change took place at p4 #cad4 ,a mixture of equal parts of muriatic acid and water was rendered deep blue by sulphate of indigo1 and a large drop put on the glass1 fig4 #dc1 so that p and n were immersed at opposite sides3 a single turn of the machine showed bleaching effects round p1 from evolved chlorine4 ,after twenty revolutions no effect of the kind was visible at n1 but so much chlorine had been set free at p1 that when the drop was stirred the whole became colourless4 #cae4 ,a drop of solution of iodide of potassium mingled with starch was put into the same position at p and n2 on turning the machine1 iodine was evolved at p1 but not at n4 #caf4 ,a still further improvement in this form of apparatus consists in wetting a piece of filtering paper in the solution to be experimented on1 and placing that under the points p and n1 on the glass3 the paper retains the substance evolved at the point of evolution1 by its whiteness renders any change of colour visible1 and allows of the point of contact between it and the decomposing wires being contracted to the utmost degree4 ,a piece of paper moistened in the solution of iodide of potassium and starch1 or of the iodide alone1 with certain precautions 7#cbb471 is a most admirable test of electro-chemical action2 and when thus placed and acted upon by the electric current1 will show iodine evolved at p by only half a turn of the machine4 ,with these adjustments and the use of iodide of potassium on paper1 chemical action is sometimes a more delicate test of electrical currents than the galvanometer 7#bgc474 ,such cases occur when the bodies traversed by the current are bad conductors1 or when the quantity of electricity evolved or transmitted in a given time is very small4 #cag4 ,a piece of litmus paper moistened in solution of common salt or sulphate of soda1 was quickly reddened at p4 ,a similar piece moistened in muriatic acid was very soon bleached at p4 ,no effects of a similar kind took place at n4 #cah4 ,a piece of turmeric paper moistened in solution of sulphate of soda was reddened at n by two or three turns of the machine1 and in twenty or thirty turns plenty of alkali was there evolved4 ,on turning the paper round1 so that the spot came under p1 and then working the machine1 the alkali soon disappeared1 the place became yellow1 and a brown alkaline spot appeared in the new part under n4 #cai4 ,on combining a piece of litmus with a piece of turmeric paper1 wetting both with solution of sulphate of soda1 and putting the paper on the glass1 so that p was on the litmus and n on the turmeric1 a very few turns of the machine sufficed to show the evolution of acid at the former and alkali at the latter1 exactly in the manner effected by a volta-electric current4 #cbj4 ,all these decompositions took place equally well1 whether the electricity passed from the machine to the foil a1 through water1 or through wire only2 by contact with the conductor1 or by sparks there2 provided the sparks were not so large as to cause the electricity to pass in sparks from p to n1 or towards n2 and ,i have seen no reason to believe that in cases of true electro-chemical decomposition by the machine1 the electricity passed in sparks from the conductor1 or at any part of the current1 is able to do more1 because of its tension1 than that which is made to pass merely as a regular current4 #cba4 ,finally1 the experiment was extended into the following form1 supplying in this case the tidiest analogy between common and voltaic electricity4 ,three compound pieces of litmus and turmeric paper 7#cai47 were moistened in solution of sulphate of soda1 and arranged on a plate of glass with platina wires1 as in fig4 #de4 ,the wire m was connected with the prime conductor of the machine1 the wire t with the discharging train1 and the wires r and s entered into the course of the electrical current by means of the pieces of moistened paper2 they were so bent as to rest each on three points1 n1 r1 p2 n1 s1 p1 the points r and s being supported by the glass1 and the others by the papers2 the three terminations p1 p1 p rested on the litmus1 and the other three n1 n1 n on the turmeric paper4 ,on working the machine for a short time only1 acid was evolved at all the poles or terminations p1 p1 p1 by which the electricity entered the solution1 and alkali at the other poles n1 n1 n1 by which the electricity left the solution4 #cbb4 ,in all experiments of electro-chemical decomposition by the common machine and moistened papers 7#caf471 it is necessary to be aware of and to avoid the following important source of error4 ,if a spark passes over moistened litmus and turmeric paper1 the litmus paper 7provided it be delicate and not too alkaline17 is reddened by it2 and if several sparks are passed1 it becomes powerfully reddened4 ,if the electricity pass a little way from the wire over the surface of the moistened paper1 before it finds mass and moisture enough to conduct it1 then the reddening extends as far as the ramifications4 ,if similar ramifications occur at the termination n1 on the turmeric paper1 they prevent the occurrence of the red spot due to the alkali1 which would otherwise collect there3 sparks or ramifications from the points n will also redden litmus paper4 ,if paper moistened by a solution of iodide of potassium 7which is an admirably delicate test of electro-chemical action17 be exposed to the sparks or ramifications1 or even a feeble stream of electricity through the air from either the point p or n1 iodine will be immediately evolved4 #cbc4 ,these effects must not be confounded with those due to the true electro-chemical powers of common electricity1 and must be carefully avoided when the latter are to be observed4 ,no sparks should be passed1 therefore1 in any part of the current1 nor any increase of intensity allowed1 by which the electricity may be induced to pass between the platina wires and the moistened papers1 otherwise than by conduction2 for if it burst through the air1 the effect referred to above 7#cbb47 ensues4 #cbd4 ,the effect itself is due to the formation of nitric acid by the combination of the oxygen and nitrogen of the air1 and is1 in fact1 only a delicate repetition of ,cavendish's beautiful experiment4 ,the acid so formed1 though small in quantity1 is in a high state of concentration as to water1 and produces the consequent effects of reddening the litmus paper2 or preventing the exhibition of alkali on the turmeric paper2 or1 by acting on the iodide of potassium1 evolving iodine4 #cbe4 ,by moistening a very small slip of litmus paper in solution of caustic potassa1 and then passing the electric spark over its length in the air1 ,i gradually neutralized the alkali1 and ultimately rendered the paper red2 on drying it1 ,i found that nitrate of potassa had resulted from the operation1 and that the paper had become touch-paper4 #cbf4 ,either litmus paper or white paper1 moistened in a strong solution of iodide of potassium1 offers therefore a very simple1 beautiful1 and ready means of illustrating ,cavendish's experiment of the formation of nitric acid from the atmosphere4 #cbg4 ,i have already had occasion to refer to an experiment 7#bfe4 #cji47 made by ,dr4 ,wollaston1 which is insisted upon too much1 both by those who oppose and those who agree with the accuracy of his views respecting the identity of voltaic and ordinary electricity4 ,by covering fine wires with glass or other insulating substances1 and then removing only so much matter as to expose the point1 or a section of the wires1 and by passing electricity through two such wires1 the guarded points of which were immersed in water1 ,wollaston found that the water could be decomposed even by the current from the machine1 without sparks1 and that two streams of gas arose from the points1 exactly resembling1 in appearance1 those produced by voltaic electricity1 and1 like the latter1 giving a mixture of oxygen and hydrogen gases4 ,but ,dr4 ,wollaston himself points out that the effect is different from that of the voltaic pile1 inasmuch as both oxygen and hydrogen are evolved from each pole2 he calls it a very close imitation of the galvanic phenomena1 but adds that in fact the resemblance is not complete1 and does not trust to it to establish the principles correctly laid down in his paper4 #cbh4 ,this experiment is neither more nor less than a repetition1 in a refined manner1 of that made by ,dr4 ,pearson in #agig;,a1 and previously by ,,mm4 ,paets ,van ,troostwyk and ,deiman in #aghi or earlier4 ,that the experiment should never be quoted as proving true electro-chemical decomposition1 is sufficiently evident from the circumstance1 that the law which regulates the transference and final place of the evolved bodies 7#bgh4 #cji47 has no influence here4 ,the water is decomposed at both poles independently of each other1 and the oxygen and hydrogen evolved at the wires are the elements of the water existing the instant before in those places4 ,that the poles1 or rather points1 have no mutual decomposing dependence1 may be shown by substituting a wire1 or the finger1 for one of them1 a change which does not at all interfere with the other1 though it stops all action at the changed pole4 ,this fact may be observed by turning the machine for some time2 for though bubbles will rise from the point left unaltered1 in quantity sufficient to cover entirely the wire used for the other communication1 if they could be applied to it1 yet not a single bubble will appear on that wire4 ,a ,nicholson's ,journal1 #dto4 vol4 ,i4 pp4 #caa1 #bii4 #cdi4 #cbi4 ,when electro-chemical decomposition takes place1 there is great reason to believe that the quantity of matter decomposed is not proportionate to the intensity1 but to the quantity of electricity passed 7#cbj474 ,of this ,i shall be able to offer some proofs in a future part of this paper 7#cge4 #cgg474 ,but in the experiment under consideration1 this is not the case4 ,if1 with a constant pair of points1 the electricity be passed from the machine in sparks1 a certain proportion of gas is evolved2 but if the sparks be rendered shorter1 less gas is evolved2 and if no sparks be passed1 there is scarcely a sensible portion of gases set free4 ,on substituting solution of sulphate of soda for water1 scarcely a sensible quantity of gas could be procured even with powerful sparks1 and nearly none with the mere current2 yet the quantity of electricity in a given time was the same in all these cases4 #ccj4 ,i do not intend to deny that with such an apparatus common electricity can decompose water in a manner analogous to that of the voltaic pile2 ,i believe at present that it can4 ,but when what ,i consider the true effect only was obtained1 the quantity of gas given off was so small that ,i could not ascertain whether it was1 as it ought to be1 oxygen at one wire and hydrogen at the other4 ,of the two streams one seemed more copious than the other1 and on turning the apparatus round1 still the same side in relation to the machine2 gave the largest stream4 ,on substituting solution of sulphate of soda for pure water 7#cbi471 these minute streams were still observed4 ,but the quantities were so small1 that on working the machine for half an hour ,i could not obtain at either pole a bubble of gas larger than a small grain of sand4 ,if the conclusion which ,i have drawn 7#cgg47 relating to the amount of chemical action be correct1 this ought to be the case4 #cca4 ,i have been the more anxious to assign the true value of this experiment as a test of electro-chemical action1 because ,i shall have occasion to refer to it in cases of supposed chemical action by magneto-electric and other electric currents 7#ccf4 #cdf47 and elsewhere4 ,but1 independent of it1 there cannot be now a doubt that ,dr4 ,wollaston was right in his general conclusion2 and that voltaic and common electricity have powers of chemical decomposition1 alike in their nature1 and governed by the same law of arrangement4 #ccb4 iv4 ,physiological effects4--,the power of the common electric current to shock and convulse the animal system1 and when weak to affect the tongue and the eyes1 may be considered as the same with the similar power of voltaic electricity1 account being taken of the intensity of the one electricity and duration of the other4 ,when a wet thread was interposed in the course of the current of common electricity from the battery 7#bia47 charged by eight or ten,a revolutions of the machine in good action 7#bij471 and the discharge made by platina spatulas through the tongue or the gums1 the effect upon the tongue and eyes was exactly that of a momentary feeble voltaic circuit4 ,a ,or even from thirty to forty4 #ccc4 v4 ,spark4--,the beautiful flash of light attending the discharge of common electricity is well known4 ,it rivals in brilliancy1 if it does not even very much surpass1 the light from the discharge of voltaic electricity2 but it endures for an instant only1 and is attended by a sharp noise like that of a small explosion4 ,still no difficulty can arise in recognising it to be the same spark as that from the voltaic battery1 especially under certain circumstances4 ,the eye cannot distinguish the difference between a voltaic and a common electricity spark1 if they be taken between amalgamated surfaces of metal1 at intervals only1 and through the same distance of air4 #ccd4 ,when the ,leyden battery 7#bia47 was discharged through a wet string placed in some part of the circuit away from the place where the spark was to pass1 the spark was yellowish1 flamy1 having a duration sensibly longer than if the water had not been interposed1 was about three-fourths of an inch in length1 was accompanied by little or no noise1 and whilst losing part of its usual character had approximated in some degree to the voltaic spark4 ,when the electricity retarded by water was discharged between pieces of charcoal1 it was exceedingly luminous and bright upon both surfaces of the charcoal1 resembling the brightness of the voltaic discharge on such surfaces4 ,when the discharge of the unretarded electricity was taken upon charcoal1 it was bright upon both the surfaces1 7in that respect resembling the voltaic spark17 but the noise was loud1 sharp1 and ringing4 #cce4 ,i have assumed1 in accordance1 ,i believe1 with the opinion of every other philosopher1 that atmospheric electricity is of the same nature with ordinary electricity 7#bhd471 and ,i might therefore refer to certain published statements of chemical effects produced by the former as proofs that the latter enjoys the power of decomposition in common with voltaic electricity4 ,but the comparison ,i am drawing is far too rigorous to allow me to use these statements without being fully assured of their accuracy2 yet ,i have no right to suppress them1 because1 if accurate1 they establish what ,i am labouring to put on an undoubted foundation1 and have priority to my results4 #ccf4 ,m4 ,bonijol of ,geneva,a is said to have constructed very delicate apparatus for the decomposition of water by common electricity4 ,by connecting an insulated lightning rod with his apparatus1 the decomposition of the water proceeded in a continuous and rapid manner even when the electricity of the atmosphere was not very powerful4 ,the apparatus is not described2 but as the diameter of the wire is mentioned as very small1 it appears to have been similar in construction to that of ,wollaston 7#cbg472 and as that does not furnish a case of true polar electro-chemical decomposition 7#cbh471 this result of ,m4 ,bonijol does not prove the identity in chemical action of common and voltaic electricity4 ,a ,bibliothque ,universelle1 #ahcj1 tome xlv4 p4 #bac4 #ccg4 ,at the same page of the ,bibliothque ,universelle1 ,m4 ,bonijol is said to have decomposed1 potash1 and also chloride of silver1 by putting them into very narrow tubes and passing electric sparks from an ordinary machine over them4 ,it is evident that these offer no analogy to cases of true voltaic decomposition1 where the electricity only decomposes when it is conducted by the body acted upon1 and ceases to decompose1 according to its ordinary laws1 when it passes in sparks4 ,these effects are probably partly analogous to that which takes place with water in ,pearson's or ,wollaston's apparatus1 and may be due to very high temperature acting on minute portions of matter2 or they may be connected with the results in air 7#cbb474 ,as nitrogen can combine directly with oxygen under the influence of the electric spark 7#cbd471 it is not impossible that it should even take it from the potassium of the potash1 especially as there would be plenty of potassa in contact with the acting particles to combine with the nitric acid formed4 ,however distinct all these actions may be from true polar electro-chemical decompositions1 they are still highly important1 and well-worthy of investigation4 #cch4 ,the late ,mr4 ,barry communicated a paper to the ,royal ,society,a last year1 so distinct in the details1 that it would seem at once to prove the identity in chemical action of common and voltaic electricity2 but1 when examined1 considerable difficulty arises in reconciling certain of the effects with the remainder4 ,he used two tubes1 each having a wire within it passing through the closed end1 as is usual for voltaic decompositions4 ,the tubes were filled with solution of sulphate of soda1 coloured with syrup of violets1 and connected by a portion of the same solution1 in the ordinary manner2 the wire in one tube was connected by a gilt thread with the string of an insulated electrical kite1 and the wire in the other tube by a similar gilt thread with the ground4 ,hydrogen soon appeared in the tube connected with the kite1 and oxygen in the other1 and in ten minutes the liquid in the first tube was green from the alkali evolved1 and that in the other red from free acid produced4 ,the only indication of the strength or intensity of the atmospheric electricity is in the expression1 the usual shocks were felt on touching the string4 ,a ,philosophical ,transactions1 #ahca1 p4 #afe4 #cci4 ,that the electricity in this case does not resemble that from any ordinary source of common electricity1 is shown by several circumstances4 ,wollaston could not effect the decomposition of water by such an arrangement1 and obtain the gases in separate vessels1 using common electricity2 nor have any of the numerous philosophers1 who have employed such an apparatus1 obtained any such decomposition1 either of water or of a neutral salt1 by the use of the machine4 ,i have lately tried the large machine 7#bij47 in full action for a quarter of an hour1 during which time seven hundred revolutions were made1 without producing any sensible effects1 although the shocks that it would then give must have been far more powerful and numerous than could have been taken1 with any chance of safety1 from an electrical kite-string2 and by reference to the comparison hereafter to be made 7#cga471 it will be seen that for common electricity to have produced the effect1 the quantity must have been awfully great1 and apparently far more than could have been conducted to the earth by a gilt thread1 and at the same time only have produced the usual shocks4 #cdj4 ,that the electricity was apparently not analogous to voltaic electricity is evident1 for the usual shocks only were produced1 and nothing like the terrible sensation due to a voltaic battery1 even when it has a tension so feeble as not to strike through the eighth of an inch of air4 #cda4 ,it seems just possible that the air which was passing by the kite and string1 being in an electrical state sufficient to produce the usual shocks only1 could still1 when the electricity was drawn off below1 renew the charge1 and so continue the current4 ,the string was #aejj feet long1 and contained two double threads4 ,but when the enormous quantity which must have been thus collected is considered 7#cga4 #cgf471 the explanation seems very doubtful4 ,i charged a voltaic battery of twenty pairs of plates four inches square with double coppers very strongly1 insulated it1 connected its positive extremity with the discharging train 7#bib471 and its negative pole with an apparatus like that of ,mr4 ,barry1 communicating by a wire inserted three inches into the wet soil of the ground4 ,this battery thus arranged produced feeble decomposing effects1 as nearly as ,i could judge answering the description ,mr4 ,barry has given4 ,its intensity was1 of course1 far lower than the electricity of the kite-string1 but the supply of quantity from the discharging train was unlimited4 ,it gave no shocks to compare with the usual shocks of a kite-string4 #cdb4 ,mr4 ,barry's experiment is a very important one to repeat and verify4 ,if confirmed1 it will be1 as far as ,i am aware1 the first recorded case of true electro-chemical decomposition of water by common electricity1 and it will supply a form of electrical current1 which1 both in quantity and intensity1 is exactly intermediate with those of the common electrical machine and the voltaic pile4 99 99 99 99 99 ,,iii4 ,magneto-,electricity4 #cdc4 ,tension4--,the attractions and repulsions due to the tension of ordinary electricity have been well observed with that evolved by magneto-electric induction4 ,m4 ,pixii1 by using an apparatus1 clever in its construction and powerful in its action,a1 was able to obtain great divergence of the gold leaves of an electrometer,b4 ,a ,annales de ,chimie1 l4 p4 #cbb4 ,b ,ibid4 li4 p #gg4 #cdd4 ,in motion3 i4 ,evolution of ,heat4--,the current produced by magneto-electric induction can heat a wire in the manner of ordinary electricity4 ,at the ,british ,association of ,science at ,oxford1 in ,june of the present year1 ,i had the pleasure1 in conjunction with ,mr4 ,harris1 ,professor ,daniell1 ,mr4 ,duncan1 and others1 of making an experiment1 for which the great magnet in the museum1 ,mr4 ,harris's new electrometer 7#bhg471 and the magneto-electric coil described in my first paper 7#cd471 were put in requisition4 ,the latter had been modified in the manner ,i have elsewhere described,a so as to produce an electric spark when its contact with the magnet was made or broken4 ,the terminations of the spiral1 adjusted so as to have their contact with each other broken when the spark was to pass1 were connected with the wire in the electrometer1 and it was found that each time the magnetic contact was made and broken1 expansion of the air within the instrument occurred1 indicating an increase1 at the moment1 of the temperature of the wire4 ,a ,phil1 ,mag4 and ,annals1 #ahcb1 vol4 xi4 p4 #dje4 #cae4 ii4 ,magnetism4--,these currents were discovered by their magnetic power4 #cdf4 iii4 ,chemical decomposition4--,i have made many endeavours to effect chemical decomposition by magneto-electricity1 but unavailingly4 ,in ,july last ,i received an anonymous letter 7which has since been published,a17 describing a magneto-electric apparatus1 by which the decomposition of water was effected4 ,as the term guarded points is used1 ,i suppose the apparatus to have been ,wollaston's 7#cbg4 c471 in which case the results did not indicate polar electro-chemical decomposition4 ,signor ,botto has recently published certain results which he has obtained,b2 but they are1 as at present described1 inconclusive4 ,the apparatus he used was apparently that of ,dr4 ,wollaston1 which gives only fallacious indications 7#cbg4 c474 ,as magneto-electricity can produce sparks1 it would be able to show the effects proper to this apparatus4 ,the apparatus of ,m4 ,pixii already referred to 7#cdc47 has however1 in the hands of himself,c and ,m4 ,hachctte,d1 given decisive chemical results1 so as to complete this link in the chain of evidence4 ,water was decomposed by it1 and the oxygen and hydrogen obtained in separate tubes according to the law governing volta-electric and machine-electric decomposition4 ,a ,lond4 and ,edinb4 ,phil4 ,mag4 and ,journ41 #ahcb1 vol4 i4 p4 #afa4 ,b ,ibid4 #ahcb4 vol4 i4 p4 #dda4 ,c ,annales de ,chimie1 li1 p4 #gg4 ,d ,ibid4 li4 p4 #gb #cdg4 iv4 ,physiological effects4--,a frog was convulsed in the earliest experiments on these currents 7#ef474 ,the sensation upon the tongue1 and the flash before the eyes1 which ,i at first obtained only in a feeble degree 7#ef471 have been since exalted by more powerful apparatus1 so as to become even disagreeable4 #cdh4 v4 ,spark4--,the feeble spark which ,i first obtained with these currents 7#cb471 has been varied and strengthened by ,signori ,nobili and ,antinori1 and others1 so as to leave no doubt as to its identity with the common electric spark4 99 99 99 99 99 ,,iv4 ,thermo-,electricity4 #cdi4 ,with regard to thermo-electricity1 7that beautiful form of electricity discovered by ,seebeck17 the very conditions under which it is excited are such as to give no ground for expecting that it can be raised like common electricity to any high degree of tension2 the effects1 therefore1 due to that state are not to be expected4 ,the sum of evidence respecting its analogy to the electricities already described1 is1 ,i believe1 as follows3--,tension4 ,the attractions and repulsions due to a certain degree of tension have not been observed4 ,in currents3 i4 ,evolution of ,heat4 ,i am not aware that its power of raising temperature has been observed4 ii4 ,magnetism4 ,it was discovered1 and is best recognised1 by its magnetic powers4 iii4 ,chemical decomposition has not been effected by it4 iv4 ,physiological effects4 ,nobili has shown,a that these currents are able to cause contractions in the limbs of a frog4 v4 ,spark4 ,the spark has not yet been seen4 ,a ,bibliothque ,universelle1 xxxvii4 #ae4 #cej4 ,only those effects are weak or deficient which depend upon a certain high degree of intensity2 and if common electricity be reduced in that quality to a similar degree with the thermo-electricity1 it can produce no effects beyond the latter4 99 99 99 99 99 ,v4 ,animal ,electricity4 #cea4 ,after an examination of the experiments of ,walsh,a ,ingenhousz,b1 ,cavendish,c1 ,sir ,h4 ,davy,d1 and ,dr4 ,davy,e1 no doubt remains on my mind as to the identity of the electricity of the torpedo with common and voltaic electricity2 and ,i presume that so little will remain on the minds of others as to justify my refraining from entering at length into the philosophical proofs of that identity4 ,the doubts raised by ,sir ,h4 ,davy have been removed by his brother ,dr4 ,davy2 the results of the latter being the reverse of those of the former4 ,at present the sum of evidence is as follows3-- ,a ,philosophical ,transactions1 #aggc1 p4 #dfa4 ,b ,ibid4 #agge1 p4 #a4 ,c ,ibid4 #aggf1 p4 #aif4 ,d ,ibid4 #ahbi1 p4 #ae4 ,e ,ibid4 #ahcb1 p4 #bei4 #ceb4 ,tension4--,no sensible attractions or repulsions due to tension have been observed4 #cec4 ,in motion3 i4 ,evolution of ,heat2 not yet observed2 ,i have little or no doubt that ,harris's electrometer would show it 7#bhg4 #cei474 #ced4 ii4 ,magnetism4--,perfectly distinct4 ,according to ,dr4 ,davy,a1 the current deflected the needle and made magnets under the same law1 as to direction1 which governs currents of ordinary and voltaic electricity4 ,a ,philosophical ,transactions1 #ahcb1 p4 #bfj4 #cee4 iii4 ,chemical decomposition4--,also distinct2 and though ,dr4 ,davy used an apparatus of similar construction with that of ,dr4 ,wollaston 7#cbg471 still no error in the present case is involved1 for the decompositions were polar1 and in their nature truly electro-chemical4 ,by the direction of the magnet it was found that the under surface of the fish was negative1 and the upper positive2 and in the chemical decompositions1 silver and lead were precipitated on the wire connected with the under surface1 and not on the other2 and when these wires were either steel or silver1 in solution of common salt1 gas 7hydrogen87 rose from the negative wire1 but none from the positive4 #cef4 ,another reason for the decomposition being electrochemical is1 that a ,wollaston's apparatus constructed with wires1 coated by sealing-wax1 would most probably not have decomposed water1 even in its own peculiar way1 unless the electricity had risen high enough in intensity to produce sparks in some part of the circuit2 whereas the torpedo was not able to produce sensible sparks4 ,a third reason is1 that the purer the water in ,wollaston's apparatus1 the more abundant is the decomposition2 and ,i have found that a machine and wire points which succeeded perfectly well with distilled water1 failed altogether when the water was rendered a good conductor by sulphate of soda1 common salt1 or other saline bodies4 ,but in ,dr4 ,davy's experiments with the torpedo1 strong solutions of salt1 nitrate of silver1 and superacetate of lead were used successfully1 and there is no doubt with more success than weaker ones4 #ceg4 iv4 ,physiological effects4--,these are so characteristic1 that by them the peculiar powers of the torpedo and gymnotus are principally recognised4 #ceh4 v4 ,spark4--,the electric spark has not yet been obtained1 or at least ,i think not2 but perhaps ,i had better refer to the evidence on this point4 ,humboldt1 speaking of results obtained by ,m4 ,fahlberg1 of ,sweden1 says1 ,this philosopher has seen an electric spark1 as ,walsh and ,ingenhousz had done before him in ,london1 by placing the gymnotus in the air1 and interrupting the conducting chain by two gold leaves pasted upon glass1 and a line distant from each other,a4 ,i cannot1 however1 find any record of such an observation by either ,walsh or ,ingenhousz1 and do not know where to refer to that by ,m4 ,fahlberg4 ,m4 ,humboldt could not himself perceive any luminous effect4 ,a ,edinburgh ,phil4 ,journal1 ii4 p4 #bdi4 ,again1 ,sir ,john ,leslie1 in his dissertation on the progress of mathematical and physical science1 prefixed to the seventh edition of the ,encyclopdia ,britannica1 ,edinb4 #ahcj1 p4 #fbb1 says1 ,from a healthy specimen of the ,silurus electricus1 meaning rather the gymnotus1 exhibited in ,london1 vivid sparks were drawn in a darkened room2 but he does not say he saw them himself1 nor state who did see them2 nor can ,i find any account of such a phenomenon2 so that the statement is doubtful,a4 ,a ,mr4 ,brayley1 who referred me to those statements1 and has extensive knowledge of recorded facts1 is unacquainted with any further account relating to them4 #cei4 ,in concluding this summary of the powers of torpedinal electricity1 ,i cannot refrain from pointing out the enormous absolute quantity of electricity which the animal must put in circulation at each effort4 ,it is doubtful whether any common electrical machine has as yet been able to supply electricity sufficient in a reasonable time to cause true electro-chemical decomposition of water 7#ccj4 #cci471 yet the current from the torpedo has done it4 ,the same high proportion is shown by the magnetic effects 7#bif4 #cga474 ,these circumstances indicate that the torpedo has power 7in the way probably that ,cavendish describes17 to continue the evolution for a sensible time1 so that its successive discharges rather resemble those of a voltaic arrangement1 intermitting in its action1 than those of a ,leyden apparatus1 charged and discharged many times in succession4 ,in reality1 however1 there is no philosophical difference between these two cases4 #cfj4 ,the general conclusion which must1 ,i think1 be drawn from this collection of facts is1 that electricity1 whatever may be its source1 is identical in its nature4 ,the phenomena in the five kinds or species quoted1 differ1 not in their character but only in degree2 and in that respect vary in proportion to the variable circumstances of quantity and intensity,a which can at pleasure be made to change in almost any one of the kinds of electricity1 as much as it does between one kind and another4 ,a ,the term quantity in electricity is perhaps sufficiently definite as to sense2 the term intensity is more difficult to define strictly4 ,i am using the terms in their ordinary and accepted meaning4 ,table of the experimental ,effects common to the ,electricities derived from different ,sources,a4 ,table headings ,a3 ,physiological ,effects ,b3 ,magnetic ,deflection4 ,c3 ,magnets made4 ,d3 ,spark4 ,e3 ,heating ,power4 ,f3 ,true chemical ,action4 ,g3 ,attraction and ,repulsion4 ,h3 ,discharge by ,hot ,air4 ,a ,b ,c ,d ,e ,f ,g ,h #a4 ,voltaic electricity ,x ,x ,x ,x ,x ,x ,x ,x #b4 ,common electricity ,x ,x ,x ,x ,x ,x ,x ,x #c4 ,magneto-,electricity ,x ,x ,x ,x ,x ,x ,x #d4 ,thermo-,electricity ,x ,x #e4 ,animal ,electricity ,x ,x ,x ,x ,a ,many of the spaces in this table originally left blank may now be filled4 ,thus with thermo-electricity1 ,botto made magnets and obtained polar chemical decomposition3 ,antinori produced the spark2 and if it has not been done before1 ,mr4 ,watkins has recently heated a wire in ,harris's thermo-electrometer4 ,in respect to animal electricity1 ,matteucci and ,linari have obtained the spark from the torpedo1 and ,i have recently procured it from the gymnotus3 ,dr4 ,davy has observed the heating power of the current from the torpedo4 ,i have therefore filled up these spaces with crosses1 in a different position to the others originally in the table4 ,there remain but five spaces unmarked1 two under attraction and repulsion1 and three under discharge by hot air2 and though these effects have not yet been obtained1 it is a necessary conclusion that they must be possible1 since the spark corresponding to them has been procured4 ,for when a discharge across cold air can occur1 that intensity which is the only essential additional requisite for the other effects must be present4--,dec4 #ac #ahch4 #h4 ,relation by ,measure of common and voltaic ,electricity4,a ,a ,in further illustration of this subject see #hee-hgc in ,series ,,vii4--,dec4 #ahch4 #cfa4 ,believing the point of identity to be satisfactorily established1 ,i next endeavoured to obtain a common measure1 or a known relation as to quantity1 of the electricity excited by a machine1 and that from a voltaic pile2 for the purpose not only of confirming their identity 7#cgh471 but also of demonstrating certain general principles 7#cff1 #cgg1 c471 and creating an extension of the means of investigating and applying the chemical powers of this wonderful and subtile agent4 #cfb4 ,the first point to be determined was1 whether the same absolute quantity of ordinary electricity1 sent through a galvanometer1 under different circumstances1 would cause the same deflection of the needle4 ,an arbitrary scale was therefore attached to the galvanometer1 each division of which was equal to about #d1 and the instrument arranged as in former experiments 7#bif474 ,the machine 7#bij471 battery 7#bia471 and other parts of the apparatus were brought into good order1 and retained for the time as nearly as possible in the same condition4 ,the experiments were alternated so as to indicate any change in the condition of the apparatus and supply the necessary corrections4 #cfc4 ,seven of the battery jars were removed1 and eight retained for present use4 ,it was found that about forty turns would fully charge the eight jars4 ,they were then charged by thirty turns of the machine1 and discharged through the galvanometer1 a thick wet string1 about ten inches long1 being included in the circuit4 ,the needle was immediately deflected five divisions and a half1 on the one side of the zero1 and in vibrating passed as nearly as possible through five divisions and a half on the other side4 #cfd4 ,the other seven jars were then added to the eight1 and the whole fifteen charged by thirty turns of the machine4 ,the ,henley's electrometer stood not quite half as high as before2 but when the discharge was made through the galvanometer1 previously at rest1 the needle immediately vibrated1 passing exactly to the same division as in the former instance4 ,these experiments with eight and with fifteen jars were repeated several times alternately with the same results4 #cfe4 ,other experiments were then made1 in which all the battery was used1 and its charge 7being fifty turns of the machine17 sent through the galvanometer3 but it was modified by being passed sometimes through a mere wet thread1 sometimes through thirty-eight inches of thin string wetted by distilled water1 and sometimes through a string of twelve times the thickness1 only twelve inches in length1 and soaked in dilute acid 7#bih474 ,with the thick string the charge passed at once2 with the thin string it occupied a sensible time1 and with the thread it required two or three seconds before the electrometer fell entirely down4 ,the current therefore must have varied extremely in intensity in these different cases1 and yet the deflection of the needle was sensibly the same in all of them4 ,if any difference occurred1 it was that the thin string and thread caused greatest deflection2 and if there is any lateral transmission1 as ,m4 ,colladon says1 through the silk in the galvanometer coil1 it ought to have been so1 because then the intensity is lower and the lateral transmission less4 #cff4 ,hence it would appear that if the same absolute quantity of electricity pass through the galvanometer1 whatever may be its intensity1 the dejecting force upon the magnetic needle is the same4 #cfg4 ,the battery of fifteen jars was then charged by sixty revolutions of the machine1 and discharged1 as before1 through the galvanometer4 ,the deflection of the needle was now as nearly as possible to the eleventh division1 but the graduation was not accurate enough for me to assert that the arc was exactly double the former arc2 to the eye it appeared to be so4 ,the probability is1 that the deflecting force of an electric current is directly proportional to the absolute quantity of electricity passed1 at whatever intensity that electricity may be,a4 ,a ,the great and general value of the galvanometer1 as an actual measure of the electricity passing through it1 either continuously or interruptedly1 must be evident from a consideration of these two conclusions4 ,as constructed by ,professor ,ritchie with glass threads 7see ,philosophical ,transactions1 #ahcj1 p4 #bah1 and ,quarterly ,journal of ,science1 ,new ,series1 vol4 i4 p4#bi471 it apparently seems to leave nothing unsupplied in its own department4 #cfh4 ,dr4 ,ritchie has shown that in a case where the intensity of the electricity remained the same1 the deflection of the magnetic needle was directly as the quantity of electricity passed through the galvanometer,a4 ,mr4 ,harris has shown that the heating power of common electricity on metallic wires is the same for the same quantity of electricity whatever its intensity might have previously been,b4 ,a ,quarterly ,journal of ,science1 ,new ,series1 vol4 i4 p4 #cc4 ,b ,plymouth ,transactions1 page #bb4 #cfi4 ,the next point was to obtain a voltaic arrangement producing an effect equal to that just described 7#cfg474 ,a platina and a zinc wire were passed through the same hole of a draw-plate1 being then one eighteenth of an inch in diameter2 these were fastened to a support1 so that their lower ends projected1 were parallel1 and five sixteenths of an inch apart4 ,the upper ends were well-connected with the galvanometer wires4 ,some acid was diluted1 and1 after various preliminary experiments1 that adopted as a standard which consisted of one drop strong sulphuric acid in four ounces distilled water4 ,finally1 the time was noted which the needle required in swinging either from right to left or left to right3 it was equal to seventeen beats of my watch1 the latter giving one hundred and fifty in a minute4 ,the object of these preparations was to arrange a voltaic apparatus1 which1 by immersion in a given acid for a given time1 much less than that required by the needle to swing in one direction1 should give equal deflection to the instrument with the discharge of ordinary electricity from the battery 7#cfc4 #cfd472 and a new part of the zinc wire having been brought into position with the platina1 the comparative experiments were made4 #cgj4 ,on plunging the zinc and platina wires five eighths of an inch deep into the acid1 and retaining them there for eight beats of the watch1 7after which they were quickly withdrawn17 the needle was deflected1 and continued to advance in the same direction some time after the voltaic apparatus had been removed from the acid4 ,it attained the five-and-a-half division1 and then returned swinging an equal distance on the other side4 ,this experiment was repeated many times1 and always with the same result4 #cga4 ,hence1 as an approximation1 and judging from magnetic force only at present 7#cgf471 it would appear that two wires1 one of platina and one of zinc1 each one eighteenth of an inch in diameter1 placed five sixteenths of an inch apart and immersed to the depth of five eighths of an inch in acid1 consisting of one drop oil of vitriol and four ounces distilled water1 at a temperature about #fj1 and connected at the other extremities by a copper wire eighteen feet long and one eighteenth of an inch thick 7being the wire of the galvanometer coils71 yield as much electricity in eight beats of my watch1 or in #h_/aejths of a minute1 as the electrical battery charged by thirty turns of the large machine1 in excellent order 7#cfc4 #cfd474 ,notwithstanding this apparently enormous disproportion1 the results are perfectly in harmony with those effects which are known to be produced by variations in the intensity and quantity of the electric fluid4 #cgb4 ,in order to procure a reference to chemical action1 the wires were now retained immersed in the acid to the depth of five eighths of an inch1 and the needle1 when stationary1 observed2 it stood1 as nearly as the unassisted eye could decide1 at #e-a_/c division4 ,hence a permanent deflection to that extent might be considered as indicating a constant voltaic current1 which in eight beats of my watch 7#cfi47 could supply as much electricity as the electrical battery charged by thirty turns of the machine4 #cgc4 ,the following arrangements and results are selected from many that were made and obtained relative to chemical action4 ,a platina wire one twelfth of an inch in diameter1 weighing two hundred and sixty grains1 had the extremity rendered plain1 so as to offer a definite surface equal to a circle of the same diameter as the wire2 it was then connected in turn with the conductor of the machine1 or with the voltaic apparatus 7#cfi471 so as always to form the positive pole1 and at the same time retain a perpendicular position1 that it might rest1 with its whole weight1 upon the test paper to be employed4 ,the test paper itself was supported upon a platina spatula1 connected either with the discharging train 7#bib471 or with the negative wire of the voltaic apparatus1 and it consisted of four thicknesses1 moistened at all times to an equal degree in a standard solution of hydriodate of potassa 7#caf474 #cgd4 ,when the platina wire was connected with the prime conductor of the machine1 and the spatula with the discharging train1 ten turns of the machine had such decomposing power as to produce a pale round spot of iodine of the diameter of the wire2 twenty turns made a much darker mark1 and thirty turns made a dark brown spot penetrating to the second thickness of the paper4 ,the difference in effect produced by two or three turns1 more or less1 could be distinguished with facility4 #cge4 ,the wire and spatula were then connected with the voltaic apparatus 7#cfi471 the galvanometer being also included in the arrangement2 and1 a stronger acid having been prepared1 consisting of nitric acid and water1 the voltaic apparatus was immersed so far as to give a permanent deflection of the needle to the #e-a_/c division 7#cgb471 the fourfold moistened paper intervening as before,a4 ,then by shifting the end of the wire from place to place upon the test paper1 the effect of the current for five1 six1 seven1 or any number of the beats of the watch 7#cfi47 was observed1 and compared with that of the machine4 ,after alternating and repeating the experiments of comparison many times1 it was constantly found that this standard current of voltaic electricity1 continued for eight beats of the watch1 was equal1 in chemical effect1 to thirty turns of the machine2 twenty-eight revolutions of the machine were sensibly too few4 ,a ,of course the heightened power of the voltaic battery was necessary to compensate for the bad conductor now interposed4 #cgf4 ,hence it results that both in magnetic deflection 7#cga47 and in chemical force1 the current of electricity of the standard voltaic battery for eight beats of the watch was equal to that of the machine evolved by thirty revolutions4 #cgg4 ,it also follows that for this case of electro-chemical decomposition1 and it is probable for all cases1 that the chemical power1 like the magnetic force 7#cf471 is in direct proportion to the absolute quantity of electricity which passes4 #cgh4 ,hence arises still further confirmation1 if any were required1 of the identity of common and voltaic electricity1 and that the differences of intensity and quantity are quite sufficient to account for what were supposed to be their distinctive qualities4 #cgi4 ,the extension which the present investigations have enabled me to make of the facts and views constituting the theory of electro-chemical decomposition1 will1 with some other points of electrical doctrine1 be almost immediately submitted to the ,royal ,society in another series of these ,researches4 ,royal ,institution1 #aeth ,dec4 #ahcb4 ,note4--,i am anxious1 and am permitted1 to add to this paper a correction of an error which ,i have attributed to ,m4 ,ampre the first series of these ,experimental ,researches4 ,in referring to his experiment on the induction of electrical currents 7#gh471 ,i have called that a disc which ,i should have called a circle or a ring4 ,m4 ,ampre used a ring1 or a very short cylinder made of a narrow plate of copper bent into a circle1 and he tells me that by such an arrangement the motion is very readily obtained4 ,i have not doubted that ,m4 ,ampre obtained the motion he described2 but merely mistook the kind of mobile conductor used1 and so far ,i described his experiment erroneously4 ,in the same paragraph ,i have stated that ,m4 ,ampre says the disc turned to take a position of equilibrium exactly as the spiral itself would have turned had it been free to move2 and further on ,i have said that my results tended to invert the sense of the proposition stated by ,m4 ,ampre1 that a current of electricity tends to put the electricity of conductors near which it passes in motion in the same direction4 ,m4 ,ampre tells me in a letter which ,i have just received from him1 that he carefully avoided1 when describing the experiment1 any reference to the direction of the induced current2 and on looking at the passages he quotes to me1 ,i find that to be the case4 ,i have therefore done him injustice in the above statements1 and am anxious to correct my error4 ,but that it may not be supposed ,i lightly wrote those passages1 ,i will briefly refer to my reasons for understanding them in the sense ,i did4 ,at first the experiment failed4 ,when re-made successfully about a year afterwards1 it was at ,geneva in company with ,m4,a4 ,de la ,rive3 the latter philosopher described the results,a1 and says that the plate of copper bent into a circle which was used as the mobile conductor sometimes advanced between the two branches of the 7horse-shoe7 magnet1 and sometimes was repelled1 according to the direction of the current in the surrounding conductors4 ,a ,bibliothque ,universelle1 xxi4 p4 #dh4 ,i have been in the habit of referring to ,demonferrand's ,manuel d',electricit ,dynamique1 as a book of authority in ,france2 containing the general results and laws of this branch of science1 up to the time of its publication1 in a well arranged form4 ,at p4 #agc1 the author1 when describing this experiment1 says1 ,the mobile circle turns to take a position of equilibrium as a conductor would do in which the current moved in the same direction as in the spiral2 and in the same paragraph he adds1 ,it is therefore proved that a current of electricity tends to put the electricity of conductors1 near which it passes1 in motion in the same direction4 ,these are the words ,i quoted in my paper 7#gh474 ,le ,lyce of #ast of ,january1 #ahcb1 ,no4 #cf1 in an article written after the receipt of my first unfortunate letter to ,m4 ,hachette1 and before my papers were printed1 reasons upon the direction of the induced currents1 and says1 that there ought to be an elementary current produced in the same direction as the corresponding portion of the producing current4 ,a little further on it says1 therefore we ought to obtain currents1 moving in the same direction1 produced upon a metallic wire1 either by a magnet or a current4 ,m4 ,ampre was so thouroughly persuaded that such ought to be the direction of the currents by influence1 that he neglected to assure himself of it in his experiment at ,geneva4 ,it was the precise statements in ,demonferrand's ,manuel1 agreeing as they did with the expression in ,m4 ,de la ,rive's paper1 7which1 however1 ,i now understand as only meaning that when the inducing current was changed1 the motion of the mobile circle changed also17 and not in discordance with anything expressed by ,m4 ,ampre himself where he speaks of the experiment1 which made me conclude1 when ,i wrote the paper1 that what ,i wrote was really his avowed opinion2 and when the ,number of the ,lyce referred to appeared1 which was before my paper was printed1 it could excite no suspicion that ,i was in error4 ,hence the mistake into which ,i unwittingly fell4 ,i am proud to correct it and do full justice to the acuteness and accuracy which1 as far as ,i can understand the subjects1 ,m4 ,ampre carries into all the branches of philosophy which he investigates4 ,finally1 my note to 7#gi47 says that the ,lyce1 ,no4 #cf4 mistakes the erroneous results of ,,mm4 ,fresnel and ,ampre for true ones1 c4 c4 ,in calling ,m4 ,ampre's results erroneous1 ,i spoke of the results described in1 and referred to by the ,lyce itself2 but now that the expression of the direction of the induced current is to be separated1 the term erroneous ought no longer to be attached to them4 ,april #bi1 #ahcc4 ,m4,f4 ,,fourth ,,series4 #i4 ,on a new ,law of ,electric ,conduction4 #aj4 ,on ,conducting ,power generally4 ,received ,april #bd1--,read ,may #bc1 #ahcc4 #i4 ,on a new ,law of ,electric ,conduction4,a ,a ,in reference to this law see further considerations at #iaj4 #aceh4 #agje4--;,dec4 #ahch4 #chj4 ,it was during the progress of investigations relating to electro-chemical decomposition1 which ,i still have to submit to the ,royal ,society1 that ,i encountered effects due to a very general law of electric conduction not hitherto recognised2 and though they prevented me from obtaining the condition ,i sought for1 they afforded abundant compensation for the momentary disappointment1 by the new and important interest which they gave to an extensive part of electrical science4 #cha4 ,i was working with ice1 and the solids resulting from the freezing of solutions1 arranged either as barriers across a substance to be decomposed1 or as the actual poles of a voltaic battery1 that ,i might trace and catch certain elements in their transit1 when ,i was suddenly stopped in my progress by finding that ice was in such circumstances a non-conductor of electricity2 and that as soon as a thin film of it was interposed1 in the circuit of a very powerful voltaic battery1 the transmission of electricity was prevented1 and all decomposition ceased4 #chb4 ,at first the experiments were made with common ice1 during the cold freezing weather of the latter end of ,january #ahcc2 but the results were fallacious1 from the imperfection of the arrangements1 and the following more unexceptionable form of experiment was adopted4 #chc4 ,tin vessels were formed1 five inches deep1 one inch and a quarter wide in one direction1 of different widths from three eighths to five eighths of an inch in the other1 and open at one extremity4 ,into these were fixed by corks1 plates of platina1 so that the latter should not touch the tin cases2 and copper wires having previously been soldered to the plate1 these were easily connected1 when required1 with a voltaic pile4 ,then distilled water1 previously boiled for three hours1 was poured into the vessels1 and frozen by a mixture of salt and snow1 so that pure transparent solid ice intervened between the platina and tin2 and finally these metals were connected with the opposite extremities of the voltaic apparatus1 a galvanometer being at the same time included in the circuit4 #chd4 ,in the first experiment1 the platina pole was three inches and a half long1 and seven eighths of an inch wide2 it was wholly immersed in the water or ice1 and as the vessel was four eighths of an inch in width1 the average thickness of the intervening ice was only a quarter of an inch1 whilst the surface of contact with it at both poles was nearly fourteen square inches4 ,after the water was frozen1 the vessel was still retained in the frigorific mixture1 whilst contact between the tin and platina respectively was made with the extremities of a well-charged voltaic battery1 consisting of twenty pairs of four-inch plates1 each with double coppers4 ,not the slightest deflection of the galvanometer needle occurred4 #che4 ,on taking the frozen arrangement out of the cold mixture1 and applying warmth to the bottom of the tin case1 so as to melt part of the ice1 the connexion with the battery being in the mean time retained1 the needle did not at first move2 and it was only when the thawing process had extended so far as to liquefy part of the ice touching the platina pole1 that conduction took place2 but then it occurred effectually1 and the galvanometer needle was permanently deflected nearly #gj4 #chf4 ,in another experiment1 a platina spatula1 five inches in length and seven eighths of an inch in width1 had four inches fixed in the ice1 and the latter was only three sixteenths of an inch thick between one metallic surface and the other2 yet this arrangement insulated as perfectly as the former4 #chg4 ,upon pouring a little water in at the top of this vessel on the ice1 still the arrangement did not conduct2 yet fluid water was evidently there4 ,this result was the consequence of the cold metals having frozen the water where they touched it1 and thus insulating the fluid part2 and it well illustrates the non-conducting power of ice1 by showing how thin a film could prevent the transmission of the battery current4 ,upon thawing parts of this thin film1 at both metals1 conduction occurred4 #chh4 ,upon warming the tin case and removing the piece of ice1 it was found that a cork having slipped1 one of the edges of the platina had been all but in contact with the inner surface of the tin vessel2 yet1 notwithstanding the extreme thinness of the interfering ice in this place1 no sensible portion of electricity had passed4 #chi4 ,these experiments were repeated many times with the same results4 ,at last a battery of fifteen troughs1 or one hundred and fifty pairs of four-inch plates1 powerfully charged1 was used2 yet even here no sensible quantity of electricity passed the thin barrier of ice4 #cij4 ,it seemed at first as if occasional departures from these effects occurred2 but they could always be traced to some interfering circumstances4 ,the water should in every instance be well-frozen2 for though it is not necessary that the ice should reach from pole to pole1 since a barrier of it about one pole would be quite sufficient to prevent conduction1 yet1 if part remain fluid1 the mere necessary exposure of the apparatus to the air or the approximation of the hands1 is sufficient to produce1 at the upper surface of the water and ice1 a film of fluid1 extending from the platina to the tin2 and then conduction occurs4 ,again1 if the corks used to block the platina in its place are damp or wet within1 it is necessary that the cold be sufficiently well applied to freeze the water in them1 or else when the surfaces of their contact with the tin become slightly warm by handling1 that part will conduct1 and the interior being ready to conduct also1 the current will pass4 ,the water should be pure1 not only that unembarrassed results may be obtained1 but also that1 as the freezing proceeds1 a minute portion of concentrated saline solution may not be formed1 which remaining fluid1 and being interposed in the ice1 or passing into cracks resulting from contraction1 may exhibit conducting powers independent of the ice itself4 #cia4 ,on one occasion ,i was surprised to find that after thawing much of the ice the conducting power had not been restored2 but ,i found that a cork which held the wire just where it joined the platina1 dipped so far into the ice1 that with the ice itself it protected the platina from contact with the melted part long after that contact was expected4 #cib4 ,this insulating power of ice is not effective with electricity of exalted intensity4 ,on touching a diverged gold-leaf electrometer with a wire connected with the platina1 whilst the tin case was touched by the hand or another wire1 the electrometer was instantly discharged 7#dai474 #cic4 ,but though electricity of an intensity so low that it cannot diverge the electrometer1 can still pass 7though in very limited quantities 7#dai4717 through ice2 the comparative relation of water and ice to the electricity of the voltaic apparatus is not less extraordinary on that account1 ,or less important in its consequences4 #cid4 ,as it did not seem likely that this law of the assumption of conducting power during liquefaction1 and loss of it during congelation1 would be peculiar to water1 ,i immediately proceeded to ascertain its influence in other cases1 and found it to be very general4 ,for this purpose bodies were chosen which were solid at common temperatures1 but readily fusible2 and of such composition as1 for other reasons connected with electrochemical action1 led to the conclusion that they would be able when fused to replace water as conductors4 ,a voltaic battery of two troughs1 or twenty pairs of four-inch plates 7#chd471 was used as the source of electricity1 and a galvanometer introduced into the circuit to indicate the presence or absence of a current4 #cie4 ,on fusing a little chloride of lead by a spirit lamp on a fragment of a ,florence flask1 and introducing two platina wires connected with the poles of the battery1 there was instantly powerful action1 the galvanometer was most violently affected1 and the chloride rapidly decomposed4 ,on removing the lamp1 the instant the chloride solidified all current and consequent effects ceased1 though the platina wires remained inclosed in the chloride not more than the one-sixteenth of an inch from each other4 ,on renewing the heat1 as soon as the fusion had proceeded far enough to allow liquid matter to connect the poles1 the electrical current instantly passed4 #cif4 ,on fusing the chloride1 with one wire introduced1 and then touching the liquid with the other1 the latter being cold1 caused a little knob to concrete on its extremity1 and no current passed2 it was only when the wire became so hot as to be able to admit or allow of contact with the liquid matter1 that conduction took place1 and then it was very powerful4 #cig4 ,when chloride of silver and chlorate of potassa were experimented with1 in a similar manner1 exactly the same results occurred4 #cih4 ,whenever the current passed in these cases1 there was decomposition of the substances2 but the electro-chemical part of this subject ,i purpose connecting with more general views in a future paper,a4 ,a ,in #ahja1 ,sir ,h4 ,davy knew that dry nitre1 caustic potash1 and soda are conductors of galvanism when rendered fluid by a high degree of heat1 7,journals of the ,royal ,institution1 #ahjb1 p4 #ec17 but was not aware of the general law which ,i have been engaged in developing4 ,it is remarkable1 that eleven years after that1 he should say1 ,there are no fluids known except such as contain water1 which are capable of being made the medium of connexion between the metal or metals of the voltaic apparatus4--,elements of ,chemical ,philosophy1 p4 #afi4 #cii4 ,other substances1 which could not be melted on glass1 were fused by the lamp and blowpipe on platina connected with one pole of the battery1 and then a wire1 connected with the other1 dipped into them4 ,in this way chloride of sodium1 sulphate of soda1 protoxide of lead1 mixed carbonates of potash and soda1 c4 c41 exhibited exactly the same phenomena as those already described3 whilst liquid1 they conducted and were decomposed2 whilst solid1 though very hot1 they insulated the battery current even when four troughs were used4 #djj4 ,occasionally the substances were contained in small bent tubes of green glass1 and when fused1 the platina poles introduced1 one on each side4 ,in such cases the same general results as those already described were procured2 but a further advantage was obtained1 namely1 that whilst the substance was conducting and suffering decomposition1 the final arrangement of the elements could be observed4 ,thus1 iodides of potassium and lead gave iodine at the positive pole1 and potassium or lead at the negative pole4 ,chlorides of lead and silver gave chlorine at the positive1 and metals at the negative pole4 ,nitre and chlorate2 of potassa gave oxygen1 c41 at the positive1 and alkali1 or even potassium1 at the negative pole4 ,illustration #dja4 ,a fourth arrangement was used for substances requiring very high temperatures for their fusion4 ,a platina wire was connected with one pole of the battery2 its extremity bent into a small ring1 in the manner described by ,berzelius1 for blowpipe experiments2 a little of the salt1 glass1 or other substance1 was melted on this ring by the ordinary blowpipe1 or even in some cases by the oxy-hydrogen blowpipe1 and when the drop1 retained in its place by the ring1 was thoroughly hot and fluid1 a platina wire from the opposite pole of the battery was made to touch it1 and the effects observed4 #djb4 ,the following are various substances1 taken from very different classes chemically considered1 which are subject to this law4 ,the list might1 no doubt1 be enormously extended2 but ,i have not had time to do more than confirm the law by a sufficient number of instances4 ,first1 water4 ,amongst oxides2--potassa1 protoxide of lead1 glass of antimony1 protoxide of antimony1 oxide of bismuth4 ,chlorides of potassium1 sodium1 barium1 strontium1 calcium1 magnesium1 manganese1 zinc1 copper 7proto-71 lead1 tin 7proto-71 antimony1 silver4 ,iodides of potassium1 zinc and lead1 protiodide of tin1 periodide of mercury2 fluoride of potassium2 cyanide of potassium2 sulpho-cyanide of potassium4 ,salts4 ,chlorate of potassa2 nitrates of potassa1 soda1 baryta1 strontia1 lead1 copper1 and silver2 sulphates of soda and lead1 proto-sulphate of mercury2 phosphates of potassa1 soda1 lead1 copper1 phosphoric glass or acid phosphate of lime2 carbonates of potassa and soda1 mingled and separate2 borax1 borate of lead1 per-borate of tin2 chromate of potassa1 bi-chromate of potassa1 chromate of lead2 acetate of potassa4 ,sulphurets4 ,sulphuret of antimony1 sulphuret of potassium made by reducing sulphate of potassa by hydrogen2 ordinary sulphuret of potassa4 ,silicated potassa2 chameleon mineral4 #djc4 ,it is highly interesting in the instances of those substances which soften before they liquefy1 to observe at what period the conducting power is acquired1 and to what degree it is exalted by perfect fluidity4 ,thus1 with the borate of lead1 when heated by the lamp upon glass1 it becomes as soft as treacle1 but it did not conduct1 and it was only when urged by the blowpipe and brought to a fair red heat1 that it conducted4 ,when rendered quite liquid1 it conducted with extreme facility4 #djd4 ,i do not mean to deny that part of the increased conducting power in these cases of softening was probably due to the elevation of temperature 7#dcb4 #dde472 but ,i have no doubt that by far the greater part was due to the influence of the general law already demonstrated1 and which in these instances came gradually1 instead of suddenly1 into operation4 #dje4 ,the following are bodies which acquired no conducting power upon assuming the liquid state3-- ,sulphur1 phosphorus2 iodide of sulphur1 per-iodide of tin2 orpiment1 realgar2 glacial acetic acid1 mixed margaric and oleic acids1 artificial camphor2 caffeine1 sugar1 adipocire1 stearine of cocoa-nut oil1 spermaceti1 camphor1 naphthaline1 resin1 gum sandarach1 shell lac4 #djf4 ,perchloride of tin1 chloride of arsenic1 and the hydrated chloride of arsenic1 being liquids1 had no sensible conducting power indicated by the galvanometer1 nor were they decomposed4 #djg4 ,some of the above substances are sufficiently remarkable as exceptions to the general law governing the former cases4 ,these are orpiment1 realgar1 acetic acid1 artificial camphor1 per-iodide of tin1 and the chlorides of tin and arsenic4 ,i shall have occasion to refer to these cases in the paper on ,electro-chemical ,decomposition4 #djh4 ,boracic acid was raised to the highest possible temperature by an oxy-hydrogen flame 7#dja471 yet it gained no conducting powers sufficient to affect the galvanometer1 and underwent no apparent voltaic decomposition4 ,it seemed to be quite as bad a conductor as air4 ,green bottle-glass1 heated in the same manner1 did not gain conducting power sensible to the galvanometer4 ,flint glass1 when highly heated1 did conduct a little and decompose2 and as the proportion of potash or oxide of lead was increased in the glass1 the effects were more powerful4 ,those glasses1 consisting of boracic acid on the one hand1 and oxide of lead or potassa on the other1 show the assumption of conducting power upon fusion and the accompanying decomposition very well4 #dji4 ,i was very anxious to try the general experiment with sulphuric acid1 of about specific gravity #a4ghc1 containing that proportion of water which gives it the power of crystallizing at #dj ,fahr42 but ,i found it impossible to obtain it so that ,i could be sure the whole would congeal even at #j ,fahr4 ,a ten-thousandth part of water1 more or less than necessary1 would1 upon cooling the whole1 cause a portion of uncongealable liquid to separate1 and that remaining in the interstices of the solid mass1 and moistening the planes of division1 would prevent the correct observation of the phenomena due to entire solidification and subsequent liquefaction4 #daj4 ,with regard to the substances on which conducting power is thus conferred by liquidity1 the degree of power so given is generally very great4 ,water is that body in which this acquired power is feeblest4 ,in the various oxides1 chlorides1 salts1 c4 c41 it is given in a much higher degree4 ,i have not had time to measure the conducting power in these cases1 but it is apparently some hundred times that of pure water4 ,the increased conducting power known to be given to water by the addition of salts1 would seem to be in a great degree dependent upon the high conducting power of these bodies when in the liquid state1 that state being given them for the time1 not by heat but solution in the water,a4 ,a ,see a doubt on this point at #acef4--;,dec4 #ahch4 #daa4 ,whether the conducting power of these liquefied bodies is a consequence of their decomposition or not 7#dac471 or whether the two actions of conduction and decomposition are essentially connected or not1 would introduce no difference affecting the probable accuracy of the preceding statement4 #dab4 ,this general assumption of conducting power by bodies as soon as they pass from the solid to the liquid state1 offers a new and extraordinary character1 the existence of which1 as far as ,i know1 has not before been suspected2 and it seems importantly connected with some properties and relations of the particles of matter which ,i may now briefly point out4 #dac4 ,in almost all the instances1 as yet observed1 which are governed by this law1 the substances experimented with have been those which were not only compound bodies1 but such as contain elements known to arrange themselves at the opposite poles2 and were also such as could be decomposed by the electrical current4 ,when conduction took place1 decomposition occurred2 when decomposition ceased1 conduction ceased also2 and it becomes a fair and an important question1 ,whether the conduction itself may not1 wherever the law holds good1 be a consequence not merely of the capability1 but of the act of decomposition8 ,and that question may be accompanied by another1 namely1 ,whether solidification does not prevent conduction1 merely by chaining the particles to their places1 under the influence of aggregation1 and preventing their final separation in the manner necessary for decomposition8 #dad4 ,but1 on the other hand1 there is one substance 7and others may occur71 the per-iodide of mercury1 which1 being experimented with like the others 7#djj471 was found to insulate when solid1 and to acquire conducting power when fluid2 yet it did not seem to undergo decomposition in the latter case4 #dae4 ,again1 there are many substances which contain elements such as would be expected to arrange themselves at the opposite poles of the pile1 and therefore in that respect fitted for decomposition1 which yet do not conduct4 ,amongst these are the iodide of sulphur1 per-iodide of zinc1 per-chloride of tin1 chloride of arsenic1 hydrated chloride of arsenic1 acetic acid1 orpiment1 realgar1 artificial camphor1 c42 and from these it might perhaps be assumed that decomposition is dependent upon conducting power1 and not the latter upon the former4 ,the true relation1 however1 of conduction and decomposition in those bodies governed by the general law which it is the object of this paper to establish1 can only be satisfactorily made out from a far more extensive series of observations than those ,i have yet been able to supply,a4 ,a ,see #fgc1 c4 c4--,dec4 #ahch4 #daf4 ,the relation1 under this law1 of the conducting power for electricity to that for heat1 is very remarkable1 and seems to imply a natural dependence of the two4 ,as the solid becomes a fluid1 it loses almost entirely the power of conduction for heat1 but gains in a high degree that for electricity2 but as it reverts hack to the solid state1 it gains the power of conducting heat1 and loses that of conducting electricity4 ,if1 therefore1 the properties are not incompatible1 still they are most strongly contrasted1 one being lost as the other is gained4 ,we may hope1 perhaps1 hereafter to understand the physical reason of this very extraordinary relation of the two conducting powers1 both of which appear to be directly connected with the corpuscular condition of the substances concerned4 #dag4 ,the assumption of conducting power and a decomposable condition by liquefaction1 promises new opportunities of1 and great facilities in1 voltaic decomposition4 ,thus1 such bodies as the oxides1 chlorides1 cyanides1 sulpho-cyanides1 fluorides1 certain vitreous mixtures1 c4 c41 may be submitted to the action of the voltaic battery under new circumstances2 and indeed ,i have already been able1 with ten pairs of plates1 to decompose common salt1 chloride of magnesium1 borax1 c4 c41 and to obtain sodium1 magnesium1 boron1 c41 in their separate states4 #aj4 ,on ,conducting ,power generally4,a ,a ,in reference to this refer to #ihc in series viii41 and the results connected with it4--,dec4 #ahch4 #dah4 ,it is not my intention here to enter into an examination of all the circumstances connected with conducting power1 but to record certain facts and observations which have arisen during recent inquiries1 as additions to the general stock of knowledge relating to this point of electrical science4 #dai4 ,i was anxious1 in the first place1 to obtain some idea of the conducting power of ice and solid salts for electricity of high tension 7#cib471 that a comparison might be made between it and the large accession of the same power gained upon liquefaction4 ,for this purpose the large electrical machine 7#bij47 was brought into excellent action1 its conductor connected with a delicate gold-leaf electrometer1 and also with the platina inclosed in the ice 7#chc471 whilst the tin case was connected with the discharging train 7#bib474 ,on working the machine moderately1 the gold leaves barely separated2 on working it rapidly1 they could be opened nearly two inches4 ,in this instance the tin case was five-eighths of an inch in width2 and as1 after the experiment1 the platina plate was found very nearly in the middle of the ice1 the average thickness of the latter had been five-sixteenths of an inch1 and the extent of surface of contact with tin and platina fourteen square inches 7#chd474 ,yet1 under these circumstances1 it was but just able to conduct the small quantity of electricity which this machine could evolve 7#cga471 even when of a tension competent to open the leaves two inches2 no wonder1 therefore1 that it could not conduct any sensible portion of the electricity of the troughs 7#chd471 which1 though almost infinitely surpassing that of the machine in quantity1 had a tension so low as not to be sensible to an electrometer4 #dbj4 ,in another experiment1 the tin case was only four-eighths of an inch in width1 and it was found afterwards that the platina had been not quite one-eighth of an inch distant in the ice from one side of the tin vessel4 ,when this was introduced into the course of the electricity from the machine 7#dai471 the gold leaves could be opened1 but not more than half an inch2 the thinness of the ice favouring the conduction of the electricity1 and permitting the same quantity to pass in the same time1 though of a much lower tension4 #dba4 ,iodide of potassium which had been fused and cooled was introduced into the course of the electricity from the machine4 ,there were two pieces1 each about a quarter of an inch in thickness1 and exposing a surface on each side equal to about half a square inch2 these were placed upon platina plates1 one connected with the machine and electrometer 7#dai471 and the other with the discharging train1 whilst a fine platina wire connected the two pieces1 resting upon them by its two points4 ,on working the electrical machine1 it was possible to open the electrometer leaves about two-thirds of an inch4 #dbb4 ,as the platina wire touched only by points1 the facts show that this salt is a far better conductor than ice2 but as the leaves of the electrometer opened1 it is also evident with what difficulty conduction1 even of the small portion of electricity produced by the machine1 is effected by this body in the solid state1 when compared to the facility with which enormous quantities at very low tensions are transmitted by it when in the fluid state4 #dbc4 ,in order to confirm these results by others1 obtained from the voltaic apparatus1 a battery of one hundred and fifty plates1 four inches square1 was well-charged3 its action was good2 the shock from it strong2 the discharge would continue from copper to copper through four-tenths of an inch of air1 and the gold-leaf electrometer before used could be opened nearly a quarter of an inch4 #dbd4 ,the ice vessel employed 7#dbj47 was half an inch in width2 as the extent of contact of the ice with the tin and platina was nearly fourteen square inches1 the whole was equivalent to a plate of ice having a surface of seven square inches1 of perfect contact at each side1 and only one fourth of an inch thick4 ,it was retained in a freezing mixture during the experiment4 #dbe4 ,the order of arrangement in the course of the electric current was as follows4 ,the positive pole of the battery was connected by a wire with the platina plate in the ice2 the plate was in contact with the ice1 the ice with the tin jacket1 the jacket with a wire1 which communicated with a piece of tin foil1 on which rested one end of a bent platina wire 7#cab471 the other or decomposing end being supported on paper moistened with solution of iodide of potassium 7#caf473 the paper was laid flat on a platina spatula connected with the negative end of the battery4 ,all that part of the arrangement between the ice vessel and the decomposing wire point1 including both these1 was insulated1 so that no electricity might pass through the latter which had not traversed the former also4 #dbf4 ,under these circumstances1 it was found that1 a pale brown spot of iodine was slowly formed under the decomposing platina point1 thus indicating that ice could conduct a little of the electricity evolved by a voltaic battery charged up to the degree of intensity indicated by the electrometer4 ,but it is quite evident that notwithstanding the enormous quantity of electricity which the battery could furnish1 it was1 under present circumstances1 a very inferior instrument to the ordinary machine2 for the latter could send as much through the ice as it could carry1 being of a far higher intensity1 i4e4 able to open the electrometer leaves half an inch or more 7#dai4 #dbj474 #dbg4 ,the decomposing wire and solution of iodide of potassium were then removed1 and replaced by a very delicate galvanometer 7#bje472 it was so nearly astatic1 that it vibrated to and fro in about sixty-three beats of a watch giving one hundred and fifty beats in a minute4 ,the same feebleness of current as before was still indicated2 the galvanometer needle was deflected1 but it required to break and make contact three or four times 7#big471 before the effect was decided4 #dbh4 ,the galvanometer being removed1 two platina plates were connected with the extremities of the wires1 and the tongue placed between them1 so that the whole charge of the battery1 so far as the ice would let it pass1 was free to go through the tongue4 ,whilst standing on the stone floor1 there was shock1 c41 but when insulated1 ,i could feel no sensation4 ,i think a frog would have been scarcely1 if at all1 affected4 #dbi4 ,the ice was now removed1 and experiments made with other solid bodies1 for which purpose they were placed under the end of the decomposing wire instead of the solution of iodide of potassium 7#abe474 ,for instance1 a piece of dry iodide of potassium was placed on the spatula connected with the negative pole of the battery1 and the point of the decomposing wire placed upon it1 whilst the positive end of the battery communicated with the latter4 ,a brown spot of iodine very slowly appeared1 indicating the passage of a little electricity1 and agreeing in that respect with the results obtained by the use of the electrical machine 7#dba474 ,when the galvanometer was introduced into the circuit at the same time with the iodide1 it was with difficulty that the action of the current on it could be rendered sensible4 #dcj4 ,a piece of common salt previously fused and solidified being introduced into the circuit was sufficient almost entirely to destroy the action on the galvanometer4 ,fused and cooled chloride of lead produced the same effect4 ,the conducting power of these bodies1 when fluid1 is very great 7#cie4 #djb474 #dca4 ,these effects1 produced by using the common machine and the voltaic battery1 agree therefore with each other1 and with the law laid down in this paper 7#cid472 and also with the opinion ,i have supported1 in the ,third ,series of these ,researches1 of the identity of electricity derived from different sources 7#cfj474 #dcb4 ,the effect of heat in increasing the conducting power of many substances1 especially for electricity of high tension1 is well known4 ,i have lately met with an extraordinary case of this kind1 for electricity of low tension1 or that of the voltaic pile1 and which is in direct contrast with the influence of heat upon metallic bodies1 as observed and described by ,sir ,humphry ,davy,a4 ,a ,philosophical ,transactions1 #ahba1 p4 #aca4 #dcc4 ,the substance presenting this effect is sulphuret of silver4 ,it was made by fusing a mixture of precipitated silver and sublimed sulphur1 removing the film of silver by a file from the exterior of the fused mass1 pulverizing the sulphuret1 mingling it with more sulphur1 and fusing it again in a green glass tube1 so that no air should obtain access during the process4 ,the surface of the sulphuret being again removed by a file or knife1 it was considered quite free from uncombined silver4 #dcd4 ,when a piece of this sulphuret1 half an inch in thickness1 was put between surfaces of platina1 terminating the poles of a voltaic battery of twenty pairs of four-inch plates1 a galvanometer being also included in the circuit1 the needle was slightly deflected1 indicating a feeble conducting power4 ,on pressing the platina poles and sulphuret together with the fingers1 the conducting power increased as the whole became warm4 ,on applying a lamp under the sulphuret between the poles1 the conducting power rose rapidly with the heat1 and at last-the galvanometer needle jumped into a fixed position1 and the sulphuret was found conducting in the manner of a metal4 ,on removing the lamp and allowing the heat to fall1 the effects were reversed1 the needle at first began to vibrate a little1 then gradually left its transverse direction1 and at last returned to a position very nearly that which it would take when no current was passing through the galvanometer4 #dce4 ,occasionally1 when the contact of the sulphuret with the platina poles was good1 the battery freshly charged1 and the commencing temperature not too low1 the mere current of electricity from the battery was sufficient to raise the temperature of the sulphuret2 and then1 without any application of extraneous heat1 it went on increasing conjointly in temperature and conducting power1 until the cooling influence of the air limited the effects4 ,in such cases it was generally necessary to cool the whole purposely1 to show the returning series of phenomena4 #dcf4 ,occasionally1 also1 the effects would sink of themselves1 and could not be renewed until a fresh surface of the sulphuret had been applied to the positive pole4 ,this was in consequence of peculiar results of decomposition1 to which ,i shall have occasion to revert in the section on ,electro-chemical ,decomposition1 and was conveniently avoided by inserting the ends of two pieces of platina wire into the opposite extremities of a portion of sulphuret fused in a glass tube1 and placing this arrangement between the poles of the battery4 #dcg4 ,the hot sulphuret of silver conducts sufficiently well to give a bright spark with charcoal1 c4 c41 in the manner of a metal4 #dch4 ,the native grey sulphuret of silver1 and the ruby silver ore1 both presented the same phenomena4 ,the native malleable sulphuret of silver presented precisely the same appearances as the artificial sulphuret4 #dci4 ,there is no other body with which ,i am acquainted1 that1 like sulphuret of silver1 can compare with metals in conducting power for electricity of low tension when hot1 but which1 unlike them1 during cooling1 loses in power1 whilst they1 on the contrary1 gain4 ,probably1 however1 many others may1 when sought for1 be found,a4 ,a ,see now on this subject1 #acdj1 #acda4--;,dec4 #ahch4 #ddj4 ,the proto-sulphuret of iron1 the native per-sulphuret of iron1 arsenical sulphuret of iron1 native yellow sulphuret of copper and iron1 grey artificial sulphuret of copper1 artificial sulphuret of bismuth1 and artificial grey sulphuret of tin1 all conduct the voltaic battery current when cold1 more or less1 some giving sparks like the metals1 others not being sufficient for that high effect4 ,they did not seem to conduct better when heated1 than before2 but ,i had not time to enter accurately into the investigation of this point4 ,almost all of them became much heated by the transmission of the current1 and present some very interesting phenomena in that respect4 ,the sulphuret of antimony does not conduct the same current sensibly either hot or cold1 but is amongst those bodies acquiring conducting power when fused 7#djb474 ,the sulphuret of silver and perhaps some others decompose whilst in the solid state2 but the phenomena of this decomposition will be reserved for its proper place in the next series of these ,researches4 #dda4 ,notwithstanding the extreme dissimilarity between sulphuret of silver and gases or vapours1 ,i cannot help suspecting the action of heat upon them to be the same1 bringing them all into the same class as conductors of electricity1 although with those great differences in degree1 which are found to exist under common circumstances4 ,when gases are heated1 they increase in conducting power1 both for common and voltaic electricity 7#bga472 and it is probable that if we could compress and condense them at the same time1 we should still further increase their conducting power4 ,cagniard de la ,tour has shown that a substance1 for instance water1 may be so expanded by heat whilst in the liquid state1 or condensed whilst in the vaporous state1 that the two states shall coincide at one point1 and the transition from one to the other be so gradual that no line of demarcation can be pointed out,a2 that1 in fact1 the two states shall become one2--which one state presents us at different times with differences in degree as to certain properties and relations2 and which differences are1 under ordinary circumstances1 so great as to be equivalent to two different states4 ,a ,annales de ,chimie1 xxi4 pp4 #abg1 #agh4 #ddb4 ,i cannot but suppose at present that at that point where the liquid and the gaseous state coincide1 the conducting properties are the same for both2 but that they diminish as the expansion of the matter into a rarer form takes place by the removal of the necessary pressure2 still1 however1 retaining1 as might be expected1 the capability of having what feeble conducting power remains1 increased by the action of heat4 #ddc4 ,i venture to give the following summary of the conditions of electric conduction in bodies1 not however without fearing that ,i may have omitted some important points,a4 ,a ,see now in relation to this subject1 #acbj--abdb4--;,dec4 #ahch4 #ddd4 ,all bodies conduct electricity in the same manner from metals to lac and gases1 but in very different degrees4 #dde4 ,conducting power is in some bodies powerfully increased by heat1 and in others diminished1 yet without our perceiving any accompanying essential electrical difference1 either in the bodies or in the changes occasioned by the electricity conducted4 #ddf4 ,a numerous class of bodies1 insulating electricity of low intensity1 when solid1 conduct it very freely when fluid1 and are then decomposed by it4 #ddg4 ,but there are many fluid bodies which do not sensibly conduct electricity of this low intensity2 there are some which conduct it and are not decomposed2 nor is fluidity essential to decomposition,a4 ,a ,see the next series of these ,experimental ,researches4 #ddh4 ,there is but one body yet discovered,a which1 insulating a voltaic current when solid1 and conducting it when fluid1 is not decomposed in the latter case 7#dad474 ,a ,it is just possible that this case may1 by more delicate experiment1 hereafter disappear4 7,see now1 #acdj1 #acda1 in relation to this note4--,dec4 #ahch47 #ddi4 ,there is no strict electrical distinction of conduction which can1 as yet1 be drawn between bodies supposed to be elementary1 and those known to be compounds4 ,royal ,institution1 ,april #ae1 #ahcc4 ,,fifth ,,series4 #aa4 ,on ,electro-chemical ,decomposition4 i4 ,new conditions of ,electro-chemical ,decomposition4 ii4 ,influence of ,water in ,electro-chemical ,decomposition4 iii4 ,theory of ,electro-chemical ,decomposition4 ,received ,june #ah1--,read ,june #bj1 #ahcc4 #aa4 ,on ,electro-chemical ,decomposition4,a ,a ,refer to the note after #ajdg1 ,series viii4--,dec4 #ahch4 #dej4 ,i have in a recent series of these ,researches 7#bfe47 proved 7to my own satisfaction1 at least17 the identity of electricities derived from different sources1 and have especially dwelt upon the proofs of the sameness of those obtained by the use of the common electrical machine and the voltaic battery4 #dea4 ,the great distinction of the electricities obtained from these two sources is the very high tension to which the small quantity obtained by aid of the machine may be raised1 and the enormous quantity 7#cga4 #cgf47 in which that of comparatively low tension1 supplied by the voltaic battery1 may be procured2 but as their actions1 whether magnetical1 chemical1 or of any other nature1 are essentially the same 7#cfj471 it appeared evident that we might reason from the former as to the manner of action of the latter2 and it was1 to me1 a probable consequence1 that the use of electricity of such intensity as that afforded by the machine1 would1 when applied to effect and elucidate electro-chemical decomposition1 show some new conditions of that action1 evolve new views of the internal arrangements and changes of the substances under decomposition1 and perhaps give efficient powers over matter as yet undecomposed4 #deb4 ,for the purpose of rendering the bearings of the different parts of this series of researches more distinct1 ,i shall divide it into several heads4 i4 ,new conditions of ,electro-chemical ,decomposition4 #dec4 ,the tension of machine electricity causes it1 however small in quantity1 to pass through any length of water1 solutions1 or other substances classing with these as conductors1 as fast as it can be produced1 and therefore1 in relation to quantity1 as fast as it could have passed through much shorter portions of the same conducting substance4 ,with the voltaic battery the case is very different1 and the passing current of electricity supplied by it suffers serious diminution in any substance1 by considerable extension of its length1 but especially in such bodies as those mentioned above4 #ded4 ,i endeavoured to apply this facility of transmitting the current of electricity through any length of a conductor1 to an investigation of the transfer of the elements in a decomposing body1 in contrary directions1 towards the poles4 ,the general form of apparatus used in these experiments has been already described 7#cab4 #caf72 and also a particular experiment 7#cai471 in which1 when a piece of litmus paper and a piece of turmeric paper were combined and moistened in solution of sulphate of soda1 the point of the wire from the machine 7representing the positive pole7 put upon the litmus paper1 and the receiving point from the discharging train 7#bib4 #caf471 representing the negative pole1 upon the turmeric paper1 a very few turns of the machine sufficed to show the evolution of acid at the former1 and alkali at the latter1 exactly in the manner effected by a volta-electric current4 #dee4 ,the pieces of litmus and turmeric paper were now placed each upon a separate plate of glass1 and connected by an insulated string four feet long1 moistened in the same solution of sulphate of soda3 the terminal decomposing wire points were placed upon the papers as before4 ,on working the machine1 the same evolution of acid and alkali appeared as in the former instance1 and with equal readiness1 notwithstanding that the places of their appearance were four feet apart from each other4 ,finally1 a piece of string1 seventy feet long1 was used4 ,it was insulated in the air by suspenders of silk1 so that the electricity passed through its entire length3 decomposition took place exactly as in former cases1 alkali and acid appearing at the two extremities in their proper places4 #def4 ,experiments were then made both with sulphate of soda and iodide of potassium1 to ascertain if any diminution of decomposing effect was produced by such great extension as those just described of the moist conductor or body under decomposition2 but whether the contact of the decomposing point connected with the discharging train was made with turmeric paper touching the prime conductor1 or with other turmeric paper connected with it through the seventy feet of string1 the spot of alkali for an equal number of turns of the machine had equal intensity of colour4 ,the same results occurred at the other decomposing wire1 whether the salt or the iodide were used2 and it was fully proved that this great extension of the distance between the poles produced no effect whatever on the amount of decomposition1 provided the same quantity of electricity were passed in both cases 7#cgg474 #deg4 ,the negative point of the discharging train1 the turmeric paper1 and the string were then removed2 the positive point was left resting upon the litmus paper1 and the latter touched by a piece of moistened string held in the hand4 ,a few turns of the machine evolved acid at the positive point as freely as before4 #deh4 ,the end of the moistened string1 instead of being held in the hand1 was suspended by glass in the air4 ,on working the machine the electricity proceeded from the conductor through the wire point to the litmus paper1 and thence away by the intervention of the string to the air1 so that there was 7as in the last experiment7 but one metallic pole2 still acid was evolved there as freely as in any former case4 #dei4 ,when any of these experiments were repeated with electricity from the negative conductor1 corresponding effects were produced whether one or two decomposing wires were used4 ,the results were always constant1 considered in relation to the direction of the electric current4 #dfj4 ,these experiments were varied so as to include the action of only one metallic pole1 but that not the pole connected with the machine4 ,turmeric paper was moistened in solution of sulphate of soda1 placed upon glass1 and connected with the discharging train 7#bib47 by a decomposing wire 7#cab472 a piece of wet string was hung from it1 the lower extremity of which was brought opposite a point connected with the positive prime conductor of the machine4 ,the machine was then worked for a few turns1 and alkali immediately appeared at the point of the discharging train which rested on the turmeric paper4 ,corresponding effects took place at the negative conductor of a machine4 #dfa4 ,these cases are abundantly sufficient to show that electrochemical decomposition does not depend upon the simultaneous action of two metallic poles1 since a single pole might be used1 decomposition ensue1 and one or other of the elements liberated1 pass to the pole1 according as it was positive or negative4 ,in considering the course taken by1 and the final arrangement of1 the other element1 ,i had little doubt that ,i should find it had receded towards the other extremity1 and that the air itself had acted as a pole1 an expectation which was fully confirmed in the following manner4 #dfb4 ,a piece of turmeric paper1 not more than #j4d of an inch in length and #j4e of an inch in width1 was moistened with sulphate of soda and placed upon the edge of a glass plate opposite to1 and about two inches from1 a point connected with the discharging train 7,plate ,,iv4 fig4 #dg472 a piece of tinfoil1 resting upon the same glass plate1 was connected with the machine1 and also with the turmeric paper1 by a decomposing wire a 7#cab474 ,the machine was then worked1 the positive electricity passing into the turmeric paper at the point p1 and out at the extremity n4 ,after forty or fifty turns of the machine1 the extremity n was examined1 and the two points or angles found deeply coloured by the presence of free alkali 7fig4 #dh474 #dfc4 ,a similar piece of litmus paper1 dipped in solution of sulphate of soda n1 fig4 #di1 was now supported upon the end of the discharging train a1 and its extremity brought opposite to a point p1 connected with the conductor of the machine4 ,after working the machine for a short time1 acid was developed at both the corners towards the point1 i4e4 at both the corners receiving the electricities from the air4 ,every precaution was taken to prevent this acid from being formed by sparks or brushes passing through the air 7#cbb472 and these1 with the accompanying general facts1 are sufficient to show that the acid was really the result of electro-chemical decomposition 7#dff474 #dfd4 ,then a long piece of turmeric paper1 large at one end and pointed at the other1 was moistened in the saline solution1 and immediately connected with the conductor of the machine1 so that its pointed extremity was opposite a point upon the discharging train4 ,when the machine was worked1 alkali was evolved at that point2 and even when the discharging train was removed1 and the electricity left to be diffused and carried off altogether by the air1 still alkali was evolved where the electricity left the turmeric paper4 #dfe4 ,arrangements were then made in which no metallic communication with the decomposing matter was allowed1 but both poles 7if they might now be called by that name7 formed of air only4 ,a piece of turmeric paper a fig4 #ej1 and a piece of litmus paper b1 were dipped in solution of sulphate of soda1 put together so as to form one moist pointed conductor1 and supported on wax between two needle points1 one1 p1 connected by a wire with the conductor of the machine1 and the other1 n1 with the discharging train4 ,the interval in each case between the points was about half an inch2 the positive point p was opposite the litmus paper2 the negative point n opposite the turmeric4 ,the machine was then worked for a time1 upon which evidence of decomposition quickly appeared1 for the point of the litmus b became reddened from acid evolved there1 and the point of the turmeric a red from a similar and simultaneous evolution of alkali4 #dff4 ,upon turning the paper conductor round1 so that the litmus point should now give off the positive electricity1 and the turmeric point receive it1 and working the machine for a short time1 both the red spots disappeared1 and as on continuing the action of the machine no red spot was re-formed at the litmus extremity1 it proved that in the first instance 7#dfc47 the effect was not due to the action of brushes or mere electric discharges causing the formation of nitric acid from the air 7#cbb474 #dfg4 ,if the combined litmus and turmeric paper in this experiment be considered as constituting a conductor independent of the machine or the discharging train1 and the final places of the elements evolved be considered in relation to this conductor1 then it will be found that the acid collects at the negative or receiving end or pole of the arrangement1 and the alkali at the positive or delivering extremity4 #dfh4 ,similar litmus and turmeric paper points were now placed upon glass plates1 and connected by a string six feet long1 both string and paper being moistened in solution of sulphate of soda2 a needle point connected with the machine was brought opposite the litmus paper point1 and another needle point connected with the discharging train brought opposite the turmeric paper4 ,on working the machine1 acid appeared on the litmus1 and alkali on the turmeric paper2 but the latter was not so abundant as in former cases1 for much of the electricity passed off from the string into the air1 and diminished the quantity discharged at the turmeric point4 #dfi4 ,finally1 a series of four small compound conductors1 consisting of litmus and turmeric paper 7fig4 #ea47 moistened in solution of sulphate of soda1 were supported on glass rods1 in a line at a little distance from each other1 between the points p and n of the machine and discharging train1 so that the electricity might pass in succession through them1 entering in at the litmus points b1 b1 and passing out at the turmeric points a1 a4 ,on working the machine carefully1 so as to avoid sparks and brushes 7#cbb471 ,i soon obtained evidence of decomposition in each of the moist conductors1 for all the litmus points exhibited free acid1 and the turmeric points equally showed free alkali4 #dgj4 ,on using solutions of iodide of potassium1 acetate of lead1 c41 similar effects were obtained2 but as they were all consistent with the results above described1 ,i refrain from describing the appearances minutely4 #dga4 ,these cases of electro-chemical decomposition are in their nature exactly of the same kind as those affected under ordinary circumstances by the voltaic battery1 notwithstanding the great differences as to the presence or absence1 or at least as to the nature of the parts usually called poles2 and also of the final situation of the elements eliminated at the electrified boundary surfaces 7#dfg474 ,they indicate at once an internal action of the parts suffering decomposition1 and appear to show that the power which is effectual in separating the elements is exerted there1 and not at the poles4 ,but ,i shall defer the consideration of this point for a short time 7#dic4 #eah471 that ,i may previously consider another supposed condition of electro-chemical decomposition,a4 ,a ,i find 7since making and describing these results17 from a note to ,sir ,humphry ,davy's paper in the ,philosophical ,transactions1 #ahjg1 p4 #ca1 that that philosopher1 in repeating ,wollaston's experiment of the decomposition of water by common electricity 7#cbg4 #ccj47 used an arrangement somewhat like some of those ,i have described4 ,he immersed a guarded platina point connected with the machine in distilled water1 and dissipated the electricity from the water into the air by moistened filaments of cotton4 ,in this way he states that he obtained oxygen and hydrogen separately from each other4 ,this experiment1 had ,i known of it1 ought to have been quoted in an earlier series of these ,researches 7#cdb472 but it does not remove any of the objections ,i have made to the use of ,wollaston's apparatus as a test of true chemical action 7#cca474 ii4 ,influence of ,water in ,electro-chemical ,decomposition4 #dgb4 ,it is the opinion of several philosophers1 that the presence of water is essential in electro-chemical decomposition1 and also for the evolution of electricity in the voltaic battery itself4 ,as the decomposing cell is merely one of the cells of the battery1 into which particular substances are introduced for the purpose of experiment1 it is probable that what is an essential condition in the one case is more or less so in the other4 ,the opinion1 therefore1 that water is necessary to decomposition1 may have been founded on the statement made by ,sir ,humphry ,davy1 that there are no fluids known1 except such as contain water1 which are capable of being made the medium of connexion between the metals or metal of the voltaic apparatus,a3 and again1 when any substance rendered fluid by heat1 consisting of water1 oxygen1 and inflammable or metallic matter1 is exposed to those wires1 similar phenomena 7of decomposition7 occur,b4 ,a ,elements of ,chemical ,philosophy1 p4 #afj1 c4 ,b ,ibid4 pp4 #add1 #ade4 #dgc4 ,this opinion has1 ,i think1 been shown by other philosophers not to be accurate1 though ,i do not know where to refer for a contradiction of it4 ,sir ,humphry ,davy himself said in #ahja;,a1 that dry nitre1 caustic potash and soda are conductors of galvanism when rendered fluid by a high degree of heat1 but he must have considered them1 or the nitre at least1 as not suffering decomposition1 for the statements above were made by him eleven years subsequently4 ,in #ahbf he also pointed out1 that bodies not containing water1 as fused litharge and chlorate of potassa1 were sufficient to form1 with platina and zinc1 powerful electromotive circles,b2 but he is here speaking of the production of electricity in the pile1 and not of its effects when evolved2 nor do his words at all imply that any correction of his former distinct statements relative to decomposition was required4 ,a ,journal of the ,royal ,institution1 #ahjb1 p4 #ec4 ,b ,philosophical ,transactions1 #ahbf1 p4 #djf4 #dgd4 ,i may refer to the last series of these ,experimental ,researches 7#chj4 #djb47 as setting the matter at rest1 by proving that there are hundreds of bodies equally influential with water in this respect2 that amongst binary compounds1 oxides1 chlorides1 iodides1 and even sulphurets 7#djb47 were effective2 and that amongst more complicated compounds1 cyanides and salts1 of equal efficacy1 occurred in great numbers 7#djb474 #dge4 ,water1 therefore1 is in this respect merely one of a very numerous class of substances1 instead of being the only one and essential2 and it is of that class one of the worst as to its capability of facilitating conduction and suffering decomposition4 ,the reasons why it obtained for a time an exclusive character which it so little deserved are evident1 and consist1 in the general necessity of a fluid condition 7#cid472 in its being the only one of this class of bodies existing in the fluid state at common temperatures2 its abundant supply as the great natural solvent2 and its constant use in that character in philosophical investigations1 because of its having a smaller interfering1 injurious1 or complicating action upon the bodies1 either dissolved or evolved1 than any other substance4 #dgf4 ,the analogy of the decomposing or experimental cell to the other cells of the voltaic battery renders it nearly certain that any of those substances which are decomposable when fluid1 as described in my last paper 7#djb471 would1 if they could be introduced between the metallic plates of the pile1 be equally effectual with water1 if not more so4 ,sir ,humphry ,davy found that litharge and chlorate of potassa were thus effectual,a4 ,i have constructed various voltaic arrangements1 and found the above conclusion to hold good4 ,when any of the following substances in a fused state were interposed between copper and platina1 voltaic action more or less powerful was produced4 ,nitre2 chlorate of potassa2 carbonate of potassa2 sulphate of soda2 chloride of lead1 of sodium1 of bismuth1 of calcium2 iodide of lead2 oxide of bismuth2 oxide of lead3 the electric current was in the same direction as if acids had acted upon the metals4 ,when any of the same substances1 or phosphate of soda1 were made to act on platina and iron1 still more powerful voltaic combinations of the same kind were produced4 ,when either nitrate of silver or chloride of silver was the fluid substance interposed1 there was voltaic action1 but the electric current was in the reverse direction4 ,a ,philosophical ,transactions1 #ahbf1 p4 #djf4 iii4 ,theory of ,electro-chemical ,decomposition4 #dgg4 ,the extreme beauty and value of electro-chemical decompositions have given to that power which the voltaic pile possesses of causing their occurrence an interest surpassing that of any other of its properties2 for the power is not only intimately connected with the continuance1 if not with the production1 of the electrical phenomena1 but it has furnished us with the most beautiful demonstrations of the nature of many compound bodies2 has in the hands of ,becquerel been employed in compounding substances2 has given us several new combinations1 and sustains us with the hope that when thoroughly understood it will produce many more4 #dgh4 ,what may be considered as the general facts of electrochemical decomposition are agreed to by nearly all who have written on the subject4 ,they consist in the separation of the decomposable substance acted upon into its proximate or sometimes ultimate principles1 whenever both poles of the pile are in contact with that substance in a proper condition2 in the evolution of these principles at distant points1 i4e4 at the poles of the pile1 where they are either finally set free or enter into union with the substance of the poles2 and in the constant determination of the evolved elements or principles to particular poles according to certain well-ascertained laws4 #dgi4 ,but the views of men of science vary much as to the nature of the action by which these effects are produced2 and as it is certain that we shall be better able to apply the power when we really understand the manner in which it operates1 this difference of opinion is a strong inducement to further inquiry4 ,i have been led to hope that the following investigations might be considered1 not as an increase of that which is doubtful1 but a real addition to this branch of knowledge4 #dhj4 ,it will be needful that ,i briefly state the views of electro-chemical decomposition already put forth1 that their present contradictory and unsatisfactory state may be seen before ,i give that which seems to me more accurately to agree with facts2 and ,i have ventured to discuss them freely1 trusting that ,i should give no offence to their high-minded authors2 for ,i felt convinced that if ,i were right1 they would be pleased that their views should serve as stepping-stones for the advance of science2 and that if ,i were wrong1 they would excuse the zeal which misled me1 since it was exerted for the service of that great cause whose prosperity and progress they have desired4 #dha4 ,grotthuss1 in the year #ahje1 wrote expressly on the decomposition of liquids by voltaic electricity,a4 ,he considers the pile as an electric magnet1 i4e4 as an attractive and repulsive agent2 the poles having attractive and repelling powers4 ,the pole from whence resinous electricity issues attracts hydrogen and repels oxygen1 whilst that from which vitreous electricity proceeds attracts oxygen and repels hydrogen2 so that each of the elements of a particle of water1 for instance1 is subject to an attractive and a repulsive force1 acting in contrary directions1 the centres of action of which are reciprocally opposed4 ,the action of each force in relation to a molecule of water situated in the course of the electric current is in the inverse ratio of the square of the distance at which it is exerted1 thus giving 7it is stated7 for such a molecule a constant force,b4 ,he explains the appearance of the elements at a distance from each other by referring to a succession of decompositions and recompositions occurring amongst the intervening particles,c1 and he thinks it probable that those which are about to separate at the poles unite to the two electricities there1 and in consequence become gases,d4 ,a ,annales de ,chimie1 #ahjf1 tom1 lviii4 p4 #fd4 ,b ,ibid4 pp4 #ff1 #fg1 also tom4 lxiii4 p4 #bj4 ,c ,ibid4 tom4 lviii4 p4 #fh1 tom1 lxiii4 p4 #bj4 ,d ,ibid4 tom4 lxiii4 p4 #cd4 #dhb4 ,sir ,humphry ,davy's celebrated ,bakerian ,lecture on some chemical agencies of electricity was read in ,november #ahjf1 and is almost entirely occupied in the consideration of electro-chemical decompositions4 ,the facts are of the utmost value1 and1 with the general points established1 are universally known4 ,the mode of action by which the effects take place is stated very generally1 so generally1 indeed1 that probably a dozen precise schemes of electro-chemical action might be drawn up1 differing essentially from each other1 yet all agreeing with the statement there given4 #dhc4 ,when ,sir ,humphry ,davy uses more particular expressions1 he seems to refer the decomposing effects to the attractions of the poles4 ,this is the case in the general expression of facts given at pp4 #bh and #bi of the ,philosophical ,transactions for #ahjg1 also at p4 #cj4 ,again at p4 #afj of the ,elements of ,chemical ,philosophy1 he speaks of the great attracting powers of the surfaces of the poles4 ,he mentions the probability of a succession of decompositions and recompositions throughout the fluid1--agreeing in that respect with ,grotthuss,a2 and supposes that the attractive and repellent agencies may be communicated from the metallic surfaces throughout the whole of the menstruum,b1 being communicated from one particle to another particle of the same kind,c1 and diminishing in strength from the place of the poles to the middle point1 which is necessarily neutral,d4 ,in reference to this diminution of power at increased distances from the poles1 he states that in a circuit of ten inches of water1 solution of sulphate of potassa placed four inches from the positive pole1 did not decompose2 whereas when only two inches from that pole1 it did render up its elements,e4 ,a ,philosophical ,transactions1 #ahjg1 pp4 #bi1 #cj4 ,b ,ibid4 p4 #ci4 ,c ,ibid4 p4 #bi4 ,d ,ibid4 p4 #db4 ,e ,ibid4 p4 #db4 #dhd4 ,when in #ahbf ,sir ,humphry ,davy wrote again on this subject1 he stated that he found nothing to alter in the fundamental theory laid down in the original communication,a1 and uses the terms attraction and repulsion apparently in the same sense as before,b4 ,a ,philosophical ,transactions1 #ahbf1 p4 #chc4 ,b ,ibid4 pp4 #chi1 #djg1 #aae4 #dhe4 ,messrs4 ,riffault and ,chompr experimented on this subject in #ahjg4 ,they came to the conclusion that the voltaic current caused decompositions throughout its whole course in the humid conductor1 not merely as preliminary to the recompositions spoken of by ,grotthuss and ,davy1 but producing final separation of the elements in the course of the current1 and elsewhere than at the poles4 ,they considered the negative current as collecting and carrying the acids1 c4 to the positive pole1 and the positive current as doing the same duty with the bases1 and collecting them at the negative pole4 ,they likewise consider the currents as more powerful the nearer they are to their respective poles1 and state that the positive current is superior in power to the negative current,a4 ,a ,annales de ,chimie1 #ahjg1 tom4 lxiii4 p4 #hc1 c4 #dhf4 ,m4 ,biot is very cautious in expressing an opinion as to the cause of the separation of the elements of a compound body,a4 ,but as far as the effects can be understood1 he refers them to the opposite electrical states of the portions of the decomposing substance in the neighbourhood of the two poles4 ,the fluid is most positive at the positive pole2 that state gradually diminishes to the middle distance1 where the fluid is neutral or not electrical2 but from thence to the negative pole it becomes more and more negative,b4 ,when a particle of salt is decomposed at the negative pole1 the acid particle is considered as acquiring a negative electrical state from the pole1 stronger than that of the surrounding undecomposed particles1 and is therefore repelled from amongst them1 and from out of that portion of the liquid towards the positive pole1 towards which also it is drawn by the attraction of the pole itself and the particles of positive undecomposed fluid around it,c4 ,a ,prcis ,elmentaire de ,physique1 #cme dition1 #ahbd1 tom4 i4 p4 #fda4 ,b ,ibid4 p4 #fcg4 ,c ,ibid4 pp4 #fda1 #fdb4 #dhg4 ,m4 ,biot does not appear to admit the successive decompositions and recompositions spoken of by ,grotthuss1 ,davy1 c4 c42 but seems to consider the substance whilst in transit as combined with1 or rather attached to1 the electricity for the time,a1 and though it communicates this electricity to the surrounding undecomposed matter with which it is in contact1 yet it retains during the transit a little superiority with respect to that kind which it first received from the pole1 and is1 by virtue of that difference1 carried forward through the fluid to the opposite pole,b4 ,a ,prcis ,elmentaire de ,physique1 #cme dition1 #ahbd1 tom4 i4 p4 #fcf4 ,b ,ibid4 p1 #fdb4 #dhh4 ,this theory implies that decomposition takes place at both poles upon distinct portions of fluid1 and not at all in the intervening parts4 ,the latter serve merely as imperfect conductors1 which1 assuming an electric state1 urge particles electrified more highly at the poles through them in opposite directions1 by virtue of a series of ordinary electrical attractions and repulsions,a4 ,a ,prcis ,elmentaire de ,physique1 #cme dition1 #ahbd1 tom4 i4 pp4 #fch1 #fdb4 #dhi4 ,m4,a4 de la ,rive investigated this subject particularly1 and published a paper on it in #ahbe;,a4 ,he thinks those who have referred the phenomena to the attractive powers of the poles1 rather express the general fact than give any explication of it4 ,he considers the results as due to an actual combination of the elements1 or rather of half of them1 with the electricities passing from the poles in consequence of a kind of play of affinities between the matter and electricity,b4 ,the current from the positive pole combining with the hydrogen1 or the bases it finds there1 leaves the oxygen and acids at liberty1 but carries the substances it is united with across to the negative pole1 where1 because of the peculiar character of the metal as a conductor,c1 it is separated from them1 entering the metal and leaving the hydrogen or bases upon its surface4 ,in the same manner the electricity from the negative pole sets the hydrogen and bases which it finds there1 free1 but combines with the oxygen and acids1 carries them across to the positive pole1 and there deposits them,d4 ,in this respect ,m4 de la ,rive's hypothesis accords in part with that of ,,mm4 ,riffault and ,chompr 7#dhe474 ,a ,annales de ,chimie1 tom1 xxviii4 p4 #aij4 ,b ,ibid4 pp4 #bjj1 #bjb4 ,c ,ibid4 p4 #bjb4 ,d ,ibid4 p4 #bja4 #dij4 ,m4 de la ,rive considers the portions of matter which are decomposed to be those contiguous to both poles,a4 ,he does not admit with others the successive decompositions and recompositions in the whole course of the electricity through the humid conductor,b1 but thinks the middle parts are in themselves unaltered1 or at least serve only to conduct the two contrary currents of electricity and matter which set off from the opposite poles,c4 ,the decomposition1 therefore1 of a particle of water1 or a particle of salt1 may take place at either pole1 and when once effected1 it is final for the time1 no recombination taking place1 except the momentary union of the transferred particle with the electricity be so considered4 ,a ,annales de ,chimie1 tom1 xxviii4 pp4 #aig1 #aih4 ,b ,ibid4 pp4 #aib1 #aii4 ,c ,ibid4 p4 #bjj4 #dia4 ,the latest communication that ,i am aware of on the subject is by ,m4 ,hachette3 its date is ,october #ahcb;,a4 ,it is incidental to the description of the decomposition of water by the magneto-electric currents 7#cdf474 ,one of the results of the experiment is1 that it is not necessary1 as has been supposed1 that for the chemical decomposition of water1 the action of the two electricities1 positive and negative1 should be simultaneous4 ,a ,annales de ,chimie1 tom1 xxviii4 tom4 li4 p4 #gc4 #dib4 ,it is more than probable that many other views of electro-chemical decomposition may have been published1 and perhaps amongst them some which1 differing from those above1 might1 even in my own opinion1 were ,i acquainted with them1 obviate the necessity for the publication of my views4 ,if such be the case1 ,i have to regret my ignorance of them1 and apologize to the authors4 99 99 99 99 99 #dic4 ,that electro-chemical decomposition does not depend upon any direct attraction and repulsion of the poles 7meaning thereby the metallic terminations either of the voltaic battery1 or ordinary electrical machine arrangements 7#cab4717 upon the elements in contact with or near to them1 appeared very evident from the experiments made in air 7#dfb1 #dfe1 c471 when the substances evolved did not collect about any poles1 but1 in obedience to the direction of the current1 were evolved1 and ,i would say ejected1 at the extremities of the decomposing substance4 ,but notwithstanding the extreme dissimilarity in the character of air and metals1 and the almost total difference existing between them as to their mode of conducting electricity1 and becoming charged with it1 it might perhaps still be contended1 although quite hypothetically1 that the bounding portions of air were now the surfaces or places of attraction1 as the metals had been supposed to be before4 ,in illustration of this and other points1 ,i endeavoured to devise an arrangement by which ,i could decompose a body against a surface of water1 as well as against air or metal1 and succeeded in doing so unexceptionably in the following manner4 ,as the experiment for very natural reasons requires many precautions1 to be successful1 and will be referred to hereafter in illustration of the views ,i shall venture to give1 ,i must describe it minutely4 #did4 ,a glass basin 7fig4 #eb471 four inches in diameter and four inches deep1 had a division of mica a1 fixed across the upper part so as to descend one inch and a half below the edge1 and be perfectly water-tight at the sides3 a plate of platina b1 three inches wide1 was put into the basin on one side of the division a1 and retained there by a glass block below1 so that any gas produced by it in a future stage of the experiment should not ascend beyond the mica1 and cause currents in the liquid on that side4 ,a strong solution of sulphate of magnesia was carefully poured without splashing into the basin1 until it rose a little above the lower edge of the mica division a1 great care being taken that the glass or mica on the unoccupied or c side of the division in the figure1 should not be moistened by agitation of the solution above the level to which it rose4 ,a thin piece of clean cork1 well-wetted in distilled water1 was then carefully and lightly placed on the solution at the c side1 and distilled water poured gently on to it until a stratum the eighth of an inch in thickness appeared over the sulphate of magnesia2 all was then left for a few minutes1 that any solution adhering to the cork might sink away from it1 or be removed by the water on which it now floated2 and then more distilled water was added in a similar manner1 until it reached nearly to the top of the glass4 ,in this way solution of the sulphate occupied the lower part of the glass1 and also the upper on the right-hand side of the mica2 but on the left-hand side of the division a stratum of water from c to d1 one inch and a half in depth1 reposed upon it1 the two presenting1 when looked through horizontally1 a comparatively definite plane of contact4 ,a second platina pole e1 was arranged so as to be just under the surface of the water1 in a position nearly horizontal1 a little inclination being given to it1 that gas evolved during decomposition might escape3 the part immersed was three inches and a half long by one inch wide1 and about seven-eighths of an inch of water intervened between it and the solution of sulphate of magnesia4 #die4 ,the latter pole e was now connected with the negative end of a voltaic battery1 of forty pairs of plates four inches square1 whilst the former pole b was connected with the positive end4 ,there was action and gas evolved at both poles2 but from the intervention of the pure water1 the decomposition was very feeble compared to what the battery would have effected in a uniform solution4 ,after a little while 7less than a minute17 magnesia also appeared at the negative side3 it did not make its appearance at the negative metallic pole1 but in the water1 at the plane where the solution and the water met2 and on looking at it horizontally1 it could be there perceived lying in the water upon the solution1 not rising more than the fourth of an inch above the latter1 whilst the water between it and the negative pole was perfectly clear4 ,on continuing the action1 the bubbles of hydrogen rising upwards from the negative pole impressed a circulatory movement on the stratum of water1 upwards in the middle1 and downwards at the side1 which gradually gave an ascending form to the cloud of magnesia in the part just under the pole1 having an appearance as if it were there attracted to it2 but this was altogether an effect of the currents1 and did not occur until long after the phenomena looked for were satisfactorily ascertained4 #dif4 ,after a little while the voltaic communication was broken1 and the platina poles removed with as little agitation as possible from the water and solution1 for the purpose of examining the liquid adhering to them4 ,the pole c1 when touched by turmeric paper1 gave no traces of alkali1 nor could anything but pure water be found upon it4 ,the pole b1 though drawn through a much greater depth and quantity of fluid1 was found so acid as to give abundant evidence to litmus paper1 the tongue1 and other tests4 ,hence there had been no interference of alkaline salts in any way1 undergoing first decomposition1 and then causing the separation of the magnesia at a distance from the pole by mere chemical agencies4 ,this experiment was repeated again and again1 and always successfully4 #dig4 ,as1 therefore1 the substances evolved in cases of electrochemical decomposition may be made to appear against air 7#dfe4 #dfi471--which1 according to common language1 is not a conductor1 nor is decomposed1 or against water 7#die471 which is a conductor1 and can be decomposed1--as well as against the metal poles1 which are excellent conductors1 but undecomposable1 there appears but little reason to consider the phenomena generally1 as due to the attraction or attractive powers of the latter1 when used in the ordinary way1 since similar attractions can hardly be imagined in the former instances4 #dih4 ,it may be said that the surfaces of air or of water in these cases become the poles1 and exert attractive powers2 but what proof is there of that1 except the fact that the matters evolved collect there1 which is the point to be explained1 and cannot be justly quoted as its own explanation8 ,or it may be said1 that any section of the humid conductor1 as that in the present case1 where the solution and the water meet1 may be considered as representing the pole4 ,but such does not appear to me to be the view of those who have written on the subject1 certainly not of some of them1 and is inconsistent with the supposed laws which they have assumed1 as governing the diminution of power at increased distances from the poles4 #dii4 ,grotthuss1 for instance1 describes the poles as centres of attractive and repulsive forces 7#dha471 these forces varying inversely as the squares of the distances1 and says1 therefore1 that a particle placed anywhere between the poles will be acted upon by a constant force4 ,but the compound force1 resulting from such a combination as he supposes1 would be anything but a constant force2 it would evidently be a force greatest at the poles1 and diminishing to the middle distance4 ,grotthuss is right1 however1 in the fact1 according to my experiments 7#ejb4 #eje471 that the particles are acted upon by equal force everywhere in the circuit1 when the conditions of the experiment are the simplest possible2 but the fact is against his theory1 and is also1 ,i think1 against all theories that place the decomposing effect in the attractive power of the poles4 #ejj4 ,sir ,humphry ,davy1 who also speaks of the diminution of power with increase of distance from the poles,a 7#dhc471 supposes1 that when both poles are acting on substances to decompose them1 still the power of decomposition diminishes to the middle distance4 ,in this statement of fact he is opposed to ,grotthuss1 and quotes an experiment in which sulphate of potassa1 placed at different distances from the poles in a humid conductor of constant length1 decomposed when near the pole1 but not when at a distance4 ,such a consequence would necessarily result theoretically from considering the poles as centres of attraction and repulsion2 but ,i have not found the statement borne out by other experiments 7#eje472 and in the one quoted by him the effect was doubtless due to some of the many interfering causes of variation which attend such investigations4 ,a ,philosophical ,transactions1 #ahjg1 p4 #db4 #eja4 ,a glass vessel had a platina plate fixed perpendicularly across it1 so as to divide it into two cells3 a head of mica was fixed over it1 so as to collect the gas it might evolve during experiments2 then each cell1 and the space beneath the mica1 was filled with dilute sulphuric acid4 ,two poles were provided1 consisting each of a platina wire terminated by a plate of the same metal2 each was fixed into a tube passing through its upper end by an air-tight joint1 that it might be moveable1 and yet that the gas evolved at it might be collected4 ,the tubes were filled with the acid1 and one immersed in each cell4 ,each platina pole was equal in surface to one side of the dividing plate in the middle glass vessel1 and the whole might be considered as an arrangement between the poles of the battery of a humid decomposable conductor divided in the middle by the interposed platina diaphragm4 ,it was easy1 when required1 to draw one of the poles further up the tube1 and then the platina diaphragm was no longer in the middle of the humid conductor4 ,but whether it were thus arranged at the middle1 or towards one side1 it always evolved a quantity of oxygen and hydrogen equal to that evolved by both the extreme plates,a4 ,a ,there are certain precautions1 in this and such experiments1 which can only be understood and guarded against by a knowledge of the phenomena to be described in the first part of the ,sixth ,series of these ,researches4 #ejb4 ,if the wires of a galvanometer be terminated by plates1 and these be immersed in dilute acid1 contained in a regularly formed rectangular glass trough1 connected at each end with a voltaic battery by poles equal to the section of the fluid1 a part of the electricity will pass through the instrument and cause a certain deflection4 ,and if the plates are always retained at the same distance from each other and from the sides of the trough1 are always parallel to each other1 and uniformly placed relative to the fluid1 then1 whether they are immersed near the middle of the decomposing solution1 or at one end1 still the instrument will indicate the same deflection1 and consequently the same electric influence4 #ejc4 ,it is very evident1 that when the width of the decomposing conductor varies1 as is always the case when mere wires or plates1 as poles1 are dipped into or are surrounded by solution1 no constant expression can be given as to the action upon a single particle placed in the course of the current1 nor any conclusion of use1 relative to the supposed attractive or repulsive force of the poles1 be drawn4 ,the force will vary as the distance from the pole varies2 as the particle is directly between the poles1 or more or less on one side2 and even as it is nearer to or further from the sides of the containing vessels1 or as the shape of the vessel itself varies2 and1 in fact1 by making variations in the form of the arrangement1 the force upon any single particle may be made to increase1 or diminish1 or remain constant1 whilst the distance between the particle and the pole shall remain the same2 or the force may be made to increase1 or diminish1 or remain constant1 either as the distance increases or as it diminishes4 #ejd4 ,from numerous experiments1 ,i am led to believe the following general expression to be correct2 but ,i purpose examining it much further1 and would therefore wish not to be considered at present as pledged to its accuracy4 ,the sum of chemical decomposition is constant for any section taken across a decomposing conductor1 uniform in its nature1 at whatever distance the poles may be from each other or from the section2 or however that section may intersect the currents1 whether directly across them1 or so oblique as to reach almost from pole to pole1 or whether it be plane1 or curved1 or irregular in the utmost degree2 provided the current of electricity be retained constant in quantity 7#cgg471 and that the section passes through every part of the current through the decomposing conductor4 #eje4 ,i have reason to believe that the statement might be made still more general1 and expressed thus3 ,that for a constant quantity of electricity1 whatever the decomposing conductor may be1 whether water1 saline solutions1 acids1 fused bodies1 c41 the amount of electro-chemical action is also a constant quantity1 i4e4 would always be equivalent to a standard chemical effect founded upon ordinary chemical affinity4 ,i have this investigation in hand1 with several others1 and shall be prepared to give it in the next series but one of these ,researches4 #ejf4 ,many other arguments might be adduced against the hypotheses of the attraction of the poles being the cause of electro-chemical decomposition2 but ,i would rather pass on to the view ,i have thought more consistent with facts1 with this single remark2 that if decomposition by the voltaic battery depended upon the attraction of the poles1 or the parts about them1 being stronger than the mutual attraction of the particles separated1 it would follow that the weakest electrical attraction was stronger than1 if not the strongest1 yet very strong chemical attraction1 namely1 such as exists between oxygen and hydrogen1 potassium and oxygen1 chlorine and sodium1 acid and alkali1 c41 a consequence which1 although perhaps not impossible1 seems in the present state of the subject very unlikely4 #ejg4 ,the view which ,m4 de la ,rive has taken 7#dhi471 and also ,,mm4 ,riffault and ,chompr 7#dhe471 of the manner in which electro-chemical decomposition is effected1 is very different to that already considered1 and is not affected by either the arguments or facts urged against the latter4 ,considering it as stated by the former philosopher1 it appears to me to be incompetent to account for the experiments of decomposition against surfaces of air 7#dfb4 #dfi47 and water 7#die471 which ,i have described2 for if the physical differences between metals and humid conductors1 which ,m4 de la ,rive supposes to account for the transmission of the compound of matter and electricity in the latter1 and the transmission of the electricity only with the rejection of the matter in the former1 be allowed for a moment1 still the analogy of air to metal is1 electrically considered1 so small1 that instead of the former replacing the latter 7#dfb471 an effect the very reverse might have been expected4 ,or if even that were allowed1 the experiment with water 7#die471 at once sets the matter at rest1 the decomposing pole being now of a substance which is admitted as competent to transmit the assumed compound of electricity and matter4 #ejh4 ,with regard to the views of ,,mm4 ,riffault and ,chompr 7#dhe471 the occurrence of decomposition alone in the course of the current is so contrary to the well-known effects obtained in the forms of experiment adopted up to this time1 that it must be proved before the hypothesis depending on it need be considered4 #eji4 ,the consideration of the various theories of electro-chemical decomposition1 whilst it has made me diffident1 has also given me confidence to add another to the number2 for it is because the one ,i have to propose appears1 after the most attentive consideration1 to explain and agree with the immense collection of facts belonging to this branch of science1 and to remain uncontradicted by1 or unopposed to1 any of them1 that ,i have been encouraged to give it4 #eaj4 ,electro-chemical decomposition is well known to depend essentially upon the current of electricity4 ,i have shown that in certain cases 7#cge47 the decomposition is proportionate to the quantity of electricity passing1 whatever may be its intensity or its source1 and that the same is probably true for all cases 7#cgg471 even when the utmost generality is taken on the one hand1 and great precision of expression on the other 7#eje474 #eaa4 ,in speaking of the current1 ,i find myself obliged to be still more particular than on a former occasion 7#bhc471 in consequence of the variety of views taken by philosophers1 all agreeing in the effect of the current itself4 ,some philosophers1 with ,franklin1 assume but one electric fluid2 and such must agree together in the general uniformity and character of the electric current4 ,others assume two electric fluids2 and here singular differences have arisen4 #eab4 ,,mm4 ,riffault and ,chompr1 for instance1 consider the positive and negative currents each as causing decomposition1 and state that the positive current is more powerful than the negative current,a1 the nitrate of soda being1 under similar circumstances1 decomposed by the former1 but not by the latter4 ,a ,annales de ,chimie1 #ahjg1 tom1 lxiii4 p4 #hd4 #eac4 ,m4 ,hachette states,a that it is not necessary1 as has been believed1 that the action of the two electricities1 positive and negative1 should be simultaneous for the decomposition of water4 ,the passage implying1 if ,i have caught the meaning aright1 that one electricity can be obtained1 and can be applied in effecting decompositions1 independent of the other4 ,a ,annales de ,chimie1 #ahcb1 tom4 li4 p4 #gc4 #ead4 ,the view of ,m4 de la ,rive to a certain extent agrees with that of ,m4 ,hachette1 for he considers that the two electricities decompose separate portions of water 7#dij47;,a4 ,in one passage he speaks of the two electricities as two influences1 wishing perhaps to avoid offering a decided opinion upon the independent existence of electric fluids2 but as these influences are considered as combining with the elements set free as by a species of chemical affinity1 and for the time entirely masking their character1 great vagueness of idea is thus introduced1 inasmuch as such a species of combination can only be conceived to take place between things having independent existences4 ,the two elementary electric currents1 moving in opposite directions1 from pole to pole1 constitute the ordinary voltaic current4 ,a ,annales de ,chimie1 #ahbe1 tom1 xxviii4 pp4 #aig1 #bja4 #eae4 ,m4 ,grotthuss is inclined to believe that the elements of water1 when about to separate at the poles1 combine with the electricities1 and so become gases4 ,m4 de la ,rive's view is the exact reverse of this3 whilst passing through the fluid1 they are1 according to him1 compounds with the electricities2 when evolved at the poles1 they are de-electrified4 #eaf4 ,i have sought amongst the various experiments quoted in support of these views1 or connected with electro-chemical decompositions or electric currents1 for any which might be considered as sustaining the theory of two electricities rather than that of one1 but have not been able to perceive a single fact which could be brought forward for such a purpose3 or1 admitting the hypothesis of two electricities1 much less have ,i been able to perceive the slightest grounds for believing that one electricity in a current can be more powerful than the other1 or that it can be present without the other1 or that one can be varied or in the slightest degree affected1 without a corresponding variation in the other,a4 ,if1 upon the supposition of two electricities1 a current of one can be obtained without the other1 or the current of one be exalted or diminished more than the other1 we might surely expect some variation either of the chemical or magnetical effects1 or of both2 but no such variations have been observed4 ,if a current be so directed that it may act chemically in one part of its course1 and magnetically in another1 the two actions are always found to take place together4 ,a current has not1 to my knowledge1 been produced which could act chemically and not magnetically1 nor any which can act on the magnet1 and not at the same time chemically,b4 ,a ,see now in relation to this subject1 #afbg-afde4--;,dec4 #ahch4 ,b ,thermo-electric currents are of course no exception1 because when they fail to act chemically they also fail to be currents4 #eag4 ,judging from facts only1 there is not as yet the slightest reason for considering the influence which is present in what we call the electric current1--whether in metals or fused bodies or humid conductors1 or even in air1 flame1 and rarefied elastic media1--as a compound or complicated influence4 ,it has never been resolved into simpler or elementary influences1 and may perhaps best be conceived of as an axis of power having contrary forces1 exactly equal in amount1 in contrary directions4 99 99 99 99 99 #eah4 ,passing to the consideration of electro-chemical decomposition1 it appears to me that the effect is produced by an internal corpuscular action1 exerted according to the direction of the electric current1 and that it is due to a force either super to1 or giving direction to the ordinary chemical affinity of the bodies present4 ,the body under decomposition may be considered as a mass of acting particles1 all those which are included in the course of the electric current contributing to the final effect2 and it is because the ordinary chemical affinity is relieved1 weakened1 or partly neutralized by the influence of the electric current in one direction parallel to the course of the latter1 and strengthened or added to in the opposite direction1 that the combining particles have a tendency to pass in opposite courses4 #eai4 ,in this view the effect is considered as essentially dependent upon the mutual chemical affinity of the particles of opposite kinds4 ,particles aa1 fig4 #ec1 could not be transferred or travel from one pole ,n towards the other ,p1 unless they found particles of the opposite kind bb1 ready to pass in the contrary direction3 for it is by virtue of their increased affinity for those particles1 combined with their diminished affinity for such as are behind them in their course1 that they are urged forward3 and when any one particle a1 fig4 #ed1 arrives at the pole1 it is excluded or set free1 because the particle b of the opposite kind1 with which it was the moment before in combination1 has1 under the superinducing influence of the current1 a greater attraction for the particle a'1 which is before it in its course1 than for the particle a1 towards which its affinity has been weakened4 #ebj4 ,as far as regards any single compound particle1 the case may be considered as analogous to one of ordinary decomposition1 for in fig4 #ed1 a may be conceived to be expelled from the compound ab by the superior attraction of a' for b1 that superior attraction belonging to it in consequence of the relative position of a'b and a to the direction of the axis of electric power 7#eag47 superinduced by the current4 ,but as all the compound particles in the course of the current1 except those actually in contact with the poles1 act conjointly1 and consist of elementary particles1 which1 whilst they are in one direction expelling1 are in the other being expelled1 the case becomes more complicated1 but not more difficult of comprehension4 #eba4 ,it is not here assumed that the acting particles must be in a right line between the poles4 ,the lines of action which may be supposed to represent the electric currents passing through a decomposing liquid1 have in many experiments very irregular forms2 and even in the simplest case of two wires or points immersed as poles in a drop or larger single portion of fluid1 these lines must diverge rapidly from the poles2 and the direction in which the chemical affinity between particles is most powerfully modified 7#eai4 #ebj47 will vary with the direction of these lines1 according constantly with them4 ,but even in reference to these lines or currents1 it is not supposed that the particles which mutually affect each other must of necessity be parallel to them1 but only that they shall accord generally with their direction4 ,two particles1 placed in a line perpendicular to the electric current passing in any particular place1 are not supposed to have their ordinary chemical relations towards each other affected2 but as the line joining them is inclined one way to the current their mutual affinity is increased2 as it is inclined in the other direction it is diminished2 and the effect is a maximum1 when that line is parallel to the current,a4 ,a ,in reference to this subject see now electrolytic induction and discharge1 ,series ,,xii4 viii4 #acdc-acea1 c4--,dec4 #ahch4 #ebb4 ,that the actions1 of whatever kind they may be1 take place frequently in oblique directions is evident from the circumstance of those particles being included which in numerous cases are not in a line between the poles4 ,thus1 when wires are used as poles in a glass of solution1 the decompositions and recompositions occur to the right or left of the direct line between the poles1 and indeed in every part to which the currents extend1 as is proved by many experiments1 and must therefore often occur between particles obliquely placed as respects the current itself2 and when a metallic vessel containing the solution is made one pole1 whilst a mere point or wire is used for the other1 the decompositions and recompositions must frequently be still more oblique to the course of the currents4 #ebc4 ,the theory which ,i have ventured to put forth 7almost7 requires an admission1 that in a compound body capable of electro-chemical decomposition the elementary particles have a mutual relation to1 and influence upon each other1 extending beyond those with which they are immediately combined4 ,thus in water1 a particle of hydrogen in combination with oxygen is considered as not altogether indifferent to other particles of oxygen1 although they are combined with other particles of hydrogen2 but to have an affinity or attraction towards them1 which1 though it does not at all approach in force1 under ordinary circumstances1 to that by which it is combined with its own particle1 can1 under the electric influence1 exerted in a definite direction1 be made even to surpass it4 ,this general relation of particles already in combination to other particles with which they are not combined1 is sufficiently distinct in numerous results of a purely chemical character2 especially in those where partial decompositions only take place1 and in ,berthollet's experiments on the effects of quantity upon affinity3 and it probably has a direct relation to1 and connexion with1 attraction of aggregation1 both in solids and fluids4 ,it is a remarkable circumstance1 that in gases and vapours1 where the attraction of aggregation ceases1 there likewise the decomposing powers of electricity apparently cease1 and there also the chemical action of quantity is no longer evident4 ,it seems not unlikely1 that the inability to suffer decomposition in these cases may be dependent upon the absence of that mutual attractive relation of the particles which is the cause of aggregation4 #ebd4 ,i hope ,i have now distinctly stated1 although in general terms1 the view ,i entertain of the cause of electro-chemical decomposition1 as far as that cause can at present be traced and understood4 ,i conceive the effects to arise from forces which are internal1 relative to the matter under decomposition--and not external1 as they might be considered1 if directly dependent upon the poles4 ,i suppose that the effects are due to a modification1 by the electric current1 of the chemical affinity of the particles through or by which that current is passing1 giving them the power of acting more forcibly in one direction than in another1 and consequently making them travel by a series of successive decompositions and recompositions in opposite directions1 and finally causing their expulsion or exclusion at the boundaries of the body under decomposition1 in the direction of the current1 and that in larger or smaller quantities1 according as the current is more or less powerful 7#cgg474 ,i think1 therefore1 it would be more philosophical1 and more directly expressive of the facts1 to speak of such a body1 in relation to the current passing through it1 rather than to the poles1 as they are usually called1 in contact with it2 and say that whilst under decomposition1 oxygen1 chlorine1 iodine1 acids1 c41 are rendered at its negative extremity1 and combustibles1 metals1 alkalies1 bases1 c41 at its positive extremity 7#dfg471 ,i do not believe that a substance can be transferred in the electric current beyond the point where it ceases to find particles with which it can combine2 and ,i may refer to the experiments made in air 7#dfe47 and in water 7#die471 already quoted1 for facts illustrating these views in the first instance2 to which ,i will now add others4 #ebe4 ,in order to show the dependence of the decomposition and transfer of elements upon the chemical affinity of the substances present1 experiments were made upon sulphuric acid in the following manner4 ,dilute sulphuric acid was prepared3 its specific gravity was #a4jbab4 ,a solution of sulphate of soda was also prepared1 of such strength that a measure of it contained exactly as much sulphuric acid as an equal measure of the diluted acid just referred to4 ,a solution of pure soda1 and another of pure ammonia1 were likewise prepared1 of such strengths that a measure of either should be exactly neutralized by a measure of the prepared sulphuric acid4 #ebf4 ,four glass cups were then arranged1 as in fig4 #ee2 seventeen measures of the free sulphuric acid 7#ebe47 were put into each of the vessels a and b1 and seventeen measures of the solution of sulphate of soda into each of the vessels ,a and ,b4 ,asbestus1 which had been well-washed in acid1 acted upon by the voltaic pile1 well-washed in water1 and dried by pressure1 was used to connect a with b and ,a with ,b1 the portions being as equal as they could be made in quantity1 and cut as short as was consistent with their performing the part of effectual communications1 b and ,a were connected by two platina plates or poles soldered to the extremities of one wire1 and the cups a and ,b were by similar platina plates connected with a voltaic battery of forty pairs of plates four inches square1 that in a being connected with the negative1 and that in ,b with the positive pole4 ,the battery1 which was not powerfully charged1 was retained in communication above half an hour4 ,in this manner it was certain that the same electric current had passed through a b and ,a ,b1 and that in each instance the same quantity and strength of acid had been submitted to its action1 but in one case merely dissolved in water1 and in the other dissolved and also combined with an alkali4 #ebg4 ,on breaking the connexion with the battery1 the portions of asbestus were lifted out1 and the drops hanging at the ends allowed to fall each into its respective vessel4 ,the acids in a and b were then first compared1 for which purpose two evaporating dishes were balanced1 and the acid from a put into one1 and that from b into the other2 but as one was a little heavier than the other1 a small drop was transferred from the heavier to the lighter1 and the two rendered equal in weight4 ,being neutralized by the addition of the soda solution 7#ebe471 that from a1 or the negative vessel1 required #ae parts of the soda solution1 and that from b1 or the positive vessel1 required #af4c parts4 ,that the sum of these is not #cd parts is principally due to the acid removed with the asbestus2 but taking the mean of #ae4fe parts1 it would appear that a twenty-fourth part of the acid originally in the vessel a had passed1 through the influence of the electric current1 from a into b4 #ebh4 ,in comparing the difference of acid in ,a and ,b1 the necessary equality of weight was considered as of no consequence1 because the solution was at first neutral1 and would not1 therefore1 affect the test liquids1 and all the evolved acid would be in ,b1 and the free alkali in ,a4 ,the solution in ,a required #c4b measures of the prepared acid 7#ebe47 to neutralize it1 and the solution in ,b required also #c4b measures of the soda solution 7#ebe47 to neutralize it4 ,as the asbestus must have removed a little acid and alkali from the glasses1 these quantities are by so much too small2 and therefore it would appear that about a tenth of the acid originally in the vessel ,a had been transferred into ,b during the continuance of the electric action4 #ebi4 ,in another similar experiment1 whilst a thirty-fifth part of the acid passed from a to b2 in the free acid vessels1 between a tenth and an eleventh passed from ,a to ,b in the combined acid vessels4 ,other experiments of the same kind gave similar results4 #ecj4 ,the variation of electro-chemical decomposition1 the transfer of elements and their accumulation at the poles1 according as the substance submitted to action consists of particles opposed more or less in their chemical affinity1 together with the consequent influence of the latter circumstances1 are sufficiently obvious in these cases1 where sulphuric acid is acted upon in the same quantity by the same electric current1 but in one case opposed to the comparatively weak affinity of water for it1 and in the other to the stronger one of soda4 ,in the latter case the quantity transferred is from two and a half to three times what it is in the former2 and it appears therefore very evident that the transfer is greatly dependent upon the mutual action of the particles of the decomposing bodies,a4 ,a ,see the note to 7#fge471--;,dec4 #ahch4 #eca4 ,in some of the experiments the acid from the vessels a and b was neutralized by ammonia1 then evaporated to dryness1 heated to redness1 and the residue examined for sulphates4 ,in these cases more sulphate was always obtained from a than from b2 showing that it had been impossible to exclude saline bases 7derived from the asbestus1 the glass1 or perhaps impurities originally in the acid17 and that they had helped in transferring the acid into b4 ,but the quantity was small1 and the acid was principally transferred by relation to the water present4 #ecb4 ,i endeavoured to arrange certain experiments by which saline solutions should be decomposed against surfaces of water2 and at first worked with the electric machine upon a piece of bibulous paper1 or asbestus moistened in the solution1 and in contact at its two extremities with pointed pieces of paper moistened in pure water1 which served to carry the electric current to and from the solution in the middle piece4 ,but ,i found numerous interfering difficulties4 ,thus1 the water and solutions in the pieces of paper could not be prevented from mingling at the point where they touched4 ,again1 sufficient acid could be derived from the paper connected with the discharging train1 or it may be even from the air itself1 under the influence of electric action1 to neutralize the alkali developed at the positive extremity of the decomposing solution1 and so not merely prevent its appearance1 but actually transfer it on to the metal termination3 and1 in fact1 when the paper points were not allowed to touch there1 and the machine was worked until alkali was evolved at the delivering or positive end of the turmeric paper1 containing the sulphate of soda solution1 it was merely necessary to place the opposite receiving point of the paper connected with the discharging train1 which had been moistened by distilled water1 upon the brown turmeric point and press them together1 when the alkaline effect immediately disappeared4 #ecc4 ,the experiment with sulphate of magnesia already described 7#die47 is a case in point1 however1 and shows most clearly that the sulphuric acid and magnesia contributed to each other's transfer and final evolution1 exactly as the same acid and soda affected each other in the results just given 7#ebg1 c472 and that so soon as the magnesia advanced beyond the reach of the acid1 and found no other substance with which it could combine1 it appeared in its proper character1 and was no longer able to continue its progress towards the negative pole4 99 99 99 99 99 #ecd4 ,the theory ,i have ventured to put forth appears to me to explain all the prominent features of electro-chemical decomposition in a satisfactory manner4 #ece4 ,in the first place1 it explains why1 in all ordinary cases1 the evolved substances appear only at the poles2 for the poles are the limiting surfaces of the decomposing substance1 and except at them1 every particle finds other particles having a contrary tendency with which it can combine4 #ecf4 ,then it explains why1 in numerous cases1 the elements or evolved substances are not retained by the poles2 and this is no small difficulty in those theories which refer the decomposing effect directly to the attractive power of the poles4 ,if1 in accordance with the usual theory1 a piece of platina be supposed to have sufficient power to attract a particle of hydrogen from the particle of oxygen with which it was the instant before combined1 there seems no sufficient reason1 nor any fact1 except those to be explained1 which show why it should not1 according to analogy with all ordinary attractive forces1 as those of gravitation1 magnetism1 cohesion1 chemical affinity1 c4 retain that particle which it had just before taken from a distance and from previous combination4 ,yet it does not do so1 but allows it to escape freely4 ,nor does this depend upon its assuming the gaseous state1 for acids and alkalies1 c4 are left equally at liberty to diffuse themselves through the fluid surrounding the pole1 and show no particular tendency to combine with or adhere to the latter4 ,and though there are plenty of cases where combination with the pole does take place1 they do not at all explain the instances of non-combination1 and do not therefore in their particular action reveal the general principle of decomposition4 #ecg4 ,but in the theory that ,i have just given1 the effect appears to be a natural consequence of the action3 the evolved substances are expelled from the decomposing mass 7#eah4 #eai471 not drawn out by an attraction which ceases to act on one particle without any assignable reason1 while it continues to act on another of the same kind3 and whether the poles be metal1 water1 or air1 still the substances are evolved1 and are sometimes set free1 whilst at others they unite to the matter of the poles1 according to the chemical nature of the latter1 i4e4 their chemical relation to those particles which are leaving the substance under operation4 #ech4 ,the theory accounts for the transfer of elements in a manner which seems to me at present to leave nothing unexplained2 and it was1 indeed1 the phenomena of transfer in the numerous cases of decomposition of bodies rendered fluid by heat 7#chj4 #djb471 which1 in conjunction with the experiments in air1 led to its construction4 ,such cases as the former where binary compounds of easy decomposability are acted upon1 are perhaps the best to illustrate the theory4 #eci4 ,chloride of lead1 for instance1 fused in a bent tube 7#djj471 and decomposed by platina wires1 evolves lead1 passing to what is usually called the negative pole1 and chlorine1 which being evolved at the positive pole1 is in part set free1 and in part combines with the platina4 ,the chloride of platina formed1 being soluble in the chloride of lead1 is subject to decomposition1 and the platina itself is gradually transferred across the decomposing matter1 and found with the lead at the negative pole4 #edj4 ,iodide of lead evolves abundance of lead at the negative pole1 and abundance of iodine at the positive pole4 #eda4 ,chloride of silver furnishes a beautiful instance1 especially when decomposed by silver wire poles4 ,upon fusing a portion of it on a piece of glass1 and bringing the poles into contact with it1 there is abundance of silver evolved at the negative pole1 and an equal abundance absorbed at the positive pole1 for no chlorine is set free3 and by careful management1 the negative wire may be withdrawn from the fused globule as the silver is reduced there1 the latter serving as the continuation of the pole1 until a wire or thread of revived silver1 five or six inches in length1 is produced2 at the same time the silver at the positive pole is as rapidly dissolved by the chlorine1 which seizes upon it1 so that the wire has to be continually advanced as it is melted away4 ,the whole experiment includes the action of only two elements1 silver and chlorine1 and illustrates in a beautiful manner their progress in opposite directions1 parallel to the electric current1 which is for the time giving a uniform general direction to their mutual affinities 7#ebd474 #edb4 ,according to my theory1 an element or a substance not decomposable under the circumstances of the experiment1 7as for instance1 a dilute acid or alkali17 should not be transferred1 or pass from pole to pole1 unless it be in chemical relation to some other element or substance tending to pass in the opposite direction1 for the effect is considered as essentially due to the mutual relation of such particles4 ,but the theories attributing the determination of the elements to the attractions and repulsions of the poles require no such condition1 i4e4 there is no reason apparent why the attraction of the positive pole1 and the repulsion of the negative pole1 upon a particle of free acid1 placed in water between them1 should not 7with equal currents of electricity7 be as strong as if that particle were previously combined with alkali2 but1 on the contrary1 as they have not a powerful chemical affinity to overcome1 there is every reason to suppose they would be stronger1 and would sooner bring the acid to rest at the positive pole,a4 ,yet such is not the case1 as has been shown by the experiments on free and combined acid 7#ebf4 #ebh474 ,a ,even ,sir ,humphry ,davy considered the attraction of the pole as being communicated from one particle to another of the same kind 7#dhc474 #edc4 ,neither does ,m4 de la ,rive's theory1 as ,i understand it1 require that the particles should be in combination3 it does not even admit1 where there are two sets of particles capable of combining with and passing by each other1 that they do combine1 but supposes that they travel as separate compounds of matter and electricity4 ,yet in fact the free substance cannot travel1 the combined one can4 #edd4 ,it is very difficult to find cases amongst solutions or fluids which shall illustrate this point1 because of the difficulty of finding two fluids which shall conduct1 shall not mingle1 and in which an element evolved from one shall not find a combinable element in the other4 ,solutions of acids or alkalies will not answer1 because they exist by virtue of an attraction2 and increasing the solubility of a body in one direction1 and diminishing it in the opposite1 is just as good a reason for transfer1 as modifying the affinity between the acids and alkalies themselves,a4 ,nevertheless the case of sulphate of magnesia is in point 7#did4 #die471 and shows that one element or principle only has no power of transference or of passing towards either pole4 ,a ,see the note to 7#fgj474--;,dec4 #ahch4 #ede4 ,many of the metals1 however1 in their solid state1 offer very fair instances of the kind required4 ,thus1 if a plate of platina be used as the positive pole in a solution of sulphuric acid1 oxygen will pass towards it1 and so will acid2 but these are not substances having such chemical relation to the platina as1 even under the favourable condition superinduced by the current 7#eah4 #ebd471 to combine with it2 the platina therefore remains where it was first placed1 and has no tendency to pass towards the negative pole4 ,but if a plate of iron1 zinc or copper1 be substituted for the platina1 then the oxygen and acid can combine with these1 and the metal immediately begins to travel 7as an oxide7 to the opposite pole1 and is finally deposited there4 ,or if1 retaining the platina pole1 a fused chloride1 as of lead1 zinc1 silver1 c41 be substituted for the sulphuric acid1 then1 as the platina finds an element it can combine with1 it enters into union1 acts as other elements do in cases of voltaic decomposition1 is rapidly transferred across the melted matter1 and expelled at the negative pole4 #edf4 ,i can see but little reason in the theories referring the electro-chemical decomposition to the attractions and repulsions of the poles1 and ,i can perceive none in ,m4 de la ,rive's theory1 why the metal of the positive pole should not be transferred across the intervening conductor1 and deposited at the negative pole1 even when it cannot act chemically upon the element of the fluid surrounding it4 ,it cannot be referred to the attraction of cohesion preventing such an effect2 for if the pole be made of the lightest spongy platina1 the effect is the same4 ,or if gold precipitated by sulphate of iron be diffused through the solution1 still accumulation of it at the negative pole will not take place2 and yet the attraction of cohesion is almost perfectly overcome1 the particles are in it so small as to remain for hours in suspension1 and are perfectly free to move by the slightest impulse towards either pole2 and if in relation by chemical affinity to any substance present1 are powerfully determined to the negative pole,a4 ,a ,in making this experiment1 care must be taken that no substance be present that can act chemically on the gold4 ,although ,i used the metal very carefully washed1 and diffused through dilute sulphuric acid1 yet in the first instance ,i obtained gold at the negative pole1 and the effect was repeated when the platina poles were changed4 ,but on examining the clear liquor in the cell1 after subsidence of the metallic gold1 ,i found a little of that metal in solution1 and a little chlorine was also present4 ,i therefore well washed the gold which had thus been subjected to voltaic action1 diffused it through other pure dilute sulphuric acid1 and then found1 that on subjecting it to the action of the pile1 not the slightest tendency to the negative pole could be perceived4 #edg4 ,in support of these arguments1 it may be observed1 that as yet no determination of a substance to a pole1 or tendency to obey the electric current1 has been observed 7that ,i am aware of17 in cases of mere mixture2 i4e4 a substance diffused through a fluid1 but having no sensible chemical affinity with it1 or with substances that may be evolved from it during the action1 does not in any case seem to be affected by the electric current4 ,pulverised charcoal was diffused through dilute sulphuric acid1 and subjected with the solution to the action of a voltaic battery1 terminated by platina poles2 but not the slightest tendency of the charcoal to the negative pole could be observed1 ,sublimed sulphur was diffused through similar acid1 and submitted to the same action1 a silver plate being used as the negative pole2 but the sulphur had no tendency to pass to that pole1 the silver was not tarnished1 nor did any sulphuretted hydrogen appear4 ,the case of magnesia and water 7#die4 #ecc471 with those of comminuted metals in certain solutions 7#edf471 are also of this kind2 and1 in fact1 substances which have the instant before been powerfully determined towards the pole1 as magnesia from sulphate of magnesia1 become entirely indifferent to it the moment they assume their independent state1 and pass away1 diffusing themselves through the surrounding fluid4 #edh4 ,there are1 it is true1 many instances of insoluble bodies being acted upon1 as glass1 sulphate of baryta1 marble1 slate1 basalt1 c41 but they form no exception2 for the substances they give up are in direct and strong relation as to chemical affinity with those which they find in the surrounding solution1 so that these decompositions enter into the class of ordinary effects4 #edi4 ,it may be expressed as a general consequence1 that the more directly bodies are opposed to each other in chemical affinity1 the more ready is their separation from each other in cases of electro-chemical decomposition1 i4e4 provided other circumstances1 as insolubility1 deficient conducting power1 proportions1 c41 do not interfere4 ,this is well known to be the case with water and saline solutions2 and ,i have found it to be equally true with dry chlorides1 iodides1 salts1 c41 rendered subject to electro-chemical decomposition by fusion 7#djb474 ,so that in applying the voltaic battery for the purpose of decomposing bodies not yet resolved into forms of matter simpler than their own1 it must be remembered1 that success may depend not upon the weakness1 or failure upon the strength1 of the affinity by which the elements sought for are held together1 but contrariwise2 and then modes of application may be devised1 by which1 in association with ordinary chemical powers1 and the assistance of fusion 7#cid4 #dag471 we may be able to penetrate much further than at present into the constitution of our chemical elements4 #eej4 ,some of the most beautiful and surprising cases of electro-chemical decomposition and transfer which ,sir ,humphry ,davy described in his celebrated paper,a1 were those in which acids were passed through alkalies1 and alkalies or earths through acids,b2 and the way in which substances having the most powerful attractions for each other were thus prevented from combining1 or1 as it is said1 had their natural affinity destroyed or suspended throughout the whole of the circuit1 excited the utmost astonishment4 ,but if ,i be right in the view ,i have taken of the effects1 it will appear1 that that which made the wonder1 is in fact the essential condition of transfer and decomposition1 and that the more alkali there is in the course of an acid1 the more will the transfer of that acid be facilitated from pole to pole2 and perhaps a better illustration of the difference between the theory ,i have ventured1 and those previously existing1 cannot be offered than the views they respectively give of such facts as these4 ,a ,philosophical ,transactions1 #ahjg1 p4 #a4 ,b ,ibid4 p1 #bd1 c4 #eea4 ,the instances in which sulphuric acid could not be passed though baryta1 or baryta through sulphuric acid,a1 because of the precipitation of sulphate of baryta1 enter within the pale of the law already described 7#chj4 #dab471 by which liquidity is so generally required for conduction and decomposition4 ,in assuming the solid state of sulphate of baryta1 these bodies became virtually non-conductors to electricity of so low a tension as that of the voltaic battery1 and the power of the latter over them was almost infinitely diminished4 ,a ,philosophical ,transactions1 #ahjg1 p4 #be1 c4 #eeb4 ,the theory ,i have advanced accords in a most satisfactory manner with the fact of an element or substance finding its place of rest1 or rather of evolution1 sometimes at one pole and sometimes at the other4 ,sulphur illustrates this effect very well,a4 ,when sulphuric acid is decomposed by the pile1 sulphur is evolved at the negative pole2 but when sulphuret of silver is decomposed in a similar way 7#dcf471 then the sulphur appears at the positive pole2 and if a hot platina pole be used so as to vaporize the sulphur evolved in the latter case1 then the relation of that pole to the sulphur is exactly the same as the relation of the same pole to oxygen upon its immersion in water4 ,in both cases the element evolved is liberated at the pole1 but not retained by it2 but by virtue of its elastic1 uncombinable1 and immiscible condition passes away into the surrounding medium4 ,the sulphur is evidently determined in these opposite directions by its opposite chemical relations to oxygen and silver2 and it is to such relations generally that ,i have referred all electro-chemical phenomena4 ,where they do not exist1 no electro-chemical action can take place4 ,where they are strongest1 it is most powerful2 where they are reversed1 the direction of transfer of the substance is reversed with them4 ,a ,at #fha and #geg of ,series ,,vii1 will be found corrections of the statement here made respecting sulphur and sulphuric acid4 ,at present there is no well-ascertained fact which proves that the same body can go directly to either of the two poles at pleasure4--,dec4 #ahch4 #eec4 ,water may be considered as one of those substances which can be made to pass to either pole4 ,when the poles are immersed in dilute sulphuric acid 7#ebg471 acid passes towards the positive pole1 and water towards the negative pole2 but when they are immersed in dilute alkali1 the alkali passes towards the negative pole1 and water towards the positive pole4 #eed4 ,nitrogen is another substance which is considered as determinable to either pole2 but in consequence of the numerous compounds which it forms1 some of which pass to one pole1 and some to the other1 ,i have not always found it easy to determine the true circumstances of its appearance4 ,a pure strong solution of ammonia is so bad a conductor of electricity that it is scarcely more decomposable than pure water2 but if sulphate of ammonia be dissolved in it1 then decomposition takes place very well2 nitrogen almost pure1 and in some cases quite1 is evolved at the positive pole1 and hydrogen at the negative pole4 #eee4 ,on the other hand1 if a strong solution of nitrate of ammonia be decomposed1 oxygen appears at the positive pole1 and hydrogen1 with sometimes nitrogen1 at the negative pole4 ,if fused nitrate of ammonia be employed1 hydrogen appears at the negative pole1 mingled with a little nitrogen4 ,strong nitric acid yields plenty of oxygen at the positive pole1 but no gas 7only nitrous acid7 at the negative pole4 ,weak nitric acid yields the oxygen and hydrogen of the water present1 the acid apparently remaining unchanged4 ,strong nitric acid with nitrate of ammonia dissolved in it1 yields a gas at the negative pole1 of which the greater part is hydrogen1 but apparently a little nitrogen is present4 ,i believe1 that in some of these cases a little nitrogen appeared at the negative pole4 ,i suspect1 however1 that in all these1 and in all former cases1 the appearance of the nitrogen at the positive or negative pole is entirely a secondary effect1 and not an immediate consequence of the decomposing power of the electric current,a4 ,a ,refer for proof of the truth of this supposition to #gdh1 #geb1 c4--,dec4 #ahch4 #eef4 ,a few observations on what are called the poles of the voltaic battery now seem necessary4 ,the poles are merely the surfaces or doors by which the electricity enters into or passes out of the substance suffering decomposition4 ,they limit the extent of that substance in the course of the electric current1 being its terminations in that direction3 ,hence the elements evolved pass so far and no further4 #eeg4 ,metals make admirable poles1 in consequence of their high conducting power1 their immiscibility with the substances generally acted upon1 their solid form1 and the opportunity afforded of selecting such as are not chemically acted upon by ordinary substances4 #eeh4 ,water makes a pole of difficult application1 except in a few cases 7#did471 because of its small conducting power1 its miscibility with most of the substances acted upon1 and its general relation to them in respect to chemical affinity4 ,it consists of elements1 which in their electrical and chemical relations are directly and powerfully opposed1 yet combining to produce a body more neutral in its character than any other4 ,so that there are but few substances which do not come into relation1 by chemical affinity1 with water or one of its elements2 and therefore either the water or its elements are transferred and assist in transferring the infinite variety of bodies which1 in association with it1 can be placed in the course of the electric current4 ,hence the reason why it so rarely happens that the evolved substances rest at the first surface of the water1 and why it therefore does not exhibit the ordinary action of a pole4 #eei4 ,air1 however1 and some gases are free from the latter objection1 and may be used as poles in many cases 7#dfa1 c472 but1 in consequence of the extremely low degree of conducting power belonging to them1 they cannot be employed with the voltaic apparatus4 ,this limits their use2 for the voltaic apparatus is the only one as yet discovered which supplies sufficient quantity of electricity 7#cga4 #cgf47 to effect electro-chemical decomposition with facility4 #efj4 ,when the poles are liable to the chemical action of the substances evolved1 either simply in consequence of their natural relation to them1 or of that relation aided by the influence of the current 7#eah471 then they suffer corrosion1 and the parts dissolved are subject to transference1 in the same manner as the particles of the body originally under decomposition4 ,an immense series of phenomena of this kind might be quoted in support of the view ,i have taken of the cause of electro-chemical decomposition1 and the transfer and evolution of the elements4 ,thus platina being made the positive and negative poles in a solution of sulphate of soda1 has no affinity or attraction for the oxygen1 hydrogen1 acid1 or alkali evolved1 and refuses to combine with or retain them4 ,zinc can combine with the oxygen and acid2 at the positive pole it does combine1 and immediately begins to travel as oxide towards the negative pole4 ,charcoal1 which cannot combine with the metals1 if made the negative pole in a metallic solution1 refuses to unite to the bodies which are ejected from the solution upon its surface2 but if made the positive pole in a dilute solution of sulphuric acid1 it is capable of combining with the oxygen evolved there1 and consequently unites with it1 producing both carbonic acid and carbonic oxide in abundance4 #efa4 ,a great advantage is frequently supplied1 by the opportunity afforded amongst the metals of selecting a substance for the pole1 which shall or shall not be acted upon by the elements to be evolved4 ,the consequent use of platina is notorious4 ,in the decomposition of sulphuret of silver and other sulphurets1 a positive silver pole is superior to a platina one1 because in the former case the sulphur evolved there combines with the silver1 and the decomposition of the original sulphuret is rendered evident2 whereas in the latter case it is dissipated1 and the assurance of its separation at the pole not easily obtained4 #efb4 ,the effects which take place when a succession of conducting decomposable and undecomposable substances are placed in the electric circuit1 as1 for instance1 of wires and solutions1 or of air and solutions 7#dfe1 #dfi471 are explained in the simplest possible manner by the theoretical view ,i have given4 ,in consequence of the reaction of the constituents of each portion of decomposable matter1 affected as they are by the supervention of the electric current 7#ebd471 portions of the proximate or ultimate elements proceed in the direction of the current as far as they find matter of a contrary kind capable of effecting their transfer1 and being equally affected by them2 and where they cease to find such matter1 they are evolved in their free state1 i4e4 upon the surfaces of metal or air bounding the extent of decomposable matter in the direction of the current4 #efc4 ,having thus given my theory of the mode in which electro-chemical decomposition is effected1 ,i will refrain for the present from entering upon the numerous general considerations which it suggests1 wishing first to submit it to the test of publication and discussion4 ,royal ,institution1 ,june #ahcc4 ,,sixth ,,series4 #ab4 ,on the power of ,metals and other ,solids to induce the ,combination of ,gaseous ,bodies4 ,received ,november #cj1 #ahcc1--,read ,january #aa1 #ahcd4 #efd4 ,the conclusion at which ,i have arrived in the present communication may seem to render the whole of it unfit to form part of a series of researches in electricity2 since1 remarkable as the phenomena are1 the power which produces them is not to be considered as of an electric origin1 otherwise than as all attraction of particles may have this subtile agent for their common cause4 ,but as the effects investigated arose out of electrical researches1 as they are directly connected with other effects which are of an electric nature1 and must of necessity be understood and guarded against in a very extensive series of electro-chemical decompositions 7#gjg471 ,i have felt myself fully justified in describing them in this place4 #efe4 ,believing that ,i had proved 7by experiments hereafter to be described 7#gje4717 the constant and definite chemical action of a certain quantity of electricity1 whatever its intensity might be1 or however the circumstances of its transmission through either the body under decomposition or the more perfect conductors were varied1 ,i endeavoured upon that result to construct a new measuring instrument1 which from its use might be called1 at least provisionally1 a ,volta-electrometer 7#gci47;,a4 ,a ,or ,voltameter4--,dec4 #ahch4 #eff4 ,during the course of the experiments made to render the instrument efficient1 ,i was occasionally surprised at observing a deficiency of the gases resulting from the decompositions of water1 and at last an actual disappearance of portions which had been evolved1 collected1 and measured4 ,the circumstances of the disappearance were these4 ,a glass tube1 about twelve inches in length and #c_/dths of an inch in diameter1 had two platina poles fixed into its upper1 hermetically sealed1 extremity3 the poles1 where they passed through the glass1 were of wire2 but terminated below in plates1 which were soldered to the wires with gold 7,plate ,v4 fig4 #ef474 ,the tube was filled with dilute sulphuric acid1 and inverted in a cup of the same fluid2 a voltaic battery was connected with the two wires1 and sufficient oxygen and hydrogen evolved to occupy #d_/eths of the tube1 or by the graduation1 #aaf parts4 ,on separating the tube from the voltaic battery the volume of gas immediately began to diminish1 and in about five hours only #ac-a_/b parts remained1 and these ultimately disappeared4 #efg4 ,it was found by various experiments1 that this effect was not due to the escape or solution of the gas1 nor to recombination of the oxygen or hydrogen in consequence of any peculiar condition they might be supposed to possess under the circumstances2 but to be occasioned by the action of one or both of the poles within the tube upon the gas around them4 ,on disuniting the poles from the pile after they had acted upon dilute sulphuric acid1 and introducing them into separate tubes containing mixed oxygen and hydrogen1 it was found that the positive pole effected the union of the gases1 but the negative pole apparently not 7#ehh474 ,it was ascertained also that no action of a sensible kind took place between the positive pole with oxygen or hydrogen alone4 #efh4 ,these experiments reduced the phenomena to the consequence of a power possessed by the platina1 after it had been the positive pole of a voltaic pile1 of causing the combination of oxygen and hydrogen at common1 or even at low1 temperatures4 ,this effect is1 as far as ,i am aware1 altogether new1 and was immediately followed out to ascertain whether it was really of an electric nature1 and how far it would interfere with the determination of the quantities evolved in the cases of electro-chemical decomposition required in the fourteenth section of these ,researches4 #efi4 ,several platina plates were prepared 7fig4 #eg474 ,they were nearly half an inch wide1 and two inches and a half long3 some were #a_/bjj;dth of an inch1 others not more than #a_/fjj;dth1 whilst some were as much as #a_/gjth of an inch in thickness4 ,each had a piece of platina wire1 about seven inches long1 soldered to it by pure gold4 ,then a number of glass tubes were prepared3 they were about nine or ten inches in length1 #e_/hths of an inch in internal diameter1 were sealed hermetically at one extremity1 and were graduated4 ,into these tubes was put a mixture of two volumes of hydrogen and one of oxygen1 at the water pneumatic trough1 and when one of the plates described had been connected with the positive or negative pole of the voltaic battery for a given time1 or had been otherwise prepared1 it was introduced through the water into the gas within the tube2 the whole set aside in a test-glass 7fig4 #eh471 and left for a longer or shorter period1 that the action might be observed4 #egj4 ,the following result may be given as an illustration of the phenomenon to be investigated4 ,diluted sulphuric acid1 of the specific gravity #a4ccf1 was put into a glass jar1 in which was placed also a large platina plate1 connected with the negative end of a voltaic battery of forty pairs of four-inch plates1 with double coppers1 and moderately charged4 ,one of the plates above described 7#efi47 was then connected with the positive extremity1 and immersed in the same jar of acid for five minutes1 after which it was separated from the battery1 washed in distilled water1 and introduced through the water of the pneumatic trough into a tube containing the mixture of oxygen and hydrogen 7#efi474 ,the volume of gases immediately began to lessen1 the diminution proceeding more and more rapidly until about #c_/dths of the mixture had disappeared4 ,the upper end of the tube became quite warm1 the plate itself so hot that the water boiled as it rose over it2 and in less than a minute a cubical inch and a half of the gases were gone1 having been combined by the power of the platina1 and converted into water4 #ega4 ,this extraordinary influence acquired by the platina at the positive pole of the pile1 is exerted far more readily and effectively on oxygen and hydrogen than on any other mixture of gases that ,i have tried4 ,one volume of nitrous gas was mixed with a volume of hydrogen1 and introduced into a tube with a plate which had been made positive in the dilute sulphuric acid for four minutes 7#egj474 ,there was no sensible action in an hour3 being left for thirty-six hours1 there was a diminution of about one-eighth of the whole volume4 ,action had taken place1 but it had been very feeble4 #egb4 ,a mixture of two volumes of nitrous oxide with one volume of hydrogen was put with a plate similarly prepared into a tube 7#efi4 #egj474 ,this also showed no action immediately2 but in thirty-six hours nearly a fourth of the whole had disappeared1 i4e4 about half of a cubic inch4 ,by comparison with another tube containing the same mixture without a plate1 it appeared that a part of the diminution was due to solution1 and the other part to the power of the platina2 but the action had been very slow and feeble4 #egc4 ,a mixture of one volume olefiant gas and three volumes oxygen was not affected by such a platina plate1 even though left together for several days 7#fdj4 #fda474 #egd4 ,a mixture of two volumes carbonic oxide and one volume oxygen was also unaffected by the prepared platina plate in several days 7#fde1 c474 #ege4 ,a mixture of equal volumes of chlorine and hydrogen was used in several experiments1 with plates prepared in a similar manner 7#egj474 ,diminution of bulk soon took place2 but when after thirty-six hours the experiments were examined1 it was found that nearly all the chlorine had disappeared1 having been absorbed1 principally by the water1 and that the original volume of hydrogen remained unchanged4 ,no combination of the gases1 therefore1 had here taken place4 #egf4 ,reverting to the action of the prepared plates on mixtures of oxygen and hydrogen 7#egj471 ,i found that the power1 though gradually diminishing in all cases1 could still be retained for a period1 varying in its length with circumstances4 ,when tubes containing plates 7#efi47 were supplied with fresh portions of mixed oxygen and hydrogen as the previous portions were condensed1 the action was found to continue for above thirty hours1 and in some cases slow combination could be observed even after eighty hours2 but the continuance of the action greatly depended upon the purity of the gases used 7#fch474 #egg4 ,some plates 7#efi47 were made positive for four minutes in dilute sulphuric acid of specific gravity #a4ccf3 they were rinsed in distilled water1 after which two were put into a small bottle and closed up1 whilst others were left exposed to the air4 ,the plates preserved in the limited portion of air were found to retain their power after eight days1 but those exposed to the atmosphere had lost their force almost entirely in twelve hours1 and in some situations1 where currents existed1 in a much shorter time4 #egh4 ,plates were made positive for five minutes in sulphuric acid1 specific gravity #a4ccf4 ,one of these was retained in similar acid for eight minutes after separation from the battery3 it then acted on mixed oxygen and hydrogen with apparently undiminished vigour4 ,others were left in similar acid for forty hours1 and some even for eight days1 after the electrization1 and then acted as well in combining oxygen and hydrogen gas as those which were used immediately after electrization4 #egi4 ,the effect of a solution of caustic potassa in preserving the platina plates was tried in a similar manner4 ,after being retained in such a solution for forty hours1 they acted exceedingly well on oxygen and hydrogen1 and one caused such rapid condensation of the gases1 that the plate became much heated1 and ,i expected the temperature would have risen to ignition4 #ehj4 ,when similarly prepared plates 7#efi47 had been put into distilled water for forty hours1 and then introduced into mixed oxygen and hydrogen1 they were found to act but very slowly and feebly as compared with those which had been preserved in acid or alkali4 ,when1 however1 the quantity of water was but small1 the power was very little impaired after three or four days4 ,as the water had been retained in a wooden vessel1 portions of it were redistilled in glass1 and this was found to preserve prepared plates for a great length of time4 ,prepared plates were put into tubes with this water and closed up2 some of them1 taken out at the end of twenty-four days1 were found very active on mixed oxygen and hydrogen2 others1 which were left in the water for fifty-three days1 were still found to cause the combination of the gases4 ,the tubes had been closed only by corks4 #eha4 ,the act of combination always seemed to diminish1 or apparently exhaust1 the power of the platina plate4 ,it is true1 that in most1 if not all instances1 the combination of the gases1 at first insensible1 gradually increased in rapidity1 and sometimes reached to explosion2 but when the latter did not happen1 the rapidity of combination diminished2 and although fresh portions of gas were introduced into the tubes1 the combination went on more and more slowly1 and at last ceased altogether4 ,the first effect of an increase in the rapidity of combination depended in part upon the water flowing off from the platina plate1 and allowing a better contact with the gas1 and in part upon the heat evolved during the progress of the combination 7#fcj474 ,but notwithstanding the effect of these causes1 diminution1 and at last cessation of the power1 always occurred4 ,it must not1 however1 be unnoticed1 that the purer the gases subjected to the action of the plate1 the longer was its combining power retained4 ,with the mixture evolved at the poles of the voltaic pile1 in pure dilute sulphuric acid1 it continued longest2 and with oxygen and hydrogen1 of perfect purity1 it probably would not be diminished at all4 #ehb4 ,different modes of treatment applied to the platina plate1 after it had ceased to be the positive pole of the pile1 affected its power very curiously4 ,a plate which had been a positive pole in diluted sulphuric acid of specific gravity #a4ccf for four or five minutes1 if rinsed in water and put into mixed oxygen and hydrogen1 would act very well1 and condense perhaps one cubic inch and a half of gas in six or seven minutes2 but if that same plate1 instead of being merely rinsed1 had been left in distilled water for twelve or fifteen minutes1 or more1 it would rarely fail1 when put into the oxygen and hydrogen1 of becoming1 in the course of a minute or two1 ignited1 and would generally explode the gases4 ,occasionally the time occupied in bringing on the action extended to eight or nine minutes1 and sometimes even to forty minutes1 and yet ignition and explosion would result4 ,this effect is due to the removal of a portion of acid which otherwise adheres firmly to the plate ,a4 ,a ,in proof that this is the case1 refer to #ajch4--;,dec4 #ahch4 #ehc4 ,occasionally the platina plates 7#efi471 after being made the positive pole of the battery1 were washed1 wiped with filtering-paper or a cloth1 and washed and wiped again4 ,being then introduced into mixed oxygen and hydrogen1 they acted apparently as if they had been unaffected by the treatment4 ,sometimes the tubes containing the gas were opened in the air for an instant1 and the plates put in dry2 but no sensible difference in action was perceived1 except that it commenced sooner4 #ehd4 ,the power of heat in altering the action of the prepared platina plates was also tried 7#eie474 ,plates which had been rendered positive in dilute sulphuric acid for four minutes were well-washed in water1 and heated to redness in the flame of a spirit-lamp3 after this they acted very well on mixed oxygen and hydrogen4 ,others1 which had been heated more powerfully by the blowpipe1 acted afterwards on the gases1 though not so powerfully as the former4 ,hence it appears that heat does not take away the power acquired by the platina at the positive pole of the pile3 the occasional diminution of force seemed always referable to other causes than the mere heat4 ,if1 for instance1 the plate had not been well-washed from the acid1 or if the flame used was carbonaceous1 or was that of an alcohol lamp trimmed with spirit containing a little acid1 or having a wick on which salt1 or other extraneous matter1 had been placed1 then the power of the plate was quickly and greatly diminished 7#fcd4 #fcf474 #ehe4 ,this remarkable property was conferred upon platina when it was made the positive pole in sulphuric acid of specific gravity #a4ccf1 or when it was considerably weaker1 or when stronger1 even up to the strength of oil of vitriol4 ,strong and dilute nitric acid1 dilute acetic acid1 solutions of tartaric1 citric1 and oxalic acids1 were used with equal success4 ,when muriatic acid was used1 the plates acquired the power of condensing the oxygen and hydrogen1 but in a much inferior degree4 #ehf4 ,plates which were made positive in solution of caustic potassa did not show any sensible action upon the mixed oxygen and hydrogen4 ,other plates made positive in solutions of carbonates of potassa and soda exhibited the action1 but only in a feeble degree4 #ehg4 ,when a neutral solution of sulphate of soda1 or of nitre1 or of chlorate of potassa1 or of phosphate of potassa1 or acetate of potassa1 or sulphate of copper1 was used1 the plates1 rendered positive in them for four minutes1 and then washed in water1 acted very readily and powerfully on the mixed oxygen and hydrogen4 #ehh4 ,it became a very important point1 in reference to the cause of this action of the platina1 to determine whether the positive pole only could confer it 7#efg471 or whether1 notwithstanding the numerous contrary cases1 the negative pole might not have the power when such circumstances as could interfere with or prevent the action were avoided4 ,three plates were therefore rendered negative1 for four minutes in diluted sulphuric acid of specific gravity #a4ccf1 washed in distilled water1 and put into mixed oxygen and hydrogen4 ,all of them acted1 though not so strongly as they would have done if they had been rendered positive4 ,each combined about a cubical inch and a quarter of the gases in twenty-five minutes4 ,on every repetition of the experiment the same result was obtained2 and when the plates were retained in distilled water for ten or twelve minutes1 before being introduced into the gas 7#ehb471 the action was very much quickened4 #ehi4 ,but when there was any metallic or other substance present in the acid1 which could be precipitated on the negative plate1 then that plate ceased to act upon the mixed oxygen and hydrogen4 #eij4 ,these experiments led to the expectation that the power of causing oxygen and hydrogen to combine1 which could be conferred upon any piece of platina by making it the positive pole of a voltaic pile1 was not essentially dependent upon the action of the pile1 or upon any structure or arrangement of parts it might receive whilst in association with it1 but belonged to the platina at all times1 and was always effective when the surface was perfectly clean4 ,and though1 when made the positive pole of the pile in acids1 the circumstances might well be considered as those which would cleanse the surface of the platina in the most effectual manner1 it did not seem impossible that ordinary operations should produce the same result1 although in a less eminent degree4 #eia4 ,accordingly1 a platina plate 7#efi47 was cleaned by being rubbed with a cork1 a little water1 and some coal-fire ashes upon a glass plate3 being washed1 it was put into mixed oxygen and hydrogen1 and was found to act at first slowly1 and then more rapidly4 ,in an hour1 a cubical inch and a half had disappeared4 #eib4 ,other plates were cleaned with ordinary sand-paper and water2 others with chalk and water2 others with emery and water2 others1 again1 with black oxide of manganese and water2 and others with a piece of charcoal and water4 ,all of these acted in tubes of oxygen and hydrogen1 causing combination of the gases4 ,the action was by no means so powerful as that produced by plates having been in communication with the battery2 but from one to two cubical inches of the gases disappeared1 in periods extending from twenty-five to eighty or ninety minutes4 #eic4 ,upon cleaning the plates with a cork1 ground emery1 and dilute sulphuric acid1 they were found to act still better4 ,in order to simplify the conditions1 the cork was dismissed1 and a piece of platina foil used instead2 still the effect took place4 ,then the acid was dismissed1 and a solution of potassa used1 but the effect occurred as before4 #eid4 ,these results are abundantly sufficient to show that the mere mechanical cleansing of the surface of the platina is sufficient to enable it to exert its combining power over oxygen and hydrogen at common temperatures4 #eie4 ,i now tried the effect of heat in conferring this property upon platina 7#ehd474 ,plates which had no action on the mixture of oxygen and hydrogen were heated by the flame of a freshly trimmed spirit-lamp1 urged by a mouth blowpipe1 and when cold were put into tubes of the mixed gases3 they acted slowly at first1 but after two or three hours condensed nearly all the gases4 #eif4 ,a plate of platina1 which was about one inch wide and two and three-quarters in length1 and which had not been used in any of the preceding experiments1 was curved a little so as to enter a tube1 and left in a mixture of oxygen and hydrogen for thirteen hours3 not the slightest action or combination of the gases occurred4 ,it was withdrawn at the pneumatic trough from the gas through the water1 heated red-hot by the spirit-lamp and blowpipe1 and then returned when cold into the same portion of gas4 ,in the course of a few minutes diminution of the gases could be observed1 and in forty-five minutes about one cubical inch and a quarter had disappeared4 ,in many other experiments platina plates when heated were found to acquire the power of combining oxygen and hydrogen4 #eig4 ,but it happened not infrequently that plates1 after being heated1 showed no power of combining oxygen and hydrogen gases1 though left undisturbed in them for two hours4 ,sometimes also it would happen that a plate which1 having been heated to dull redness1 acted feebly1 upon being heated to whiteness ceased to act2 and at other times a plate which1 having been slightly heated1 did not act1 was rendered active by a more powerful ignition4 #eih4 ,though thus uncertain in its action1 and though often diminishing the power given to the plates at the positive pole of the pile 7#ehd471 still it is evident that heat can render platina active1 which before was inert 7#eie474 ,the cause of its occasional failure appears to be due to the surface of the metal becoming soiled1 either from something previously adhering to it1 which is made to adhere more closely by the action of the heat1 or from matter communicated from the flame of the lamp1 or from the air itself4 ,it often happens that a polished plate of platina1 when heated by the spirit-lamp and a blowpipe1 becomes dulled and clouded on its surface by something either formed or deposited there2 and this1 and much less than this1 is sufficient to prevent it from exhibiting the curious power now under consideration 7#fcd4 #fcf474 ,platina also has been said to combine with carbon2 and it is not at all unlikely that in processes of heating1 where carbon or its compounds are present1 a film of such a compound may be thus formed1 and thus prevent the exhibition of the properties belonging to pure platina,a4 ,a ,when heat does confer the property it is only by the destruction or dissipation of organic or other matter which had previously soiled the plate 7#fcb4 #fcc4 #fcd474--;,dec4 #ahch4 #eii4 ,the action of alkalies and acids in giving platina this property was now experimentally examined4 ,platina plates 7#efi47 having no action on mixed oxygen and hydrogen1 being boiled in a solution of caustic potassa1 washed1 and then put into the gases1 were found occasionally to act pretty well1 but at other times to fail4 ,in the latter case ,i concluded that the impurity upon the surface of the platina was of a nature not to be removed by the mere solvent action of the alkali1 for when the plates were rubbed with a little emery1 and the same solution of alkali 7#eib471 they became active4 #fjj4 ,the action of acids was far more constant and satisfactory4 ,a platina plate was boiled in dilute nitric acid3 being washed and put into mixed oxygen and hydrogen gases1 it acted well4 ,other plates were boiled in strong nitric acid for periods extending from half a minute to four minutes1 and then being washed in distilled water1 were found to act very well1 condensing one cubic inch and a half of gas in the space of eight or nine minutes1 and rendering the tube warm 7#egj474 #fja4 ,strong sulphuric acid was very effectual in rendering the platina active4 ,a plate 7#efi47 was heated in it for a minute1 then washed and put into the mixed oxygen and hydrogen1 upon which it acted as well as if it had been made the positive pole of a voltaic pile 7#egj474 #fjb4 ,plates which1 after being heated or electrized in alkali1 or after other treatment1 were found inert1 immediately received power by being dipped for a minute or two1 or even only for an instant1 into hot oil of vitriol1 and then into water4 #fjc4 ,when the plate was dipped into the oil of vitriol1 taken out1 and then heated so as to drive off the acid1 it did not act1 in consequence of the impurity left by the acid upon its surface4 #fjd4 ,vegetable acids1 as acetic and tartaric1 sometimes rendered inert platina active1 at other times not4 ,this1 ,i believe1 depended upon the character of the matter previously soiling the plates1 and which may easily be supposed to be sometimes of such a nature as to be removed by these acids1 and at other times not4 ,weak sulphuric acid showed the same difference1 but strong sulphuric acid 7#fja47 never failed in its action4 #fje4 ,the most favourable treatment1 except that of making the plate a positive pole in strong acid1 was as follows4 ,the plate was held over a spirit-lamp flame1 and when hot1 rubbed with a piece of potassa fusa 7caustic potash71 which melting1 covered the metal with a coat of very strong alkali1 and this was retained fused upon the surface for a second or two,a3 it was then put into water for four or five minutes to wash off the alkali1 shaken1 and immersed for about a minute in hot strong oil of vitriol2 from this it was removed into distilled water1 where it was allowed to remain ten or fifteen minutes to remove the last traces of acid 7#ehb474 ,being then put into a mixture of oxygen and hydrogen1 combination immediately began1 and proceeded rapidly2 the tube became warm1 the platina became red-hot1 and the residue of the gases was inflamed4 ,this effect could be repeated at pleasure1 and thus the maximum phenomenon could be produced without the aid of the voltaic battery4 ,a ,the heat need not be raised so much as to make the alkali tarnish the platina1 although if that effect does take place it does not prevent the ultimate action4 #fjf4 ,when a solution of tartaric or acetic acid was substituted1 in this mode of preparation1 for the sulphuric acid1 still the plate was found to acquire the same power1 and would often produce explosion in the mixed gases2 but the strong sulphuric acid was most certain and powerful4 #fjg4 ,if borax1 or a mixture of the carbonates of potash and soda1 be fused on the surface of a platina plate1 and that plate be well-washed in water1 it will be found to have acquired the power of combining oxygen and hydrogen1 but only in a moderate degree2 but if1 after the fusion and washing1 it be dipped in the hot sulphuric acid 7#fja471 it will become very active4 #fjh4 ,other metals than platina were then experimented with4 ,gold and palladium exhibited the power either when made the positive pole of the voltaic battery 7#egj471 or when acted on by hot oil of vitriol 7#fja474 ,when palladium is used1 the action of the battery or acid should be moderated1 as that metal is soon acted upon under such circumstances4 ,silver and copper could not be made to show any effect at common temperatures4 99 99 99 99 99 #fji4 ,there can remain no doubt that the property of inducing combination1 which can thus be conferred upon masses of platina and other metals by connecting them with the poles of the battery1 or by cleansing processes either of a mechanical or chemical nature1 is the same as that which was discovered by ,dbereiner,a1 in #ahbc1 to belong in so eminent a degree to spongy platina1 and which was afterwards so well experimented upon and illustrated by ,,mm4 ,dulong and ,thenard,b1 in #ahbc4 ,the latter philosophers even quote experiments in which a very fine platina wire1 which had been coiled up and digested in nitric1 sulphuric1 or muriatic acid1 became ignited when put into a jet of hydrogen gas,c4 ,this effect ,i can now produce at pleasure with either wires or plates by the processes described 7#egj4 #fja4 #fje472 and by using a smaller plate cut so that it shall rest against the glass by a few points1 and yet allow the water to flow off 7fig4 #ei471 the loss of heat is less1 the metal is assimilated somewhat to the spongy state1 and the probability of failure almost entirely removed4 ,a ,annales de ,chimie1 tom4 xxiv4 p4 #ic4 ,b ,ibid4 tom4 xxiii4 p4 #ddj2 tom4 xxiv4 p4 #chj4 ,c ,ibid4 tom4 xxiv4 p4 #chc4 #faj4 ,m4 ,dbereiner refers the effect entirely to an electric action4 ,he considers the platina and hydrogen as forming a voltaic element of the ordinary kind1 in which the hydrogen1 being very highly positive1 represents the zinc of the usual arrangement1 and like it1 therefore1 attracts oxygen and combines with it,a4 ,a tom4 xxiv4 pp4 #id1 #ie4 ,also ,bibliothque ,universelle1 tom4 xxiv4 p4 #ed4 #faa4 ,in the two excellent experimental papers by ,,mm4 ,dulong and ,thenard,a1 those philosophers show that elevation of temperature favours the action1 but does not alter its character2 ,sir ,humphry ,davy's incandescent platina wire being the same phenomenon with ,dbereiner's spongy platina4 ,they show that all metals have this power in a greater or smaller degree1 and that it is even possessed by such bodies as charcoal1 pumice1 porcelain1 glass1 rock crystal1 c41 when their temperatures are raised2 and that another of ,davy's effects1 in which oxygen and hydrogen had combined slowly together at a heat below ignition1 was really dependent upon the property of the heated glass1 which it has in common with the bodies named above4 ,they state that liquids do not show this effect1 at least that mercury1 at or below the boiling point1 has not the power2 that it is not due to porosity2 that the same body varies very much in its action1 according to its state2 and that many other gaseous mixtures besides oxygen and hydrogen are affected1 and made to act chemically1 when the temperature is raised4 ,they think it probable that spongy platina acquires its power from contact with the acid evolved during its reduction1 or from the heat itself to which it is then submitted4 ,a ,annales de ,chimie1 tom4 xxiii4 p4 #ddj2 tom4 xxiv4 p1 #chj4 #fab4 ,,mm4 ,dulong and ,thenard express themselves with great caution on the theory of this action2 but1 referring to the decomposing power of metals on ammonia when heated to temperatures not sufficient alone to affect the alkali1 they remark that those metals which in this case are most efficacious1 are the least so in causing the combination of oxygen and hydrogen2 whilst platina1 gold1 c41 which have least power of decomposing ammonia1 have most power of combining the elements of water3--from which they are led to believe1 that amongst gases1 some tend to unite under the influence of metals1 whilst others tend to separate1 and that this property varies in opposite directions with the different metals4 ,at the close of their second paper they observe1 that the action is of a kind that cannot be connected with any known theory2 and though it is very remarkable that the effects are transient1 like those of most electrical actions1 yet they state that the greater number of the results observed by them are inexplicable1 by supposing them to be of a purely electric origin4 #fac4 ,dr4 ,fusinieri has also written on this subject1 and given a theory which he considers as sufficient to account for the phenomena,a4 ,he expresses the immediate cause thus3 ,the platina determines upon its surface a continual renovation of concrete lamin of the combustible substance of the gases or vapours1 which flowing over it are burnt1 pass away1 and are renewed3 this combustion at the surface raises and sustains the temperature of the metal4 ,the combustible substance1 thus reduced into imperceptible lamin1 of which the concrete parts are in contact with the oxygen1 is presumed to be in a state combinable with the oxygen at a much lower temperature than when it is in the gaseous state1 and more in analogy with what is called the nascent condition4 ,that combustible gases should lose their elastic state1 and become concrete1 assuming the form of exceedingly attenuated but solid strata1 is considered as proved by facts1 some of which are quoted in the ,giornale di ,fisica for #ahbd;,b2 and though the theory requires that they should assume this state at high temperatures1 and though the similar films of aqueous and other matter are dissipated by the action of heat1 still the facts are considered as justifying the conclusion against all opposition of reasoning4 ,a ,giornale di ,fisica1 c41 #ahbe1 tom4 viii4 p4 #bei4 ,b pp4 #ach1 #cga4 #fad4 ,the power or force which makes combustible gas or vapour abandon its elastic state in contact with a solid1 that it may cover the latter with a thin stratum of its own proper substance1 is considered as being neither attraction nor affinity4 ,it is able also to extend liquids and solids in concrete lamin over the surface of the acting solid body1 and consists in a repulsion1 which is developed from the parts of the solid body by the simple fact of attenuation1 and is highest when the attenuation is most complete4 ,the force has a progressive development1 and acts most powerfully1 or at first1 in the direction in which the dimensions of the attenuated mass decrease1 and then in the direction of the angles or corners which from any cause may exist on the surface4 ,this force not only causes spontaneous diffusion of gases and other substances over the surface1 but is considered as very elementary in its nature1 and competent to account for all the phenomena of capillarity1 chemical affinity1 attraction of aggregation1 rarefaction1 ebullition1 volatilization1 explosion1 and other thermometric effects1 as well as inflammation1 detonation1 c4 c4 ,it is considered as a form of heat to which the term native calorie is given1 and is still further viewed as the principle of the two electricities and the two magnetisms4 #fae4 ,i have been the more anxious to give a correct abstract of ,dr4 ,fusinieri's view1 both because ,i cannot form a distinct idea of the power to which he refers the phenomena1 and because of my imperfect knowledge of the language in which the memoir is written4 ,i would therefore beg to refer those who pursue the subject to the memoir itself4 #faf4 ,not feeling1 however1 that the problem has yet been solved1 ,i venture to give the view which seems to me sufficient1 upon known principles1 to account for the effect4 #fag4 ,it may be observed of this action1 that1 with regard to platina1 it cannot be due to any peculiar1 temporary condition1 either of an electric or of any other nature3 the activity of plates rendered either positive or negative by the pole1 or cleaned with such different substances as acids1 alkalies1 or water2 charcoal1 emery1 ashes1 or glass2 or merely heated1 is sufficient to negative such an opinion4 ,neither does it depend upon the spongy and porous1 or upon the compact and burnished1 or upon the massive or the attenuated state of the metal1 for in any of these states it may be rendered effective1 or its action may be taken away4 ,the only essential condition appears to be a perfectly clean and metallic surface1 for whenever that is present the platina acts1 whatever its form and condition in other respects may be2 and though variations in the latter points will very much affect the rapidity1 and therefore the visible appearances and secondary effects1 of the action1 i4e4 the ignition of the metal and the inflammation of the gases1 they1 even in their most favourable state1 cannot produce any effect unless the condition of a clean1 pure1 metallic surface be also fulfilled4 #fah4 ,the effect is evidently produced by most1 if not all1 solid bodies1 weakly perhaps by many of them1 but rising to a high degree in platina4 ,dulong and ,thenard have very philosophically extended our knowledge of the property to its possession by all the metals1 and by earths1 glass1 stones1 c4 7#faa472 and every idea of its being a known and recognised electric action is in this way removed4 #fai4 ,all the phenomena connected with this subject press upon my mind the conviction that the effects in question are entirely incidental and of a secondary nature2 that they are dependent upon the natural conditions of gaseous elasticity1 combined with the exertion of that attractive force possessed by many bodies1 especially those which are solid1 in an eminent degree1 and probably belonging to all2 by which they are drawn into association more or less close1 without at the same time undergoing chemical combination1 though often assuming the condition of adhesion2 and which occasionally leads1 under very favourable circumstances1 as in the present instance1 to the combination of bodies simultaneously subjected to this attraction4 ,i am prepared myself to admit 7and probably many others are of the same opinion71 both with respect to the attraction of aggregation and of chemical affinity1 that the sphere of action of particles extends beyond those other particles with which they are immediately and evidently in union 7#ebc471 and in many cases produces effects rising into considerable importance3 and ,i think that this kind of attraction is a determining cause of ,dbereiner's effect1 and of the many others of a similar nature4 #fbj4 ,bodies which become wetted by fluids with which they do not combine chemically1 or in which they do not dissolve1 are simple and well-known instances of this kind of attraction4 #fba4 ,all those cases of bodies which being insoluble in water and not combining with it are hygrometric1 and condense its vapour around or upon their surface1 are stronger instances of the same power1 and approach a little nearer to the cases under investigation4 ,if pulverized clay1 protoxide or peroxide of iron1 oxide of manganese1 charcoal1 or even metals1 as spongy platina or precipitated silver1 be put into an atmosphere containing vapour of water1 they soon become moist by virtue of an attraction which is able to condense the vapour upon1 although not to combine it with1 the substances2 and if1 as is well known1 these bodies so damped be put into a dry atmosphere1 as1 for instance1 one confined over sulphuric acid1 or if they be heated1 then they yield up this water again almost entirely1 it not being in direct or permanent combination,a4 ,a ,i met at ,edinburgh with a case1 remarkable as to its extent1 of hygrometric action1 assisted a little perhaps by very slight solvent power4 ,some turf had been well-dried by long exposure in a covered place to the atmosphere1 but being then submitted to the action of a hydrostatic press1 it yielded1 by the mere influence of the pressure1 #ed per cent4 of water4 #fbb4 ,still better instances of the power ,i refer to1 because they are more analogous to the cases to be explained1 are furnished by the attraction existing between glass and air1 so well known to barometer and thermometer makers1 for here the adhesion or attraction is exerted between a solid and gases1 bodies having very different physical conditions1 having no power of combination with each other1 and each retaining1 during the time of action1 its physical state unchanged,a4 ,when mercury is poured into a barometer tube1 a film of air will remain between the metal and glass for months1 or1 as far as is known1 for years1 for it has never been displaced except by the action of means especially fitted for the purpose4 ,these consist in boiling the mercury1 or in other words1 of forming an abundance of vapour1 which coming in contact with every part of the glass and every portion of surface of the mercury1 gradually mingles with1 dilutes1 and carries off the air attracted by1 and adhering to1 those surfaces1 replacing it by other vapour1 subject to an equal or perhaps greater attraction1 but which when cooled condenses into the same liquid as that with which the tube is filled4 ,a ,fusinieri and ,bellani consider the air as forming solid concrete films in these cases4--,giornale di ,fisica1 tom4 viii1 p4 #bfb4 #ahbe4 #fbc4 ,extraneous bodies1 which1 acting as nuclei in crystallizing or depositing solutions1 cause deposition of substances on them1 when it does not occur elsewhere in the liquid1 seem to produce their effects by a power of the same kind1 i4e4 a power of attraction extending to neighbouring particles1 and causing them to become attached to the nuclei1 although it is not strong enough to make them combine chemically with their substance4 #fbd4 ,it would appear from many cases of nuclei in solutions1 and from the effects of bodies put into atmospheres containing the vapours of water1 or camphor1 or iodine1 c41 as if this attraction were in part elective1 partaking in its characters both of the attraction of aggregation and chemical affinity3 nor is this inconsistent with1 but agreeable to1 the idea entertained1 that it is the power of particles acting1 not upon others with which they can immediately and intimately combine1 but upon such as are either more distantly situated with respect to them1 or which1 from previous condition1 physical constitution1 or feeble relation1 are unable to enter into decided union with them4 #fbe4 ,then1 of all bodies1 the gases are those which might be expected to show some mutual action whilst jointly under the attractive influence of the platina or other solid acting substance4 ,liquids1 such as water1 alcohol1 c41 are in so dense and comparatively incompressible a state1 as to favour no expectation that their particles should approach much closer to each other by the attraction of the body to which they adhere1 and yet that attraction must 7according to its effects7 place their particles as near to those of the solid wetted body as they are to each other1 and in many cases it is evident that the former attraction is the stronger4 ,but gases and vapours are bodies competent to suffer very great changes in the relative distances of their particles by external agencies2 and where they are in immediate contact with the platina1 the approximation of the particles to those of the metal may be very great4 ,in the case of the hygrometric bodies referred to 7#fba471 it is sufficient to reduce the vapour to the fluid state1 frequently from atmospheres so rare that without this influence it would be needful to compress them by mechanical force into a bulk not more than #a_/ajth or even #a_/bjth of their original volume before the vapours would become liquids4 #fbf4 ,another most important consideration in relation to this action of bodies1 and which1 as far as ,i am aware1 has not hitherto been noticed1 is the condition of elasticity under which the gases are placed against the acting surface4 ,we have but very imperfect notions of the real and intimate conditions of the particles of a body existing in the solid1 the liquid1 and the gaseous state2 but when we speak of the gaseous state as being due to the mutual repulsions of the particles or of their atmospheres1 although we may err in imagining each particle to be a little nucleus to an atmosphere of heat1 or electricity1 or any other agent1 we are still not likely to be in error in considering the elasticity as dependent on mutuality of action4 ,now this mutual relation fails altogether on the side of the gaseous particles next to the platina1 and we might be led to expect priori a deficiency of elastic force there to at least one half2 for if1 as ,dalton has shown1 the elastic force of the particles of one gas cannot act against the elastic force of the particles of another1 the two being as vacua to each other1 so is it far less likely that the particles of the platina can exert any influence on those of the gas against it1 such as would be exerted by gaseous particles of its own kind4 #fbg4 ,but the diminution of power to one-half on the side of the gaseous body towards the metal is only a slight result of what seems to me to flow as a necessary consequence of the known constitution of gases4 ,an atmosphere of one gas or vapour1 however dense or compressed1 is in effect as a vacuum to another3 thus1 if a little water were put into a vessel containing a dry gas1 as air1 of the pressure of one hundred atmospheres1 as much vapour of the water would rise as if it were in a perfect vacuum4 ,here the particles of watery vapour appear to have no difficulty in approaching within any distance of the particles of air1 being influenced solely by relation to particles of their own kind2 and if it be so with respect to a body having the same elastic powers as itself1 how much more surely must it be so with particles1 like those of the platina1 or other limiting body1 which at the same time that they have not these elastic powers1 are also unlike it in nature6 ,hence it would seem to result that the particles of hydrogen or any other gas or vapour which are next to the platina1 c41 must be in such contact with it as if they were in the liquid state1 and therefore almost infinitely closer to it than they are to each other1 even though the metal be supposed to exert no attractive influence over them4 #fbh4 ,a third and very important consideration in favour of the mutual action of gases under these circumstances is their perfect miscibility4 ,if fluid bodies capable of combining together are also capable of mixture1 they do combine when they are mingled1 not waiting for any other determining circumstance2 but if two such gases as oxygen and hydrogen are put together1 though they are elements having such powerful affinity as to unite naturally under a thousand different circumstances1 they do not combine by mere mixture4 ,still it is evident that1 from their perfect association1 the particles are in the most favourable state possible for combination upon the supervention of any determining cause1 such either as the negative action of the platina in suppressing or annihilating1 as it were1 their elasticity on its side2 or the positive action of the metal in condensing them against its surface by an attractive force2 or the influence of both together4 #fbi4 ,although there are not many distinct cases of combination under the influence of forces external to the combining particles1 yet there are sufficient to remove any difficulty which might arise on that ground4 ,sir ,james ,hull found carbonic acid and lime to remain combined under pressure at temperatures at which they would not have remained combined if the pressure had been removed2 and ,i have had occasion to observe a case of direct combination in chlorine,a1 which being compressed at common temperatures will combine with water1 and form a definite crystalline hydrate1 incapable either of being formed or of existing if that pressure be removed4 ,a ,philosophical ,transactions1 #ahbc1 p4 #afa4 #fcj4 ,the course of events when platina acts upon1 and combines oxygen and hydrogen1 may be stated1 according to these principles1 as follows4 ,from the influence of the circumstances mentioned 7#fai4 c471 i4e4 the deficiency of elastic power and the attraction of the metal for the gases1 the latter1 when they are in association with the former1 are so far condensed as to be brought within the action of their mutual affinities at the existing temperature2 the deficiency of elastic power1 not merely subjecting them more closely to the attractive influence of the metal1 but also bringing them into a more favourable state for union1 by abstracting a part of that power 7upon which depends their elasticity17 which elsewhere in the mass of gases is opposing their combination4 ,the consequence of their combination is the production of the vapour of water and an elevation of temperature4 ,but as the attraction of the platina for the water formed is not greater than for the gases1 if so great1 7for the metal is scarcely hygrometric17 the vapour is quickly diffused through the remaining gases2 fresh portions of this latter1 therefore1 come into juxtaposition with the metal1 combine1 and the fresh vapour formed is also diffused1 allowing new portions of gas to be acted upon4 ,in this way the process advances1 but is accelerated by the evolution of heat1 which is known by experiment to facilitate the combination in proportion to its intensity1 and the temperature is thus gradually exalted until ignition results4 #fca4 ,the dissipation of the vapour produced at the surface of the platina1 and the contact of fresh oxygen and hydrogen with the metal1 form no difficulty in this explication4 ,the platina is not considered as causing the combination of any particles with itself1 but only associating them closely around it2 and the compressed particles are as free to move from the platina1 being replaced by other particles1 as a portion of dense air upon the surface of the globe1 or at the bottom of a deep mine1 is free to move by the slightest impulse1 into the upper and rarer parts of the atmosphere4 #fcb4 ,it can hardly be necessary to give any reasons why platina does not show this effect under ordinary circumstances4 ,it is then not sufficiently clean 7#fag471 and the gases are prevented from touching it1 and suffering that degree of effect which is needful to commence their combination at common temperatures1 and which they can only experience at its surface4 ,in fact1 the very power which causes the combination of oxygen and hydrogen1 is competent1 under the usual casual exposure of platina1 to condense extraneous matters upon its surface1 which soiling it1 take away for the time its power of combining oxygen and hydrogen1 by preventing their contact with it 7#eih474 #fcc4 ,clean platina1 by which ,i mean such as has been made the positive pole of a pile 7#egj471 or has been treated with acid 7#fje471 and has then been put into distilled water for twelve or fifteen minutes1 has a peculiar friction when one piece is rubbed against another4 ,it wets freely with pure water1 even after it has been shaken and dried by the heat of a spirit-lamp2 and if made the pole of a voltaic pile in a dilute acid1 it evolves minute bubbles from every part of its surface4 ,but platina in its common state wants that peculiar friction3 it will not wet freely with water as the clean platina does2 and when made the positive pole of a pile1 it for a time gives off large bubbles1 which seem to cling or adhere to the metal1 and are evolved at distinct and separate points of the surface4 ,these appearances and effects1 as well as its want of power on oxygen and hydrogen1 are the consequences1 and the indications1 of a soiled surface4 #fcd4 ,i found also that platina plates which had been cleaned perfectly soon became soiled by mere exposure to the air2 for after twenty-four hours they no longer moistened freely with water1 but the fluid ran up into portions1 leaving part of the surface bare1 whilst other plates which had been retained in water for the same time1 when they were dried 7#ehj47 did moisten1 and gave the other indications of a clean surface4 #fce4 ,nor was this the case with platina or metals only1 but also with earthy bodies1 ,rock crystal and obsidian would not wet freely upon the surface1 but being moistened with strong oil of vitriol1 then washed1 and left in distilled water to remove all the acid1 they did freely become moistened1 whether they were previously dry or whether they were left wet2 but being dried and left exposed to the air for twenty-four hours1 their surface became so soiled that water would not then adhere freely to it1 but ran up into partial portions4 ,wiping with a cloth 7even the cleanest7 was still worse than exposure to air2 the surface either of the minerals or metals immediately became as if it were slightly greasy4 ,the floating upon water of small particles of metals under ordinary circumstances is a consequence of this kind of soiled surface4 ,the extreme difficulty of cleaning the surface of mercury when it has once been soiled or greased1 is due to the same cause4 #fcf4 ,the same reasons explain why the power of the platina plates in some circumstances soon disappear1 and especially upon use3 ,,mm4 ,dulong and ,thenard have observed the same effect with the spongy metal,a1 as indeed have all those who have used ,dbereiner's instantaneous light machines4 ,if left in the air1 if put into ordinary distilled water1 if made to act upon ordinary oxygen and hydrogen1 they can still find in all these cases that minute portion of impurity which1 when once in contact with the surface of the platina1 is retained there1 and is sufficient to prevent its full action upon oxygen and hydrogen at common temperatures3 a slight elevation of temperature is again sufficient to compensate this effect1 and cause combination4 ,a ,annales de ,chimie1 tom4 xxiv4 p4 #chf4 #fcg4 ,no state of a solid body can be conceived more favourable for the production of the effect than that which is possessed by platina obtained from the ammonio-muriate by heat4 ,its surface is most extensive and pure1 yet very accessible to the gases brought in contact with it3 if placed in impurity1 the interior1 as ,thenard and ,dulong have observed1 is preserved clean by the exterior2 and as regards temperature1 it is so bad a conductor of heat1 because of its divided condition1 that almost all which is evolved by the combination of the first portions of gas is retained within the mass1 exalting the tendency of the succeeding portions to combine4 99 99 99 99 99 #fch4 ,i have now to notice some very extraordinary interferences with this phenomenon1 dependent1 not upon the nature or condition of the metal or other acting solid1 but upon the presence of certain substances mingled with the gases acted upon2 and as ,i shall have occasion to speak frequently of a mixture of oxygen and hydrogen1 ,i wish it always to be understood that ,i mean a mixture composed of one volume of oxygen to two volumes of hydrogen1 being the proportions that form water4 ,unless otherwise expressed1 the hydrogen was always that obtained by the action of dilute sulphuric acid on pure zinc1 and the oxygen that obtained by the action of heat from the chlorate of potassa4 #fci4 ,mixtures of oxygen and hydrogen with air1 containing one-fourth1 one-half1 and even two-thirds of the latter1 being introduced with prepared platina plates 7#egj4 #fje47 into tubes1 were acted upon almost as well as if no air were present3 the retardation was far less than might have been expected from the mere dilution and consequent obstruction to the contact of the gases with the plates4 ,in two hours and a half nearly all the oxygen and hydrogen introduced as mixture was gone4 #fdj4 ,but when similar experiments were made with olefiant gas 7the platina plates having been made the positive poles of a voltaic pile 7#egj47 in acid71 very different results occurred4 ,a mixture was made of #bi4b volumes hydrogen and #ad4f volumes oxygen1 being the proportions for water2 and to this was added another mixture of #c volumes oxygen and one volume olefiant gas1 so that the olefiant gas formed but #a_/djth part of the whole2 yet in this mixture the platina plate would not act in forty-five hours4 ,the failure was not for want of any power in the plate1 for when after that time it was taken out of this mixture and put into one of oxygen and hydrogen1 it immediately acted1 and in seven minutes caused explosion of the gas4 ,this result was obtained several times1 and when larger proportions of olefiant gas were used1 the action seemed still more hopeless4 #fda4 ,a mixture of forty-nine volumes oxygen and hydrogen 7#fch47 with one volume of olefiant gas had a well-prepared platina plate introduced4 ,the diminution of gas was scarcely sensible at the end of two hours1 during which it was watched2 but on examination twenty-four hours afterwards1 the tube was found blown to pieces4 ,the action1 therefore1 though it had been very much retarded1 had occurred at last1 and risen to a maximum4 #fdb4 ,with a mixture of ninety-nine volumes of oxygen and hydrogen 7#fch47 with one of olefiant gas1 a feeble action was evident at the end of fifty minutes2 it went on accelerating 7#fcj47 until the eighty-fifth minute1 and then became so intense that the gas exploded4 ,here also the retarding effect of the olefiant gas was very beautifully illustrated4 #fdc4 ,plates prepared by alkali and acid 7#fje47 produced effects corresponding to those just described4 #fdd4 ,it is perfectly clear from these experiments1 that olefiant gas1 even in small quantities1 has a very remarkable influence in preventing the combination of oxygen and hydrogen under these circumstances1 and yet without at all injuring or affecting the power of the platina4 #fde4 ,another striking illustration of similar interference may be shown in carbonic oxide2 especially if contrasted with carbonic acid4 ,a mixture of one volume oxygen and hydrogen 7#fch47 with four volumes of carbonic acid was affected at once by a platina plate prepared with acid1 c4 7#fje472 and in one hour and a quarter nearly all the oxygen and hydrogen was gone4 ,mixtures containing less carbonic acid were still more readily affected4 #fdf4 ,but when carbonic oxide was substituted for the carbonic acid1 not the slightest effect of combination was produced2 and when the carbonic oxide was only one-eighth of the whole volume1 no action occurred in forty and fifty hours4 ,yet the plates had not lost their power2 for being taken out and put into pure oxygen and hydrogen1 they acted well and at once4 #fdg4 ,two volumes of carbonic oxide and one of oxygen were mingled with nine volumes of oxygen and hydrogen 7#fch474 ,this mixture was not affected by a plate which had been made positive in acid1 though it remained in it fifteen hours4 ,but when to the same volumes of carbonic oxide and oxygen were added thirty-three volumes of oxygen and hydrogen1 the carbonic oxide being then only #a_/ahth part of the whole1 the plate acted1 slowly at first1 and at the end of forty-two minutes the gases exploded4 #fdh4 ,these experiments were extended to various gases and vapours1 the general results of which may be given as follow4 ,oxygen1 hydrogen1 nitrogen1 and nitrous oxide1 when used to dilute the mixture of oxygen and hydrogen1 did not prevent the action of the plates even when they made four-fifths of the whole volume of gas acted upon4 ,nor was the retardation so great in any case as might have been expected from the mere dilution of the oxygen and hydrogen1 and the consequent mechanical obstruction to its contact with the platina4 ,the order in which carbonic acid and these substances seemed to stand was as follows1 the first interfering least with the action2 nitrous oxide1 hydrogen1 carbonic acid1 nitrogen1 oxygen3 but it is possible the plates were not equally well prepared in all the cases1 and that other circumstances also were unequal2 consequently more numerous experiments would be required to establish the order accurately4 #fdi4 ,as to cases of retardation1 the powers of olefiant gas and carbonic oxide have been already described4 ,mixtures of oxygen and hydrogen1 containing from #a_/afth to #a_/bjth of sulphuretted hydrogen or phosphuretted hydrogen1 seemed to show a little action at first1 but were not further affected by the prepared plates1 though in contact with them for seventy hours4 ,when the plates were removed they had lost all power over pure oxygen and hydrogen1 and the interference of these gases was therefore of a different nature from that of the two former1 having permanently affected the plate4 #fej4 ,a small piece of cork was dipped in sulphuret of carbon and passed up through water into a tube containing oxygen and hydrogen 7#fch471 so as to diffuse a portion of its vapour through the gases4 ,a plate being introduced appeared at first to act a little1 but after sixty-one hours the diminution was very small4 ,upon putting the same plate into a pure mixture of oxygen and hydrogen1 it acted at once and powerfully1 having apparently suffered no diminution of its force4 #fea4 ,a little vapour of ether being mixed with the oxygen and hydrogen retarded the action of the plate1 but did not prevent it altogether4 ,a little of the vapour of the condensed oil-gas liquor,a retarded the action still more1 but not nearly so much as an equal volume of olefiant gas would have done4 ,in both these cases it was the original oxygen and hydrogen which combined together1 the ether and the oil-gas vapour remaining unaffected1 and in both cases the plates retained the power of acting on fresh oxygen and hydrogen4 ,a ,philosophical ,transactions1 #ahbe1 p4#ddj4 #feb4 ,spongy platina was then used in place of the plates1 and jets of hydrogen mingled with the different gases thrown against it in air4 ,the results were exactly of the same kind1 although presented occasionally in a more imposing form4 ,thus1 mixtures of one volume of olefiant gas or carbonic oxide with three of hydrogen could not heat the spongy platina when the experiments were commenced at common temperatures2 but a mixture of equal volumes of nitrogen and hydrogen acted very well1 causing ignition4 ,with carbonic acid the results were still more striking4 ,a mixture of three volumes of that gas with one of hydrogen caused ignition of the platina1 yet that mixture would not continue to burn from the jet when attempts were made to light it by a taper4 ,a mixture even of seven volumes of carbonic acid and one of hydrogen will thus cause the ignition of cold spongy platina1 and yet1 as if to supply a contrast1 than which none can be greater1 it cannot burn at a taper1 but causes the extinction of the latter4 ,on the other hand1 the mixtures of carbonic oxide or olefiant gas1 which can do nothing with the platina1 are inflamed by the taper1 burning well4 #fec4 ,hydrogen mingled with the vapour of ether or oil-gas liquor causes the ignition of the spongy platina4 ,the mixture with oil-gas burns with a flame far brighter than that of the mixture of hydrogen and olefiant gas already referred to1 so that it would appear that the retarding action of the hydrocarbons is not at all in proportion merely to the quantity of carbon present4 #fed4 ,in connexion with these interferences1 ,i must state1 that hydrogen itself1 prepared from steam passed over ignited iron1 was found when mingled with oxygen to resist the action of platina4 ,it had stood over water seven days1 and had lost all fetid smell2 but a jet of it would not cause the ignition of spongy platina1 commencing at common temperatures2 nor would it combine with oxygen in a tube either under the influence of a prepared plate or of spongy platina4 ,a mixture of one volume of this gas with three of pure hydrogen1 and the due proportion of oxygen1 was not affected by plates after fifty hours4 ,i am inclined to refer the effect to carbonic oxide present in the gas1 but have not had time to verify the suspicion4 ,the power of the plates was not destroyed 7#fdj4 #fdf474 #fee4 ,such are the general facts of these remarkable interferences4 ,whether the effect produced by such small quantities of certain gases depends upon any direct action which they may exert upon the particles of oxygen and hydrogen1 by which the latter are rendered less inclined to combine1 or whether it depends upon their modifying the action of the plate temporarily 7for they produce no real change on it71 by investing it through the agency of a stronger attraction than that of the hydrogen1 or otherwise1 remains to be decided by more extended experiments4 99 99 99 99 99 #fef4 ,the theory of action which ,i have given for the original phenomena appears to me quite sufficient to account for all the effects by reference to known properties1 and dispenses with the assumption of any new power of matter4 ,i have pursued this subject at some length1 as one of great consequence1 because ,i am convinced that the superficial actions of matter1 whether between two bodies1 or of one piece of the same body1 and the actions of particles not directly or strongly in combination1 are becoming daily more and more important to our theories of chemical as well as mechanical philosophy,a4 ,in all ordinary cases of combustion it is evident that an action of the kind considered1 occurring upon the surface of the carbon in the fire1 and also in the bright part of a flame1 must have great influence over the combinations there taking place4 ,a ,as a curious illustration of the influence of mechanical forces over chemical affinity1 ,i will quote the refusal of certain substances to effloresce when their surfaces are perfect1 which yield immediately upon the surface being broken1 ,if crystals of carbonate of soda1 or phosphate of soda1 or sulphate of soda1 having no part of their surfaces broken1 be preserved from external violence1 they will not effloresce4 ,i have thus retained crystals of carbonate of soda perfectly transparent and unchanged from ,september #ahbg to ,january #ahcc2 and crystals of sulphate of soda from ,may #ahcb to the present time1 ,november #ahcc4 ,if any part of the surface were scratched or broken1 then efflorescence began at that part1 and covered the whole4 ,the crystals were merely placed in evaporating basins and covered with paper4 #feg4 ,the condition of elasticity upon the exterior of the gaseous or vaporous mass already referred to 7#fbf4 #fbg471 must be connected directly with the action of solid bodies1 as nuclei1 on vapours1 causing condensation upon them in preference to any condensation in the vapours themselves2 and in the well-known effect of nuclei on solutions a similar condition may have existence 7#fbc471 for an analogy in condition exists between the parts of a body in solution1 and those of a body in the vaporous or gaseous state4 ,this thought leads us to the consideration of what are the respective conditions at the surfaces of contact of two portions of the same substance at the same temperature1 one in the solid or liquid1 and the other in the vaporous state2 as1 for instance1 steam and water4 ,it would seem that the particles of vapour next to the particles of liquid are in a different relation to the latter to what they would be with respect to any other liquid or solid substance2 as1 for instance1 mercury or platina1 if they were made to replace the water1 i4e4 if the view of independent action which ,i have taken 7#fbf4 #fbg47 as a consequence of ,dalton's principles1 be correct4 ,it would also seem that the mutual relation of similar particles1 and the indifference of dissimilar particles which ,dalton has established as a matter of fact amongst gases and vapours1 extends to a certain degree amongst solids and fluids1 that is1 when they are in relation by contact with vapours1 either of their own substance or of other bodies4 ,but though ,i view these points as of great importance with respect to the relations existing between different substances and their physical constitution in the solid1 liquid1 or gaseous state1 ,i have not sufficiently considered them to venture any strong opinions or statements here,a4 ,a ,in reference to this paragraph and also #fbf1 see a correction by ,dr4 ,c4 ,henry1 in his valuable paper on this curious subject4 ,philosophical ,magazine1 #ahce4 vol4 vi4 p4 #cje4--;,dec4 #ahch4 #feh4 ,there are numerous well-known cases1 in which substances1 such as oxygen and hydrogen1 act readily in their nascent state1 and produce chemical changes which they are not able to effect if once they have assumed the gaseous condition4 ,such instances are very common at the poles of the voltaic pile1 and are1 ,i think1 easily accounted for1 if it be considered that at the moment of separation of any such particle it is entirely surrounded by other particles of a different kind with which it is in close contact1 and has not yet assumed those relations and conditions which it has in its fully developed state1 and which it can only assume by association with other particles of its own kind4 ,for1 at the moment1 its elasticity is absent1 and it is in the same relation to particles with which it is in contact1 and for which it has an affinity1 as the particles of oxygen and hydrogen are to each other on the surface of clean platina 7#fbf4 #fbg474 #fei4 ,the singular effects of retardation produced by very small quantities of some gases1 and not by large quantities of others 7#fdj4 #fde4 #feb471 if dependent upon any relation of the added gas to the surface of the solid1 will then probably be found immediately connected with the curious phenomena which are presented by different gases when passing through narrow tubes at low pressures1 which ,i observed many years ago,a2 and this action of surfaces must1 ,i think1 influence the highly interesting phenomena of the diffusion of gases1 at least in the form in which it has been experimented upon by ,mr4 ,graham in #ahbi and #ahca;,b1 and also by ,dr4 ,mitchell of ,philadelphia,c in #ahcj4 ,it seems very probable that if such a substance as spongy platina were used1 another law for the diffusion of gases under the circumstances would come out than that obtained by the use of plaster of ,paris4 ,a ,quarterly ,journal of ,science1 #ahai1 vol4 vii4 p4 #ajf4 ,b ,quarterly ,journal of ,science1 vol4 xxviii4 p4 #gd1 and ,edinburgh ,transactions1 #ahca4 ,c ,journal of the ,royal ,institution for #ahca1 p4 #aja4 #ffj4 ,i intended to have followed this section by one on the secondary piles of ,ritter1 and the peculiar properties of the poles of the pile1 or of metals through which electricity has passed1 which have been observed by ,ritter1 ,van ,marum1 ,yelin1 ,de la ,rive1 ,marianini1 ,berzelius1 and others4 ,it appears to me that all these phenomena bear a satisfactory explanation on known principles1 connected with the investigation just terminated1 and do not require the assumption of any new state or new property4 ,but as the experiments advanced1 especially those of ,marianini1 require very careful repetition and examination1 the necessity of pursuing the subject of electro-chemical decomposition obliges me for a time to defer the researches to which ,i have just referred4 ,royal ,institution1 ,november #cj1 #ahcc4 ,,seventh ,,series4 #aa4 ,on ,electro-chemical ,decomposition1 continued4,a iv4 ,on some general conditions of ,electro-decomposition4 v4 ,on a new ,measurer of ,volta-electricity4 vi4 ,on the primary or secondary character of bodies evolved in ,electro-decomposition4 vii4 ,on the definite nature and extent of ,electro-chemical ,decompositions4 #ac4 ,on the absolute quantity of ,electricity associated with the particles or atoms of ,matter4 ,a ,refer to the note after #ajdg1 ,series ,,viii4--,dec4 #ahch4 ,received ,january #i1--,read ,january #bc1 ,february #f and #ac1 #ahcd4 ,preliminary4 #ffa4 ,the theory which ,i believe to be a true expression of the facts of electro-chemical decomposition1 and which ,i have therefore detailed in a former series of these ,researches1 is so much at variance with those previously advanced1 that ,i find the greatest difficulty in stating results1 as ,i think1 correctly1 whilst limited to the use of terms which are current with a certain accepted meaning4 ,of this kind is the term pole1 with its prefixes of positive and negative1 and the attached ideas of attraction and repulsion4 ,the general phraseology is that the positive pole attracts oxygen1 acids1 c41 or more cautiously1 that it determines their evolution upon its surface2 and that the negative pole acts in an equal manner upon hydrogen1 combustibles1 metals1 and bases4 ,according to my view1 the determining force is not at the poles1 but within the body under decomposition2 and the oxygen and acids are rendered at the negative extremity of that body1 whilst hydrogen1 metals1 c41 are evolved at the positive extremity 7#eah4 #ebd474 #ffb4 ,to avoid1 therefore1 confusion and circumlocution1 and for the sake of greater precision of expression than ,i can otherwise obtain1 ,i have deliberately considered the subject with two friends1 and with their assistance and concurrence in framing them1 ,i purpose henceforward using certain other terms1 which ,i will now define4 ,the poles1 as they are usually called1 are only the doors or ways by which the electric current passes into and out of the decomposing body 7#eef472 and they of course1 when in contact with that body1 are the limits of its extent in the direction of the current4 ,the term has been generally applied to the metal surfaces in contact with the decomposing substance2 but whether philosophers generally would also apply it to the surfaces of air 7#dfe4 #dga47 and water 7#dic471 against which ,i have effected electro-chemical decomposition1 is subject to doubt4 ,in place of the term pole1 ,i propose using that of ,electrode,a1 and ,i mean thereby that substance1 or rather surface1 whether of air1 water1 metal1 or any other body1 which bounds the extent of the decomposing matter in the direction of the electric current4 ,a ,greek3 elektron1 and ,greek3 -odos a way4 #ffc4 ,the surfaces at which1 according to common phraseology1 the electric current enters and leaves a decomposing body1 are most important places of action1 and require to be distinguished apart from the poles1 with which they are mostly1 and the electrodes1 with which they are always1 in contact4 ,wishing for a natural standard of electric direction to which ,i might refer these1 expressive of their difference and at the same time free from all theory1 ,i have thought it might be found in the earth4 ,if the magnetism of the earth be due to electric currents passing round it1 the latter must be in a constant direction1 which1 according to present usage of speech1 would be from east to west1 or1 which will strengthen this help to the memory1 that in which the sun appears to move4 ,if in any case of electro-decomposition we consider the decomposing body as placed so that the current passing through it shall be in the same direction1 and parallel to that supposed to exist in the earth1 then the surfaces at which the electricity is passing into and out of the substance would have an invariable reference1 and exhibit constantly the same relations of powers4 ,upon this notion we purpose calling that towards the east the anode,a1 and that towards the west the cathode,b2 and whatever changes may take place in our views of the nature of electricity and electrical action1 as they must affect the natural standard referred to1 in the same direction1 and to an equal amount with any decomposing substances to which these terms may at any time be applied1 there seems no reason to expect that they will lead to confusion1 or tend in any way to support false views4 ,the anode is therefore that surface at which the electric current1 according to our present expression1 enters3 it is the negative extremity of the decomposing body2 is where oxygen1 chlorine1 acids1 c41 are evolved2 and is against or opposite the positive electrode4 ,the cathode is that surface at which the current leaves the decomposing body1 and is its positive extremity2 the combustible bodies1 metals1 alkalies1 and bases1 are evolved there1 and it is in contact with the negative electrode4 ,a ,greek3 ano upwards1 and ,greek3 -odos a way2 the way which the sun rises4 ,b ,greek3 kata downwards1 and ,greek3 -odos a way2 the way which the sun sets4 #ffd4 ,i shall have occasion in these ,researches1 also1 to class bodies together according to certain relations derived from their electrical actions 7#hbb472 and wishing to express those relations without at the same time involving the expression of any hypothetical views1 ,i intend using the following names and terms4 ,many bodies are decomposed directly by the electric current1 their elements being set free2 these ,i propose to call electrolytes4,a ,water1 therefore1 is an electrolyte4 ,the bodies which1 like nitric or sulphuric acids1 are decomposed in a secondary manner 7#geb4 #geg471 are not included under this term4 ,then for electro-chemically decomposed1 ,i shall often use the term electrolyzed1 derived in the same way1 and implying that the body spoken of is separated into its components under the influence of electricity3 it is analogous in its sense and sound to analyse1 which is derived in a similar manner4 ,the term electrolytical will be understood at once3 muriatic acid is electrolytical1 boracic acid is not4 ,a ,greek3 elektron1 and ,greek3 lyo1 soluo4 ,n4 ,electrolyte1 ,v4 ,electrolyze4 #ffe4 ,finally1 ,i require a term to express those bodies which can pass to the electrodes1 or1 as they are usually called1 the poles4 ,substances are frequently spoken of as being electro-negative1 or electro-positive1 according as they go under the supposed influence of a direct attraction to the positive or negative pole4 ,but these terms are much too significant for the use to which ,i should have to put them2 for though the meanings are perhaps right1 they are only hypothetical1 and may be wrong2 and then1 through a very imperceptible1 but still very dangerous1 because continual1 influence1 they do great injury to science1 by contracting and limiting the habitual views of those engaged in pursuing it4 ,i propose to distinguish such bodies by calling those anions,a which go to the anode of the decomposing body2 and those passing to the cathode1 cations,b2 and when ,i have occasion to speak of these together1 ,i shall call them ions4 ,thus the chloride of lead is an electrolyte1 and when electrolyzed evolves the two ions1 chlorine and lead1 the former being an anion1 and the latter a cation4 ,a ,greek3 anin that which goes up4 7,neuter participle47 ,b ,greek3 katin that which goes down4 #fff4 ,these terms being once well-defined1 will1 ,i hope1 in their use enable me to avoid much periphrasis and ambiguity of expression4 ,i do not mean to press them into service more frequently than will be required1 for ,i am fully aware that names are one thing and science another4 #ffg4 ,it will be well understood that ,i am giving no opinion respecting the nature of the electric current now1 beyond what ,i have done on former occasions 7#bhc4 #eag472 and that though ,i speak of the current as proceeding from the parts which are positive to those which are negative 7#ffc471 it is merely in accordance with the conventional1 though in some degree tacit1 agreement entered into by scientific men1 that they may have a constant1 certain1 and definite means of referring to the direction of the forces of that current4 ,since this paper was read1 ,i have changed some of the terms which were first proposed1 that ,i might employ only such as were at the same time simple in their nature1 clear in their reference1 and free from hypothesis4 iv4 ,on some general conditions of ,electro-chemical ,decomposition4 #ffi4 ,from the period when electro-chemical decomposition was first effected to the present time1 it has been a remark1 that those elements which1 in the ordinary phenomena of chemical affinity1 were the most directly opposed to each other1 and combined with the greatest attractive force1 were those which were the most readily evolved at the opposite extremities of the decomposing bodies 7#edi474 #fgj4 ,if this result was evident when water was supposed to be essential to1 and was present in1 almost every case of such decomposition 7#dgb471 it is far more evident now that it has been shown and proved that water is not necessarily concerned in the phenomena 7#dgd471 and that other bodies much surpass it in some of the effects supposed to be peculiar to that substance4 #fga4 ,water1 from its constitution and the nature of its elements1 and from its frequent presence in cases of electrolytic action1 has hitherto stood foremost in this respect4 ,though a compound formed by very powerful affinity1 it yields up its elements under the influence of a very feeble electric current2 and it is doubtful whether a case of electrolyzation can occur1 where1 being present1 it is not resolved into its first principles4 #fgb4 ,the various oxides1 chlorides1 iodides1 and salts1 which ,i have shown are decomposable by the electric current when in the liquid state1 under the same general law with water 7#djb471 illustrate in an equally striking manner the activity1 in such decompositions1 of elements directly and powerfully opposed to each other by their chemical relations4 #fgc4 ,on the other hand1 bodies dependent on weak affinities very rarely give way4 ,take1 for instance1 glasses3 many of those formed of silica1 lime1 alkali1 and oxide of lead1 may be considered as little more than solutions of substances one in another,a4 ,if bottle-glass be fused1 and subjected to the voltaic pile1 it does not appear to be at all decomposed 7#djh474 ,if flint glass1 which contains substances more directly opposed1 be operated upon1 it suffers some decomposition2 and if borate of lead glass1 which is a definite chemical compound1 be experimented with1 it readily yields up its elements 7#djh474 ,a ,philosophical ,transactions1 #ahcj1 p4 #di4 #fgd4 ,but the result which is found to be so striking in the instances quoted is not at all borne out by reference to other cases where a similar consequence might have been expected4 ,it may be said1 that my own theory of electro-chemical decomposition would lead to the expectation that all compound bodies should give way under the influence of the electric current with a facility proportionate to the strength of the affinity by which their elements1 either proximate or ultimate1 are combined4 ,i am not sure that that follows as a consequence of the theory2 but if the objection is supposed to be one presented by the facts1 ,i have no doubt it will be removed when we obtain a more intimate acquaintance with1 and precise idea of1 the nature of chemical affinity and the mode of action of an electric current over it 7#eah4 #ebd473 besides which1 it is just as directly opposed to any other theory of electro-chemical decomposition as the one ,i have propounded2 for if it be admitted1 as is generally the case1 that the more directly bodies are opposed to each other in their attractive forces1 the more powerfully do they combine1 then the objection applies with equal force to any of the theories of electrolyzation which have been considered1 and is an addition to those which ,i have taken against them4 #fge4 ,amongst powerful compounds which are not decomposed1 boracic acids stand prominent 7#djh474 ,then again1 the iodide of sulphur1 and the chlorides of sulphur1 phosphorus1 and carbon1 are not decomposable under common circumstances1 though their elements are of a nature which would lead to a contrary expectation4 ,chloride of antimony 7#djb4 #fij471 the hydro-carbons1 acetic acid1 ammonia1 and many other bodies undecomposable by the voltaic pile1 would seem to be formed by an affinity sufficiently strong to indicate that the elements were so far contrasted in their nature as to sanction the expectation that1 the pile would separate them1 especially as in some cases of mere solution 7#ecj4 #edd471 where the affinity must by comparison be very weak1 separation takes place,a4 ,a ,with regard to solution1 ,i have met with some reasons for supposing that it will probably disappear as a cause of transference1 and intend resuming the consideration at a convenient opportunity4 #fgf4 ,it must not be forgotten1 however1 that much of this difficulty1 and perhaps the whole1 may depend upon the absence of conducting power1 which1 preventing the transmission of the current1 prevents of course the effects due to it4 ,all known compounds being non-conductors when solid1 but conductors when liquid1 are decomposed1 with perhaps the single exception at present known of periodide of mercury 7#fgi4 #fia47;,a2 and even water itself1 which so easily yields up its elements when the current passes1 if rendered quite pure1 scarcely suffers change1 because it then becomes a very bad conductor4 ,a ,see now1 #acdj1 #acda4--;,dec4 #ahch4 #fgg4 ,if it should hereafter be proved that the want of decomposition in those cases where1 from chemical considerations1 it might be so strongly expected 7#ffi1 #fgb4 #fgd471 is due to the absence or deficiency of conducting power1 it would also at the same time be proved that decomposition depends upon conduction1 and not the latter upon the former 7#dac472 and in water this seems to be very nearly decided4 ,on the other hand1 the conclusion is almost irresistible1 that in electrolytes the power of transmitting the electricity across the substance is dependent upon their capability of suffering decomposition2 taking place only whilst they are decomposing1 and being proportionate to the quantity of elements separated 7#hba474 ,i may not1 however1 stop to discuss this point experimentally at present4 #fgh4 ,when a compound contains such elements as are known to pass towards the opposite extremities of the voltaic pile1 still the proportions in which they are present appear to be intimately connected with capability in the compound of suffering or resisting decomposition4 ,thus1 the protochloride of tin readily conducts1 and is decomposed 7#djb471 but the perchloride neither conducts nor is decomposed 7#djf474 ,the protiodide of tin is decomposed when fluid 7#djb472 the periodide is not 7#dje474 ,the periodide of mercury when fused is not decomposed 7#fia471 even though it does conduct4 ,i was unable to contrast it with the protiodide1 the latter being converted into mercury and periodide by heat4 #fgi4 ,these important differences induced me to look more closely to certain binary compounds1 with a view of ascertaining whether a law regulating the decomposability according to some relation of the proportionals or equivalents of the elements1 could be discovered4 ,the proto compounds only1 amongst those just referred to1 were decomposable2 and on referring to the substances quoted to illustrate the force and generality of the law of conduction and decomposition which ,i discovered 7#djb471 it will be found that all the oxides1 chlorides1 and iodides subject to it1 except the chloride of antimony and the periodide of mercury1 7to which may now perhaps be added corrosive sublimate17 are also decomposable1 whilst many per compounds of the same elements1 not subject to the law1 were not so 7#dje4 #djf474 #fhj4 ,the substances which appeared to form the strongest exceptions to this general result were such bodies as the sulphuric1 phosphoric1 nitric1 arsenic1 and other acids4 #fha4 ,on experimenting with sulphuric acid1 ,i found no reason to believe that it was by itself a conductor of1 or decomposable by1 electricity1 although ,i had previously been of that opinion 7#eeb474 ,when very strong it is a much worse conductor than if diluted,a4 ,if then subjected to the action of a powerful battery1 oxygen appears at the anode1 or positive electrode1 although much is absorbed 7#gbh471 and hydrogen and sulphur appear at the cathode1 or negative electrode4 ,now the hydrogen has with me always been pure1 not sulphuretted1 and has been deficient in proportion to the sulphur present1 so that it is evident that when decomposition occurred water must have been decomposed4 ,i endeavoured to make the experiment with anhydrous sulphuric acid2 and it appeared to me that1 when fused1 such acid was not a conductor1 nor decomposed2 but ,i had not enough of the dry acid in my possession to allow me to decide the point satisfactorily4 ,my belief is1 that when sulphur appears during the action of the pile on sulphuric acid1 it is the result of a secondary action1 and that the acid itself is not electrolyzable 7#geg474 ,a ,de la ,rive4 #fhb4 ,phosphoric acid is1 ,i believe1 also in the same condition2 but ,i have found it impossible to decide the point1 because of the difficulty of operating on fused anhydrous phosphoric acid4 ,phosphoric acid which has once obtained water cannot be deprived of it by heat alone4 ,when heated1 the hydrated acid volatilizes4 ,upon subjecting phosphoric acid1 fused upon the ring end of a wire 7#dja471 to the action of the voltaic apparatus1 it conducted1 and was decomposed2 but gas1 which ,i believe to be hydrogen1 was always evolved at the negative electrode1 and the wire was not affected as would have happened had phosphorus been separated4 ,gas was also evolved at the positive electrode4 ,from all the facts1 ,i conclude it was the water and not the acid which was decomposed4 #fhc4 ,arsenic acid4 ,this substance conducted1 and was decomposed2 but it contained water1 and ,i was unable at the time to press the investigation so as to ascertain whether a fusible anhydrous arsenic acid could be obtained4 ,it forms1 therefore1 at present no exception to the general result4 #fhd4 ,nitrous acid1 obtained by distilling nitrate of lead1 and keeping it in contact with strong sulphuric acid1 was found to conduct and decompose slowly4 ,but on examination there were strong reasons for believing that water was present1 and that the decomposition and conduction depended upon it4 ,i endeavoured to prepare a perfectly anhydrous portion1 but could not spare the time required to procure an unexceptionable result4 #fhe4 ,nitric acid is a substance which ,i believe is not decomposed directly by the electric current4 ,as ,i want the facts in illustration of the distinction existing between primary and secondary decomposition1 ,i will merely refer to them in this place 7#geb474 #fhf4 ,that these mineral acids should confer facility of conduction and decomposition on water1 is no proof that they are competent to favour and suffer these actions in themselves4 ,boracic acid does the same thing1 though not decomposable4 ,m4 de la ,rive has pointed out that chlorine has this power also2 but being to us an elementary substance1 it cannot be due to its capability of suffering decomposition4 #fhg4 ,chloride of sulphur does not conduct1 nor is it decomposed4 ,it consists of single proportionals of its elements1 but is not on that account an exception to the rule 7#fgi471 which does not affirm that all compounds of single proportionals of elements are decomposable1 but that such as are decomposable are so constituted4 #fhh4 ,protochloride of phosphorus does not conduct nor become decomposed4 #fhi4 ,protochloride of carbon does not conduct nor suffer decomposition4 ,in association with this substance1 ,i submitted the hydro-chloride of carbon from olefiant gas and chlorine to the action of the electric current2 but it also refused to conduct or yield up its elements4 #fjj4 ,with regard to the exceptions 7#fgi471 upon closer examination some of them disappear4 ,chloride of antimony 7a compound of one proportional of antimony and one and a half of chlorine7 of recent preparation was put into a tube 7fig4 #fh47 7#ghi471 and submitted when fused to the action of the current1 the positive electrode being of plumbago4 ,no electricity passed1 and no appearance of decomposition was visible at first2 but when the positive and negative electrodes were brought very near each other in the chloride1 then a feeble action occurred and a feeble current passed4 ,the effect altogether was so small 7although quite amenable to the law before given 7#cid4771 and so unlike the decomposition and conduction occurring in all the other cases1 that ,i attribute it to the presence of a minute quantity of water1 7for which this and many other chlorides have strong attractions1 producing hydrated chlorides17 or perhaps of a true protochloride consisting of single proportionals 7#fie1 #gif474 #fia4 ,periodide of mercury being examined in the same manner1 was found most distinctly to insulate whilst solid1 but conduct when fluid1 according to the law of liquido-conduction 7#djb472 but there was no appearance of decomposition4 ,no iodine appeared at the anode1 nor mercury or other substance at the cathode4 ,the case is1 therefore1 no exception to the rule1 that only compounds of single proportionals are decomposable2 but it is an exception1 and ,i think the only one1 to the statement1 that all bodies subject to the law of liquido-conduction are decomposable4 ,i incline1 however1 to believe1 that a portion of protiodide of mercury is retained dissolved in the periodide1 and that to its slow decomposition the feeble conducting power is due4 ,periodide would be formed1 as a secondary result1 at the anode2 and the mercury at the cathode would also form1 as a secondary result1 protiodide4 ,both these bodies would mingle with the fluid mass1 and thus no final separation appear1 notwithstanding the continued decomposition4 #fib4 ,when perchloride of mercury was subjected to the voltaic current1 it did not conduct in the solid state1 but it did conduct when fluid4 ,i think1 also1 that in the latter case it was decomposed2 but there are many interfering circumstances which require examination before a positive conclusion can be drawn,a4 ,a ,with regard to perchloride and periodide of mercury1 see now #acdj1 #acda4--;,dec4 #ahch4 #fic4 ,when the ordinary protoxide of antimony is subjected to the voltaic current in a fused state1 it also is decomposed1 although the effect from other causes soon ceases 7#djb1 #hja474 ,this oxide consists of one proportional of antimony and one and a half of oxygen1 and is therefore an exception to the general law assumed4 ,but in working with this oxide and the chloride1 ,i observed facts which lead me to doubt whether the compounds usually called the protoxide and the protochloride do not often contain other compounds1 consisting of single proportions1 which are the true proto compounds1 and which1 in the case of the oxide1 might give rise to the decomposition above described4 #fid4 ,the ordinary sulphuret of antimony its considered as being the compound with the smallest quantity of sulphur1 and analogous in its proportions to the ordinary protoxide4 ,but ,i find that if it be fused with metallic antimony1 a new sulphuret is formed1 containing much more of the metal than the former1 and separating distinctly1 when fused1 both from the pure metal on the one hand1 and the ordinary gray sulphuret on the other4 ,in some rough experiments1 the metal thus taken up by the ordinary sulphuret of antimony was equal to half the proportion of that previously in the sulphuret1 in which case the new sulphuret would consist of single proportionals4 #fie4 ,when this new sulphuret was dissolved in muriatic acid1 although a little antimony separated1 yet it appeared to me that a true protochloride1 consisting of single proportionals1 was formed1 and from that by alkalies1 c41 a true protoxide1 consisting also of single proportionals1 was obtainable4 ,but ,i could not stop to ascertain this matter strictly by analysis4 #fif4 ,i believe1 however1 that there is such an oxide2 that it is often present in variable proportions in what is commonly called protoxide1 throwing uncertainty upon the results of its analysis1 and causing the electrolytic decomposition above described,a4 ,a ,in relation to this and the three preceding paragraphs1 and also #hja1 see ,berzelius's correction of the nature of the supposed now sulphuret and oxide1 ,phil4 ,mag4 #ahcf1 vol4 viii4 #dgf3 and for the probable explanation of the effects obtained with the protoxide1 refer to #acdj1 #acda4--;,dec4 #ahch4 #fig4 ,upon the whole1 it appears probable that all those binary compounds of elementary bodies which are capable of being electrolyzed when fluid1 but not whilst solid1 according to the law of liquido-conduction 7#cid471 consist of single proportionals of their elementary principles2 and it may be because of their departure from this simplicity of composition1 that boracic acid1 ammonia1 perchlorides1 periodides1 and many other direct compounds of elements1 are indecomposable4 #fih4 ,with regard to salts and combinations of compound bodies1 the same simple relation does not appear to hold good4 ,i could not decide this by bisulphates of the alkalies1 for as long as the second proportion of acid remained1 water was retained with it4 ,the fused salts conducted1 and were decomposed2 but hydrogen always appeared at the negative electrode4 #fii4 ,a biphosphate of soda was prepared by heating1 and ultimately fusing1 the ammonia-phosphate of soda4 ,in this case the fused bisalt conducted1 and was decomposed2 but a little gas appeared at the negative electrode2 and though ,i believe the salt itself was electrolyzed1 ,i am not quite satisfied that water was entirely absent4 #gjj4 ,then a biborate of soda was prepared2 and this1 ,i think1 is an unobjectionable case4 ,the salt1 when fused1 conducted1 and was decomposed1 and gas appeared at both electrodes3 even when the boracic acid was increased to three proportionals1 the same effect took place4 #gja4 ,hence this class of compound combinations does not seem to be subject to the same simple law as the former class of binary combinations4 ,whether we may find reason to consider them as mere solutions of the compound of single proportionals in the excess of acid1 is a matter which1 with some apparent exceptions occurring amongst the sulphurets1 must be left for decision by future examination4 #gjb4 ,in any investigation of these points1 great care must be taken to exclude water2 for if present1 secondary effects are so frequently produced as often seemingly to indicate an electro-decomposition of substances1 when no true result of the kind has occurred 7#gdb1 c474 #gjc4 ,it is evident that all the cases in which decomposition does not occur1 may depend upon the want of conduction 7#fgg4 #dac472 but that does not at all lessen the interest excited by seeing the great difference of effect due to a change1 not in the nature of the elements1 but merely in their proportions2 especially in any attempt which may be made to elucidate and expound the beautiful theory put forth by ,sir ,humphry ,davy,a1 and illustrated by ,berzelius and other eminent philosophers1 that ordinary chemical affinity is a mere result of the electrical attractions of the particles of matter4 ,a ,philosophical ,transactions1 #ahjg1 pp4 #cb1 #ci2 also #ahbf1 pp4 #chg1 #chi4 v4 ,on a new measure of ,volta-electricity4 #gjd4 ,i have already said1 when engaged in reducing common and voltaic electricity to one standard of measurement 7#cgg471 and again when introducing my theory of electro-chemical decomposition 7#ejd4 #eje4 #eaj471 that the chemical decomposing action of a current is constant for a constant quantity of electricity1 notwithstanding the greatest variations in its sources1 in its intensity1 in the size of the electrodes used1 in the nature of the conductors 7or non-conductors 7#cjg477 through which it is passed1 or in other circumstances4 ,the conclusive proofs of the truth of these statements shall be given almost immediately 7#ghc1 c474 #gje4 ,i endeavoured upon this law to construct an instrument which should measure out the electricity passing through it1 and which1 being interposed in the course of the current used in any particular experiment1 should serve at pleasure1 either as a comparative standard of effect1 or as a positive measurer of this subtile agent4 #gjf4 ,there is no substance better fitted1 under ordinary circumstances1 to be the indicating body in such an instrument than water2 for it is decomposed with facility when rendered a better conductor by the addition of acids or salts2 its elements may in numerous cases be obtained and collected without any embarrassment from secondary action1 and1 being gaseous1 they are in the best physical condition for separation and measurement4 ,water1 therefore1 acidulated by sulphuric acid1 is the substance ,i shall generally refer to1 although it may become expedient in peculiar cases or forms of experiment to use other bodies 7#hdc474 #gjg4 ,the first precaution needful in the construction of the instrument was to avoid the recombination of the evolved gases1 an effect which the positive electrode has been found so capable of producing 7#ega474 ,for this purpose various forms of decomposing apparatus were used4 ,the first consisted of straight tubes1 each containing a plate and wire of platina soldered together by gold1 and fixed hermetically in the glass at the closed extremity of the tube 7,plate ,v4 fig4 #fj474 ,the tubes were about eight inches long1 #j4g of an inch in diameter1 and graduated4 ,the platina plates were about an inch long1 as wide as the tubes would permit1 and adjusted as near to the mouths of the tubes as was consistent with the safe collection of the gases evolved4 ,in certain cases1 where it was required to evolve the elements upon as small a surface as possible1 the metallic extremity1 instead of being a plate1 consisted of the wire bent into the form of a ring 7fig4 #fa474 ,when these tubes were used as measurers1 they were filled with the dilute sulphuric acid1 inverted in a basin of the same liquid 7fig4 #fb471 and placed in an inclined position1 with their mouths near to each other1 that as little decomposing matter should intervene as possible2 and also1 in such a direction that the platina plates should be in vertical planes 7#gbj74 #gjh4 ,another form of apparatus is that delineated 7fig4 #fc474 ,the tube is bent in the middle2 one end is closed2 in that end is fixed a wire and plate1 a1 proceeding so far downwards1 that1 when in the position figured1 it shall be as near to the angle as possible1 consistently with the collection1 at the closed extremity of the tube1 of all the gas evolved against it4 ,the plane of this plate is also perpendicular 7#gbj474 ,the other metallic termination1 b1 is introduced at the time decomposition is to be effected1 being brought as near the angle as possible1 without causing any gas to pass from it towards the closed end of the instrument4 ,the gas evolved against it is allowed to escape4 #gji4 ,the third form of apparatus contains both electrodes in the same tube2 the transmission1 therefore1 of the electricity1 and the consequent decomposition1 is far more rapid than in the separate tubes4 ,the resulting gas is the sum of the portions evolved at the two electrodes1 and the instrument is better adapted than either of the former as a measurer of the quantity of voltaic electricity transmitted in ordinary cases4 ,it consists of a straight tube 7fig4 #fd47 closed at the upper extremity1 and graduated1 through the sides of which pass platina wires 7being fused into the glass71 which are connected with two plates within4 ,the tube is fitted by grinding into one mouth of a double-necked bottle4 ,if the latter be one-half or two-thirds full of the dilute sulphuric acid 7#gjf471 it will1 upon inclination of the whole1 flow into the tube and fill it4 ,when an electric current is passed through the instrument1 the gases evolved against the plates collect in the upper portion of the tube1 and are not subject to the recombining power of the platina4 #gaj4 ,another form of the instrument is given at fig4 #fe4 #gaa4 ,a fifth form is delineated 7fig4 #ff474 ,this ,i have found exceedingly useful in experiments continued in succession for days together1 and where large quantities of indicating gas were to be collected4 ,it is fixed on a weighted foot1 and has the form of a small retort containing the two electrodes3 the neck is narrow1 and sufficiently long to deliver gas issuing from it into a jar placed in a small pneumatic trough4 ,the electrode chamber1 sealed hermetically at the part held in the stand1 is five inches in length1 and #j4f of an inch in diameter2 the neck about nine inches in length1 and #j4d of an inch in diameter internally4 ,the figure will fully indicate the construction4 #gab4 ,it can hardly be requisite to remark1 that in the arrangement of any of these forms of apparatus1 they1 and the wires connecting them with the substance1 which is collaterally subjected to the action of the same electric current1 should be so far insulated as to ensure a certainty that all the electricity which passes through the one shall also be transmitted through the other4 99 99 99 99 99 #gac4 ,next to the precaution of collecting the gases1 if mingled1 out of contact with the platinum1 was the necessity of testing the law of a definite electrolytic action1 upon water at least1 under all varieties of condition2 that1 with a conviction of its certainty1 might also be obtained a knowledge of those interfering circumstances which would require to be practically guarded against4 #gad4 ,the first point investigated was the influence or indifference of extensive variations in the size of the electrodes1 for which purpose instruments like those last described 7#gji4 #gaj4 #gaa47 were used4 ,one of these had plates #j4g of an inch wide1 and nearly four inches long2 another had plates only #j4e of an inch wide1 and #j4h of an inch long2 a third had wires #j4jb of an inch in diameter1 and three inches long2 and a fourth1 similar wires only half an inch in length4 ,yet when these were filled with dilute sulphuric acid1 and1 being placed in succession1 had one common current of electricity passed through them1 very nearly the same quantity of gas was evolved in all4 ,the difference was sometimes in favour of one and sometimes on the side of another2 but the general result was that the largest quantity of gases was evolved at the smallest electrodes1 namely1 those consisting merely of platina wires4 #gae4 ,experiments of a similar kind were made with the single-plate1 straight tubes 7#gjg471 and also with the curved tubes 7#gjh471 with similar consequences2 and when these1 with the former tubes1 were arranged together in various ways1 the result1 as to the equality of action of large and small metallic surfaces when delivering and receiving the same current of electricity1 was constantly the same4 ,as an illustration1 the following numbers are given4 ,an instrument with two wires evolved #gd4c volumes of mixed gases2 another with plates #gc4be volumes2 whilst the sum of the oxygen and hydrogen in two separate tubes amounted to #gc4fe volumes4 ,in another experiment the volumes were #ee4c1 #ee4c1 and #ed4d4 #gaf4 ,but it was observed in these experiments1 that in single-plate tubes 7#gjg47 more hydrogen was evolved at the negative electrode than was proportionate to the oxygen at the positive electrode2 and generally1 also1 more than was proportionate to the oxygen and hydrogen in a double-plate tube4 ,upon more minutely examining these effects1 ,i was led to refer them1 and also the differences between wires and plates 7#gad471 to the solubility of the gases evolved1 especially at the positive electrode4 #gag4 ,when the positive and negative electrodes are equal in surface1 the bubbles which rise from them in dilute sulphuric acid are always different in character4 ,those from the positive plate are exceedingly small1 and separate instantly from every part of the surface of the metal1 in consequence of its perfect cleanliness 7#fcc472 whilst in the liquid they give it a hazy appearance1 from their number and minuteness2 are easily carried down by currents1 and therefore not only present far greater surface of contact with the liquid than larger bubbles would do1 but are retained a much longer time in mixture with it4 ,but the bubbles at the negative surface1 though they constitute twice the volume of the gas at the positive electrode1 are nevertheless very inferior in number4 ,they do not rise so universally from every part of the surface1 but seem to be evolved at different parts2 and though so much larger1 they appear to cling to the metal1 separating with difficulty from it1 and when separated1 instantly rising to the top of the liquid4 ,if1 therefore1 oxygen and hydrogen had equal solubility in1 or powers of combining with1 water under similar circumstances1 still under the present conditions the oxygen would be far the most liable to solution2 but when to these is added its well-known power of forming a compound with water1 it is no longer surprising that such a compound should be produced in small quantities at the positive electrode2 and indeed the blenching power which some philosophers have observed in a solution at this electrode1 when chlorine and similar bodies have been carefully excluded1 is probably due to the formation there1 in this manner1 of oxywater4 #gah4 ,that more gas was collected from the wires than from the plates1 ,i attribute to the circumstance1 that as equal quantities were evolved in equal times1 the bubbles at the wires having been more rapidly produced1 in relation to any part of the surface1 must have been much larger2 have been therefore in contact with the fluid by a much smaller surface1 and for a much shorter time than those at the plates2 hence less solution and a greater amount collected4 #gai4 ,there was also another effect produced1 especially by the use of large electrodes1 which was both a consequence and a proof of the solution of part of the gas evolved there4 ,the collected gas1 when examined1 was found to contain small portions of nitrogen4 ,this ,i attribute to the presence of air dissolved in the acid used for decomposition4 ,it is a well-known fact1 that when bubbles of a gas but slightly soluble in water or solutions pass through them1 the portion of this gas which is dissolved displaces a portion of that previously in union with the liquid3 and so1 in the decompositions under consideration1 as the oxygen dissolves1 it displaces a part of the air1 or at least of the nitrogen1 previously united to the acid2 and this effect takes place most extensively with large plates1 because the gas evolved at them is in the most favourable condition for solution1 #gbj4 ,with the intention of avoiding this solubility of the gases as much as possible1 ,i arranged the decomposing plates in a vertical position 7#gjg4 #gjh471 that the bubbles might quickly escape upwards1 and that the downward currents in the fluid should not meet ascending currents of gas4 ,this precaution ,i found to assist greatly in producing constant results1 and especially in experiments to be hereafter referred to1 in which other liquids than dilute sulphuric acid1 as for instance solution of potash1 were used4 #gba4 ,the irregularities in the indications of the measurer proposed1 arising from the solubility just referred to1 are but small1 and may be very nearly corrected by comparing the results of two or three experiments4 ,they may also be almost entirely avoided by selecting that solution which is found to favour them in the least degree 7#gbh472 and still further by collecting the hydrogen only1 and using that as the indicating gas2 for being much less soluble than oxygen1 being evolved with twice the rapidity and in larger bubbles 7#gag471 it can be collected more perfectly and in greater purity4 #gbb4 ,from the foregoing and many other experiments1 it results that variation in the size of the electrodes causes no variation in the chemical action of a given quantity of electricity upon water4 #gbc4 ,the next point in regard to which the principle of constant electro-chemical action was tested1 was variation of intensity4 ,in the first place1 the preceding experiments were repeated1 using batteries of an equal number of plates1 strongly and weakly charged2 but the results were alike4 ,they were then repeated1 using batteries sometimes containing forty1 and at other times only five pairs of plates2 but the results were still the same4 ,variations therefore in the intensity1 caused by difference in the strength of charge1 or in the number of alternations used1 produced no difference as to the equal action of large and small electrodes4 #gbd4 ,still these results did not prove that variation in the intensity of the current was not accompanied by a corresponding variation in the electro-chemical effects1 since the actions at all the surfaces might have increased or diminished together4 ,the deficiency in the evidence is1 however1 completely supplied by the former experiments on different-sized electrodes2 for with variation in the size of these1 a variation in the intensity must have occurred4 ,the intensity of an electric current traversing conductors alike in their nature1 quality1 and length1 is probably as the quantity of electricity passing through a given sectional area perpendicular to the current1 divided by the time 7#cfj4 note72 and therefore when large plates were contrasted with wires separated by an equal length of the same decomposing conductor 7#gad471 whilst one current of electricity passed through both arrangements1 that electricity must have been in a very different state1 as to tension1 between the plates and between the wires2 yet the chemical results were the same4 #gbe4 ,the difference in intensity1 under the circumstances described1 may be easily shown practically1 by arranging two decomposing apparatus as in fig4 #fg1 where the same fluid is subjected to the decomposing power of the same current of electricity1 passing in the vessel ,a4 between large platina plates1 and in the vessel ,b4 between small wires4 ,if a third decomposing apparatus1 such as that delineated fig4 #ff4 7#gaa471 be connected with the wires at ab1 fig4 #fg1 it will serve sufficiently well1 by the degree of decomposition occurring in it1 to indicate the relative state of the two plates as to intensity2 and if it then be applied in the same way1 as a test of the state of the wires at a'b'1 it will1 by the increase of decomposition within1 show how much greater the intensity is there than at the former points4 ,the connexions of ,p and ,n with the voltaic battery are of course to be continued during the whole time4 #gbf4 ,a third form of experiment1 in which difference of intensity was obtained1 for the purpose of testing the principle of equal chemical action1 was to arrange three volta-electrometers1 so that after the electric current had passed through one1 it should divide into two parts1 each of which should traverse one of the remaining instruments1 and should then reunite4 ,the sum of the decomposition in the two latter vessels was always equal to the decomposition in the former vessel4 ,but the intensity of the divided current could not be the same as that it had in its original state2 and therefore variation of intensity has no influence on the results if the quantity of electricity remain the same4 ,the experiment1 in fact1 resolves itself simply into an increase in the size of the electrodes 7#gbe474 #gbg4 ,the third point1 in respect to which the principle of equal electro-chemical action on water was tested1 was variation of the strength of the solution used4 ,in order to render the water a conductor1 sulphuric acid had been added to it 7#gjg472 and it did not seem unlikely that this substance1 with many others1 might render the water more subject to decomposition1 the electricity remaining the same in quantity4 ,but such did not prove to be the case4 ,diluted sulphuric acid1 of different strengths1 was introduced into different decomposing apparatus1 and submitted simultaneously to the action of the same electric current 7#gad474 ,slight differences occurred1 as before1 sometimes in one direction1 sometimes in another2 but the final result was1 that exactly the same quantity of water was decomposed in all the solutions by the same quantity of electricity1 though the sulphuric acid in some was seventy-fold what it was in others4 ,the strengths used were of specific gravity #a4die1 and downwards4 #gbh4 ,when an acid having a specific gravity of about #a4ccf was employed1 the results were most uniform1 and the oxygen and hydrogen 7#gaf47 most constantly in the right proportion to each other4 ,such an acid gave more gas than one much weaker acted upon by the same current1 apparently because it had less solvent power4 ,if the acid were very strong1 then a remarkable disappearance of oxygen took place2 thus1 one made by mixing two measures of strong oil of vitriol with one of water1 gave forty-two volumes of hydrogen1 but only twelve of oxygen4 ,the hydrogen was very nearly the same with that evolved from acid of the specific gravity #a4bcb4 ,i have not yet had time to examine minutely the circumstances attending the disappearance of the oxygen in this case1 but imagine it is due to the formation of oxywater1 which ,thenard has shown is favoured by the presence of acid4 #gbi4 ,although not necessary for the practical use of the instrument ,i am describing1 yet as connected with the important point of constant chemical action upon water1 ,i now investigated the effects produced by an electro-electric current passing through aqueous solutions of acids1 salts1 and compounds1 exceedingly different from each other in their nature1 and found them to yield astonishingly uniform results4 ,but many of them which are connected with a secondary action will be more usefully described hereafter 7#ggh474 #gcj4 ,when solutions of caustic potassa or soda1 or sulphate of magnesia1 or sulphate of soda1 were acted upon by the electric current1 just as much oxygen and hydrogen was evolved from them as from the diluted sulphuric acid1 with which they were compared4 ,when a solution of ammonia1 rendered a better conductor by sulphate of ammonia 7#eed471 or a solution of subcarbonate of potassa was experimented with1 the hydrogen evolved was in the same quantity as that set free from the diluted sulphuric acid with which they were compared4 ,hence changes in the nature of the solution do not alter the constancy of electrolytic action upon water4 #gca4 ,i have already said1 respecting large and small electrodes1 that change of order caused no change in the general effect 7#gae474 ,the same was the case with different solutions1 or with different intensities2 and however the circumstances of an experiment might be varied1 the results came forth exceedingly consistent1 and proved that the electro-chemical action was still the same4 #gcb4 ,i consider the foregoing investigation as sufficient to prove the very extraordinary and important principle with respect to ,,water1 that when subjected to the influence of the electric current1 a quantity of it is decomposed exactly proportionate to the quantity of electricity which has passed1 notwithstanding the thousand variations in the conditions and circumstances under which it may at the time be placed2 and further1 that when the interference of certain secondary effects 7#gdb4 c471 together with the solution or recombination of the gas and the evolution of air1 are guarded against1 the products of the decomposition may be collected with such accuracy1 as to afford a very excellent and valuable measurer of the electricity concerned in their evolution4 #gcc4 ,the forms of instrument which ,i have given1 figg4 #fd1 #fe1 #ff4 7#gji4 #gaj4 #gaa471 are probably those which will be found most useful1 as they indicate the quantity of electricity by the largest volume of gases1 and cause the least obstruction to the passage of the current4 ,the fluid which my present experience leads me to prefer1 is a solution of sulphuric acid of specific gravity about #a4ccf1 or from that to #a4be2 but it is very essential that there should be no organic substance1 nor any vegetable acid1 nor other body1 which1 by being liable to the action of the oxygen or hydrogen evolved at the electrodes 7#ggc4 c471 shall diminish their quantity1 or add other gases to them4 #gcd4 ,in many cases when the instrument is used as a comparative standard1 or even as a measurer1 it may be desirable to collect the hydrogen only1 as being less liable to absorption or disappearance in other ways than the oxygen2 whilst at the same time its volume is so large1 as to render it a good and sensible indicator4 ,in such cases the first and second form of apparatus have been used1 figg4 #fb1 #fc4 7#gjg4 #gjh474 ,the indications obtained were very constant1 the variations being much smaller than in those forms of apparatus collecting both gases2 and they can also be procured when solutions are used in comparative experiments1 which1 yielding no oxygen or only secondary results of its action1 can give no indications if the educts at both electrodes be collected4 ,such is the case when solutions of ammonia1 muriatic acid1 chlorides1 iodides1 acetates or other vegetable salts1 c41 are employed4 #gce4 ,in a few cases1 as where solutions of metallic salts liable to reduction at the negative electrode are acted upon1 the oxygen may be advantageously used as the measuring substance4 ,this is the case1 for instance1 with sulphate of copper4 #gcf4 ,there are therefore two general forms of the instrument which ,i submit as a measurer of electricity2 one1 in which both the gases of the water decomposed are collected 7#gji4 #gaj4 #gaa472 and the other1 in which a single gas1 as the hydrogen only1 is used 7#gjg4 #gjh474 ,when referred to as a comparative instrument1 7a use ,i shall now make of it very extensively17 it will not often require particular precaution in the observation2 but when used as an absolute measurer1 it will be needful that the barometric pressure and the temperature be taken into account1 and that the graduation of the instruments should be to one scale2 the hundredths and smaller divisions of a cubical inch are quite fit for this purpose1 and the hundredth may be very conveniently taken as indicating a ,,degree of electricity4 #gcg4 ,it can scarcely be needful to point out further than has been done how this instrument is to be used4 ,it is to be introduced into the course of the electric current1 the action of which is to be exerted anywhere else1 and if #fj or #gj of electricity are to be measured out1 either in one or several portions1 the current1 whether strong or weak1 is to be continued until the gas in the tube occupies that number of divisions or hundredths of a cubical inch4 ,or if a quantity competent to produce a certain effect is to be measured1 the effect is to be obtained1 and then the indication read off4 ,in exact experiments it is necessary to correct the volume of gas for changes in temperature and pressure1 and especially for moisture,a4 ,for the latter object the volta-electrometer 7fig4 #ff47 is most accurate1 as its gas can be measured over water1 whilst the others retain it over acid or saline solutions4 ,a ,for a simple table of correction for moisture1 ,i may take the liberty of referring to my ,chemical ,manipulation1 edition of #ahcj1 p4 #cgf4 #gch4 ,i have not hesitated to apply the term degree 7#gcf471 in analogy with the use made of it with respect to another most important imponderable agent1 namely1 heat2 and as the definite expansion of air1 water1 mercury1 c41 is there made use of to measure heat1 so the equally definite evolution of gases is here turned to a similar use for electricity4 #gci4 ,the instrument offers the only actual measurer of voltaic electricity which we at present possess4 ,for without being at all affected by variations in time or intensity1 or alterations in the current itself1 of any kind1 or from any cause1 or even of intermissions of action1 it takes note with accuracy of the quantity of electricity which has passed through it1 and reveals that quantity by inspection2 ,i have therefore named it a ,,volta-,,electrometer4 #gdj4 ,another mode of measuring volta-electricity may be adopted with advantage in many cases1 dependent on the quantities of metals or other substances evolved either as primary or as secondary results2 but ,i refrain from enlarging on this use of the products1 until the principles on which their constancy depends have been fully established 7#gia4 #hdh472 #gda4 ,by the aid of this instrument ,i have been able to establish the definite character of electro-chemical action in its most general sense2 and ,i am persuaded it will become of the utmost use in the extensions of the science which these views afford4 ,i do not pretend to have made its detail perfect1 but to have demonstrated the truth of the principle1 and the utility of the application,a4 ,a ,as early as the year #ahaa1 ,messrs4 ,gay-,lussac and ,thnard employed chemical decomposition as a measure of the electricity of the voltaic pile4 ,see ,recherches ,physico-chymiques1 p4 #ab4 ,the principles and precautions by which it becomes an exact measure were of course not then known4--,dec4 #ahch4 vi4 ,on the primary or secondary character of the bodies evolved at the ,electrodes4 #gdb4 ,before the volta-electrometer could be employed in determining1 as a general law1 the constancy of electro-decomposition1 it became necessary to examine a distinction1 already recognised among scientific men1 relative to the products of that action1 namely1 their primary or secondary character2 and1 if possible1 by some general rule or principle1 to decide when they were of the one or the other kind4 ,it will appear hereafter that great mistakes inspecting electro-chemical action and its consequences have arisen from confounding these two classes of results together4 #gdc4 ,when a substance under decomposition yields at the electrodes those bodies uncombined and unaltered which the electric current has separated1 then they may be considered as primary results1 even though themselves compounds4 ,thus the oxygen and hydrogen from water are primary results2 and so also are the acid and alkali 7themselves compound bodies7 evolved from sulphate of soda4 ,but when the substances separated by the current are changed at the electrodes before their appearance1 then they give rise to secondary results1 although in many cases the bodies evolved are elementary4 #gdd4 ,these secondary results occur in two ways1 being sometimes due to the mutual action of the evolved substance and the matter of the electrode1 and sometimes to its action upon the substances contained in the body itself under decomposition4 ,thus1 when carbon is made the positive electrode in dilute sulphuric acid1 carbonic oxide and carbonic acid occasionally appear there instead of oxygen2 for the latter1 acting upon the matter of the electrode1 produces these secondary results4 ,or if the positive electrode1 in a solution of nitrate or acetate of lead1 be platina1 then peroxide of lead appears there1 equally a secondary result with the former1 but now depending upon an action of the oxygen on a substance in the solution4 ,again1 when ammonia is decomposed by platina electrodes1 nitrogen appears at the anode,a2 but though an elementary body1 it is a secondary result in this case1 being derived from the chemical action of the oxygen electrically evolved there1 upon the ammonia in the surrounding solution 7#eed474 ,in the same manner when aqueous solutions of metallic salts are decomposed by the current1 the metals evolved at the cathode1 though elements1 are always secondary results1 and not immediate consequences of the decomposing power of the electric current4 ,a ,annales de ,chimie1 #ahja1 tom4 li4 p4 #afg4 #gde4 ,many of these secondary results are extremely valuable2 for instance1 all the interesting compounds which ,m4 ,becquerel has obtained by feeble electric currents are of this nature2 but they are essentially chemical1 and must1 in the theory of electrolytic action1 be carefully distinguished from those which are directly due to the action of the electric current4 #gdf4 ,the nature of the substances evolved will often lead to a correct judgement of their primary or secondary character1 but is not sufficient alone to establish that point4 ,thus1 nitrogen is said to be attracted sometimes by the positive and sometimes by the negative electrode1 according to the bodies with which it may be combined 7#eed4 #eee471 and it is on such occasions evidently viewed as a primary result,a2 but ,i think ,i shall show1 that1 when it appears at the positive electrode1 or rather at the anode1 it is a secondary result 7#gdh474 ,thus1 also1 ,sir ,humphry ,davy,b1 and with him the great body of chemical philosophers1 7including myself17 have given the appearance of copper1 lead1 tin1 silver1 gold1 c41 at the negative electrode1 when their aqueous solutions were acted upon by the voltaic current1 as proofs that the metals1 as a class1 were attracted to that surface2 thus assuming the metal1 in each case1 to be a primary result4 ,these1 however1 ,i expect to prove1 are all secondary results2 the mere consequence of chemical action1 and no proofs either of the attraction or of the law announced respecting their places,c4 ,a ,annales de ,chimie1 #ahjd1 tom4 li4 p4 #agb4 ,b ,elements of ,chemical ,philosophy1 pp4 #add4 #afa4 ,c ,it is remarkable that up to #ahjd it was the received opinion that the metals were reduced by the nascent hydrogen4 ,at that date the general opinion was reversed by ,hisinger and ,berzelius 7,annales de ,chimie1 #ahjd1 tom4 li4 p4 #agd171 who stated that the metals were evolved directly by the electricity3 in which opinion it appears1 from that time1 ,davy coincided 7,philosophical ,transactions1 #ahbf1 p4 #chh74 #gdg4 ,but when we take to our assistance the law of constant electro-chemical action already proved with regard to water 7#gcb471 and which ,i hope to extend satisfactorily to all bodies 7#hba471 and consider the quantities as well as the nature of the substances set free1 a generally accurate judgement of the primary or secondary character of the results may be formed3 and this important point1 so essential to the theory of electrolyzation1 since it decides what are the particles directly under the influence of the current1 7distinguishing them from such as are not affected17 and what are the results to be expected1 may be established with such degree of certainty as to remove innumerable ambiguities and doubtful considerations from this branch of the science4 #gdh4 ,let us apply these principles to the case of ammonia1 and the supposed determination of nitrogen to one or the other electrode 7#eed4 #eee174 ,a pure strong solution of ammonia is as bad a conductor1 and therefore as little liable to electrolyzation1 as pure water2 but when sulphate of ammonia is dissolved in it1 the whole becomes a conductor2 nitrogen almost and occasionally quite pure is evolved at the anode1 and hydrogen at the cathode2 the ratio of the volume of the former to that of the latter varying1 but being as #a to about #c or #d4 ,this result would seem at first to imply that the electric current had decomposed ammonia1 and that the nitrogen had been determined towards the positive electrode4 ,but when the electricity used was measured out by the volta-electrometer 7#gjg4 #gcf471 it was found that the hydrogen obtained was exactly in the proportion which would have been supplied by decomposed water1 whilst the nitrogen had no certain or constant relation whatever4 ,when1 upon multiplying experiments1 it was found that1 by using a stronger or weaker solution1 or a more or less powerful battery1 the gas evolved at the anode was a mixture of oxygen and nitrogen1 varying both in proportion and absolute quantity1 whilst the hydrogen at the cathode remained constant1 no doubt could be entertained that the nitrogen at the anode was a secondary result1 depending upon the chemical action of the nascent oxygen1 determined to that surface by the electric current1 upon the ammonia in solution4 ,it was the water1 therefore1 which was electrolyzed1 not the ammonia4 ,further1 the experiment gives no real indication of the tendency of the element nitrogen to either one electrode or the other2 nor do ,i know of any experiment with nitric acid1 or other compounds of nitrogen1 which shows the tendency of this element1 under the influence of the electric current1 to pass in either direction along its course4 #gdi4 ,as another illustration of secondary results1 the effects on a solution of acetate of potassa1 may be quoted4 ,when a very strong solution was used1 more gas was evolved at the anode than at the cathode1 in the proportion of #d to #c nearly3 that from the anode was a mixture of carbonic oxide and carbonic acid2 that from the cathode pure hydrogen4 ,when a much weaker solution was used1 less gas was evolved at the anode than at the cathode2 and it now contained carburetted hydrogen1 as well as carbonic oxide and carbonic acid4 ,this result of carburetted hydrogen at the positive electrode has a very anomalous appearance1 if considered as an immediate consequence of the decomposing power of the current4 ,it1 however1 as well as the carbonic oxide and acid1 is only a secondary result2 for it is the water alone which suffers electro-decomposition1 and it is the oxygen eliminated at the anode which1 reacting on the acetic acid1 in the midst of which it is evolved1 produces those substances that finally appear there4 ,this is fully proved by experiments with the volta-electrometer 7#gjg472 for then the hydrogen evolved from the acetate at the cathode is always found to be definite1 being exactly proportionate to the electricity which has passed through the solution1 and1 in quantity1 the same as the hydrogen evolved in the volta-electrometer itself4 ,the appearance of the carbon in combination with the hydrogen at the positive electrode1 and its non-appearance at the negative electrode1 are in curious contrast with the results which might have been expected from the law usually accepted respecting the final places of the elements4 #gej4 ,if the salt in solution be an acetate of lead1 then the results at both electrodes are secondary1 and cannot be used to estimate or express the amount of electro-chemical action1 except by a circuitous process 7#hdc474 ,in place of oxygen or even the gases already described 7#gdi471 peroxide of lead now appears at the positive1 and lead itself at the negative electrode4 ,when other metallic solutions are used1 containing1 for instance1 peroxides1 as that of copper1 combined with this or any other decomposable acid1 still more complicated results will be obtained2 which1 viewed as direct results of the electro-chemical action1 will1 in their proportions1 present nothing but confusion1 but will appear perfectly harmonious and simple if they be considered as secondary results1 and will accord in their proportions with the oxygen and hydrogen evolved from water by the action of a definite quantity of electricity4 #gea4 ,i have experimented upon many bodies1 with a view to determine whether the results were primary or secondary4 ,i have been surprised to find how many of them1 in ordinary cases1 are of the latter class1 and how frequently water is the only body electrolyzed in instances where other substances have been supposed to give way4 ,some of these results ,i will give in as few words as possible4 #geb4 ,nitric acid4--,when very strong1 it conducted well1 and yielded oxygen at the positive electrode4 ,no gas appeared at the negative electrode2 but nitrous acid1 and apparently nitric oxide1 were formed there1 which1 dissolving1 rendered the acid yellow or red1 and at last even effervescent1 from the spontaneous separation of nitric oxide4 ,upon diluting the acid with its bulk or more of water1 gas appeared at the negative electrode4 ,its quantity could be varied by variations1 either in the strength of the acid or of the voltaic current3 for that acid from which no gas separated at the cathode1 with a weak voltaic battery1 did evolve gas there with a stronger2 and that battery which evolved no gas there with a strong acid1 did cause its evolution with an acid more dilute4 ,the gas at the anode was always oxygen2 that at the cathode hydrogen4 ,when the quantity of products was examined by the volta-electrometer 7#gjg471 the oxygen1 whether from strong or weak acid1 proved to be in the same proportion as from water4 ,when the acid was diluted to specific gravity #a4bd1 or less1 the hydrogen also proved to be the same in quantity as from water4 ,hence ,i conclude that the nitric acid does not undergo electrolyzation1 but the water only2 that the oxygen at the anode is always a primary result1 but that the products at the cathode are often secondary1 and due to the reaction of the hydrogen upon the nitric acid4 #gec4 ,nitre4--,a solution of this salt yields very variable results1 according as one or other form of tube is used1 or as the electrodes are large or small4 ,sometimes the whole of the hydrogen of the water decomposed may be obtained at the negative electrode2 at other times1 only a part of it1 because of the ready formation of secondary results4 ,the solution is a very excellent conductor of electricity4 #ged4 ,nitrate of ammonia1 in aqueous solution1 gives rise to secondary results very varied and uncertain in their proportions4 #gee4 ,sulphurous acid4--,pure liquid sulphurous acid does not conduct nor suffer decomposition by the voltaic current,a1 but1 when dissolved in water1 the solution acquires conducting power1 and is decomposed1 yielding oxygen at the anode1 and hydrogen and sulphur at the cathode4 ,a ,see also ,de la ,rive1 ,bibliothque ,universelle1 tom4 xl4 p4 #bje2 or ,quarterly ,journal of ,science1 vol4 xxvii4 p1 #djg4 #gef4 ,a solution containing sulphuric acid in addition to the sulphurous acid1 was a better conductor4 ,it gave very little gas at either electrode3 that at the anode was oxygen1 that at the cathode pure hydrogen4 ,from the cathode also rose a white turbid stream1 consisting of diffused sulphur1 which soon rendered the whole solution milky4 ,the volumes of gases were in no regular proportion to the quantities evolved from water in the voltameter4 ,i conclude that the sulphurous acid was not at all affected by the electric current in any of these cases1 and that the water present was the only body electro-chemically decomposed2 that1 at the anode1 the oxygen from the water converted the sulphurous acid into sulphuric acid1 and1 at the cathode1 the hydrogen electrically evolved decomposed the sulphurous acid1 combining with its oxygen1 and setting its sulphur free4 ,i conclude that the sulphur at the negative electrode was only a secondary result2 and1 in fact1 no part of it was found combined with the small portion of hydrogen which escaped when weak solutions of sulphurous acid were used4 #geg4 ,sulphuric acid4--,i have already given my reasons for concluding that sulphuric acid is not electrolyzable1 i4e4 not decomposable directly by the electric current1 but occasionally suffering by a secondary action at the cathode from the hydrogen evolved there 7#fha474 ,in the year #ahjj1 ,davy considered the sulphur from sulphuric acid as the result of the action of the nascent hydrogen,a4 ,in #ahjd1 ,hisinger and ,berzelius stated that it was the direct result of the action of the voltaic pile,b1 an opinion which from that time ,davy seems to have adopted1 and which has since been commonly received by all4 ,the change of my own opinion requires that ,i should correct what ,i have already said of the decomposition of sulphuric acid in a former series of these ,researches 7#eeb473 ,i do not now think that the appearance of the sulphur at the negative electrode is an immediate consequence of electrolytic action4 ,a ,nicholson's ,quarterly ,journal1 vol4 iv4 pp4 #bhj1 #bha4 ,b ,annales de ,chimie1 #ahjd1 tom4 li4 p4 #agc4 #geh4 ,muriatic acid4--,a strong solution gave hydrogen at the negative electrode1 and chlorine only at the positive electrode2 of the latter1 a part acted on the platina and a part was dissolved4 ,a minute bubble of gas remained2 it was not oxygen1 but probably air previously held in solution4 #gei4 ,it was an important matter to determine whether the chlorine was a primary result1 or only a secondary product1 due to the action of the oxygen evolved from water at the anode upon the muriatic acid2 i4e4 whether the muriatic acid was electrolyzable1 and if so1 whether the decomposition was definite4 #gfj4 ,the muriatic acid was gradually diluted4 ,one part with six of water gave only chlorine at the anode4 ,one part with eight of water gave only chlorine2 with nine of water1 a little oxygen appeared with the chlorine2 but the occurrence or non-occurrence of oxygen at these strengths depended1 in part1 on the strength of the voltaic battery used4 ,with fifteen parts of water1 a little oxygen1 with much chlorine1 was evolved at the anode4 ,as the solution was now becoming a bad conductor of electricity1 sulphuric acid was added to it3 this caused more ready decomposition1 but did not sensibly alter the proportion of chlorine and oxygen4 #gfa4 ,the muriatic acid was now diluted with #ajj times its volume of dilute sulphuric acid4 ,it still gave a large proportion of chlorine at the anode1 mingled with oxygen2 and the result was the same1 whether a voltaic battery of #dj pairs of plates or one containing only #e pairs were used4 ,with acid of this strength1 the oxygen evolved at the anode was to the hydrogen at the cathode1 in volume1 as #ag is to #fd2 and therefore the chlorine would have been #cj volumes1 had it not been dissolved by the fluid4 #gfb4 ,next with respect to the quantity of elements evolved4 ,on using the volta-electrometer1 it was found that1 whether the strongest or the weakest muriatic acid were used1 whether chlorine alone or chlorine mingled with oxygen appeared at the anode1 still the hydrogen evolved at the cathode was a constant quantity1 i4e4 exactly the same as the hydrogen which the same quantity of electricity could evolve from water4 #gfc4 ,this constancy does not decide whether the muriatic acid is electrolyzed or not1 although it proves that if so1 it must be in definite proportions to the quantity of electricity used4 ,other considerations may1 however1 be allowed to decide the point4 ,the analogy between chlorine and oxygen1 in their relations to hydrogen1 is so strong1 as to lead almost to the certainty1 that1 when combined with that element1 they would perform similar parts in the process of electro-decomposition4 ,they both unite with it in single proportional or equivalent quantities2 and the number of proportionals appearing to have an intimate and important relation to the decomposability of a body 7#fig471 those in muriatic acid1 as well as in water1 are the most favourable1 or those perhaps even necessary1 to decomposition4 ,in other binary compounds of chlorine also1 where nothing equivocal depending on the simultaneous presence of it and oxygen is involved1 the chlorine is directly eliminated at the anode by the electric current4 ,such is the case with the chloride of lead 7#cie471 which may be justly compared with protoxide of lead 7#djb471 and stands in the same relation to it as muriatic acid to water4 ,the chlorides of potassium1 sodium1 barium1 c41 are in the same relation to the protoxides of the same metals and present the same results under the influence of the electric current 7#djb474 #gfd4 ,from all the experiments1 combined with these considerations1 ,i conclude that muriatic acid is decomposed by the direct influence of the electric current1 and that the quantities evolved are1 and therefore the chemical action is1 definite for a definite quantity of electricity4 ,for though ,i have not collected and measured the chlorine1 in its separate state1 at the anode1 there can exist no doubt as to its being proportional to the hydrogen at the cathode2 and the results are therefore sufficient to establish the general law of constant electro-chemical action in the case of muriatic acid4 #gfe4 ,in the dilute acid 7#gfa471 ,i conclude that a part of the water is electro-chemically decomposed1 giving origin to the oxygen1 which appears mingled with the chlorine at the anode4 ,the oxygen may be viewed as a secondary result2 but ,i incline to believe that it is not so2 for1 if it were1 it might be expected in largest proportion from the stronger acid1 whereas the reverse is the fact4 ,this consideration1 with others1 also leads me to conclude that muriatic acid is more easily decomposed by the electric current than water2 since1 even when diluted with eight or nine times its quantity of the latter fluid1 it alone gives way1 the water remaining unaffected4 #gff4 ,chlorides4--,on using solutions of chlorides in water1--for instance1 the chlorides of sodium or calcium1--there was evolution of chlorine only at the positive electrode1 and of hydrogen1 with the oxide of the base1 as soda or lime1 at the negative electrode4 ,the process of decomposition may be viewed as proceeding in two or three ways1 all terminating in the same results4 ,perhaps the simplest is to consider the chloride as the substance electrolyzed1 its chlorine being determined to and evolved at the anode1 and its metal passing to the cathode1 where1 finding no more chlorine1 it acts upon the water1 producing hydrogen and an oxide as secondary results4 ,as the discussion would detain me from more important matter1 and is not of immediate consequence1 ,i shall defer it for the present4 ,it is1 however1 of great consequence to state1 that1 on using the volta-electrometer1 the hydrogen in both cases was definite2 and if the results do not prove the definite decomposition of chlorides1 7which shall be proved elsewhere1--#ghi4 #gid4 #had417 they are not in the slightest degree opposed to such a conclusion1 and do support the general law4 #gfg4 ,hydriodic acid4--,a solution of hydriodic acid was affected exactly in the same manner as muriatic acid4 ,when strong1 hydrogen was evolved at the negative electrode1 in definite proportion to the quantity of electricity which had passed1 i4e4 in the same proportion as was evolved by the same current from water2 and iodine without any oxygen was evolved at the positive electrode4 ,but when diluted1 small quantities of oxygen appeared with the iodine at the anode1 the proportion of hydrogen at the cathode remaining undisturbed4 #gfh4 ,i believe the decomposition of the hydriodic acid in this case to be direct1 for the reasons already given respecting muriatic acid 7#gfc4 #gfd474 #gfi4 ,iodides4--,a solution of iodide of potassium being subjected to the voltaic current1 iodine appeared at the positive electrode 7without any oxygen71 and hydrogen with free alkali at the negative electrode4 ,the same observations as to the mode of decomposition are applicable here as were made in relation to the chlorides when in solution 7#gff474 #ggj4 ,hydro-fluoric acid and fluorides4--,solution of hydrofluoric acid did not appear to be decomposed under the influence of the electric current3 it was the water which gave way apparently4 ,the fused fluorides were electrolysed 7#dag472 but having during these actions obtained fluorine in the separate state1 ,i think it better to refer to a future series of these ,researches1 in which ,i purpose giving a fuller account of the results than would be consistent with propriety here,a4 ,a ,i have not obtained fluorine3 my expectations1 amounting to conviction1 passed away one by one when subjected to rigorous examination2 some very singular results were obtained2 and to one of these ,i refer at #acdj4--;,dec4 #ahch4 #gga4 ,hydro-cyanic acid in solution conducts very badly4 ,the definite proportion of hydrogen 7equal to that from water7 was set free at the cathode1 whilst at the anode a small quantity of oxygen was evolved and apparently a solution of cyanogen formed4 ,the action altogether corresponded with that on a dilute muriatic or hydriodic acid4 ,when the hydrocyanic acid was made a better conductor by sulphuric acid1 the same results occurred4 ,cyanides4--,with a solution of the cyanide of potassium1 the result was precisely the same as with a chloride or iodide4 ,no oxygen was evolved at the positive electrode1 but a brown solution formed there4 ,for the reasons given when speaking of the chlorides 7#gff471 and because a fused cyanide of potassium evolves cyanogen at the positive electrode,a1 ,i incline to believe that the cyanide in solution is directly decomposed4 ,a ,it is a very remarkable thing to see carbon and nitrogen in this case determined powerfully towards the positive surface of the voltaic battery2 but it is perfectly in harmony with the theory of electro-chemical decomposition which ,i have advanced4 #ggb4 ,ferro-cyanic acid and the ferro-cyanides1 as also sulpho-cyanic acid and the sulpho-cyanides1 presented results corresponding with those just described 7#gga474 #ggc4 ,acetic acid4--,glacial acetic acid1 when fused 7#dje471 is not decomposed by1 nor does it conduct1 electricity4 ,on adding a little water to it1 still there were no signs of action2 on adding more water1 it acted slowly and about as pure water would do4 ,dilute sulphuric acid was added to it in order to make it a better conductor2 then the definite proportion of hydrogen was evolved at the cathode1 and a mixture of oxygen in very deficient quantity1 with carbonic acid1 and a little carbonic oxide1 at the anode4 ,hence it appears that acetic acid is not electrolyzable1 but that a portion of it is decomposed by the oxygen evolved at the anode1 producing secondary results1 varying with the strength of the acid1 the intensity of the current1 and other circumstances4 #ggd4 ,acetates4--,one of these has been referred to already1 as affording only secondary results relative to the acetic acid 7#gdi474 ,with many of the metallic acetates the results at both electrodes are secondary 7#gdf4 #gej474 ,acetate of soda fused and anhydrous is directly decomposed1 being1 as ,i believe1 a true electrolyte1 and evolving soda and acetic acid at the cathode and anode4 ,these however have no sensible duration1 but are immediately resolved into other substances2 charcoal1 sodiuretted hydrogen1 c41 being set free at the former1 and1 as far as ,i could judge under the circumstances1 acetic acid mingled with carbonic oxide1 carbonic acid1 c4 at the latter4 #gge4 ,tartaric acid4--,pure solution of tartaric acid is almost as bad a conductor as pure water4 ,on adding sulphuric acid1 it conducted well1 the results at the positive electrode being primary or secondary in different proportions1 according to variations in the strength of the acid and the power of the electric current 7#geb474 ,alkaline tartrates gave a large proportion of secondary results at the positive electrode4 ,the hydrogen at the negative electrode remained constant unless certain triple metallic salts were used4 #ggf4 ,solutions1 of salts containing other vegetable acids1 as the benzoates2 of sugar1 gum1 c41 dissolved in dilute sulphuric acid2 of resin1 albumen1 c41 dissolved in alkalies1 were in turn submitted to the electrolytic power of the voltaic current4 ,in all these cases1 secondary results to a greater or smaller extent were produced at the positive electrode4 #ggg4 ,in concluding this division of these ,researches1 it cannot but occur to the mind that the final result of the action of the electric current upon substances1 placed between the electrodes1 instead of being simple may be very complicated4 ,there are two modes by which these substances may be decomposed1 either by the direct force of the electric current1 or by the action of bodies which that current may evolve4 ,there are also two modes by which new compounds may be formed1 i4e4 by combination of the evolving substances whilst in their nascent state 7#feh471 directly with the matter of the electrode2 or else their combination with those bodies1 which being contained in1 or associated with1 the body suffering decomposition1 are necessarily present at the anode and cathode4 ,the complexity is rendered still greater by the circumstance that two or more of these actions may occur simultaneously1 and also in variable proportions to each other4 ,but it may in a great measure be resolved by attention to the principles already laid down 7#gdg474 #ggh4 ,when aqueous solutions of bodies are used1 secondary results are exceedingly frequent4 ,even when the water is not present in large quantity1 but is merely that of combination1 still secondary results often ensue3 for instance1 it is very possible that in ,sir ,humphry ,davy's decomposition of the hydrates of potassa and soda1 a part of the potassium produced was the result of a secondary action4 ,hence1 also1 a frequent cause for the disappearance of the oxygen and hydrogen which would otherwise be evolved3 and when hydrogen does not appear at the cathode in an aqueous solution1 it perhaps always indicates that a secondary action has taken place there4 ,no exception to this rule has as yet occurred to my observation4 #ggi4 ,secondary actions are not confined to aqueous solutions1 or cases where water is present4 ,for instance1 various chlorides acted upon1 when fused 7#djb471 by platina electrodes1 have the chlorine determined electrically to the anode4 ,in many cases1 as with the chlorides of lead1 potassium1 barium1 c41 the chlorine acts on the platina and forms a compound with it1 which dissolves2 but when protochloride of tin is used1 the chlorine at the anode does not act upon the platina1 but upon the chloride already there1 forming a perchloride which rises in vapour 7#gij4 #hjd474 ,these are1 therefore1 instances of secondary actions of both kinds1 produced in bodies containing no water4 #ghj4 ,the production of boron from fused borax 7#djb4 #dag47 is also a case of secondary action2 for boracic acid is not decomposable by electricity 7#djh471 and it was the sodium evolved at the cathode which1 re-acting on the boracic acid around it1 took oxygen from it and set boron free in the experiments formerly described4 #gha4 ,secondary actions have already1 in the hands of ,m4 ,becquerel1 produced many interesting results in the formation of compounds2 some of them new1 others imitations of those occurring naturally,a4 ,it is probable they may prove equally interesting in an opposite direction1 i4e4 as affording cases of analytic decomposition4 ,much information regarding the composition1 and perhaps even the arrangement1 of the particles of such bodies as the vegetable acids and alkalies1 and organic compounds generally1 will probably be obtained by submitting them to the action of nascent oxygen1 hydrogen1 chlorine1 c4 at the electrodes2 and the action seems the more promising1 because of the thorough command which we possess over attendant circumstances1 such as the strength of the current1 the size of the electrodes1 the nature of the decomposing conductor1 its strength1 c41 all of which may be expected to have their corresponding influence upon the final result4 #ghb4 ,it is to me a great satisfaction that the extreme variety of secondary results has presented nothing opposed to the doctrine of a constant and definite electro-chemical action1 to the particular consideration of which ,i shall now proceed4 vii4 ,on the definite nature and extent of ,electro-chemical ,decomposition4 #ghc4 ,in the third series of these ,researches1 after proving the identity of electricities derived from different sources1 and showing1 by actual measurement1 the extraordinary quantity of electricity evolved by a very feeble voltaic arrangement 7#cga4 #cgf471 ,i announced a law1 derived from experiment1 which seemed to me of the utmost importance to the science of electricity in general1 and that branch of it denominated electro-chemistry in particular4 ,the law was expressed thus3 ,the chemical power of a current of electricity is in direct proportion to the absolute quantity of electricity which passes 7#cgg474 ,a ,annales de ,chimie1 tom1 xxxv4 p4 #aac4 #ghd4 ,in the further progress of the successive investigations1 ,i have had frequent occasion to refer to the same law1 sometimes in circumstances offering powerful corroboration of its truth 7#def4 #ejd4 #eje472 and the present series already supplies numerous new cases in which it holds good 7#gjd4 #gbb4 #gbf4 #gcb474 ,it is now my object to consider this great principle more closely1 and to develope some of the consequences to which it leads4 ,that the evidence for it may be the more distinct and applicable1 ,i shall quote cases of decomposition subject to as few interferences from secondary results as possible1 effected upon bodies very simple1 yet very definite in their nature4 #ghe4 ,in the first place1 ,i consider the law as so fully established with respect to the decomposition of water1 and under so many circumstances which might be supposed1 if anything could1 to exert an influence over it1 that ,i may be excused entering into further detail respecting that substance1 or even summing up the results here 7#gcb474 ,i refer1 therefore1 to the whole of the subdivision of this series of ,researches which contains the account of the volta-electrometer 7#gjd4 c474 #ghf4 ,in the next place1 ,i also consider the law as established with respect to muriatic acid by the experiments and reasoning already advanced1 when speaking of that substance1 in the subdivision respecting primary and secondary results 7#geh4 c474 #ghg4 ,i consider the law as established also with regard to hydriodic acid by the experiments and considerations already advanced in the preceding division of this series of ,researches 7#gfg4 #gfh474 #ghh4 ,without speaking with the same confidence1 yet from the experiments described1 and many others not described1 relating to hydro-fluoric1 hydro-cyanic1 ferro-cyanic1 and sulpho-cyanic acids 7#ggj4 #gga4 #ggb471 and from the close analogy which holds between these bodies and the hydracids of chlorine1 iodine1 bromine1 c41 ,i consider these also as coming under subjection to the law1 and assisting to prove its truth4 #ghi4 ,in the preceding cases1 except the first1 the water is believed to be inactive2 but to avoid any ambiguity arising from its presence1 ,i sought for substances from which it should be absent altogether2 and1 taking advantage of the law of conduction already developed 7#chj4 c471 ,i soon found abundance1 amongst which protochloride of tin was first subjected to decomposition in the following manner4 ,a piece of platina wire had one extremity coiled up into a small knob1 and1 having been carefully weighed1 was sealed hermetically into a piece of bottle-glass tube1 so that the knob should be at the bottom of the tube within 7fig4 #fh474 ,the tube was suspended by a piece of platina wire1 so that the heat of a spirit-lamp could be applied to it4 ,recently fused protochloride of tin was introduced in sufficient quantity to occupy1 when melted1 about one-half of the tube2 the wire of the tube was connected with a volta-electrometer 7#gaa471 which was itself connected with the negative end of a voltaic battery2 and a platina wire connected with the positive end of the same battery was dipped into the fused chloride in the tube2 being however so bent1 that it could not by any shake of the hand or apparatus touch the negative electrode at the bottom of the vessel4 ,the whole arrangement is delineated in fig4 #fi4 #gij4 ,under these circumstances the chloride of tin was decomposed3 the chlorine evolved at the positive electrode formed bichloride of tin 7#ggi471 which passed away in fumes1 and the tin evolved at the negative electrode combined with the platina1 forming an alloy1 fusible at the temperature to which the tube was subjected1 and therefore never occasioning metallic communication through the decomposing chloride4 ,when the experiment had been continued so long as to yield a reasonable quantity of gas in the volta-electrometer1 the battery connexion was broken1 the positive electrode removed1 and the tube and remaining chloride allowed to cool4 ,when cold1 the tube was broken open1 the rest of the chloride and the glass being easily separable from the platina wire and its button of alloy4 ,the latter when washed was then reweighed1 and the increase gave the weight of the tin reduced4 #gia4 ,i will give the particular results of one experiment1 in illustration of the mode adopted in this and others1 the results of which ,i shall have occasion to quote4 ,the negative electrode weighed at first #bj grains2 after the experiment1 it1 with its button of alloy1 weighed #bc4b grains4 ,the tin evolved by the electric current at the cathode3 weighed therefore #c4b grains4 ,the quantity of oxygen and hydrogen collected in the volta-electrometer #c4he cubic inches4 ,as #ajj cubic inches of oxygen and hydrogen1 in the proportions to form water1 may be considered as weighing #ab4ib grains1 the #c4he cubic inches would weigh #j4digdb of a grain2 that being1 therefore1 the weight of water decomposed by the same electric current as was able to decompose such weight of protochloride of tin as could yield #c4b grains of metal4 ,now #j4digdb 3 #c4b 33 #i the equivalent of water is to #eg4i1 which should therefore be the equivalent of tin1 if the experiment had been made without error1 and if the electro-chemical decomposition is in this case also definite4 ,in some chemical works #eh is given as the chemical equivalent of tin1 in others #eg4i4 ,both are so near to the result of the experiment1 and the experiment itself is so subject to slight causes of variation 7as from the absorption of gas in the volta-electrometer 7#gaf471 c471 that the numbers leave little doubt of the applicability of the law of definite action in this and all similar cases of electro-decomposition4 #gib4 ,it is not often ,i have obtained an accordance in numbers so near as that ,i have just quoted4 ,four experiments were made on the protochloride of tin1 the quantities of gas evolved in the volta-electrometer being from #b4je to #aj4bi cubic inches4 ,the average of the four experiments gave #eh4ec as the electro-chemical equivalent for tin4 #gic4 ,the chloride remaining after the experiment was pure protochloride of tin2 and no one can doubt for a moment that the equivalent of chlorine had been evolved at the anode1 and1 having formed bichloride of tin as a secondary result1 had passed away4 #gid4 ,chloride of lead was experimented upon in a manner exactly similar1 except that a change was made in the nature of the positive electrode2 for as the chlorine evolved at the anode forms no perchloride of lead1 but acts directly upon the platina1 it produces1 if that metal be used1 a solution of chloride of platina in the chloride of lead2 in consequence of which a portion of platina can pass to the cathode1 and would then produce a vitiated result4 ,i therefore sought for1 and found in plumbago1 another substance1 which could be used safely as the positive electrode in such bodies as chlorides1 iodides1 c4 ,the chlorine or iodine does not act upon it1 but is evolved in the free state2 and the plumbago has no re-action1 under the circumstances1 upon the fused chloride or iodide in which it is plunged4 ,even if a few particles of plumbago should separate by the heat or the mechanical action of the evolved gas1 they can do no harm in the chloride4 #gie4 ,the mean of three experiments gave the number of #ajj4he as the equivalent for lead4 ,the chemical equivalent is #ajc4e4 ,the deficiency in my experiments ,i attribute to the solution of part of the gas 7#gaf47 in the volta-electrometer2 but the results leave no doubt on my mind that both the lead and the chlorine are1 in this case1 evolved in definite quantities by the action of a given quantity of electricity 7#had4 c474 #gif4 ,chloride of antimony4--,it was in endeavouring to obtain the electro-chemical equivalent of antimony from the chloride1 that ,i found reasons for the statement ,i have made respecting the presence of water in it in an earlier part of these ,researches 7#fij4 #fic4 c474 #gig4 ,i endeavoured to experiment upon the oxide of lead obtained by fusion and ignition of the nitrate in a platina crucible1 but found great difficulty1 from the high temperature required for perfect fusion1 and the powerful fluxing qualities of the substance4 ,green-glass tubes repeatedly failed4 ,i at last fused the oxide in a small porcelain crucible1 heated fully in a charcoal fire2 and1 as it is was essential that the evolution of the lead at the cathode should take place beneath the surface1 the negative electrode was guarded by a green-glass tube1 fused around it in such a manner as to expose only the knob of platina at the lower end 7fig4 #gj471 so that it could be plunged beneath the surface1 and thus exclude contact of air or oxygen with the lead reduced there4 ,a platina wire was employed for the positive electrode1 that metal not being subject to any action from the oxygen evolved against it4 ,the arrangement is given in fig4 #ga4 #gih4 ,in an experiment of this kind the equivalent for the lead came out #ic4ag1 which is very much too small4 ,this1 ,i believe1 was because of the small interval between the positive and negative electrodes in the oxide of lead2 so that it was not unlikely that some of the froth and bubbles formed by the oxygen at the anode should occasionally even touch the lead reduced at the cathode1 and re-oxidize it4 ,when ,i endeavoured to correct this by having more litharge1 the greater heat required to keep it all fluid caused a quicker action on the crucible1 which was soon eaten through1 and the experiment stopped4 #gii4 ,in one experiment of this kind ,i used borate of lead 7#djh4 #fgc474 ,it evolves lead1 under the influence of the electric current1 at the anode1 and oxygen at the cathode2 and as the boracic acid is not either directly 7#djh47 or incidentally decomposed during the operation1 ,i expected a result dependent on the oxide of lead4 ,the borate is not so violent a flux as the oxide1 but it requires a higher temperature to make it quite liquid2 and if not very hot1 the bubbles of oxygen cling to the positive electrode1 and retard the transfer of electricity4 ,the number for lead came out #aja4bi1 which is so near to #ajc4e as to show that the action of the current had been definite4 #hjj4 ,oxide of bismuth4--,i found this substance required too high a temperature1 and acted too powerfully as a flux1 to allow of any experiment being made on it1 without the application of more time and care than ,i could give at present4 #hja4 ,the ordinary protoxide of antimony1 which consists of one proportional of metal and one and a half of oxygen1 was subjected to the action of the electric current in a green-glass tube 7#ghi471 surrounded by a jacket of platina foil1 and heated in a charcoal fire4 ,the decomposition began and proceeded very well at first1 apparently indicating1 according to the general law 7#fgi4 #fig471 that this substance was one containing such elements and in such proportions as made it amenable to the power of the electric current4 ,this effect ,i have already given reasons for supposing may be due to the presence of a true protoxide1 consisting of single proportionals 7#fif4 #fic474 ,the action soon diminished1 and finally ceased1 because of the formation of a higher oxide of the metal at the positive electrode4 ,this compound1 which was probably the peroxide1 being infusible and insoluble in the protoxide1 formed a crystalline crust around the positive electrode2 and thus insulating it1 prevented the transmission of the electricity4 ,whether1 if it had been fusible and still immiscible1 it would have decomposed1 is doubtful1 because of its departure from the required composition 7#fig474 ,it was a very natural secondary product at the positive electrode 7#ggi474 ,on opening the tube it was found that a little antimony had been separated at the negative electrode2 but the quantity was too small to allow of any quantitative result being obtained,a4 ,a ,this paragraph is subject to the corrective note now appended to paragraph #fif4--;,dec4 #ahch4 #hjb4 ,iodide of lead4--,this substance can be experimented with in tubes heated by a spirit-lamp 7#ghi472 but ,i obtained no good results from it1 whether ,i used positive electrodes of platina or plumbago4 ,in two experiments the numbers for the lead came out only #ge4df and #gc4de1 instead of #ajc4e4 ,this ,i attribute to the formation of a periodide at the positive electrode1 which1 dissolving in the mass of liquid iodide1 came in contact with the lead evolved at the negative electrode1 and dissolved part of it1 becoming itself again protiodide4 ,such a periodide does exist2 and it is very rarely that the iodide of lead formed by precipitation1 and well-washed1 can be fused without evolving much iodine1 from the presence of this percompound2 nor does crystallization from its hot aqueous solution free it from this substance4 ,even when a little of the protiodide and iodine are merely rubbed together in a mortar1 a portion of the periodide is formed4 ,and though it is decomposed by being fused and heated to dull redness for a few minutes1 and the whole reduced to protiodide1 yet that is not at all opposed to the possibility1 that a little of that which is formed in great excess of iodine at the anode1 should be carried by the rapid currents in the liquid into contact with the cathode4 #hjc4 ,this view of the result was strengthened by a third experiment1 where the space between the electrodes was increased to one third of an inch2 for now the interfering effects were much diminished1 and the number of the lead came out #hi4jd2 and it was fully confirmed by the results obtained in the cases of transfer to be immediately described 7#hah474 ,the experiments on iodide of lead therefore offer no exception to the general law under consideration1 but on the contrary may1 from general considerations1 be admitted as included in it4 #hjd4 ,protiodide of tin4--,this substance1 when fused 7#djb471 conducts and is decomposed by the electric current1 tin is evolved at the anode1 and periodide of tin as a secondary result 7#ggi4 #gij47 at the cathode4 ,the temperature required for its fusion is too high to allow of the production of any results fit for weighing4 #hje4 ,iodide of potassium was subjected to electrolytic action in a tube1 like that in fig4 #fh4 7#ghi474 ,the negative electrode was a globule of lead1 and ,i hoped in this way to retain the potassium1 and obtain results that could be weighed and compared with the volta-electrometer indication2 but the difficulties dependent upon the high temperature required1 the action upon the glass1 the fusibility of the platina induced by the presence of the lead1 and other circumstances1 prevented me from procuring such results4 ,the iodide was decomposed with the evolution of iodine at the anode1 and of potassium at the cathode1 as in former cases4 #hjf4 ,in some of these experiments several substances were placed in succession1 and decomposed simultaneously by the same electric current3 thus1 protochloride of tin1 chloride of lead1 and water1 were thus acted on at once4 ,it is needless to say that the results were comparable1 the tin1 lead1 chlorine1 oxygen1 and hydrogen evolved being definite in quantity and electro-chemical equivalents to each other4 99 99 99 99 99 #hjg4 ,let us turn to another kind of proof of the definite chemical action of electricity4 ,if any circumstances could be supposed to exert an influence over the quantity of the matters evolved during electrolytic action1 one would expect them to be present when electrodes of different substances1 and possessing very different chemical affinities for such matters1 were used4 ,platina has no power in dilute sulphuric acid of combining with the oxygen at the anode1 though the latter be evolved in the nascent state against it4 ,copper1 on the other hand1 immediately unites with the oxygen1 as the electric current sets it free from the hydrogen2 and zinc is not only able to combine with it1 but can1 without any help from the electricity1 abstract it directly from the water1 at the same time setting torrents of hydrogen free4 ,yet in cases where these three substances were used as the positive electrodes in three similar portions of the same dilute sulphuric acid1 specific gravity #a4ccf1 precisely the same quantity of water was decomposed by the electric current1 and precisely the same quantity of hydrogen set free at the cathodes of the three solutions4 #hjh4 ,the experiment was made thus4 ,portions of the dilute sulphuric acid were put into three basins4 ,three volta-electrometer tubes1 of the form figg4 #fj4 #fb4 were filled with the same acid1 and one inverted in each basin 7#gjg474 ,a zinc plate1 connected with the positive end of a voltaic battery1 was dipped into the first basin1 forming the positive electrode there1 the hydrogen1 which was abundantly evolved from it by the direct action of the acid1 being allowed to escape4 ,a copper plate1 which dipped into the acid of the second basin1 was connected with the negative electrode of the first basin2 and a platina plate1 which dipped into the acid of the third basin1 was connected with the negative electrode of the second basin4 ,the negative electrode of the third basin was connected with a volta-electrometer 7#gaa471 and that with the negative end of the voltaic battery4 #hji4 ,immediately that the circuit was complete1 the electro-chemical action commenced in all the vessels4 ,the hydrogen still rose in1 apparently1 undiminished quantities from the positive zinc electrode in the first basin4 ,no oxygen was evolved at the positive copper electrode in the second basin1 but a sulphate of copper was formed there2 whilst in the third basin the positive platina electrode evolved pure oxygen gas1 and was itself unaffected4 ,but in all the basins the hydrogen liberated at the negative platina electrodes was the same in quantity1 and the same with the volume of hydrogen evolved in the volta-electrometer1 showing that in all the vessels the current had decomposed an equal quantity of water4 ,in this trying case1 therefore1 the chemical action of electricity proved to be perfectly definite4 #haj4 ,a similar experiment was made with muriatic acid diluted with its bulk of water4 ,the three positive electrodes were zinc1 silver1 and platina2 the first being able to separate and combine with the chlorine without the aid of the current2 the second combining with the chlorine only after the current had set it free2 and the third rejecting almost the whole of it4 ,the three negative electrodes were1 as before1 platina plates fixed within glass tubes4 ,in this experiment1 as in the former1 the quantity of hydrogen evolved at the cathodes was the same for all1 and the same as the hydrogen evolved in the volta-electrometer4 ,i have already given my reasons for believing that in these experiments it is the muriatic acid which is directly decomposed by the electricity 7#gfd472 and the results prove that the quantities so decomposed are perfectly definite and proportionate to the quantity of electricity which has passed4 #haa4 ,in this experiment the chloride of silver formed in the second basin retarded the passage of the current of electricity1 by virtue of the law of conduction before described 7#cid471 so that it had to be cleaned off four or five times during the course of the experiment2 but this caused no difference between the results of that vessel and the others4 #hab4 ,charcoal was used as the positive electrode in both sulphuric and muriatic acids 7#hjh4 #haj472 but this change produced no variation of the results4 ,a zinc positive electrode1 in sulphate of soda or solution of common salt1 gave the same constancy of operation4 #hac4 ,experiments of a similar kind were then made with bodies altogether in a different state1 i4e4 with fused chlorides1 iodides1 c4 ,i have already described an experiment with fused chloride of silver1 in which the electrodes were of metallic silver1 the one rendered negative becoming increased and lengthened by the addition of metal1 whilst the other was dissolved and eaten away by its abstraction4 ,this experiment was repeated1 two weighed pieces of silver wire being used as the electrodes1 and a volta-electrometer included in the circuit4 ,great care was taken to withdraw the negative electrodes so regularly and steadily that the crystals of reduced silver should not form a metallic communication beneath the surface of the fused chloride4 ,on concluding the experiment the positive electrode was re-weighed1 and its loss ascertained4 ,the mixture of chloride of silver1 and metal1 withdrawn in successive portions at the negative electrode1 was digested in solution of ammonia1 to remove the chloride1 and the metallic silver remaining also weighed3 it was the reduction at the cathode1 and exactly equalled the solution at the anode2 and each portion was as nearly as possible the equivalent to the water decomposed in the volta-electrometer4 #had4 ,the infusible condition of the silver at the temperature used1 and the length and ramifying character of its crystals1 render the above experiment difficult to perform1 and uncertain in its results4 ,i therefore wrought with chloride of lead1 using a green-glass tube1 formed as in fig4 #gb4 ,a weighed platina wire was fused into the bottom of a small tube1 as before described 7#ghi474 ,the tube was then bent to an angle1 at about half an inch distance from the closed end2 and the part between the angle and the extremity being softened1 was forced upward1 as in the figure1 so as to form a bridge1 or rather separation1 producing two little depressions or basins a1 b1 within the tube4 ,this arrangement was suspended by a platina wire1 as before1 so that the heat of a spirit-lamp could be applied to it1 such inclination being given to it as would allow all air to escape during the fusion of the chloride of lead4 ,a positive electrode was then provided1 by bending up the end of a platina wire into a knot1 and fusing about twenty grains of metallic lead on to it1 in a small closed tube of glass1 which was afterwards broken away4 ,being so furnished1 the wire with its lead was weighed1 and the weight recorded4 #hae4 ,chloride of lead was now introduced into the tube1 and carefully fused4 ,the leaded electrode was also introduced2 after which the metal1 at its extremity1 soon melted4 ,in this state of things the tube was filled up to c with melted chloride of lead2 the end of the electrode to be rendered negative was in the basin b1 and the electrode of melted lead was retained in the basin a1 and1 by connexion with the proper conducting wire of a voltaic battery1 was rendered positive4 ,a volta-electrometer was included in the circuit4 #haf4 ,immediately upon the completion of the communication with the voltaic battery1 the current passed1 and decomposition proceeded4 ,no chlorine was evolved at the positive electrode2 but as the fused chloride was transparent1 a button of alloy could be observed gradually forming and increasing in size at b1 whilst the lead at a could also be seen gradually to diminish4 ,after a time1 the experiment was stopped2 the tube allowed to cool1 and broken open2 the wires1 with their buttons1 cleaned and weighed2 and their change in weight compared with the indication of the volta-electrometer4 #hag4 ,in this experiment the positive electrode had lost just as much lead as the negative one had gained 7#gie471 and the loss and gain were very nearly the equivalents of the water decomposed in the volta-electrometer1 giving for lead the number #aja4e4 ,it is therefore evident1 in this instance1 that causing a strong affinity1 or no affinity1 for the substance evolved at the anode1 to be active during the experiment 7#hjg471 produces no variation in the definite action of the electric current4 #hah4 ,a similar experiment was then made with iodide of lead1 and in this manner all confusion from the formation of a periodide avoided 7#hjc474 ,no iodine was evolved during the whole action1 and finally the loss of lead at the anode was the same as the gain at the cathode1 the equivalent number1 by comparison with the result in the volta-electrometer1 being #ajc4e4 #hai4 ,then protochloride of tin was subjected to the electric current in the same manner1 using of course1 a tin positive electrode4 ,no bichloride of tin was now formed 7#ggi4 #gij474 ,on examining the two electrodes1 the positive had lost precisely as much as the negative had gained2 and by comparison with the volta-electrometer1 the number for tin came out #ei4 #hbj4 ,it is quite necessary in these and similar experiments to examine the interior of the bulbs of alloy at the ends of the conducting wires2 for occasionally1 and especially with those which have been positive1 they are cavernous1 and contain portions of the chloride or iodide used1 which must be removed before the final weight is ascertained4 ,this is more usually the case with lead than tin4 #hba4 ,all these facts combine into1 ,i think1 an irresistible mass of evidence1 proving the truth of the important proposition which ,i at first laid down1 namely1 that the chemical power of a current of electricity is in direct proportion to the absolute quantity of electricity which passes 7#cgg4 #ghc474 ,they prove1 too1 that this is not merely true with one substance1 as water1 but generally with all electrolytic bodies2 and1 further1 that the results obtained with any one substance do not merely agree amongst themselves1 but also with those obtained from other substances1 the whole combining together into one series of definite electro-chemical actions 7#eje474 ,i do not mean to say that no exceptions will appear3 perhaps some may arise1 especially amongst substances existing only by weak affinity2 but ,i do not expect that any will seriously disturb the result announced4 ,if1 in the well-considered1 well-examined1 and1 ,i may surely say1 well-ascertained doctrines of the definite nature of ordinary chemical affinity1 such exceptions occur1 as they do in abundance1 yet1 without being allowed to disturb our minds as to the general conclusion1 they ought also to be allowed if they should present themselves at this1 the opening of a new view of electro-chemical action2 not being held up as obstructions to those who may be engaged in rendering that view more and more perfect1 but laid aside for a while1 in hopes that their perfect and consistent explanation will ultimately appear4 99 99 99 99 99 #hbb4 ,the doctrine of definite electro-chemical action just laid down1 and1 ,i believe1 established1 leads to some new views of the relations and classifications of bodies associated with or subject to this action4 ,some of these ,i shall proceed to consider4 #hbc4 ,in the first place1 compound bodies may be separated into two great classes1 namely1 those which are decomposable by the electric current1 and those which are not3 of the latter1 some are conductors1 others non-conductors1 of voltaic electricity,a4 ,the former do not depend for their decomposability upon the nature of their elements only2 for1 of the same two elements1 bodies may be formed1 of which one shall belong to one class and another to the other class2 but probably on the proportions also 7#fig474 ,it is further remarkable1 that with very few1 if any1 exceptions 7#dad4 #fia471 these decomposable bodies are exactly those governed by the remarkable law of conduction ,i have before described 7#fid472 for that law does not extend to the many compound fusible substances that are excluded from this class4 ,i propose to call bodies of this1 the decomposable class1 ,electrolytes 7#ffd474 ,a ,i mean here by voltaic electricity1 merely electricity from a most abundant source1 but having very small intensity4 #hbd4 ,then1 again1 the substances into which these divide1 under the influence of the electric current1 form an exceedingly important general class4 ,they are combining bodies2 are directly associated with the fundamental parts of the doctrine of chemical affinity2 and have each a definite proportion1 in which they are always evolved during electrolytic action4 ,i have proposed to call these bodies generally ions1 or particularly anions and cations1 according as they appear at the anode or cathode 7#ffe472 and the numbers representing the proportions in which they are evolved electro-chemical equivalents4 ,thus hydrogen1 oxygen1 chlorine1 iodine1 lead1 tin are ions2 the three former are anions1 the two metals are cations1 and #a1 #h1 #c1 #abe1 #ajd1 #eh1 are their electro-chemical equivalents nearly4 #hbe4 ,a summary of certain points already ascertained respecting electrolytes1 ions1 and electro-chemical equivalents1 may be given in the following general form of propositions1 without1 ,i hope1 including any serious error4 #hbf4 i4 ,a single ion1 i4e4 one not in combination with another1 will have no tendency to pass to either of the electrodes1 and will be perfectly indifferent to the passing current1 unless it be itself a compound of more elementary ions1 and so subject to actual decomposition4 ,upon this fact is founded much of the proof adduced in favour of the new theory of electro-chemical decomposition1 which ,i put forth in a former series of these ,researches 7#eah4 c474 #hbg4 ii4 ,if one ion be combined in right proportions 7#fig47 with another strongly opposed to it in its ordinary chemical relations1 i4e4 if an anion be combined with a cation1 then both will travel1 the one to the anode1 the other to the cathode1 of the decomposing body 7#ecj1 #edb4 #edg474 #hbh4 iii4 ,if1 therefore1 an ion pass towards one of the electrodes1 another ion must also be passing simultaneously to the other electrode1 although1 from secondary action1 it may not make its appearance 7#gdc474 #hbi4 iv4 ,a body decomposable directly by the electric current1 i4e4 an electrolyte1 must consist of two ions1 and must also render them up during the act of decomposition4 #hcj4 v4 ,there is but one electrolyte composed of the same two elementary ions2 at least such appears to be the fact 7#fig471 dependent upon a law1 that only single electro-chemical equivalents of elementary ions can go to the electrodes1 and not multiples4 #hca4 vi4 ,a body not decomposable when alone1 as boracic acid1 is not directly decomposable by the electric current when in combination 7#ghj474 ,it may act as an ion going wholly to the anode or cathode1 but does not yield up its elements1 except occasionally by a secondary action4 ,perhaps it is superfluous for me to point out that this proposition has no relation to such cases as that of water1 which1 by the presence of other bodies1 is rendered a better conductor of electricity1 and therefore is more freely decomposed4 #hcb4 vii4 ,the nature of the substance of which the electrode is formed1 provided it be a conductor1 causes no difference in the electro-decomposition1 either in kind or degree 7#hjg4 #hac473 but it seriously influences1 by secondary action 7#gad471 the state in which the finally appear4 ,advantage may be taken of this principle in combining and ions collecting such ions as1 if evolved in their free state1 would be unmanageable,a4 ,a ,it will often happen that the electrodes used may be of such a nature as1 with the fluid in which they are immersed1 to produce an electric current1 either according with or opposing that of the voltaic arrangement used1 and in this way1 or by direct chemical action1 may sadly disturb the results4 ,still1 in the midst of all these confusing effects1 the electric current1 which actually passes in any direction through the body suffering decomposition1 will produce its own definite electrolytic action4 #hcc4 viii4 ,a substance which1 being used as the electrode1 can combine with the ion evolved against it1 is also1 ,i believe1 an ion1 and combines1 in such cases1 in the quantity represented by its electro-chemical equivalent4 ,all the experiments ,i have made agree with this view2 and it seems to me1 at present1 to result as a necessary consequence4 ,whether1 in the secondary actions that take place1 where the ion acts1 not upon the matter of the electrode1 but on that which is around it in the liquid 7#gdd471 the same consequence follows1 will require more extended investigation to determine4 #hcd4 ix4 ,compound ions are not necessarily composed of electro-chemical equivalents of simple ions4 ,for instance1 sulphuric acid1 boracic acid1 phosphoric acid1 are ions1 but not electrolytes1 i4e4 not composed of electro-chemical equivalents of simple ions4 #hce4 x4 ,electro-chemical equivalents are always consistent2 i4e4 the same number which represents the equivalent of a substance ,a when it is separating from a substance ,b1 will also represent ,a when separating from a third substance ,c4 ,thus1 #h is the electro-chemical equivalent of oxygen1 whether separating from hydrogen1 or tin1 or lead2 and #ajc4e is the electrochemical equivalent of lead1 whether separating from oxygen1 or chlorine1 or iodine4 #hcf4 xi4 ,electro-chemical equivalents coincide1 and are the same1 with ordinary chemical equivalents4 #hcg4 ,by means of experiment and the preceding propositions1 a knowledge of ions and their electro-chemical equivalents may be obtained in various ways4 #hch4 ,in the first place1 they may be determined directly1 as has been done with hydrogen1 oxygen1 lead1 and tin1 in the numerous experiments already quoted4 #hci4 ,in the next place1 from propositions ii4 and iii41 may be deduced the knowledge of many other ions1 and also their equivalents4 ,when chloride of lead was decomposed1 platina being used for both electrodes 7#cie471 there could remain no more doubt that chlorine was passing to the anode1 although it combined with the platina there1 than when the positive electrode1 being of plumbago 7#gid471 allowed its evolution in the free state2 neither could there1 in either case1 remain any doubt that for every #ajc4e parts of lead evolved at the cathode1 #cf parts of chlorine were evolved at the anode1 for the remaining chloride of lead was unchanged4 ,so also1 when in a metallic solution one volume of oxygen1 or a secondary compound containing that proportion1 appeared at the anode1 no doubt could arise that hydrogen1 equivalent to two volumes1 had been determined to the cathode1 although1 by a secondary action1 it had been employed in reducing oxides of lead1 copper1 or other metals1 to the metallic state4 ,in this manner1 then1 we learn from the experiments already described in these ,researches1 that chlorine1 iodine1 bromine1 fluorine1 calcium1 potassium1 strontium1 magnesium1 manganese1 c41 are ions and that their electro-chemical equivalents are the same as their ordinary chemical equivalents4 #hdj4 ,propositions iv4 and v4 extend our means of gaining information4 ,for if a body of known chemical composition is found to be decomposable1 and the nature of the substance evolved as a primary or even a secondary result 7#gdc4 #ggg47 at one of the electrodes1 be ascertained1 the electro-chemical equivalent of that body may be deduced from the known constant composition of the substance evolved4 ,thus1 when fused protiodide of tin is decomposed by the voltaic current 7#hjd471 the conclusion may be drawn1 that both the iodine and tin are ions1 and that the proportions in which they combine in the fused compound express their electro-chemical equivalents4 ,again1 with respect to the fused iodide of potassium 7#hje471 it is an electrolyte2 and the chemical equivalents will also be the electro-chemical equivalents4 #hda4 ,if proposition viii4 sustain extensive experimental investigation1 then it will not only help to confirm the results obtained by the use of the other propositions1 but will give abundant original information of its own4 #hdb4 ,in many instances1 the secondary results obtained by the action of the evolved ion on the substances present in the surrounding liquid or solution1 will give the electro-chemical equivalent4 ,thus1 in the solution of acetate of lead1 and1 as far as ,i have gone1 in other proto-salts subjected to the reducing action of the nascent hydrogen at the cathode1 the metal precipitated has been in the same quantity as if it had been a primary product1 7provided no free hydrogen escaped there17 and therefore gave accurately the number representing its electro-chemical equivalent4 #hdc4 ,upon this principle it is that secondary results may occasionally be used as measurers of the volta-electric current 7#gjf4 #gdj472 but there are not many metallic solutions that answer this purpose well3 for unless the metal is easily precipitated1 hydrogen will be evolved at the cathode and vitiate the result4 ,if a soluble peroxide is formed at the anode1 or if the precipitated metal crystallize across the solution and touch the positive electrode1 similar vitiated results are obtained4 ,i expect to find in some salts1 as the acetates of mercury and zinc1 solutions favourable for this use4 #hdd4 ,after the first experimental investigations to establish the definite chemical action of electricity1 ,i have not hesitated to apply the more strict results of chemical analysis to correct the numbers obtained as electrolytic results4 ,this1 it is evident1 may be done in a great number of cases1 without using too much liberty towards the due severity of scientific research4 ,the series of numbers representing electro-chemical equivalents must1 like those expressing the ordinary equivalents of chemically acting bodies1 remain subject to the continual correction of experiment and sound reasoning4 #hde4 ,i give the following brief ,table of ions and their electro-chemical equivalents1 rather as a specimen of a first attempt than as anything that can supply the want which must very quickly be felt1 of a full and complete tabular account of this class of bodies4 ,looking forward to such a table as of extreme utility 7if well-constructed7 in developing the intimate relation of ordinary chemical affinity to electrical actions1 and identifying the two1 not to the imagination merely1 but to the conviction of the senses and a sound judgement1 ,i may be allowed to express a hope1 that the endeavour will always be to make it a table of real1 and not hypothetical1 electro-chemical equivalents2 for we shall else overrun the facts1 and lose all sight and consciousness of the knowledge lying directly in our path4 #hdf4 ,the equivalent numbers do not profess to be exact1 and are taken almost entirely from the chemical results of other philosophers in whom ,i could repose more confidence1 as to these points1 than in myself4 #hdg4 ,,table ,,of ,,ions4 ,anions4 ,oxygen #h ,chlorine #ce4e ,iodine #abf ,bromine #gh4c ,fluorine #ah4g ,cyanogen #bf ,sulphuric acid #dj ,selenic acid #fd ,nitric acid #ed ,chloric acid #ge4e ,phosphoric acid #ce4g ,carbonic acid #bb ,boracic acid #bd ,acetic acid #ea ,tartaric acid #ff ,citric acid #eh ,oxalic acid #cf ,sulphur 787 #af ,selenium 787 ,salpho-cyanogen ,cations4 ,hydrogen #a ,potassium #ci4b ,sodium #bc4c ,lithium #aj ,barium #fh4g ,strontium #dc4h ,calcium #bj4e ,magnesium #ab4g ,manganese #bg4g ,zinc #cb4e ,tin #eg4i ,lead #ajc4e ,iron #bh ,copper #ca4f ,cadmium #ee4h ,cerium #df ,cobalt #bi4e ,nickel #bi4e ,antimony #fa4fg ,bismuth #ga ,mercury #bjj ,silver #ajh ,platina #ih4f8 ,gold 787 ,ammonia #ag ,potassa #dg4b ,soda #ca4c ,lithia #ah ,baryta #gf4g ,strontia #ea4h ,lime #bh4e ,magnesia #bj4g ,alumina4 787 ,protoxides generally4 ,quinia #aga4f ,cinchona #afj ,morphia #bij ,vegeto-alkalies generally4 #hdh4 ,this ,table might be further arrange into groups of such substances as either act with1 or replace1 each other4 ,thus1 for instance1 acids and bases act in relation to each other2 but they do not act in association with oxygen1 hydrogen1 or elementary substances4 ,there is indeed little or no doubt that1 when the electrical relations of the particles of matter come to be closely examined1 this division must be made4 ,the simple substances1 with cyanogen1 sulpho-cyanogen1 and one or two other compound bodies1 will probably form the first group2 and the acids and bases1 with such analogous compounds as may prove to be ions1 the second group4 ,whether these will include all ions1 or whether a third class of more complicated results will be required1 must be decided by future experiments4 #hdi4 ,it is probable that all our present elementary bodies are ions1 but that is not as yet certain4 ,there are some1 such as carbon1 phosphorus1 nitrogen1 silicon1 boron1 alumium1 the right of which to the title of ion it is desirable to decide as soon as possible4 ,there are also many compound bodies1 and amongst them alumina and silica1 which it is desirable to class immediately by unexceptionable experiments4 ,it is also possible1 that all combinable bodies1 compound as well as simple1 may enter into the class of ions2 but at present it does not seem to me probable4 ,still the experimental evidence ,i have is so small in proportion to what must gradually accumulate around1 and bear upon1 this point1 that ,i am afraid to give a strong opinion upon it4 #hej4 ,i think ,i cannot deceive myself in considering the doctrine of definite electro-chemical action as of the utmost importance4 ,it touches by its facts more directly and closely than any former fact1 or set of facts1 have done1 upon the beautiful idea1 that ordinary chemical affinity is a mere consequence of the electrical attractions of the particles of different kinds of matter2 and it will probably lead us to the means by which we may enlighten that which is at present so obscure1 and either fully demonstrate the truth of the idea1 or develope that which ought to replace it4 #hea4 ,a very valuable use of electro-chemical equivalents will be to decide1 in cases of doubt1 what is the true chemical equivalent1 or definite proportional1 or atomic number of a body2 for ,i have such conviction that the power which governs electro-decomposition and ordinary chemical attractions is the same2 and such confidence in the overruling influence of those natural laws which render the former definite1 as to feel no hesitation in believing that the latter must submit to them also4 ,such being the case1 ,i can have1 no doubt that1 assuming hydrogen as #a1 and dismissing small fractions for the simplicity of expression1 the equivalent number or atomic weight of oxygen is #h1 of chlorine #cf1 of bromine #gh4d1 of lead #ajc4e1 of tin #ei1 c41 notwithstanding that a very high authority doubles several of these numbers4 #ac4 ,on the absolute quantity of ,electricity associated with the particles or atoms of ,matter4 #heb4 ,the theory of definite electrolytical or electro-chemical action appears to me to touch immediately upon the absolute quantity of electricity or electric power belonging to different bodies4 ,it is impossible1 perhaps1 to speak on this point without committing oneself beyond what present facts will sustain2 and yet it is equally impossible1 and perhaps would be impolitic1 not to reason upon the subject4 ,although we know nothing of what an atom is1 yet we cannot resist forming some idea of a small particle1 which represents it to the mind2 and though we are in equal1 if not greater1 ignorance of electricity1 so as to be unable to say whether it is a particular matter or matters1 or mere motion of ordinary matter1 or some third kind of power or agent1 yet there is an immensity of facts which justify us in believing that the atoms of matter are in some way endowed or associated with electrical powers1 to which they owe their most striking qualities1 and amongst them their mutual chemical affinity4 ,as soon as we perceive1 through the teaching of ,dalton1 that chemical powers are1 however varied the circumstances in which they are exerted1 definite for each body1 we learn to estimate the relative degree of force which resides in such bodies3 and when upon that knowledge comes the fact1 that the electricity1 which we appear to be capable of loosening from its habitation for a while1 and conveying from place to place1 whilst it retains its chemical force1 can be measured out1 and being so measured is found to be as definite in its action as any of those portions which1 remaining associated with the particles of matter1 give them their chemical relation2 we seem to have found the link which connects the proportion of that we have evolved to the proportion of that belonging to the particles in their natural state4 #hec4 ,now it is wonderful to observe how small a quantity of a compound body is decomposed by a certain portion of electricity4 ,let us1 for instance1 consider this and a few other points in relation to water4 ,one grain of water1 acidulated to facilitate conduction1 will require an electric current to be continued for three minutes and three quarters of time to effect its decomposition1 which current must be powerful enough to retain a platina wire #a_/ajd of an inch in thickness,a1 red-hot1 in the air during the whole time2 and if interrupted anywhere by charcoal points1 will produce a very brilliant and constant star of light4 ,if attention be paid to the instantaneous discharge of electricity of tension1 as illustrated in the beautiful experiments of ,mr4 ,wheatstone,b1 and to what ,i have said elsewhere on the relation of common and voltaic electricity 7#cga4 #cge471 it will not be too much to say that this necessary quantity of electricity is equal to a very powerful flash of lightning4 ,yet we have it under perfect command2 can evolve1 direct1 and employ it at pleasure2 and when it has performed its full work of electrolyzation1 it has only separated the elements of a single grain of water4 ,a ,i have not stated the length of wire used1 because ,i find by experiment1 as would be expected in theory1 that it is indifferent4 ,the same quantity of electricity which1 passed in a given time1 can heat an inch of platina wire of a certain diameter red-hot1 can also heat a hundred1 a thousand1 or any length of the same wire to the same degree1 provided the cooling circumstances are the same for every part in all cases4 ,this ,i have proved by the volta-electrometer4 ,i found that whether half an inch or eight inches were retained at one constant temperature of dull redness1 equal quantities of water were decomposed in equal times4 ,when the half-inch was used1 only the centre portion of wire was ignited4 ,a fine wire may even be used as a rough but ready regulator of a voltaic current2 for if it be made part of the circuit1 and the larger wires communicating with it be shifted nearer to or further apart1 so as to keep the portion of wire in the circuit sensibly at the same temperature1 the current passing through it will be nearly uniform4 ,b ,literary ,gazette1 #ahcc1 ,march #a and #h4 ,philosophical ,magazine1 #ahcc1 p4 #bja4 ,l',institut1 #ahcc1 p4#bfa4 #hed4 ,on the other hand1 the relation between the conduction of the electricity and the decomposition of the water is so close1 that one cannot take place without the other4 ,if the water is altered only in that small degree which consists in its having the solid instead of the fluid state1 the conduction is stopped1 and the decomposition is stopped with it4 ,whether the conduction be considered as depending upon the decomposition1 or not 7#ddc4 #gjc471 still the relation of the two functions is equally intimate and inseparable4 #hee4 ,considering this close and twofold relation1 namely1 that without decomposition transmission of electricity does not occur2 and1 that for a given definite quantity of electricity passed1 an equally definite and constant quantity of water or other matter is decomposed2 considering also that the agent1 which is electricity1 is simply employed in overcoming electrical powers in the body subjected to its action2 it seems a probable1 and almost a natural consequence1 that the quantity which passes is the equivalent of1 and therefore equal to1 that of the particles separated2 i4e4 that if the electrical power which holds the elements of a grain of water in combination1 or which makes a grain of oxygen and hydrogen in the right proportions unite into water when they are made to combine1 could be thrown into the condition of a current1 it would exactly equal the current required for the separation of that grain of water into its elements again4 #hef4 ,this view of the subject gives an almost overwhelming idea of the extraordinary quantity or degree of electric power which naturally belongs to the particles of matter2 but it is not inconsistent in the slightest degree with the facts which can be brought to bear on this point4 ,to illustrate this ,i must say a few words on the voltaic pile,a4 ,a ,by the term voltaic pile1 ,i mean such apparatus or arrangement of metals as up to this time have been called so1 and which contain water1 brine1 acids1 or other aqueous solutions or decomposable substances 7#dgf471 between their plates4 ,other kinds of electric apparatus may be hereafter invented1 and ,i hope to construct some not belonging to the class of instruments discovered by ,volta4 #heg4 ,intending hereafter to apply the results given in this and the preceding series of ,researches to a close investigation of the source of electricity in the voltaic instrument1 ,i have refrained from forming any decided opinion on the subject2 and without at all meaning to dismiss metallic contact1 or the contact of dissimilar substances1 being conductors1 but not metallic1 as if they had nothing to do with the origin of the current1 ,i still am fully of opinion with ,davy1 that it is at least continued by chemical action1 and that the supply constituting the current is almost entirely from that source4 #heh4 ,those bodies which1 being interposed between the metals of the voltaic pile1 render it active1 are all of them electrolytes 7#dgf472 and it cannot but press upon the attention of every one engaged in considering this subject1 that in those bodies 7so essential to the pile7 decomposition and the transmission of a current are so intimately connected1 that one cannot happen without the other4 ,this ,i have shown abundantly in water1 and numerous other cases 7#djb4 #dgf474 ,if1 then1 a voltaic trough have its extremities connected by a body capable of being decomposed1 as water1 we shall have a continuous current through the apparatus2 and whilst it remains in this state we may look at the part where the acid is acting upon the plates1 and that where the current is acting upon the water1 as the reciprocals of each other4 ,in both parts we have the two conditions inseparable in such bodies as these1 namely1 the passing of a current1 and decomposition2 and this is as true of the cells in the battery as of the water cell2 for no voltaic battery has as yet been constructed in which the chemical action is only that of combination3 decomposition is always included1 and is1 ,i believe1 an essential chemical part4 #hei4 ,but the difference in the two parts of the connected battery1 that is1 the decomposition or experimental cell1 and the acting cells1 is simply this4 ,in the former we urge the current through1 but it1 apparently of necessity1 is accompanied by decomposition3 in the latter we cause decompositions by ordinary chemical actions1 7which are1 however1 themselves electrical17 and1 as a consequence1 have the electrical current2 and as the decomposition dependent upon the current is definite in the former case1 so is the current associated with the decomposition also definite in the latter 7#hfb4 c474 #hfj4 ,let us apply this in support of what ,i have surmised respecting the enormous electric power of each particle or atom of matter 7#hef474 ,i showed in a former series of these ,researches on the relation by measure of common and voltaic electricity1 that two wires1 one of platina and one of zinc1 each one-eighteenth of an inch in diameter1 placed five-sixteenths of an inch apart1 and immersed to the depth of five-eighths of an inch in acid1 consisting of one drop of oil of vitriol and four ounces of distilled water at a temperature of about #fj ,fahr41 and connected at the other extremities by a copper wire eighteen feet long1 and one-eighteenth of an inch in thickness1 yielded as much electricity in little more than three seconds of time as a ,leyden battery charged by thirty turns of a very large and powerful plate electric machine in full action 7#cga474 ,this quantity1 though sufficient if passed at once through the head of a rat or cat to have killed it1 as by a flash of lightning1 was evolved by the mutual action of so small a portion of the zinc wire and water in contact with it1 that the loss of weight sustained by either would be inappreciable by our most delicate instruments2 and as to the water which could be decomposed by that current1 it must have been insensible in quantity1 for no trace of hydrogen appeared upon the surface of the platina during those three seconds4 #hfa4 ,what an enormous quantity of electricity1 therefore1 is required for the decomposition of a single grain of water6 ,we have already seen that it must be in quantity sufficient to sustain a platina wire #a_/ajd of an inch in thickness1 red-hot1 in contact with the air1 for three minutes and three quarters 7#hec471 a quantity which is almost infinitely greater than that which could be evolved by the little standard voltaic arrangement to which ,i have just referred 7#hfj4 #hga474 ,i have endeavoured to make a comparison by the loss of weight of such a wire in a given time in such an acid1 according to a principle and experiment to be almost immediately described 7#hfb472 but the proportion is so high that ,i am almost afraid to mention it4 ,it would appear that #hjj1jjj such charges of the ,leyden battery as ,i have referred to above1 would be necessary to supply electricity sufficient to decompose a single grain of water2 or1 if ,i am right1 to equal the quantity of electricity which is naturally associated with the elements of that grain of water1 endowing them with their mutual chemical affinity4 #hfb4 ,in further proof of this high electric condition of the particles of matter1 and the identity as to quantity of that belonging to them with that necessary for their separation1 ,i will describe an experiment of great simplicity but extreme beauty1 when viewed in relation to the evolution of an electric current and its decomposing powers4 #hfc4 ,a dilute sulphuric acid1 made by adding about one part by measure of oil of vitriol to thirty parts of water1 will act energetically upon a piece of zinc plate in its ordinary and simple state3 but1 as ,mr4 ,sturgeon has shown,a1 not at all1 or scarcely so1 if the surface of the metal has in the first instance been amalgamated2 yet the amalgamated zinc will act powerfully with platina as an electromotor1 hydrogen being evolved on the surface of the latter metal1 as the zinc is oxidized and dissolved4 ,the amalgamation is best effected by sprinkling a few drops of mercury upon the surface of the zinc1 the latter being moistened with the dilute acid1 and rubbing with the fingers or two so as to extend the liquid metal over the whole of the surface4 ,any mercury in excess1 forming liquid drops upon the zinc1 should be wiped off,b4 ,a ,recent ,experimental ,researches1 c41 #ahcj1 p4#gd1 c4 ,b ,the experiment may be made with pure zinc1 which1 as chemists well know1 is but slightly acted upon by dilute sulphuric acid in comparison with ordinary zinc1 which during the action is subject to an infinity of voltaic actions4 ,see ,de la ,rive on this subject1 ,bibliothque ,universelle1 #ahcj1 p4#cia4 #hfd4 ,two plates of zinc thus amalgamated were dried and accurately weighed2 one1 which we will call ,a1 weighed #afc4a grains2 the other1 to be called ,b1 weighed #adh4c grains4 ,they were about five inches long1 and #j4d of an inch wide4 ,an earthenware pneumatic trough was filled with dilute sulphuric acid1 of the strength just described 7#hfc471 and a gas jar1 also filled with the acid1 inverted in it,a4 ,a plate of platina of nearly the same length1 but about three times as wide as the zinc plates1 was put up into this jar4 ,the zinc plate ,a was also introduced into the jar1 and brought in contact with the platina1 and at the same moment the plate ,b was put into the acid of the trough1 but out of contact with other metallic matter4 ,a ,the acid was left during a night with a small piece of unamalgamated zinc in it1 for the purpose of evolving such air as might be inclined to separate1 and bringing the whole into a constant state4 #hfe4 ,strong action immediately occurred in the jar upon the contact of the zinc and platina plates4 ,hydrogen gas rose from the platina1 and was collected in the jar1 but no hydrogen or other gas rose from either zinc plate4 ,in about ten or twelve minutes1 sufficient hydrogen having been collected1 the experiment was stopped2 during its progress a few small bubbles had appeared upon plate ,b1 but none upon plate ,a4 ,the plates were washed in distilled water1 dried1 and reweighed4 ,plate ,b weighed #adh4c grains1 as before1 having lost nothing by the direct chemical action of the acid4 ,plate ,a weighed #aed4fe grains1 #h4de grains of it having been oxidized and dissolved during the experiment4 #hff4 ,the hydrogen gas was next transferred to a water-trough and measured2 it amounted to #ab4e cubic inches1 the temperature being #eb1 and the barometer #bi4b inches4 ,this quantity1 corrected for temperature1 pressure1 and moisture1 becomes #ab4aedec cubic inches of dry hydrogen at mean temperature and pressure2 which1 increased by one half for the oxygen that must have gone to the anode1 i4e4 to the zinc1 gives #ah4bcb cubic inches as the quantity of oxygen and hydrogen evolved from the water decomposed by the electric current4 ,according to the estimate of the weight of the mixed gas before adopted 7#gia471 this volume is equal to #b4ceceedd grains1 which therefore is the weight of water decomposed2 and this quantity is to #h4de1 the quantity of zinc oxidized1 as #i is to #cb4ca4 ,now taking #i as the equivalent number of water1 the number #cb4e is given as the equivalent number of zinc2 a coincidence sufficiently near to show1 what indeed could not but happen1 that for an equivalent of zinc oxidized an equivalent of water must be decomposed,a4 ,a ,the experiment was repeated several times with the same results4 #hfg4 ,but let us observe how the water is decomposed4 ,it is electrolyzed1 i4e4 is decomposed voltaically1 and not in the ordinary manner 7as to appearance7 of chemical decompositions2 for the oxygen appears at the anode and the hydrogen at the cathode of the body under decomposition1 and these were in many parts of the experiment above an inch asunder4 ,again1 the ordinary chemical affinity was not enough under the circumstances to effect the decomposition of the water1 as was abundantly proved by the inaction on plate ,b2 the voltaic current was essential4 ,and to prevent any idea that the chemical affinity was almost sufficient to decompose the water1 and that a smaller current of electricity might1 under the circumstances1 cause the hydrogen to pass to the cathode1 ,i need only refer to the results which ,i have given 7#hjg4 #hac47 to shew that the chemical action at the electrodes has not the slightest influence over the quantities of water or other substances decomposed between them1 but that they are entirely dependent upon the quantity of electricity which passes4 #hfh4 ,what1 then1 follows as a necessary consequence of the whole experiment8 ,why1 this3 that the chemical action upon #cb4ca parts1 or one equivalent of zinc1 in this simple voltaic circle1 was able to evolve such quantity of electricity in the form of a current1 as1 passing through water1 should decompose #i parts1 or one equivalent of that substance3 and considering the definite relations of electricity as developed in the preceding parts of the present paper1 the results prove that the quantity of electricity which1 being naturally associated with the particles of matter1 gives them their combining power1 is able1 when thrown into a current1 to separate those particles from their state of combination2 or1 in other words1 that the electricity which decomposes1 and that which is evolved by the decomposition of a certain quantity of matter1 are alike4 #hfi4 ,the harmony which this theory of the definite evolution and the equivalent definite action of electricity introduces into the associated theories of definite proportions and electrochemical affinity1 is very great4 ,according to it1 the equivalent weights of bodies are simply those quantities of them which contain equal quantities of electricity1 or have naturally equal electric powers2 it being the ,,electricity which determines the equivalent number1 because it determines the combining force4 ,or1 if we adopt the atomic theory or phraseology1 then the atoms of bodies which are equivalents to each other in their ordinary chemical action1 have equal quantities of electricity naturally associated with them4 ,but ,i must confess ,i am jealous of the term atom2 for though it is very easy to talk of atoms1 it is very difficult to form a clear idea of their nature1 especially when compound bodies are under consideration4 #hgj4 ,i cannot refrain from recalling here the beautiful idea put forth1 ,i believe1 by ,berzelius 7#gjc47 in his development of his views of the electro-chemical theory of affinity1 that the heat and light evolved during cases of powerful combination are the consequence of the electric discharge which is at the moment taking place4 ,the idea is in perfect accordance with the view ,i have taken of the quantity of electricity associated with the particles of matter4 #hga4 ,in this exposition of the law of the definite action of electricity1 and its corresponding definite proportion in the particles of bodies1 ,i do not pretend to have brought1 as yet1 every case of chemical or electro-chemical action under its dominion4 ,there are numerous considerations of a theoretical nature1 especially respecting the compound particles of matter and the resulting electrical forces which they ought to possess1 which ,i hope will gradually receive their development2 and there are numerous experimental cases1 as1 for instance1 those of compounds formed by weak affinities1 the simultaneous decomposition of water and salts1 c41 which still require investigation4 ,but whatever the results on these and numerous other points may be1 ,i do not believe that the facts which ,i have advanced1 or even the general laws deduced from them1 will suffer any serious change2 and they are of sufficient importance to justify their publication1 though much may yet remain imperfect or undone4 ,indeed1 it is the great beauty of our science1 ,,chemistry1 that advancement in it1 whether in a degree great or small1 instead of exhausting the subjects of research1 opens the doors to further and more abundant knowledge1 overflowing with beauty and utility1 to those who will be at the easy personal pains of undertaking its experimental investigation4 #hgb4 ,the definite production of electricity 7#hfh47 in association with its definite action proves1 ,i think1 that the current of electricity in the voltaic pile3 is sustained by chemical decomposition1 or rather by chemical action1 and not by contact only4 ,but here1 as elsewhere 7#heg471 ,i beg to reserve my opinion as to the real action of contact1 not having yet been able to make up my mind as to whether it is an exciting cause of the current1 or merely necessary to allow of the conduction of electricity1 otherwise generated1 from one metal to the other4 #hgc4 ,but admitting that chemical action is the source of electricity1 what an infinitely small fraction of that which is active do we obtain and employ in our voltaic batteries6 ,zinc and platina wires1 one-eighteenth of an inch in diameter and about half an inch long1 dipped into dilute sulphuric acid1 so weak that it is not sensibly sour to the tongue1 or scarcely to our most delicate test-papers1 will evolve more electricity in one-twentieth of a minute 7#hfj47 than any man would willingly allow to pass through his body at once4 ,the chemical action of a grain of water upon four grains of zinc can evolve electricity equal in quantity to that of a powerful thunder-storm 7#hfh4 #hfa474 ,nor is it merely true that the quantity is active2 it can be directed and made to perform its full equivalent duty 7#hfg4 c474 ,is there not1 then1 great reason to hope and believe that1 by a closer experimental investigation of the principles which govern the development and action of this subtile agent1 we shall be able to increase the power of our batteries1 or invent new instruments which shall a thousandfold surpass in energy those which we at present possess8 #hgd4 ,here for a while ,i must leave the consideration of the definite chemical action of electricity4 ,but before ,i dismiss this series of experimental ,researches1 ,i would call to mind that1 in a former series1 ,i showed the current of electricity was also definite in its magnetic action 7#baf4 #cff4 #cfg4 #cgf4 #cgg472 and1 though this result was not pursued to any extent1 ,i have no doubt that the success which has attended the development of the chemical effects is not more than would accompany an investigation of the magnetic phenomena4 ,royal ,institution1 ,december #cast1 #ahcc4 ,,eighth ,,series4 #ad4 ,on the ,electricity of the ,voltaic ,pile2 its source1 quantity1 intensity1 and general characters4 i4 ,on simple ,voltaic ,circles4 ii4 ,on the intensity necessary for ,electrolyzation4 iii4 ,on associated ,voltaic ,circles1 or the ,voltaic ,battery4 iv4 ,on the resistance of an ,electrolyte to ,electrolytic action4 v4 ,general remarks on the active ,voltaic ,battery4 ,received ,april #g1--,read ,june #e1 #ahca4 i4 ,on simple ,voltaic ,circles4 #hge4 ,the great question of the source of electricity1 in the voltaic pile has engaged the attention of so many eminent philosophers1 that a man of liberal mind and able to appreciate their powers would probably conclude1 although he might not have studied the question1 that the truth was somewhere revealed4 ,but if in pursuance of this impression he were induced to enter upon the work of collating results and conclusions1 he would find such contradictory evidence1 such equilibrium of opinion1 such variation and combination of theory1 as would leave him in complete doubt respecting what he should accept as the true interpretation of nature3 he would be forced to take upon himself the labour of repeating and examining the facts1 and then use his own judgement on them in preference to that of others4 #hgf4 ,this state of the subject must1 to those who have made up their minds on the matter1 be my apology for entering upon its investigation4 ,the views ,i have taken of the definite action of electricity in decomposing bodies 7#ghc471 and the identity of the power so used with the power to be overcome 7#hee471 founded not on a mere opinion or general notion1 but on facts which1 being altogether new1 were to my mind precise and conclusive1 gave me1 as ,i conceived1 the power of examining the question with advantages not before possessed by any1 and which might compensate1 on my part1 for the superior clearness and extent of intellect on theirs4 ,such are the considerations which have induced me to suppose ,i might help in deciding the question1 and be able to render assistance in that great service of removing doubtful knowledge4 ,such knowledge is the early morning light of every advancing science1 and is essential to its development2 but the man who is engaged in dispelling that which is deceptive in it1 and revealing more clearly that which is true1 is as useful in his place1 and as necessary to the general progress of the science1 as he who first broke through the intellectual darkness1 and opened a path into knowledge before unknown to man4 #hgg4 ,the identity of the force constituting the voltaic current or electrolytic agent1 with that which holds the elements of electrolytes together 7#hee471 or in other words with chemical affinity1 seemed to indicate that the electricity of the pile itself was merely a mode of exertion1 or exhibition1 or existence of true chemical action1 or rather of its cause2 and ,i have consequently already said that ,i agree with those who believe that the supply of electricity is due to chemical powers 7#heg474 #hgh4 ,but the great question of whether it is originally due to metallic contact or to chemical action1 i4e4 whether it is the first or the second which originates and determines the current1 was to me still doubtful2 and the beautiful and simple experiment with amalgamated zinc and platina1 which ,i have described minutely as to its results 7#hfc1 c471 did not decide the point2 for in that experiment the chemical action does not take place without the contact of the metals1 and the metallic contact is inefficient without the chemical action4 ,hence either might be looked upon as the determining cause of the current4 #hgi4 ,i thought it essential to decide this question by the simplest possible forms of apparatus and experiment1 that no fallacy might be inadvertently admitted4 ,the well-known difficulty of effecting decomposition by a single pair of plates1 except in the fluid exciting them into action 7#hfc471 seemed to throw insurmountable obstruction in the way of such experiments2 but ,i remembered the easy decomposability of the solution of iodide of potassium 7#caf471 and seeing no theoretical reason1 if metallic contact was not essential1 why true electro-decomposition should not be obtained without it1 even in a single circuit1 ,i persevered and succeeded4 #hhj4 ,a plate of zinc1 about eight inches long and half an inch wide1 was cleaned and bent in the middle to a right angle1 fig4 #gc a1 ,plate ,,vi4 ,a plate of platina1 about three inches long and half an inch wide1 was fastened to a platina wire1 and the latter bent as in the figure1 b4 ,these two pieces of metal were arranged together as delineated1 but as yet without the vessel c1 and its contents1 which consisted of dilute sulphuric acid mingled with a little nitric acid4 ,at x a piece of folded bibulous paper1 moistened in a solution of iodide of potassium1 was placed on the zinc1 and was pressed upon by the end of the platina wire4 ,when under these circumstances the plates were dipped into the acid of the vessel c1 there was an immediate effect at x1 the iodide being decomposed1 and iodine appearing at the anode 7#ffc471 i4e4 against the end of the platina wire4 #hha4 ,as long as the lower ends of the plates remained in the acid the electric current continued1 and the decomposition proceeded at x4 ,on removing the end of the wire from place to place on the paper1 the effect was evidently very powerful2 and on placing a piece of turmeric paper between the white paper and zinc1 both papers being moistened with the solution of iodide of potassium1 alkali was evolved at the cathode 7#ffc47 against the zinc1 in proportion to the evolution of iodine at the anode4 ,hence the decomposition was perfectly polar1 and decidedly dependent upon a current of electricity passing from the zinc through the acid to the platina in the vessel c1 and back from the platina through the solution to the zinc at the paper x4 #hhb4 ,that the decomposition at x was a true electrolytic action1 due to a current determined by the state of things in the vessel c1 and not dependent upon any mere direct chemical action of the zinc and platina on the iodide1 or even upon any current which the solution of iodide might by its action on those metals tend to form at x1 was shown1 in the first place1 by removing the vessel c and its acid from the plates1 when all decomposition at x ceased1 and in the next by connecting the metals1 either in or out of the acid1 together1 when decomposition of the iodide at x occurred1 but in a reverse order2 for now alkali appeared against the end of the platina wire1 and the iodine passed to the zinc1 the current being the contrary of what it was in the former instance1 and produced directly by the difference of action of the solution in the paper on the two metals4 ,the iodine of course combined with the zinc4 #hhc4 ,when this experiment was made with pieces of zinc amalgamated over the whole surface 7#hfc471 the results were obtained with equal facility and in the same direction1 even when only dilute sulphuric acid was contained in the vessel c 7fig4 #gc474 ,whichsoever end of the zinc was immersed in the acid1 still the effects were the same3 so that if1 for a moment1 the mercury might be supposed to supply the metallic contact1 the inversion of the amalgamated piece destroys that objection4 ,the use of unamalgamated zinc 7#hhj47 removes all possibility of doubt,a4 ,a ,the following is a more striking mode of making the above elementary experiment4 ,prepare a plate of zinc1 ten or twelve inches long and two inches wide1 and clean it thoroughly3 provide also two discs of clean platina1 about one inch and a half in diameter3--dip three or four folds of bibulous paper into a strong solution of iodide of potassium1 place them on the clean zinc at one end of the plate1 and put on them one of the platina discs3 finally dip similar folds of paper or a piece of linen cloth into a mixture of equal parts nitric acid and water1 and place it at the other end of the zinc plate with the second platina disc upon it4 ,in this state of things no change at the solution of the iodide will be perceptible2 but if the two discs be connected by a platina 7or any other7 wire for a second or two1 and then that over the iodide be raised1 it will be found that the whole of the surface beneath is deeply stained with evolved iodine4--,dec4 #ahch4 #hhd ,when1 in pursuance of other views 7#icj471 the vessel c was made to contain a solution of caustic potash in place of acid1 still the same results occurred4 ,decomposition of the iodide was effected freely1 though there was no metallic contact of dissimilar metals1 and the current of electricity was in the same direction as when acid was used at the place of excitement4 #hhe4 ,even a solution of common salt in the glass c could produce all these effects4 #hhf4 ,having made a galvanometer with platina wires1 and introduced it into the course of the current between the platina plate and the place of decomposition x1 it was affected1 giving indications of currents in the same direction as those shown to exist by the chemical action4 #hhg4 ,if we consider these results generally1 they lead to very important conclusions4 ,in the first place1 they prove1 in the most decisive manner1 that metallic contact is not necessary for the production of the voltaic current4 ,in the next place1 they show a most extraordinary mutual relation of the chemical affinities of the fluid which excites the current1 and the fluid which is decomposed by it4 #hhh4 ,for the purpose of simplifying the consideration1 let us take the experiment with amalgamated zinc4 ,the metal so prepared exhibits no effect until the current can pass3 it at the same time introduces no new action1 but merely removes an influence which is extraneous to those belonging either to the production or the effect of the electric current under investigation 7#ajjj472 an influence also which1 when present1 tends only to confuse the results4 #hhi4 ,let two plates1 one of amalgamated zinc and the other of platina1 be placed parallel to each other 7fig4 #gd471 and introduce a drop of dilute sulphuric acid1 y1 between them at one end3 there will be no sensible chemical action at that spot unless the two plates are connected somewhere else1 as at ,,pz1 by a body capable of conducting electricity4 ,if that body be a metal or certain forms of carbon1 then the current passes1 and1 as it circulates through the fluid at y1 decomposition ensues4 #hij4 ,then remove the acid from y1 and introduce a drop of the solution of iodide of potassium at x 7fig4 #ge474 ,exactly the same set of effects occur1 except that when the metallic communication is made at ,,pz1 the electric current is in the opposite direction to what it was before1 as is indicated by the arrows1 which show the courses of the currents 7#ffg474 #hia4 ,now both the solutions used are conductors1 but the conduction in them is essentially connected with decomposition 7#heh47 in a certain constant order1 and therefore the appearance of the elements in certain places shows in what direction a current has passed when the solutions are thus employed4 ,moreover1 we find that when they are used at opposite ends of the plates1 as in the last two experiments 7#hhi4 #hij471 metallic contact being allowed at the other extremities1 the currents are in opposite directions4 ,we have evidently1 therefore1 the power of opposing the actions of the two fluids simultaneously to each other at the opposite ends of the plates1 using each one as a conductor for the discharge of the current of electricity1 which the other tends to generate2 in fact1 substituting them for metallic contact1 and combining both experiments into one 7fig4 #gf474 ,under these circumstances1 there is an opposition of forces3 the fluid1 which brings into play the stronger set of chemical affinities for the zinc1 7being the dilute acid17 overcomes the force of the other1 and determines the formation and direction of the electric current2 not merely making that current pass through the weaker liquid1 but actually reversing the tendency which the elements of the latter have in relation to the zinc and platina if not thus counteracted1 and forcing them in the contrary direction to that they are inclined to follow1 that its own current may have free course4 ,if the dominant action at y be removed by making metallic contact there1 then the liquid at x resumes its power2 or if the metals be not brought into contact at y but the affinities of the solution there weakened1 whilst those active x are strengthened1 then the latter gains the ascendency1 and the decompositions are produced in a contrary order4 #hib4 ,before drawing a final conclusion from this mutual dependence and state of the chemical affinities of two distant portions of acting fluids 7#iaf471 ,i will proceed to examine more minutely the various circumstances under which the re-action of the body suffering decomposition is rendered evident upon the action of the body1 also undergoing decomposition1 which produces the voltaic current4 #hic4 ,the use of metallic contact in a single pair of plates1 and the cause of its great superiority above contact made by other kinds of matter1 become now very evident4 ,when an amalgamated zinc plate is dipped into dilute sulphuric acid1 the force of chemical affinity exerted between the metal and the fluid is not sufficiently powerful to cause sensible action at the surfaces of contact1 and occasion the decomposition of water by the oxidation of the metal1 although it is sufficient to produce such a condition of the electricity 7or the power upon which chemical affinity depends7 as would produce a current if there were a path open for it 7#iaf4 #ief472 and that current would complete the conditions necessary1 under the circumstances1 for the decomposition of the water4 #hid4 ,now the presence of a piece of platina touching both the zinc and the fluid to be decomposed1 opens the path required for the electricity4 ,its direct communication with the zinc is effectual1 far beyond any communication made between it and that metal1 7i4e4 between the platina and zinc17 by means of decomposable conducting bodies1 or1 in other words1 electrolytes1 as in the experiment already described 7#hia472 because1 when they are used1 the chemical affinities between them and the zinc produce a contrary and opposing action to that which is influential in the dilute sulphuric acid2 or if that action be but small1 still the affinity of their component parts for each other has to be overcome1 for they cannot conduct without suffering decomposition2 and this decomposition is found experimentally to re-act back upon the forces which in the acid tend to produce the current 7#ijd4 #iaj4 c471 and in numerous cases entirely to neutralize them4 ,where direct contact of the zinc and platina occurs1 these obstructing forces are not brought into action1 and therefore the production and the circulation of the electric current and the concomitant action of decomposition are then highly favoured4 #hie4 ,it is evident1 however1 that one of these opposing actions may be dismissed1 and yet an electrolyte be used for the purpose of completing the circuit between the zinc and platina immersed separately into the dilute acid2 for if1 in fig4 #gc1 the platina wire be retained in metallic contact with the zinc plate a1 at x1 and a division of the platina be made elsewhere1 as at s1 then the solution of iodide placed there1 being in contact with platina at both surfaces1 exerts no chemical affinities for that metal2 or if it does1 they are equal on both sides4 ,its power1 therefore1 of forming a current in opposition to that dependent upon the action of the acid in the vessel c1 is removed1 and only its resistance to decomposition remains as the obstacle to be overcome by the affinities exerted in the dilute sulphuric acid4 #hif4 ,this becomes the condition of a single pair of active plates where metallic contact is allowed4 ,in such cases1 only one set of opposing affinities are to be overcome by those which are dominant in the vessel c2 whereas1 when metallic contact is not allowed1 two sets of opposing affinities must be conquered 7#hid474 #hig4 ,it has been considered a difficult1 and by some an impossible thing1 to decompose bodies by the current from a single pair of plates1 even when it was so powerful as to heat bars of metal red-hot1 as in the case of ,hare's calorimeter1 arranged as a single voltaic circuit1 or of ,wollaston's powerful single pair of metals4 ,this difficulty has arisen altogether from the antagonism of the chemical affinity engaged in producing the current with the chemical affinity to be overcome1 and depends entirely upon their relative intensity2 for when the sum of forces in one has a certain degree of superiority over the sum of forces in the other1 the former gain the ascendency1 determine the current1 and overcome the latter so as to make the substance exerting them yield up its elements in perfect accordance1 both as to direction and quantity1 with the course of those which are exerting the most intense and dominant action4 #hih4 ,water has generally been the substance1 the decomposition of which has been sought for as a chemical test of the passage of an electric current4 ,but ,i now began to perceive a reason for its failure1 and for a fact which ,i had observed long before 7#cae4 #caf47 with regard to the iodide of potassium1 namely1 that bodies would differ in facility of decomposition by a given electric current1 according to the condition and intensity of their ordinary chemical affinities4 ,this reason appeared in their re-action upon the affinities tending to cause the current2 and it appeared probable1 that many substances might be found which could be decomposed by the current of a single pair of zinc and platina plates immersed in dilute sulphuric acid1 although water resisted its action4 ,i soon found this to be the case1 and as the experiments offer new and beautiful proofs of the direct relation and opposition of the chemical affinities concerned in producing and in resisting the stream of electricity1 ,i shall briefly describe them4 #hii4 ,the arrangement of the apparatus was as in fig4 #gg4 ,the vessel v contained dilute sulphuric acid2 ,z and ,p are the zinc and platina plates2 a1 b1 and c are platina wires2 the decompositions were effected at x1 and occasionally1 indeed generally1 a galvanometer was introduced into the circuit at g3 its place only is here given1 the circle at g having no reference to the size of the instrument4 ,various arrangements were made at x1 according to the kind of decomposition to be effected4 ,if a drop of liquid was to be acted upon1 the two ends were merely dipped into it2 if a solution contained in the pores of paper was to be decomposed1 one of the extremities was connected with a platina plate supporting the paper1 whilst the other extremity rested on the paper1 e1 fig4 #ha3 or sometimes1 as with sulphate of soda1 a plate of platina sustained two portions of paper1 one of the ends of the wires resting upon each piece1 c1 fig4 #hf4 ,the darts represent the direction of the electric current 7#ffg474 #ijj4 ,solution of iodide of potassium1 in moistened paper1 being placed at the interruption of the circuit at x1 was readily decomposed4 ,iodine was evolved at the anode1 and alkali at the cathode1 of the decomposing body4 #ija4 ,protochloride of tin1 when fused and placed at x1 was also readily decomposed1 yielding perchloride of tin at the anode 7#ggi471 and tin at the cathode4 #ijb4 ,fused chloride of silver1 placed at x1 was also easily decomposed2 chlorine was evolved at the anode1 and brilliant metallic silver1 either in films upon the surface of the liquid1 or in crystals beneath1 evolved at the cathode4 #ijc4 ,water acidulated with sulphuric acid1 solution of muriatic acid1 solution of sulphate of soda1 fused nitre1 and the fused chloride and iodide of lead were not decomposed by this single pair of plates1 excited only by dilute sulphuric acid4 #ijd4 ,these experiments give abundant proofs that a single pair of plates can electrolyze bodies and separate their elements4 ,they also show in a beautiful manner the direct relation and opposition of the chemical affinities concerned at the two points of action4 ,in those cases where the sum of the opposing affinities at x was sufficiently beneath the sum of the acting affinities in v1 decomposition took place2 but in those cases where they rose higher1 decomposition was effectually resisted and the current ceased to pass 7#hia474 #ije4 ,it is however1 evident1 that the sum of acting affinities in v may be increased by using other fluids than dilute sulphuric acid1 in which latter case1 as ,i believe1 it is merely the affinity of the zinc for the oxygen already combined with hydrogen in the water that is exerted in producing the electric current 7#iai473 and when the affinities are so increased1 the view ,i am supporting leads to the conclusion1 that bodies which resisted in the preceding experiments would then be decomposed1 because of the increased difference between their affinities and the acting affinities thus exalted4 ,this expectation was fully confirmed in the following manner4 #ijf4 ,a little nitric acid was added to the liquid in the vessel r1 so as to make a mixture which ,i shall call diluted nitro-sulphuric acid4 ,on repeating the experiments with this mixture1 all the substances before decomposed again gave way1 and much more readily4 ,but1 besides that1 many which before resisted electrolyzation1 now yielded up their elements4 ,thus1 solution of sulphate of soda1 acted upon in the interstices of litmus and turmeric paper1 yielded acid at the anode and alkali at the cathode2 solution of muriatic acid tinged by indigo yielded chlorine at the anode and hydrogen at the cathode2 solution of nitrate of silver yielded silver at the cathode4 ,again1 fused nitre and the fused iodide and chloride of lead were decomposable by the current of this single pair of plates1 though they were not by the former 7#ijc474 #ijg4 ,a solution of acetate of lead was apparently not decomposed by this pair1 nor did water acidulated by sulphuric acid seem at first to give way 7#igc474 #ijh4 ,the increase of intensity or power of the current produced by a simple voltaic circle1 with the increase of the force of the chemical action at the exciting place1 is here sufficiently evident4 ,but in order to place it in a clearer point of view1 and to show that the decomposing effect was not at all dependent1 in the latter cases1 upon the mere capability of evolving more electricity1 experiments were made in which the quantity evolved could be increased without variation in the intensity of the exciting cause4 ,thus the experiments in which dilute sulphuric acid was used 7#hii471 were repeated1 using large plates of zinc and platina in the acid2 but still those bodies which resisted decomposition before1 resisted it also under these new circumstances4 ,then again1 where nitro-sulphuric acid was used 7#ijf471 mere wires of platina and zinc were immersed in the exciting acid2 yet1 notwithstanding this change1 those bodies were now decomposed which resisted any current tending to be formed by the dilute sulphuric acid4 ,for instance1 muriatic acid could not be decomposed by a single pair of plates when immersed in dilute sulphuric acid2 nor did making the solution of sulphuric acid strong1 nor enlarging the size of the zinc and platina plates immersed in it1 increase the power2 but if to a weak sulphuric acid a very little nitric acid was added1 then the electricity evolved had power to decompose the muriatic acid1 evolving chlorine at the anode and hydrogen at the cathode1 even when mere wires of metals were used4 ,this mode of increasing the intensity of the electric current1 as it excludes the effect dependent upon many pairs of plates1 or even the effect of making any one acid stronger or weaker1 is at once referable to the condition and force of the chemical affinities which are brought into action1 and may1 both in principle and practice1 be considered as perfectly distinct from any other mode4 #iji4 ,the direct reference which is thus experimentally made in the simple voltaic circle of the intensity of the electric current to the intensity of the chemical action going on at the place where the existence and direction of the current is determined1 leads to the conclusion that by using selected bodies1 as fused chlorides1 salts1 solutions of acids1 c41 which may act upon the metals employed with different degrees of chemical force2 and using also metals in association with platina1 or with each other1 which shall differ in the degree of chemical action exerted between them and the exciting fluid or electrolyte1 we shall be able to obtain a series of comparatively constant effects due to electric currents of different intensities1 which will serve to assist in the construction of a scale competent to supply the means of determining relative degrees of intensity with accuracy in future researches,a4 ,a ,in relation to this difference and its probable cause1 see considerations on inductive polarization1 #aced1 c4--,dec4 #ahch4 #iaj4 ,i have already expressed the view which ,i take of the decomposition in the experimental place1 as being the direct consequence of the superior exertion at some other spot of the same kind of power as that to be overcome1 and therefore as the result of an antagonism of forces of the same nature 7#hia4 #ijd474 ,those at the place of decomposition have a re-action upon1 and a power over1 the exerting or determining set proportionate to what is needful to overcome their own power2 and hence a curious result of resistance offered by decompositions to the original determining force1 and consequently to the current4 ,this is well shown in the cases where such bodies as chloride of lead1 iodide of lead1 and water would not decompose with the current produced by a single pair of zinc and platina plates in sulphuric acid 7#ijc471 although they would with a current of higher intensity produced by stronger chemical powers4 ,in such cases no sensible portion of the current passes 7#ifg472 the action is stopped2 and ,i am now of opinion that in the case of the law of conduction which ,i described in the ,fourth ,series of these ,researches 7#dac471 the bodies which are electrolytes in the fluid state cease to be such in the solid form1 because the attractions of the particles by which they are retained in combination and in their relative position1 are then too powerful for the electric current,a4 ,the particles retain their places2 and as decomposition is prevented1 the transmission of the electricity is prevented also2 and although a battery of many plates may be used1 yet if it be of that perfect kind which allows of no extraneous or indirect action 7#ajjj471 the whole of the affinities concerned in the activity of that battery are at the same time also suspended and counteracted4 ,a ,refer onwards to #agje4--;,dec4 #ahch4 #iaa4 ,but referring to the resistance of each single case of decomposition1 it would appear that as these differ in force according to the affinities by which the elements in the substance tend to retain their places1 they also would supply cases constituting a series of degrees by which to measure the initial intensities of simple voltaic or other currents of electricity1 and which1 combined with the scale of intensities determined by different degrees of acting force 7#iji471 would probably include a sufficient set of differences to meet almost every important case where a reference to intensity would be required4 #iab4 ,according to the experiments ,i have already had occasion to make1 ,i find that the following bodies are electrolytic in the order in which ,i have placed them1 those which are first being decomposed by the current of lowest intensity4 ,these currents were always from a single pair of plates1 and may be considered as elementary voltaic forces4 ,iodide of potassium 7solution74 ,chloride of silver 7fused74 ,protochloride of tin 7fused74 ,chloride of lead 7fused74 ,iodide of lead 7fused74 ,muriatic acid 7solution74 ,water1 acidulated with sulphuric acid4 #iac4 ,it is essential that1 in all endeavours to obtain the relative electrolytic intensity necessary for the decomposition of different bodies1 attention should be paid to the nature of the electrodes and the other bodies present which may favour secondary actions 7#ihf474 ,if in electro-decomposition one of the elements separated has an affinity for the electrode1 or for bodies present in the surrounding fluid1 then the affinity resisting decomposition is in part balanced by such power1 and the true place of the electrolyte in a table of the above kind is not obtained3 thus1 chlorine combines with a positive platina electrode freely1 but iodine scarcely at all1 and therefore ,i believe it is that the fused chlorides stand first in the preceding ,table4 ,again1 if in the decomposition of water not merely sulphuric but also a little nitric acid be present1 then the water is more freely decomposed1 for the hydrogen at the cathode is not ultimately expelled1 but finds oxygen in the nitric acid1 with which it can combine to produce a secondary result2 the affinities opposing decomposition are in this way diminished1 and the elements of the water can then be separated by a current of lower intensity4 #iad4 ,advantage may be taken of this principle to interpolate more minute degrees into the scale of initial intensities already referred to 7#iji4 #iaa47 than is there spoken of2 for by combining the force of a current constant in its intensity1 with the use of electrodes consisting of matter1 having more or less affinity for the elements evolved from the decomposing electrolyte1 various intermediate degrees may be obtained4 99 99 99 99 99 #iae4 ,returning to the consideration of the source of electricity 7#hgh4 c471 there is another proof of the most perfect kind that metallic contact has nothing to do with the production of electricity in the voltaic circuit1 and further1 that electricity is only another mode of the exertion of chemical forces4 ,it is1 the production of the electric spark before any contact of metals is made1 and by the exertion of pure and unmixed chemical forces4 ,the experiment1 which will be described further on 7#ief471 consists in obtaining the spark upon making contact between a plate of zinc and a plate of copper plunged into dilute sulphuric acid4 ,in order to make the arrangement as elementary as possible1 mercurial surfaces were dismissed1 and the contact made by a copper wire connected with the copper plate1 and then brought to touch a clean part of the zinc plate4 ,the electric spark appeared1 and it must of necessity have existed and passed before the zinc and the copper were in contact4 #iaf4 ,in order to render more distinct the principles which ,i have been endeavouring to establish1 ,i will restate them in their simplest form1 according to my present belief4 ,the electricity of the voltaic pile 7#hef4 note7 is not dependent either in its origin or its continuance upon the contact of the metals with each other 7#hhj4 #iae474 ,it is entirely due to chemical action 7#hhb471 and is proportionate in its intensity to the intensity of the affinities concerned in its production 7#ijh472 and in its quantity to the quantity of matter which has been chemically active during its evolution 7#hfi474 ,this definite production is again one of the strongest proofs that the electricity is of chemical origin4 #iag4 ,as volta-electro-generation is a case of mere chemical action1 so volta-electro-decomposition is simply a case of the preponderance of one set of chemical affinities more powerful in their nature1 over another set which are less powerful3 and if the instance of two opposing sets of such forces 7#hia47 be considered1 and their mutual relation and dependence borne in mind1 there appears no necessity for using1 in respect to such cases1 any other term than chemical affinity1 7though that of electricity may be very convenient17 or supposing any new agent to be concerned in producing the results2 for we may consider that the powers at the two places of action are in direct communion and balanced against each other through the medium of the metals 7#hia471 fig4 #gf1 in a manner analogous to that in which mechanical forces are balanced against each other by the intervention of the lever 7#ajca474 #iah4 ,all the facts show us that that power commonly called chemical affinity1 can be communicated to a distance through the metals and certain forms of carbon2 that the electric current is only another form of the forces of chemical affinity2 that its power is in proportion to the chemical affinities producing it2 that when it is deficient in force it may be helped by calling in chemical aid1 the want in the former being made up by an equivalent of the latter2 that1 in other words1 the forces termed chemical affinity and electricity are one and the same4 #iai4 ,when the circumstances connected with the production of electricity in the ordinary voltaic circuit are examined and compared1 it appears that the source of that agent1 always meaning the electricity which circulates and completes the current in the voltaic apparatus1 and gives that apparatus power and character 7#idg4 #iif471 exists in the chemical action which takes place directly between the metal and the body with which it combines1 and not at all in the subsequent action of the substance so produced with the acid present,a4 ,thus1 when zinc1 platina1 and dilute sulphuric acid are used1 it is the union of the zinc with the oxygen of the water which determines the current2 and though the acid is essential to the removal of the oxide so formed1 in order that another portion of zinc may act on another portion of water1 it does not1 by combination with that oxide1 produce any sensible portion of the current of electricity which circulates2 for the quantity of electricity is dependent upon the quantity of zinc oxidized1 and in definite proportion to it3 its intensity is in proportion to the intensity of the chemical affinity of the zinc for the oxygen under the circumstances1 and is scarcely1 if at all1 affected by the use of either strong or weak acid 7#ijh474 ,a ,wollaston1 ,philosophical ,transactions1 #ahja1 p4 #dbg4 #ibj4 ,again1 if zinc1 platina1 and muriatic acid are used1 the electricity appears to be dependent upon the affinity of the zinc for the chlorine1 and to be circulated in exact proportion to the number of particles of zinc and chlorine which unite1 being in fact an equivalent to them4 #iba4 ,but in considering this oxidation1 or other direct action upon the ,,metal itself1 as the cause and source of the electric current1 it is of the utmost importance to observe that the oxygen or other body must be in a peculiar condition1 namely1 in the state of combination2 and not only so1 but limited still further to such a state of combination and in such proportions as will constitute an electrolyte 7#hbc474 ,a pair of zinc and platina plates cannot be so arranged in oxygen gas as to produce a current of electricity1 or act as a voltaic circle1 even though the temperature may be raised so high as to cause oxidation of the zinc far more rapidly than if the pair of plates were plunged into dilute sulphuric acid2 for the oxygen is not part of an electrolyte1 and cannot therefore conduct the forces onwards by decomposition1 or even as metals do by itself4 ,or if its gaseous state embarrass the minds of some1 then liquid chlorine may be taken4 ,it does not excite a current of electricity through the two plates by combining with the zinc1 for its particles cannot transfer the electricity active at the point of combination across to the platina4 ,it is not a conductor of itself1 like the metals2 nor is it an electrolyte1 so as to be capable of conduction during decomposition1 and hence there is simple chemical action at the spot1 and no electric current,a4 ,a ,i do not mean to affirm that no traces of electricity ever appear in such cases4 ,what ,i mean is1 that no electricity is evolved in any way1 due or related to the causes which excite voltaic electricity1 or proportionate to them4 ,that which does appear occasionally is the smallest possible fraction of that which the acting matter could produce if arranged so as to act voltaically1 probably not the one hundred thousandth1 or even the millionth part1 and is very probably altogether different in its source4 #ibb4 ,it might at first be supposed that a conducting body not electrolytic1 might answer as the third substance between the zinc and the platina2 and it is true that we have some such capable of exerting chemical action upon the metals4 ,they must1 however1 be chosen from the metals themselves1 for there are no bodies of this kind except those substances and charcoal4 ,to decide the matter by experiment1 ,i made the following arrangement4 ,melted tin was put into a glass tube bent into the form of the letter ,v1 fig4 #gh1 so as to fill the half of each limb1 and two pieces of thick platina wire1 p1 w1 inserted1 so as to have their ends immersed some depth in the tin3 the whole was then allowed to cool1 and the ends p and w connected with a delicate galvanometer4 ,the part of the tube at x was now reheated1 whilst the portion y was retained cool4 ,the galvanometer was immediately influenced by the thermo-electric current produced4 ,the heat was steadily increased at x1 until at last the tin and platina combined there2 an effect which is known to take place with strong chemical action and high ignition2 but not the slightest additional effect occurred at the galvanometer4 ,no other deflection than that due to the thermo-electric current was observable the whole time4 ,hence1 though a conductor1 and one capable of exerting chemical action on the tin1 was used1 yet1 not being an electrolyte1 not the slightest effect of an electrical current could be observed 7#idg474 #ibc4 ,from this it seems apparent that the peculiar character and condition of an electrolyte is essential in one part of the voltaic circuit2 and its nature being considered1 good reasons appear why it and it alone should be effectual4 ,an electrolyte is always a compound body3 it can conduct1 but only whilst decomposing4 ,its conduction depends upon its decomposition and the transmission of its particles in directions parallel to the current2 and so intimate is this connexion1 that if their transition be stopped1 the current is stopped also2 if their course be changed1 its course and direction change with them2 if they proceed in one direction1 it has no power to proceed in any other than a direction invariably dependent on them4 ,the particles of an electrolytic body are all so mutually connected1 are in such relation with each other through their whole extent in the direction of the current1 that if the last is not disposed of1 the first is not at liberty to take up its place in the new combination which the powerful affinity of the most active metal tends to produce2 and then the current itself is stopped2 for the dependencies of the current and the decomposition are so mutual1 that whichsoever be originally determined1 i4e4 the motion of the particles or the motion of the current1 the other is invariable in its concomitant production and its relation to it4 #ibd4 ,consider1 then1 water as an electrolyte and also as an oxidizing body4 ,the attraction of the zinc for the oxygen is greater1 under the circumstances1 than that of the oxygen for the hydrogen2 but in combining with it1 it tends to throw into circulation a current of electricity in a certain direction4 ,this direction is consistent 7as is found by innumerable experiments7 with the transfer of the hydrogen from the zinc towards the platina1 and the transfer in the opposite direction of fresh oxygen from the platina towards the zinc2 so that the current can pass in that one line1 and1 whilst it passes1 can consist with and favour the renewal of the conditions upon the surface of the zinc1 which at first determined both the combination and circulation4 ,hence the continuance of the action there1 and the continuation of the current4 ,it therefore appears quite as essential that there should be an electrolyte in the circuit1 in order that the action may be transferred forward1 in a certain constant direction1 as that there should be an oxidizing or other body capable of acting directly on the metal2 and it also appears to be essential that these two should merge into one1 or that the principle directly active on the metal by chemical action should be one of the ions of the electrolyte used4 ,whether the voltaic arrangement be excited by solution of acids1 or alkalies1 or sulphurets1 or by fused substances 7#dgf471 this principle has always hitherto1 as far as ,i am aware1 been an anion 7#idc472 and ,i anticipate1 from a consideration of the principles of electric action1 that it must of necessity be one of that class of bodies4 #ibe4 ,if the action of the sulphuric acid used in the voltaic circuit be considered1 it will be found incompetent to produce any sensible portion of the electricity of the current by its combination with the oxide formed1 for this simple reason1 it is deficient in a most essential condition3 it forms no part of an electrolyte1 nor is it in relation with any other body present in the solution which will permit of the mutual transfer of the particles and the consequent transfer of the electricity4 ,it is true1 that as the plane at which the acid is dissolving the oxide of zinc formed by the action of the water1 is in contact with the metal zinc1 there seems no difficulty in considering how the oxide there could communicate an electrical state1 proportionate to its own chemical action on the acid1 to the metal1 which is a conductor without decomposition4 ,but on the side of the acid there is no substance to complete the circuit3 the water1 as water1 cannot conduct it1 or at least only so small a proportion that it is merely an incidental and almost inappreciable effect 7#igj472 and it cannot conduct it as an electrolyte1 because an electrolyte conducts in consequence of the mutual relation and action of its particles2 and neither of the elements of the water1 nor even the water itself1 as far as we can perceive1 are ions with respect to the sulphuric acid 7#hdh47;,a4 ,a ,it will be seen that ,i here agree with ,sir ,humphry ,davy1 who has experimentally supported the opinion that acids and alkalies in combining do not produce any current of electricity4 ,philosophical ,transactions1 #ahbf1 p4 #cih4 #ibf4 ,this view of the secondary character of the sulphuric acid as an agent in the production of the voltaic current1 is further confirmed by the fact1 that the current generated and transmitted is directly and exactly proportional to the quantity of water decomposed and the quantity of zinc oxidized 7#hfh4 #iia471 and is the same as that required to decompose the same quantity of water4 ,as1 therefore1 the decomposition of the water shows that the electricity has passed by its means1 there remains no other electricity to be accounted for or to be referred to any action other than that of the zinc and the water on each other4 #ibg4 ,the general case 7for it includes the former one 7#ibd4717 of acids and bases1 may theoretically be stated in the following manner4 ,let a1 fig4 #gi1 be supposed to be a dry oxacid1 and b a dry base1 in contact at c1 and in electric communication at their extremities by plates of platina pp1 and a platina wire w4 ,if this acid and base were fluid1 and combination took place at c1 with an affinity ever so vigorous1 and capable of originating an electric current1 the current could not circulate in any important degree2 because1 according to the experimental results1 neither a nor b could conduct without being decomposed1 for they are either electrolytes or else insulators1 under all circumstances1 except to very feeble and unimportant currents 7#igj4 #ihf474 ,now the affinities at c are not such as tend to cause the elements either of a or b to separate1 but only such as would make the two bodies combine together as a whole2 the point of action is1 therefore1 insulated1 the action itself local 7#iba4 #idg471 and no current can be formed4 #ibh4 ,if the acid and base be dissolved in water1 then it is possible that a small portion of the electricity due to chemical action may be conducted by the water without decomposition 7#iff4 #ihd472 but the quantity will be so small as to be utterly disproportionate to that due to the equivalents of chemical force2 will be merely incidental2 and1 as it does not involve the essential principles of the voltaic pile1 it forms no part of the phenomena at present under investigation,a4 ,a ,it will ,i trust be fully understood1 that in these investigations ,i am not professing to take an account of every small1 incidental1 or barely possible effect1 dependent upon slight disturbances of the electric fluid during chemical action1 but am seeking to distinguish and identify those actions on which the power of the voltaic battery essentially depends4 #ibi4 ,if for the oxacid a hydracid be substituted 7#ibg471--;as one analogous to the muriatic1 for instance1--then the state of things changes altogether1 and a current due to the chemical action of the acid on the base is possible4 ,but now both the bodies act as electrolytes1 for it is only one principle of each which combine mutually1--as1 for instance1 the chlorine with the metal1--and the hydrogen of the acid and the oxygen of the base are ready to traverse with the chlorine of the acid and the metal of the base in conformity with the current and according to the general principles already so fully laid down4 #icj4 ,this view of the oxidation of the metal1 or other direct chemical action upon it1 being the sole cause of the production of the electric current in the ordinary voltaic pile1 is supported by the effects which take place when alkaline or sulphuretted solutions 7#ica4 #idc47 are used for the electrolytic conductor instead of dilute sulphuric acid4 ,it was in elucidation of this point that the experiments without metallic contact1 and with solution of alkali as the exciting fluid1 already referred to 7#hhd471 were made4 #ica4 ,advantage was then taken of the more favourable condition offered1 when metallic contact is allowed 7#hie471 and the experiments upon the decomposition of bodies by a single pair of plates 7#hii47 were repeated1 solution of caustic potassa being employed in the vessel v1 fig4 #gg4 in place of dilute sulphuric acid4 ,all the effects occurred as before3 the galvanometer was deflected2 the decompositions of the solutions of iodide of potassium1 nitrate of silver1 muriatic acid1 and sulphate of soda ensued at x2 and the places where the evolved principles appeared1 as well as the deflection of the galvanometer1 indicated a current in the same direction as when acid was in the vessel v2 i4e4 from the zinc through the solution to the platina1 and back by the galvanometer and substance suffering decomposition to the zinc4 #icb4 ,the similarity in the action of either dilute sulphuric acid or potassa goes indeed far beyond this1 even to the proof of identity in quantity as well as in direction of the electricity produced4 ,if a plate of amalgamated zinc be put into a solution of potassa1 it is not sensibly acted upon2 but if touched in the solution by a plate of platina1 hydrogen is evolved on the surface of the latter metal1 and the zinc is oxidized exactly as when immersed in dilute sulphuric acid 7#hfc474 ,i accordingly repeated the experiment before described with weighed plates of zinc 7#hfd4 c471 using however solution of potassa instead of dilute sulphuric acid4 ,although the time required was much longer than when acid was used1 amounting to three hours for the oxidizement of #g4ee grains of zinc1 still ,i found that the hydrogen evolved at the platina plate was the equivalent of the metal oxidized at the surface of the zinc4 ,hence the whole of the reasoning which was applicable in the former instance applies also here1 the current being in the same direction1 and its decomposing effect in the same degree1 as if acid instead of alkali had been used 7#hfh474 #icc4 ,the proof1 therefore1 appears to me complete1 that the combination of the acid with the oxide1 in the former experiment1 had nothing to do with the production of the electric current2 for the same current is here produced when the action of the acid is absent1 and the reverse action of an alkali is present4 ,i think it cannot be supposed for a moment1 that the alkali acted chemically as an acid to the oxide formed2 on the contrary1 our general chemical knowledge leads to the conclusion1 that the ordinary metallic oxides act rather as acids to the alkalies2 yet that kind of action would tend to give a reverse current in the present case1 if any were due to the union of the oxide of the exciting metal with the body which combines with it4 ,but instead of any variation of this sort1 the direction of the electricity was constant1 and its quantity also directly proportional to the water decomposed1 or the zinc oxidized4 ,there are reasons for believing that acids and alkalies1 when in contact with metals upon which they cannot act directly1 still have a power of influencing their attractions for oxygen 7#ida472 but all the effects in these experiments prove1 ,i think1 that it is the oxidation of the metal necessarily dependent upon1 and associated as it is with1 the electrolyzation of the water 7#iba4 #ibc47 that produces the current2 and that the acid or alkali merely acts as solvents1 and by removing the oxidized zinc1 allows other portions to decompose fresh water1 and so continues the evolution or determination of the current4 #icd4 ,the experiments were then varied by using solution of ammonia instead of solution of potassa2 and as it1 when pure1 is like water1 a bad conductor 7#eed471 it was occasionally improved in that power by adding sulphate of ammonia to it4 ,but in all the cases the results were the same as before2 decompositions of the same kind were effected1 and the electric current producing these was in the same direction as in the experiments just described4 #ice4 ,in order to put the equal and similar action of acid and alkali to stronger proof1 arrangements were made as in fig4 #hj42 the glass vessel ,a contained dilute sulphuric acid1 the corresponding glass vessel ,b solution of potassa1 ,,pp was a plate of platina dipping into both solutions1 and ,,zz two plates of amalgamated zinc connected with a delicate galvanometer4 ,when these were plunged at the same time into the two vessels1 there was generally a first feeble effect1 and that in favour of the alkali1 i4e4 the electric current tended to pass through the vessels in the direction of the arrow1 being the reverse direction of that which the acid in ,a would have produced alone3 but the effect instantly ceased1 and the action of the plates in the vessels was so equal1 that1 being contrary because of the contrary position of the plates1 no permanent current resulted4 #icf4 ,occasionally a zinc plate was substituted for the plate ,,pp1 and platina plates for the plates ,,zz2 but this caused no difference in the results3 nor did a further change of the middle plate to copper produce any alteration4 #icg4 ,as the opposition of electro-motive pairs of plates produces results other than those due to the mere difference of their independent actions 7#ajaa4 #ajde471 ,i devised another form of apparatus1 in which the action of acid and alkali might be more directly compared4 ,a cylindrical glass cup1 about two inches deep within1 an inch in internal diameter1 and at least a quarter of an inch in thickness1 was cut down the middle into halves1 fig4 #ha4 ,a broad brass ring1 larger in diameter than the cup1 was supplied with a screw at one side2 so that when the two halves of the cup were within the ring1 and the screw was made to press tightly against the glass1 the cup held any fluid put into it4 ,bibulous paper of different degrees of permeability was then cut into pieces of such a size as to be easily introduced between the loosened halves of the cup1 and served when the latter were tightened again to form a porous division down the middle of the cup1 sufficient to keep any two fluids on opposite sides of the paper from mingling1 except very slowly1 and yet allowing them to act freely as one electrolyte4 ,the two spaces thus produced ,i will call the cells ,a and ,b1 fig4 #hb4 ,this instrument ,i have found of most general application in the investigation of the relation of fluids and metals amongst themselves and to each other4 ,by combining its use with that of the galvanometer1 it is easy to ascertain the relation of one metal with two fluids1 or of two metals with one fluid1 or of two metals and two fluids upon each other4 #ich4 ,dilute sulphuric acid1 sp4 gr4 #a4be1 was put into the cell ,a1 and a strong solution of caustic potassa into the cell ,b2 they mingled slowly through the paper1 and at last a thick crust of sulphate of potassa formed on the side of the paper next to the alkali4 ,a plate of clean platina was put into each cell and connected with a delicate galvanometer1 but no electric current could be observed4 ,hence the contact of acid with one platina plate1 and alkali with the other1 was unable to produce a current2 nor was the combination of the acid with the alkali more effectual 7#ibe474 #ici4 ,when one of the platina plates was removed and a zinc plate substituted1 either amalgamated or not1 a strong electric current was produced4 ,but1 whether the zinc were in the acid whilst the platina was in the alkali1 or whether the reverse order were chosen1 the electric current was always from the zinc through the electrolyte to the platina1 and back through the galvanometer to the zinc1 the current seeming to be strongest when the zinc was in the alkali and the platina in the acid4 #idj4 ,in these experiments1 therefore1 the acid seems to have no power over the alkali1 but to be rather inferior to it in force4 ,hence there is no reason to suppose that the combination of the oxide formed with the acid around it has any direct influence in producing the electricity evolved1 the whole of which appears to be due to the oxidation of the metal 7#iai474 #ida4 ,the alkali1 in fact1 is superior to the acid in bringing a metal into what is called the positive state2 for if plates of the same metal1 as zinc1 tin1 lead1 or copper1 be used both in the acid or alkali1 the electric current is from the alkali across the cell to the acid1 and back through the galvanometer to the alkali1 as ,sir ,humphry ,davy formerly stated ,a4 ,this current is so powerful1 that if amalgamated zinc1 or tin1 or lead be used1 the metal in the acid evolves hydrogen the moment it is placed in communication with that in the alkali1 not from any direct action of the acid upon it1 for if the contact be broken the action ceases1 but because it is powerfully negative with regard to the metal in the alkali4 ,a ,elements of ,chemical ,philosophy1 p4 #adi2 or ,philosophical ,transactions1 #ahbf1 p4 #djc4 #idb4 ,the superiority of alkali is further proved by this1 that if zinc and tin be used1 or tin and lead1 whichsoever metal is put into the alkali becomes positive1 that in the acid being negative4 ,whichsoever is in the alkali is oxidized1 whilst that in the acid remains in the metallic state1 as far as the electric current is concerned4 #idc4 ,when sulphuretted solutions are used 7#icj47 in illustration of the assertion1 that it is the chemical action of the metal and one of the ions of the associated electrolyte that produces all the electricity of the voltaic circuit1 the proofs are still the same4 ,thus1 as ,sir ,humphry ,davy,a has shown1 if iron and copper be plunged into dilute acid1 the current is from the iron through the liquid to the copper2 in solution of potassa it is in the same direction1 but in solution of sulphuret of potassa it is reversed4 ,in the two first cases it is oxygen which combines with the iron1 in the latter sulphur which combines with the copper1 that produces the electric current2 but both of these are ions1 existing as such in the electrolyte1 which is at the same moment suffering decomposition2 and1 what is more1 both of these are anions1 for they leave the electrolytes at their anodes1 and act just as chlorine1 iodine1 or any other anion would act which might have been previously chosen as that which should be used to throw the voltaic circle into activity4 ,a ,elements of ,chemical ,philosophy1 p4 #adh4 #idd4 ,the following experiments complete the series of proofs of the origin of the electricity in the voltaic pile4 ,a fluid amalgam of potassium1 containing not more than a hundredth of that metal1 was put into pure water1 and connected1 through the galvanometer with a plate of platina in the same water4 ,there was immediately an electric current from the amalgam through the electrolyte to the platina4 ,this must have been due to the oxidation only of the metal1 for there was neither acid nor alkali to combine with1 or in any way act on1 the body produced4 #ide4 ,again1 a plate of clean lead and a plate of platina were put into pure water4 ,there was immediately a powerful current produced from the lead through the fluid to the platina3 it was even intense enough to decompose solution of the iodide of potassium when introduced into the circuit in the form of apparatus already described 7#hhj471 fig4 #gc4 ,here no action of acid or alkali on the oxide formed from the lead could supply the electricity3 it was due solely to the oxidation of the metal4 99 99 99 99 99 #idf4 ,there is no point in electrical science which seems to me of more importance than the state of the metals and the electrolytic conductor in a simple voltaic circuit before and at the moment when metallic contact is first completed4 ,if clearly understood1 ,i feel no doubt it would supply us with a direct key to the laws under which the great variety of voltaic excitements1 direct and incidental1 occur1 and open out new fields of research for our investigation,a4 ,a ,in connexion with this part of the subject refer now to ,series ,,xi4 #aafd1 ,series ,,xii4 #acdc-aceh1 and ,series ,,xiii4 #afba4 c4--,dec4 #ahch4 #idg4 ,we seem to have the power of deciding to a certain extent in numerous cases of chemical affinity1 7as of zinc with the oxygen of water1 c4 c47 which of two modes of action of the attractive power shall be exerted 7#iif474 ,in the one mode we can transfer the power onwards1 and make it produce elsewhere its equivalent of action 7#hfg4 #iag472 in the other1 it is not transferred1 but exerted wholly at the spot4 ,the first is the case of volta-electric excitation1 the other ordinary chemical affinity3 but both are chemical actions and due to one force or principle4 #idh4 ,the general circumstances of the former mode occur in all instances of voltaic currents1 but may be considered as in their perfect condition1 and then free from those of the second mode1 in some only of the cases2 as in those of plates of zinc and platina in solution of potassa1 or of amalgamated zinc and platina in dilute sulphuric acid4 #idi4 ,assuming it sufficiently proved1 by the preceding experiments and considerations1 that the electro-motive action depends1 when zinc1 platina1 and dilute sulphuric acid are used1 upon the mutual affinity of the metal zinc and the oxygen of the water 7#iba4 #ibd471 it would appear that the metal1 when alone1 has not power enough1 under the circumstances1 to take the oxygen and expel the hydrogen from the water2 for1 in fact1 no such action takes place4 ,but it would also appear that it has power so far to act1 by its attraction for the oxygen of the particles in contact with it1 as to place the similar forces already active between these and the other particles of oxygen and the particles of hydrogen in the water1 in a peculiar state of tension or polarity1 and probably also at the same time to throw those of its own particles which are in contact with the water into a similar but opposed state4 ,whilst this state is retained1 no further change occurs2 but when it is relieved1 by completion of the circuit1 in which case the forces determined in opposite directions1 with respect to the zinc and the electrolyte1 are found exactly competent to neutralize each other1 then a series of decompositions and recompositions takes place amongst the particles of oxygen and hydrogen constituting the water1 between the place of contact with the platina and the place where the zinc is active2 these intervening particles being evidently in close dependence upon and relation to each other4 ,the zinc forms a direct compound with those particles of oxygen which were1 previously1 in divided relation to both it and the hydrogen3 the oxide is removed by the acid1 and a fresh surface of zinc is presented to the water1 to renew and repeat the action4 #iej4 ,practically1 the state of tension is best relieved by dipping a metal which has less attraction for oxygen than the zinc1 into the dilute acid1 and making it also touch the zinc4 ,the force of chemical affinity1 which has been influenced or polarized in the particles of the water by the dominant attraction of the zinc for the oxygen1 is then transferred1 in a most extraordinary manner1 through the two metals1 so as to re-enter upon the circuit in the electrolytic conductor1 which1 unlike the metals in that respect1 cannot convey or transfer it without suffering decomposition2 or rather1 probably1 it is exactly balanced and neutralized by the force which at the same moment completes the combination of the zinc with the oxygen of the water4 ,the forces1 in fact1 of the two particles which are acting towards each other1 and which are therefore in opposite directions1 are the origin of the two opposite forces1 or directions of force1 in the current4 ,they are of necessity equivalent to each other4 ,being transferred forward in contrary directions1 they produce what is called the voltaic current3 and it seems to me impossible to resist the idea that it must be preceded by a state of tension in the fluid1 and between the fluid and the zinc2 the first consequence of the affinity of the zinc for the oxygen of the water4 #iea4 ,i have sought carefully for indications of a state of tension in the electrolytic conductor2 and conceiving that it might produce something like structure1 either before or during its discharge1 ,i endeavoured to make this evident by polarized light4 ,a glass cell1 seven inches long1 one inch and a half wide1 and six inches deep1 had two sets of platina electrodes adapted to it1 one set for the ends1 and the other for the sides4 ,those for the sides were seven inches long by three inches high1 and when in the cell were separated by a little frame of wood covered with calico2 so that when made active by connexion with a battery upon any solution in the cell1 the bubbles of gas rising from them did not obscure the central parts of the liquid4 #ieb4 ,a saturated solution of sulphate of soda was put into the cell1 and the electrodes connected with a battery of #aej pairs of #d-;inch plates3 the current of electricity was conducted across the cell so freely1 that the discharge was as good as if a wire had been used4 ,a ray of polarized light was then transmitted through this solution1 directly across the course of the electric current1 and examined by an analysing plate2 but though it penetrated seven inches of solution thus subject to the action of the electricity1 and though contact was sometimes made1 sometimes broken1 and occasionally reversed during the observations1 not the slightest trace of action on the ray could be perceived4 #iec4 ,the large electrodes were then removed1 and others introduced which fitted the ends of the cell4 ,in each a slit was cut1 so as to allow the light to pass4 ,the course of the polarized ray was now parallel to the current1 or in the direction of its axis 7#eag472 but still no effect1 under any circumstances of contact or disunion1 could be perceived upon it4 #ied4 ,a strong solution of nitrate of lead was employed instead of the sulphate of soda1 but no effects could be detected4 #iee4 ,thinking it possible that the discharge of the electric forces by the successive decompositions and recompositions of the particles of the electrolyte might neutralize and therefore destroy any effect which the first state of tension could by possibility produce1 ,i took a substance which1 being an excellent electrolyte when fluid1 was a perfect insulator when solid1 namely1 borate of lead1 in the form of a glass plate1 and connecting the sides and the edges of this mass with the metallic plates1 sometimes in contact with the poles of a voltaic battery1 and sometimes even with the electric machine1 for the advantage of the much higher intensity then obtained1 ,i passed a polarized ray across it in various directions1 as before1 but could not obtain the slightest appearance of action upon the light4 ,hence ,i conclude1 that notwithstanding the new and extraordinary state which must be assumed by an electrolyte1 either during decomposition 7when a most enormous quantity of electricity must be traversing it71 or in the state of tension which is assumed as preceding decomposition1 and which might be supposed to be retained in the solid form of the electrolyte1 still it has no power of affecting a polarized ray of light2 for no kind of structure or tension can in this way be rendered evident4 #ief4 ,there is1 however1 one beautiful experimental proof of a state of tension acquired by the metals and the electrolyte before the electric current is produced1 and before contact of the different metals is made 7#iae472 in fact1 at that moment when chemical forces only are efficient as a cause of action4 ,i took a voltaic apparatus1 consisting of a single pair of large plates1 namely1 a cylinder of amalgamated zinc1 and a double cylinder of copper4 ,these were put into a jar containing dilute sulphuric acid,a1 and could at pleasure be placed in metallic communication by a copper wire adjusted so as to dip at the extremities into two cups of mercury connected with the two plates4 ,a ,when nitro-sulphuric acid is used1 the spark is more powerful1 but local chemical action can then commence1 and proceed without requiring metallic contact4 #ieg4 ,being thus arranged1 there was no chemical action whilst the plates were not connected4 ,on making the connexion a spark was obtained,a1 and the solution was immediately decomposed4 ,on breaking it1 the usual spark was obtained1 and the decomposition ceased4 ,in this case it is evident that the first spark must have occurred before metallic contact was made1 for it passed through an interval of air2 and also that it must have tended to pass before the electrolytic action began2 for the latter could not take place until the current passed1 and the current could not pass before the spark appeared4 ,hence ,i think there is sufficient proof1 that as it is the zinc and water which by their mutual action produce the electricity of this apparatus1 so these1 by their first contact with each other1 were placed in a state of powerful tension 7#iea471 which1 though it could not produce the actual decomposition of the water1 was able to make a spark of electricity pass between the zinc and a fit discharger as soon as the interval was rendered sufficiently small4 ,the experiment demonstrates the direct production of the electric spark from pure chemical forces4 ,a ,it has been universally supposed that no spark is produced on making the contact between a single pair of plates4 ,i was led to expect one from the considerations already advanced in this paper4 ,the wire of communication should be short2 for with a long wire1 circumstances strongly affecting the spark are introduced4 #ieh4 ,there are a few circumstances connected with the production of this spark by a single pair of plates1 which should be known1 to ensure success to the experiment,b4 ,when the amalgamated surfaces of contact are quite clean and dry1 the spark1 on making contact1 is quite as brilliant as on breaking it1 if not even more so4 ,when a film of oxide or dirt was present at either mercurial surface1 then the first spark was often feeble1 and often failed1 the breaking spark1 however1 continuing very constant and bright4 ,when a little water was put over the mercury1 the spark was greatly diminished in brilliancy1 but very regular both on making and breaking contact4 ,when the contact was made between clean platina1 the spark was also very small1 but regular both ways4 ,the true electric spark is1 in fact1 very small1 and when surfaces of mercury are used1 it is the combustion of the metal which produces the greater part of the light4 ,the circumstances connected with the burning of the mercury are most favourable on breaking contact2 for the act of separation exposes clean surfaces of metal1 whereas1 on making contact1 a thin film of oxide1 or soiling matter1 often interferes4 ,hence the origin of the general opinion that it is only when the contact is broken that the spark passes4 ,b ,see in relation to precautions respecting a spark1 #ajgd4--;,dec4 #ahch4 #iei4 ,with reference to the other set of cases1 namely1 those of local action 7#idg47 in which chemical affinity being exerted causes no transference of the power to a distance where no electric current is produced1 it is evident that forces of the most intense kind must be active1 and in some way balanced in their activity1 during such combinations2 these forces being directed so immediately and exclusively towards each other1 that no signs of the powerful electric current they can produce become apparent1 although the same final state of things is obtained as if that current had passed4 ,it was ,berzelius1 ,i believe1 who considered the heat and light evolved in cases of combustion as the consequences of this mode of exertion of the electric powers of the combining particles4 ,but it will require a much more exact and extensive knowledge of the nature of electricity1 and the manner in which it is associated with the atoms of matter1 before we can understand accurately the action of this power in thus causing their union1 or comprehend the nature of the great difference which it presents in the two modes of action just distinguished4 ,we may imagine1 but such imaginations must for the time be classed with the great mass of doubtful knowledge 7#hgf47 which we ought rather to strive to diminish than to increase2 for the very extensive contradictions of this knowledge by itself shows that but a small portion of it can ultimately prove true,a4 ,a ,refer to #agch1 c4 ,series ,,xiv4--,dec4 #ahch4 #ifj4 ,of the two modes of action in which chemical affinity is exerted1 it is important to remark1 that that which produces the electric current is as definite as that which causes ordinary chemical combination2 so that in examining the production or evolution of electricity in cases of combination or decomposition1 it will be necessary1 not merely to observe certain effects dependent upon a current of electricity1 but also their quantity3 and though it may often happen that the forces concerned in any particular case of chemical action may be partly exerted in one mode and partly in the other1 it is only those which are efficient in producing the current that have any relation to voltaic action4 ,thus1 in the combination of oxygen and hydrogen to produce water1 electric powers to a most enormous amount are for the time active 7#hfa4 #hgc472 but any mode of examining the flame which they form during energetic combination1 which has as yet been devised1 has given but the feeblest traces4 ,these therefore may not1 cannot1 be taken as evidences of the nature of the action2 but are merely incidental results1 incomparably small in relation to the forces concerned1 and supplying no information of the way in which the particles are active on each other1 or in which their forces are finally arranged4 #ifa4 ,that such cases of chemical action produce no current of electricity1 is perfectly consistent with what we know of the voltaic apparatus1 in which it is essential that one of the combining elements shall form part of1 or be in direct relation with1 an electrolytic conductor 7#iba4 #ibc474 ,that such cases produce no free electricity of tension1 and that when they are converted into cases of voltaic action they produce a current in which the opposite forces are so equal as to neutralize each other1 prove the equality of the forces in the opposed acting particles of matter1 and therefore the equality of electric power in those quantities of matter which are called electro-chemical equivalents 7#hbd74 ,hence another proof of the definite nature of electro-chemical action 7#ghc4 c471 and that chemical affinity and electricity are forms of the same power 7#iag4 c474 #ifb4 ,the direct reference of the effects produced by the voltaic pile at the place of experimental decomposition to the chemical affinities active at the place of excitation 7#hia4 #iag471 gives a very simple and natural view of the cause why the bodies 7or ions7 evolved pass in certain directions2 for it is only when they pass in those directions that their forces can consist with and compensate 7in direction at least7 the superior forces which are dominant at the place where the action of the whole is determined4 ,if1 for instance1 in a voltaic circuit1 the activity of which is determined1 by the attraction of zinc for the oxygen of water1 the zinc move from right to left1 then any other cation included in the circuit1 being part of an electrolyte1 or forming part of it at the moment1 will also move from right to left3 and as the oxygen of the water1 by its natural affinity for the zinc1 moves from left to right1 so any other body of the same class with it 7i4e4 any other anion71 under its government for the time1 will move from left to right4 #ifc4 ,this ,i may illustrate by reference to fig4 #hc1 the double circle of which may represent a complete voltaic circuit1 the direction of its forces being determined by supposing for a moment the zinc b and the platina c as representing plates of those metals acting upon water1 d1 e1 and other substances1 but having their energy exalted so as to effect several decompositions by the use of a battery at a 7#ihi474 ,this supposition may be allowed1 because the action in the battery will only consist of repetitions of what would take place between b and c1 if they really constituted but a single pair4 ,the zinc b1 and the oxygen d1 by their mutual affinity1 tend to unite2 but as the oxygen is already in association with the hydrogen e1 and has its inherent chemical or electric powers neutralized for the time by those of the latter1 the hydrogen e must leave the oxygen d1 and advance in the direction of the arrow head1 or else the zinc b cannot move in the same direction to unite to the oxygen d1 nor the oxygen d move in the contrary direction to unite to the zinc b1 the relation of the similar forces of b and c1 in contrary directions1 to the opposite forces of d being the preventive4 ,as the hydrogen e advances1 it1 on coming against the platina c1 f1 which forms a part of the circuit1 communicates its electric or chemical forces through it to the next electrolyte in the circuit1 fused chloride of lead1 g1 h1 where the chlorine must move in conformity with the direction of the oxygen at d1 for it has to compensate the forces disturbed in its part of the circuit by the superior influence of those between the oxygen and zinc at d1 b1 aided as they are by those of the battery a2 and for a similar reason the lead must move in the direction pointed out by the arrow head1 that it may be in right relation to the first moving body of its own class1 namely1 the zinc b4 ,if copper intervene in the circuit from i to k1 it acts as the platina did before2 and if another electrolyte1 as the iodide of tin1 occur at l1 m1 then the iodine l1 being an anion1 must move in conformity with the exciting anion1 namely1 the oxygen d1 and the cation tin m move in correspondence with the other cations b1 e1 and h1 that the chemical forces may be in equilibrium as to their direction and quantity throughout the circuit4 ,should it so happen that the anions in their circulation can combine with the metals at the anodes of the respective electrolytes1 as would be the case at the platina f and the copper k1 then those bodies becoming parts of electrolytes1 under the influence of the current1 immediately travel2 but considering their relation to the zinc b1 it is evidently impossible that they can travel in any other direction than what will accord with its course1 and therefore can never tend to pass otherwise than from the anode and to the cathode4 #ifd4 ,in such a circle as that delineated1 therefore1 all the known anions may be grouped within1 and all the cations without4 ,if any number of them enter as ions into the constitution of electrolytes1 and1 forming one circuit1 are simultaneously subject to one common current1 the anions must move in accordance with each other in one direction1 and the cations in the other4 ,nay1 more than that1 equivalent portions of these bodies must so advance in opposite directions3 for the advance of every #cb4e parts of the zinc b must be accompanied by a motion in the opposite direction of #h parts of oxygen at d1 of #cf parts of chlorine at g1 of #abf parts of iodine at l2 and in the same direction by electro-chemical equivalents of hydrogen1 lead1 copper and tin1 at e1 h1 k4 and m4 #ife4 ,if the present paper be accepted as a correct expression of facts1 it will still only prove a confirmation of certain general views put forth by ,sir ,humphry ,davy in his ,bakerian ,lecture for #ahjf;,a1 and revised and re-stated by him in another ,bakerian ,lecture1 on electrical and chemical changes1 for the year #ahbf;,b4 ,his general statement is1 that chemical and electrical attractions were produced by the same cause1 acting in one case on particles1 in the other on masses1 of matter2 and that the same property1 under different modifications1 was the cause of all the phenomena exhibited by different voltaic combinations,c4 ,this statement ,i believe to be true2 but in admitting and supporting it1 ,i must guard myself from being supposed to assent to all that is associated with it in the two papers referred to1 or as admitting the experiments which are there quoted as decided proofs of the truth of the principle4 ,had ,i thought them so1 there would have been no occasion for this investigation4 ,it may be supposed by some that ,i ought to go through these papers1 distinguishing what ,i admit from what ,i reject1 and giving good experimental or philosophical reasons for the judgment in both cases4 ,but then ,i should be equally bound to review1 for the same purpose1 all that has been written both for and against the necessity of metallic contact1--for and against the origin of voltaic electricity in chemical action1--a duty which ,i may not undertake in the present paper,d4 ,a ,philosophical ,transactions1 #ahjg4 ,b ,ibid4 #ahbf1 p4 #chc4 ,c ,ibid4 #ahbf1 p4 #chi4 ,d ,i at one time intended to introduce here1 in the form of a note1 a table of reference to the papers of the different philosophers who have referred the origin of the electricity in the voltaic pile to contact1 or to chemical action1 or to both2 but on the publication of the first volume of ,m4 ,becquerel's highly important and valuable ,trait de l',electricit et du ,magntisme1 ,i thought it far better to refer to that work for these references1 and the views held by the authors quoted4 ,see pages #hf1 #ia1 #ajd1 #aaj1 #aab1 #aag1 #aah1 #abj1 #aea1 #aeb1 #bbd1 #bbg1 #bbh1 #bcb1 #bcc1 #beb1 #bee1 #beg1 #beh1 #bij1 c4--,july #crd1 #ahcd4 ii4 ,on the ,intensity necessary for ,electrolyzation4 #iff4 ,it became requisite1 for the comprehension of many of the conditions attending voltaic action1 to determine positively1 if possible1 whether electrolytes could resist the action of an electric current when beneath a certain intensity8 whether the intensity at which the current ceased to act would be the same for all bodies8 and also whether the electrolytes thus resisting decomposition would conduct the electric current as a metal does1 after they ceased to conduct as electrolytes1 or would act as perfect insulators8 #ifg4 ,it was evident from the experiments described 7#ijd4 #ijf47 that different bodies were decomposed with very different facilities1 and apparently that they required for their decomposition currents of different intensities1 resisting some1 but giving way to others4 ,but it was needful1 by very careful and express experiments1 to determine whether a current could really pass through1 and yet not decompose an electrolyte 7#iaj474 #ifh4 ,an arrangement 7fig4 #hd47 was made1 in which two glass vessels contained the same dilute sulphuric acid1 sp4 gr4 #a4be4 ,the plate z was amalgamated zinc1 in connexion1 by a platina wire a1 with the platina plate e2 b was a platina wire connecting the two platina plates ,,pp'2 c was a platina wire connected with the platina plate ,p4 ,on the plate e was placed a piece of paper moistened in solution of iodide of potassium3 the wire c was so curved that its end could be made to rest at pleasure on this paper1 and show1 by the evolution of iodine there1 whether a current was passing2 or1 being placed in the dotted position1 it formed a direct communication with the platina plate e1 and the electricity could pass without causing decomposition4 ,the object was to produce a current by the action of the acid on the amalgamated zinc in the first vessel ,a2 to pass it through the acid in the second vessel ,b by platina electrodes1 that its power of decomposing water might1 if existing1 be observed2 and to verify the existence of the current at pleasure1 by decomposition at e1 without involving the continual obstruction to the current which would arise from making the decomposition there constant4 ,the experiment1 being arranged1 was examined and the existence of a current ascertained by the decomposition at e2 the whole was then left with the end of the wire c resting on the plate e1 so as to form a constant metallic communication there4 #ifi4 ,after several hours1 the end of the wire c was replaced on the test-paper at e3 decomposition occurred1 and the proof of a passing current was therefore complete4 ,the current was very feeble compared to what it had been at the beginning of the experiment1 because of a peculiar state acquired by the metal surfaces in the second vessel1 which caused them to oppose the passing current by a force which they possess under these circumstances 7#ajdj474 ,still it was proved1 by the decomposition1 that this state of the plates in the second vessel was not able entirely to stop the current determined in the first1 and that was all that was needful to be ascertained in the present inquiry4 #igj4 ,this apparatus was examined from time to time1 and an electric current always found circulating through it1 until twelve days had elapsed1 during which the water in the second vessel had been constantly subject to its action4 ,notwithstanding this lengthened period1 not the slightest appearance of a bubble upon either of the plates in that vessel occurred4 ,from the results of the experiment1 ,i conclude that a current had passed1 but of so low an intensity as to fall beneath that degree at which the elements of water1 unaided by any secondary force resulting from the capability of combination with the matter of the electrodes1 or of the liquid surrounding them1 separated from each other4 #iga4 ,it may be supposed1 that the oxygen and hydrogen had been evolved in such small quantities as to have entirely dissolved in the water1 and finally to have escaped at the surface1 or to have reunited into water4 ,that the hydrogen can be so dissolved was shown in the first vessel2 for after several days minute bubbles of gas gradually appeared upon a glass rod1 inserted to retain the zinc and platina apart1 and also upon the platina plate itself1 and these were hydrogen4 ,they resulted principally in this way3--notwithstanding the amalgamation of the zinc1 the acid exerted a little direct action upon it1 so that a small stream of hydrogen bubbles was continually rising from its surface2 a little of this hydrogen gradually dissolved in the dilute acid1 and was in part set free against the surfaces of the rod and the plate1 according to the well-known action of such solid bodies in solutions of gases 7#fbc4 c474 #igb4 ,but if the gases had been evolved in the second vessel by the decomposition of water1 and had tended to dissolve1 still there would have been every reason to expect that a few bubbles should have appeared on the electrodes1 especially on the negative one1 if it were only because of its action as a nucleus on the solution supposed to be formed2 but none appeared even after twelve days4 #igc4 ,when a few drops only of nitric acid were added to the vessel ,a1 fig4 #hd1 then the results were altogether different4 ,in less than five minutes bubbles of gas appeared on the plates ,p' and ,p in the second vessel4 ,to prove that this was the effect of the electric current 7which by trial at c was found at the same time to be passing17 the connexion at c was broken1 the plates ,p',p cleared from bubbles and left in the acid of the vessel ,b1 for fifteen minutes3 during that time no bubbles appeared upon them2 but on restoring the communication at c1 a minute did not elapse before gas appeared in bubbles upon the plates4 ,the proof1 therefore1 is most full and complete1 that the current excited by dilute sulphuric acid with a little nitric acid in vessel ,a1 has intensity enough to overcome the chemical affinity exerted between the oxygen and hydrogen of the water in the vessel ,b1 whilst that excited by dilute sulphuric acid alone has not sufficient intensity4 #igd4 ,on using a strong solution of caustic potassa in the vessel ,a1 to excite the current1 it was found by the decomposing effects at e1 that the current passed4 ,but it had not intensity enough to decompose the water in the vessel ,b2 for though left for fourteen days1 during the whole of which time the current was found to be passing1 still not the slightest appearance of gas appeared on the plates ,p',p1 nor any other signs of the water having suffered decomposition4 #ige4 ,sulphate of soda in solution was then experimented with1 for the purpose of ascertaining with respect to it1 whether a certain electrolytic intensity was also required for its decomposition in this state1 in analogy with the result established with regard to water 7#igd74 ,the apparatus was arranged as in fig4 #he2 ,p and ,z are the platina and zinc plates dipping into a solution of common salt2 a and b are platina plates connected by wires of platina 7except in the galvanometer g7 with ,p and ,z2 c is a connecting wire of platina1 the ends of which can be made to rest either on the plates a1 b1 or on the papers moistened in solutions which are placed upon them2 so that the passage of the current without decomposition1 or with one or two decompositions1 was under ready command1 as far as arrangement was concerned4 ,in order to change the anodes and cathodes at the places of decomposition1 the form of apparatus fig4 #hf1 was occasionally adopted4 ,here only one platina plate1 c1 was used2 both pieces of paper on which decomposition was to be effected were placed upon it1 the wires from ,p and ,z resting upon these pieces of paper1 or upon the plate c1 according as the current with or without decomposition of the solutions was required4 #igf4 ,on placing solution of iodide of potassium in paper at one of the decomposing localities1 and solution of sulphate of soda at the other1 so that the electric current should pass through both at once1 the solution of iodide was slowly decomposed1 yielding iodine at the anode and alkali at the cathode2 but the solution of sulphate of soda exhibited no signs of decomposition1 neither acid nor alkali being evolved from it4 ,on placing the wires so that the iodide alone was subject to the action of the current 7#ijj471 it was quickly and powerfully decomposed2 but on arranging them so that the sulphate of soda alone was subject to action1 it still refused to yield up its elements4 ,finally1 the apparatus was so arranged under a wet bell-glass1 that it could be left for twelve hours1 the current passing during the whole time through a solution of sulphate of soda1 retained in its place by only two thicknesses of bibulous litmus and turmeric paper4 ,at the end of that time it was ascertained by the decomposition of iodide of potassium at the second place of action1 that the current was passing and had passed for the twelve hours1 and yet no trace of acid or alkali from the sulphate of soda appeared4 #igg4 ,from these experiments it may1 ,i think1 be concluded1 that a solution of sulphate of soda can conduct a current of electricity1 which is unable to decompose the neutral salt present2 that this salt in the state of solution1 like water1 requires a certain electrolytic intensity for its decomposition2 and that the necessary intensity is much higher for this substance than for the iodide of potassium in a similar state of solution4 #igh4 ,i then experimented on bodies rendered decomposable by fusion1 and first on chloride of lead4 ,the current was excited by dilute sulphuric acid without any nitric acid between zinc and platina plates1 fig4 #hg1 and was then made to traverse a little chloride of lead fused upon glass at a1 a paper moistened in solution of iodide of potassium at b1 and a galvanometer at g4 ,the metallic terminations at a and b were of platina4 ,being thus arranged1 the decomposition at b and the deflection at g showed that an electric current was passing1 but there was no appearance of decomposition at a1 not even after a metallic communication at b was established4 ,the experiment was repeated several times1 and ,i am led to conclude that in this case the current has not intensity sufficient to cause the decomposition of the chloride of lead2 and further1 that1 like water 7#igd471 fused chloride of lead can conduct an electric current having an intensity below that required to effect decomposition4 #igi4 ,chloride of silver was then placed at a1 fig4 #hg1 instead of chloride of lead4 ,there was a very ready decomposition of the solution of iodide of potassium at b1 and when metallic contact was made there1 very considerable deflection of the galvanometer needle at g4 ,platina also appeared to be dissolved at the anode of the fused chloride at a1 and there was every appearance of a decomposition having been effected there4 #ihj4 ,a further proof of decomposition was obtained in the following manner4 ,the platina wires in the fused chloride at a were brought very near together 7metallic contact having been established at b71 and left so2 the deflection at the galvanometer indicated the passage of a current1 feeble in its force1 but constant4 ,after a minute or two1 however1 the needle would suddenly be violently affected1 and indicate a current as strong as if metallic contact had taken place at a4 ,this ,i actually found to be the case1 for the silver reduced by the action of the current crystallized in long delicate spicul1 and these at last completed the metallic communication2 and at the same time that they transmitted a more powerful current than the fused chloride1 they proved that electro-chemical decomposition of that chloride had been going on4 ,hence it appears1 that the current excited by dilute sulphuric acid between zinc and platina1 has an intensity above that required to electrolyze the fused chloride of silver when placed between platina electrodes1 although it has not intensity enough to decompose chloride of lead under the same circumstances4 #iha4 ,a drop of water placed at a instead of the fused chlorides1 showed as in the former case 7#igj471 that it could conduct a current unable to decompose it1 for decomposition of the solution of iodide at b occurred after some time4 ,but its conducting power was much below that of the fused chloride of lead 7#igh474 #ihb4 ,fused nitre at a conducted much better than water3 ,i was unable to decide with certainty whether it was electrolyzed1 but ,i incline to think not1 for there was no discoloration against the platina at the cathode4 ,if sulpho-nitric acid had been used in the exciting vessel1 both the nitre and the chloride of lead would have suffered decomposition like the water 7#ijf474 #ihc4 ,the results thus obtained of conduction without decomposition1 and the necessity of a certain electrolytic intensity for the separation of the ions of different electrolytes1 are immediately connected with the experiments and results given in #aj4 of the ,fourth ,series of these ,researches 7#dah4 #dbc4 #ddd4 #dai474 ,but it will require a more exact knowledge of the nature of intensity1 both as regards the first origin of the electric current1 and also the manner in which it may be reduced1 or lowered by the intervention of longer or shorter portions of bad conductors1 whether decomposable or not1 before their relation can be minutely and fully understood4 #ihd4 ,in the case of water1 the experiments ,i have as yet made1 appear to show1 that1 when the electric current is reduced in intensity below the point required for decomposition1 then the degree of conduction is the same whether sulphuric acid1 or any other of the many bodies which can affect its transferring power as an electrolyte1 are present or not4 ,or1 in other words1 that the necessary electrolytic intensity for water is the same whether it be pure1 or rendered a better conductor by the addition of these substances2 and that for currents of less intensity than this1 the water1 whether pure or acidulated1 has equal conducting power4 ,an apparatus1 fig4 #hd1 was arranged with dilute sulphuric acid in the vessel ,a1 and pure distilled water in the vessel ,b4 ,by the decomposition at c1 it appeared as if water was a better conductor than dilute sulphuric acid for a current of such low intensity as to cause no decomposition4 ,i am inclined1 however1 to attribute this apparent superiority of water to variations in that peculiar condition of the platina electrodes which is referred to further on in this ,series 7#ajdj471 and which is assumed1 as far as ,i can judge1 to a greater degree in dilute sulphuric acid than in pure water4 ,the power therefore1 of acids1 alkalies1 salts1 and other bodies in solution1 to increase conducting power1 appears to hold good only in those cases where the electrolyte subject to the current suffers decomposition1 and loses all influence when the current transmitted has too low an intensity to affect chemical change4 ,it is probable that the ordinary conducting power of an electrolyte in the solid state 7#dai47 is the same as that which it possesses in the fluid state for currents1 the tension of which is beneath the due electrolytic intensity4 #ihe4 ,currents of electricity1 produced by less than eight or ten series of voltaic elements1 can be reduced to that intensity at which water can conduct them without suffering decomposition1 by causing them to pass through three or four vessels in which water shall be successively interposed between platina surfaces4 ,the principles of interference upon which this effect depends1 will be described hereafter 7#ajji4 #ajah471 but the effect may be useful in obtaining currents of standard intensity1 and is probably applicable to batteries of any number of pairs of plates4 #ihf4 ,as there appears every reason to expect that all electrolytes will be found subject to the law which requires an electric current of a certain intensity for their decomposition1 but that they will differ from each other in the degree of intensity required1 it will be desirable hereafter to arrange them in a table1 in the order of their electrolytic intensities4 ,investigations on this point must1 however1 be very much extended1 and include many more bodies than have been here mentioned before such a table can be constructed4 ,it will be especially needful in such experiments1 to describe the nature of the electrodes used1 or1 if possible1 to select such as1 like platina or plumbago in certain cases1 shall have no power of assisting the separation of the ions to be evolved 7#iac74 #ihg4 ,of the two modes in which bodies can transmit the electric forces1 namely1 that which is so characteristically exhibited by the metals1 and usually called conduction1 and that in which it is accompanied by decomposition1 the first appears common to all bodies1 although it occurs with almost infinite degrees of difference2 the second is at present distinctive of the electrolytes4 ,it is1 however1 just possible that it may hereafter be extended to the metals2 for their power of conducting without decomposition may1 perhaps justly1 be ascribed to their requiring a very high electrolytic intensity for their decomposition4 #ihg-a_/b4 ,the establishment of the principle that a certain electrolytic intensity is necessary before decomposition can be effected1 is of great importance to all those considerations which arise regarding the probable effects of weak currents1 such for instance as those produced by natural thermo-electricity1 or natural voltaic arrangements in the earth4 ,for to produce an effect of decomposition or of combination1 a current must not only exist1 but have a certain intensity before it can overcome the quiescent affinities opposed to it1 otherwise it will be conducted1 producing no permanent chemical effects4 ,on the other hand1 the principles are also now evident by which an opposing action can be so weakened by the juxtaposition of bodies not having quite affinity enough to cause direct action between them 7#iac471 that a very weak current shall be able to raise the sum of actions sufficiently high1 and cause chemical changes to occur4 #ihh4 ,in concluding this division on the intensity necessary for electrolyzation1 ,i cannot resist pointing out the following remarkable conclusion in relation to intensity generally4 ,it would appear that when a voltaic current is produced1 having a certain intensity1 dependent upon the strength of the chemical affinities by which that current is excited 7#iaf471 it can decompose a particular electrolyte without relation to the quantity of electricity passed1 the intensity deciding whether the electrolyte shall give way or not4 ,if that conclusion be confirmed1 then we may arrange circumstances so that the same quantity of electricity may pass in the same time1 in at the same surface1 into the same decomposing body in the same state1 and yet1 differing in intensity1 will decompose in one case and in the other not3--for taking a source of too low an intensity to decompose1 and ascertaining the quantity passed in a given time1 it is easy to take another source having a sufficient intensity1 and reducing the quantity of electricity from it by the intervention of bad conductors to the same proportion as the former current1 and then all the conditions will be fulfilled which are required to produce the result described4 iii4 ,on associated ,voltaic ,circles1 or the ,voltaic ,battery4 #ihi4 ,passing from the consideration of single circles 7#hge4 c47 to their association in the voltaic battery1 it is a very evident consequence1 that if matters are so arranged that two sets of affinities1 in place of being opposed to each other as in figg4 #gc4 #gf4 7#hhj4 #hia471 are made to act in conformity1 then1 instead of either interfering with the other1 it will rather assist it4 ,this is simply the case of two voltaic pairs of metals arranged so as to form one circuit4 ,in such arrangements the activity of the whole is known to be increased1 and when ten1 or a hundred1 or any larger number of such alternations are placed in conformable association with each other1 the power of the whole becomes proportionally exalted1 and we obtain that magnificent instrument of philosophic research1 the voltaic battery4 #iij4 ,but it is evident from the principles of definite action already laid down1 that the quantity of electricity in the current cannot be increased with the increase of the quantity of metal oxidized and dissolved at each new place of chemical action4 ,a single pair of zinc and platina plates throws as much electricity into the form of a current1 by the oxidation of #cb4e grains of the zinc 7#hfh47 as would be circulated by the same alteration of a thousand times that quantity1 or nearly five pounds of metal oxidized at the surface of the zinc plates of a thousand pairs placed in regular battery order4 ,for it is evident1 that the electricity which passes across the acid from the zinc to the platina in the first cell1 and which has been associated with1 or even evolved by1 the decomposition of a definite portion of water in that cell1 cannot pass from the zinc to the platina across the acid in the second cell1 without the decomposition of the same quantity of water there1 and the oxidation of the same quantity of zinc by it 7#ibd4 #idi474 ,the same result recurs in every other cell2 the electro-chemical equivalent of water must be decomposed in each1 before the current can pass through it2 for the quantity of electricity passed and the quantity of electrolyte decomposed1 must be the equivalents of each other4 ,the action in each cell1 therefore1 is not to increase the quantity set in motion in any one cell1 but to aid in urging forward that quantity1 the passing of which is consistent with the oxidation of its own zinc2 and in this way it exalts that peculiar property of the current which we endeavour to express by the term intensity1 without increasing the quantity beyond that which is proportionate to the quantity of zinc oxidized in any single cell of the series4 #iia4 ,to prove this1 ,i arranged ten pairs of amalgamated zinc and platina plates with dilute sulphuric acid in the form of a battery4 ,on completing the circuit1 all the pairs acted and evolved gas at the surfaces of the platina4 ,this was collected and found to be alike in quantity for each plate2 and the quantity of hydrogen evolved at any one platina plate was in the same proportion to the quantity of metal dissolved from any one zinc plate1 as was given in the experiment with a single pair 7#hfd4 c474 ,it was therefore certain1 that1 just as much electricity and no more had passed through the series of ten pair of plates as had passed through1 or would have been put into motion by1 any single pair1 notwithstanding that ten times the quantity of zinc had been consumed4 #iib4 ,this truth has been proved also long ago in another way1 by the action of the evolved current on a magnetic needle2 the deflecting power of one pair of plates in a battery being equal to the deflecting power of the whole1 provided the wires used be sufficiently large to carry the current of the single pair freely2 but the cause of this equality of action could not be understood whilst the definite action and evolution of electricity 7#ghc4 #hfi47 remained unknown4 #iic4 ,the superior decomposing power of a battery over a single pair of plates is rendered evident in two ways4 ,electrolytes held together by an affinity so strong as to resist the action of the current from a single pair1 yield up their elements to the current excited by many pairs2 and that body which is decomposed by the action of one or of few pairs of metals1 c41 is resolved into its ions the more readily as it is acted upon by electricity urged forward by many alternations4 #iid4 ,both these effects are1 ,i think1 easily understood4 ,whatever intensity may be1 7and that must of course depend upon the nature of electricity1 whether it consist of a fluid or fluids1 or of vibrations of an ether1 or any other kind or condition of matter17 there seems to be no difficulty in comprehending that the degree of intensity at which a current of electricity is evolved by a first voltaic element1 shall be increased when that current is subjected to the action of a second voltaic element1 acting in conformity and possessing equal powers with the first3 and as the decompositions are merely opposed actions1 but exactly of the same kind as those which generate the current 7#iag471 it seems to be a natural consequence1 that the affinity which can resist the force of a single decomposing action may be unable to oppose the energies of many decomposing actions1 operating conjointly1 as in the voltaic battery4 #iie4 ,that a body which can give way to a current of feeble intensity1 should give way more freely to one of stronger force1 and yet involve no contradiction to the law of definite electrolytic action1 is perfectly consistent4 ,all the facts and also the theory ,i have ventured to put forth1 tend to show that the act of decomposition opposes a certain force to the passage of the electric current2 and1 that this obstruction should be overcome more or less readily1 in proportion to the greater or less intensity of the decomposing current1 is in perfect consistency with all our notions of the electric agent4 #iif4 ,i have elsewhere 7#idg47 distinguished the chemical action of zinc and dilute sulphuric acid into two portions2 that which1 acting effectually on the zinc1 evolves hydrogen at once upon its surface1 and that which1 producing an arrangement of the chemical forces throughout the electrolyte present1 7in this case water17 tends to take oxygen from it1 but cannot do so unless the electric current consequent thereon can have free passage1 and the hydrogen be delivered elsewhere than against the zinc4 ,the electric current depends altogether upon the second of these2 but when the current can pass1 by favouring the electrolytic action it tends to diminish the former and increase the latter portion4 #iig4 ,it is evident1 therefore1 that when ordinary zinc is used in a voltaic arrangement1 there is an enormous waste of that power which it is the object to throw into the form of an electric current2 a consequence which is put in its strongest point of view when it is considered that three ounces and a half of zinc1 properly oxidized1 can circulate enough electricity to decompose nearly one ounce of water1 and cause the evolution of about #bajj cubic inches of hydrogen gas4 ,this loss of power not only takes place during the time the electrodes of the battery are in communication1 being then proportionate to the quantity of hydrogen evolved against the surface of any one of the zinc plates1 but includes also all the chemical action which goes on when the extremities of the pile are not in communication4 #iih4 ,this loss is far greater with ordinary zinc than with the pure metal1 as ,m4 ,de la ,rive has shown,a4 ,the cause is1 that when ordinary zinc is acted upon by dilute sulphuric acid1 portions of copper1 lead1 cadmium1 or other metals which it may contain1 are set free upon its surface2 and these1 being in contact with the zinc1 form small but very active voltaic circles1 which cause great destruction of the zinc and evolution of hydrogen1 apparently upon the zinc surface1 but really upon the surface of these incidental metals4 ,in the same proportion as they serve to discharge or convey the electricity back to the zinc1 do they diminish its power of producing an electric current which shall extend to a greater distance across the acid1 and be discharged only through the copper or platina plate which is associated with it for the purpose of forming a voltaic apparatus4 ,a ,quarterly ,journal of ,science1 #ahca1 p4 #chh2 or ,bibliothque ,universelle1 #ahcj1 p4 #cia4 #iii4 ,all these evils are removed by the employment of an amalgam of zinc in the manner recommended by ,mr4 ,kemp,a1 or the use of the amalgamated zinc plates of ,mr4 ,sturgeon 7#hfc471 who has himself suggested and objected to their application in galvanic batteries2 for he says1 ,were it not on account of the brittleness and other inconveniences occasioned by the incorporation of the mercury with the zinc1 amalgamation of the zinc surfaces in galvanic batteries would become an important improvement2 for the metal would last much longer1 and remain bright for a considerable time1 even for several successive hours2 essential considerations in the employment of this apparatus,b4 ,a ,jameson's ,edinburgh ,journal1 ,october #ahbh4 ,b ,recent ,experimental ,researches1 p4 #db1 c4 ,mr4 ,sturgeon is of course unaware of the definite production of electricity by chemical action1 and is in fact quoting the experiment as the strongest argument against the chemical theory of galvanism4 #ajjj4 ,zinc so prepared1 even though impure1 does not sensibly decompose the water of dilute sulphuric acid1 but still has such affinity for the oxygen1 that the moment a metal which1 like copper or platina1 has little or no affinity1 touches it in the acid1 action ensues1 and a powerful and abundant electric current is produced4 ,it is probable that the mercury acts by bringing the surface1 in consequence of its fluidity1 into one uniform condition1 and preventing those differences in character between one spot and another which are necessary for the formation of the minute voltaic circuits referred to 7#iih474 ,if any difference does exist at the first moment1 with regard to the proportion of zinc and mercury1 at one spot on the surface1 as compared with another1 that spot having the least mercury is first acted on1 and1 by solution of the zinc1 is soon placed in the same condition as the other parts1 and the whole plate rendered superficially uniform4 ,one part cannot1 therefore1 act as a discharger to another2 and hence all the chemical power upon the water at its surface is in that equable condition 7#idi471 which1 though it tends to produce an electric current through the liquid to another plate of metal which can act as a discharger 7#iej471 presents no irregularities by which any one part1 having weaker affinities for oxygen1 can act as a discharger to another4 ,two excellent and important consequences follow upon this state of the metal4 ,the first is1 that the full equivalent of electricity is obtained for the oxidation of a certain quantity of zinc2 the second1 that a battery constructed with the zinc so prepared1 and charged with dilute sulphuric acid1 is active only whilst the electrodes are connected1 and ceases to act or be acted upon by the acid the instant the communication is broken4 #ajja4 ,i have had a small battery of ten pairs of plates thus constructed1 and am convinced that arrangements of this kind will be very important1 especially in the development and illustration of the philosophical principles of the instrument4 ,the metals ,i have used are amalgamated zinc and platina1 connected together by being soldered to platina wires1 the whole apparatus having the form of the couronne des tasses4 ,the liquid used was dilute sulphuric acid of sp4 gr4 #a4be4 ,no action took place upon the metals except when the electrodes were in communication1 and then the action upon the zinc was only in proportion to the decomposition in the experimental cell2 for when the current was retarded there1 it was retarded also in the battery1 and no waste of the powers of the metal was incurred4 #ajjb4 ,in consequence of this circumstance1 the acid in the cells remained active for a very much longer time than usual4 ,in fact1 time did not tend to lower it in any sensible degree3 for whilst the metal was preserved to be acted upon at the proper moment1 the acid also was preserved almost at its first strength4 ,hence a constancy of action far beyond what can be obtained by the use of common zinc4 #ajjc4 ,another excellent consequence was the renewal1 during the interval of rest1 between two experiments of the first and most efficient state4 ,when an amalgamated zinc and a platina plate1 immersed in dilute sulphuric acid1 are first connected1 the current is very powerful1 but instantly sinks very much in force1 and in some cases actually falls to only an eighth or a tenth of that first produced 7#ajcf474 ,this is due to the acid which is in contact with the zinc becoming neutralized by the oxide formed2 the continued quick oxidation of the metal being thus prevented4 ,with ordinary zinc1 the evolution of gas at its surface tends to mingle all the liquid together1 and thus bring fresh acid against the metal1 by which the oxide formed there can be removed4 ,with the amalgamated zinc battery1 at every cessation of the current1 the saline solution against the zinc is gradually diffused amongst the rest of the liquid2 and upon the renewal of contact at the electrodes1 the zinc plates are found most favourably circumstanced for the production of a ready and powerful current4 #ajjd4 ,it might at first be imagined that amalgamated zinc would be much inferior in force to common zinc1 because1 of the lowering of its energy1 which the mercury might be supposed to occasion over the whole of its surface2 but this is not the case4 ,when the electric currents of two pairs of platina and zinc plates were opposed1 the difference being that one of the zincs was amalgamated and the other not1 the current from the amalgamated zinc was most powerful1 although no gas was evolved against it1 and much was evolved at the surface of the unamalgamated metal4 ,again1 as ,davy has shown,a1 if amalgamated and unamalgamated zinc be put in contact1 and dipped into dilute sulphuric acid1 or other exciting fluids1 the former is positive to the latter1 i4e4 the current passes from the amalgamated zinc1 through the fluid1 to the unprepared zinc4 ,this he accounts for by supposing that there is not any inherent and specific property in each metal which gives it the electrical character1 but that it depends upon its peculiar state--on that form of aggregation which fits it for chemical change4 ,a ,philosophical ,transactions1 #ahbf1 p4 #dje4 #ajje4 ,the superiority of the amalgamated zinc is not1 however1 due to any such cause1 but is a very simple consequence of the state of the fluid in contact with it2 for as the unprepared zinc acts directly and alone upon the fluid1 whilst that which is amalgamated does not1 the former 7by the oxide it produces7 quickly neutralizes the acid in contact with its surface1 so that the progress of oxidation is retarded1 whilst at the surface of the amalgamated zinc1 any oxide formed is instantly removed by the free acid present1 and the clean metallic surface is always ready to act with full energy upon the water4 ,hence its superiority 7#ajcg474 #ajjf4 ,the progress of improvement in the voltaic battery and its applications1 is evidently in the contrary direction at present to what it was a few years ago2 for in place of increasing the number of plates1 the strength of acid1 and the extent altogether of the instrument1 the change is rather towards its first state of simplicity1 but with a far more intimate knowledge and application of the principles which govern its force and action4 ,effects of decomposition can now be obtained with ten pairs of plates 7#dag471 which required five hundred or a thousand pairs for their production in the first instance4 ,the capability of decomposing fused chlorides1 iodides1 and other compounds1 according to the law before established 7#chj4 c471 and the opportunity of collecting certain of the products1 without any loss1 by the use of apparatus of the nature of those already described 7#ghi4 #had4 c471 render it probable that the voltaic battery may become a useful and even economical manufacturing instrument2 for theory evidently indicates that an equivalent of a rare substance may be obtained at the expense of three or four equivalents of a very common body1 namely1 zinc3 and practice seems thus far to justify the expectation4 ,in this point of view ,i think it very likely that plates of platina or silver may be used instead of plates of copper with advantage1 and that then the evil arising occasionally from solution of the copper1 and its precipitation on the zinc1 7by which the electromotive power of the zinc is so much injured17 will be avoided 7#ajdg474 iv4 ,on the ,resistance of an ,electrolyte to ,electrolytic ,action1 and on ,interpositions4 #ajjg4 ,i have already illustrated1 in the simplest possible form of experiment 7#hia4 #iaj471 the resistance established at the place of decomposition to the force active at the exciting place4 ,i purpose examining the effects of this resistance more generally2 but it is rather with reference to their practical interference with the action and phenomena of the voltaic battery1 than with any intention at this time to offer a strict and philosophical account of their nature4 ,their general and principal cause is the resistance of the chemical affinities to be overcome2 but there are numerous other circumstances which have a joint influence with these forces 7#ajcd4 #ajdj4 c471 each of which would require a minute examination before a correct account of the whole could be given4 #ajjh4 ,as it will be convenient to describe the experiments in a form different to that in which they were made1 both forms shall first be explained4 ,plates of platina1 copper1 zinc1 and other metals1 about three quarters of an inch wide and three inches long1 were associated together in pairs by means of platina wires to which they were soldered1 fig4 #hh1 the plates of one pair being either alike or different1 as might be required4 ,these were arranged in glasses1 fig4 #hi1 so as to form ,volta's crown of cups4 ,the acid or fluid in the cups never covered the whole of any plate2 and occasionally small glass rods were put into the cups1 between the plates1 to prevent their contact4 ,single plates were used to terminate the series and complete the connexion with a galvanometer1 or with a decomposing apparatus 7#hii4 #ifh4 c471 or both4 ,now if fig4 #ij be examined and compared with fig4 #ia1 the latter may be admitted as representing the former in its simplest condition2 for the cups i1 ii1 and iii of the former1 with their contents1 are represented by the cells i1 ii1 and iii of the latter1 and the metal plates ,z and ,p of the former by the similar plates represented ,z and ,p in the latter4 ,the only difference1 in fact1 between the apparatus1 fig4 #ij1 and the trough represented fig4 #ia1 is that twice the quantity of surface of contact between the metal and acid is allowed in the first to what would occur in the second4 #ajji4 ,when the extreme plates of the arrangement just described1 fig4 #ij1 are connected metallically through the galvanometer g1 then the whole represents a battery consisting of two pairs of zinc and platina plates urging a current forward1 which has1 however1 to decompose water unassisted by any direct chemical affinity before it can be transmitted across the cell iii1 and therefore before it can circulate4 ,this decomposition of water1 which is opposed to the passage of the current1 may1 as a matter of convenience1 be considered as taking place either against the surfaces of the two platina plates which constitute the electrodes in the cell in1 or against the two surfaces of that platina plate which separates the cells ii and iii1 fig4 #ia1 from each other4 ,it is evident that if that plate were away1 the battery would consist of two pairs of plates and two cells1 arranged in the most favourable position for the production of a current4 ,the platina plate therefore1 which being introduced as at x1 has oxygen evolved at one surface and hydrogen at the other 7that is1 if the decomposing current passes71 may be considered as the cause of any obstruction arising from the decomposition of water by the electrolytic action of the current2 and ,i have usually called it the interposed plate4 #ajaj4 ,in order to simplify the conditions1 dilute sulphuric acid was first used in all the cells1 and platina for the interposed plates2 for then the initial intensity of the current which tends to be formed is constant1 being due to the power which zinc has of decomposing water2 and the opposing force of decomposition is also constant1 the elements of the water being unassisted in their separation at the interposed plates by any affinity or secondary action at the electrodes 7#gdd471 arising either from the nature of the plate itself or the surrounding fluid4 #ajaa4 ,when only one voltaic pair of zinc and platina plates was used1 the current of electricity was entirely stopped to all practical purposes by interposing one platina plate1 fig4 #ib1 i4e4 by requiring of the current that it should decompose water1 and evolve both its elements1 before it should pass4 ,this consequence is in perfect accordance with the views before given 7#iaj4 #iag4 #igc474 ,for as the whole result depends upon the opposition of forces at the places of electric excitement and electro-decomposition1 and as water is the substance to be decomposed at both before the current can move1 it is not to be expected that the zinc should have such powerful attraction for the oxygen1 as not only to be able to take it from its associated hydrogen1 but leave such a surplus of force as1 passing to the second place of decomposition1 should be there able to effect a second separation of the elements of water4 ,such an effect would require that the force of attraction between zinc and oxygen should under the circumstances be at least twice as great as the force of attraction between the oxygen and hydrogen4 #ajab4 ,when two pairs of zinc and platina exciting plates were used1 the current was also practically stopped by one interposed platina plate1 fig4 #ic4 ,there was a very feeble effect of a current at first1 but it ceased almost immediately4 ,it will be referred to1 with many other similar effects1 hereafter 7#ajag474 #ajac4 ,three pairs of zinc and platina plates1 fig4 #id1 were able to produce a current which could pass an interposed platina plate1 and effect the electrolyzation of water in cell iv4 ,the current was evident1 both by the continued deflection of the galvanometer1 and the production of bubbles of oxygen and hydrogen at the electrodes in cell iv4 ,hence the accumulated surplus force of three plates of zinc1 which are active in decomposing water1 is more than equal1 when added together1 to the force with which oxygen and hydrogen are combined in water1 and is sufficient to cause the separation of these elements from each other4 #ajad4 ,the three pairs of zinc and platina plates were now opposed by two intervening platina plates1 fig4 #ie4 ,in this case the current was stopped4 #ajae4 ,four pairs of zinc and platina plates were also neutralized by two interposed platina plates1 fig4 #if4 #ajaf4 ,five pairs of zinc and platina1 with two interposed platina plates1 fig4 #ig1 gave a feeble current2 there was permanent deflection at the galvanometer1 and decomposition in the cells vi and vii4 ,but the current was very feeble2 very much less than when all the intermediate plates were removed and the two extreme ones only retained3 for when they were placed six inches asunder in one cell1 they gave a powerful current4 ,hence five exciting pairs1 with two interposed obstructing plates1 do not give a current at all comparable to that of a single unobstructed pair4 #ajag4 ,i have already said that a very feeble current passed when the series included one interposed platina and two pairs of zinc and platina plates 7#ajab474 ,a similarly feeble current passed in every case1 and even when only one exciting pair and four intervening platina plates were used1 fig4 #ih1 a current passed which could be detected at x1 both by chemical action on the solution of iodide of potassium1 and by the galvanometer4 ,this current ,i believe to be due to electricity reduced in intensity below the point requisite for the decomposition of water 7#igj4 #ihd472 for water can conduct electricity of such low intensity by the same kind of power which it possesses in common with metals and charcoal1 though it cannot conduct electricity of higher intensity without suffering decomposition1 and then opposing a new force consequent thereon4 ,with an electric current of1 or under this intensity1 it is probable that increasing the number of interposed platina plates would not involve an increased difficulty of conduction4 #ajah4 ,in order to obtain an idea of the additional interfering power of each added platina plate1 six voltaic pairs and four intervening platinas were arranged as in fig4 #ii2 a very feeble current then passed 7#ihe4 #ajag474 ,when one of the platinas was removed so that three intervened1 a current somewhat stronger passed4 ,with two intervening platinas a still stronger current passed2 and with only one intervening platina a very fair current was obtained4 ,but the effect of the successive plates1 taken in the order of their interposition1 was very different1 as might be expected2 for the first retarded the current more powerfully than the second1 and the second more than the third4 #ajai4 ,in these experiments both amalgamated and unamalgamated zinc were used1 but the results generally were the same4 #ajbj4 ,the effects of retardation just described were altered altogether when changes were made in the nature of the liquid used between the plates1 either in what may be called the exciting or the retarding cells4 ,thus1 retaining the exciting force the same1 by still using pure dilute sulphuric acid for that purpose1 if a little nitric acid were added to the liquid in the retarding cells1 then the transmission of the current was very much facilitated4 ,for instance1 in the experiment with one pair of exciting plates and one intervening plate 7#ajaa471 fig4 #ib1 when a few drops of nitric acid were added to the contents of cell ii1 then the current of electricity passed with considerable strength 7though it soon fell from other causes 7#ajcf2 #ajdj4717 and the same increased effect was produced by the nitric acid when many interposed plates were used4 #ajba4 ,this seems to be a consequence of the diminution of the difficulty of decomposing water when its hydrogen1 instead of being absolutely expelled1 as in the former cases1 is transferred to the oxygen of the nitric acid1 producing a secondary result at the cathode 7#geb472 for in accordance with the chemical views of the electric current and its action already advanced 7#iac471 the water1 instead of opposing a resistance to decomposition equal to the full amount of the force of mutual attraction between its oxygen and hydrogen1 has that force counteracted in part1 and therefore diminished by the attraction of the hydrogen at the cathode for the oxygen of the nitric acid which surrounds it1 and with which it ultimately combines instead of being evolved in its free state4 #ajbb4 ,when a little nitric acid was put into the exciting cells1 then again the circumstances favouring the transmission of the current were strengthened1 for the intensity of the current itself was increased by the addition 7#ijf474 ,when therefore a little nitric acid was added to both the exciting and the retarding cells1 the current of electricity passed with very considerable freedom4 #ajbc4 ,when dilute muriatic acid was used1 it produced and transmitted a current more easily than pure dilute sulphuric acid1 but not so readily as dilute nitric acid4 ,as muriatic acid appears to be decomposed more freely than water 7#gfe471 and as the affinity of zinc for chlorine is very powerful1 it might be expected to produce a current more intense than that from the use of dilute sulphuric acid2 and also to transmit it more freely by undergoing decomposition at a lower intensity 7#iab474 #ajbd4 ,in relation to the effect of these interpositions1 it is necessary to state that they do not appear to be at all dependent upon the size of the electrodes1 or their distance from each other in the acid1 except that when a current can pass1 changes in these facilitate or retard its passage4 ,for on repeating the experiment with one intervening and one pair of exciting plates 7#ajaa471 fig4 #ib1 and in place of the interposed plate ,p using sometimes a mere wire1 and sometimes very large plates 7#ajjh471 and also changing the terminal exciting plates ,z and ,p1 so that they were sometimes wires only and at others of great size1 still the results were the same as those already obtained4 #ajbe4 ,in illustration of the effect of distance1 an experiment like that described with two exciting pairs and one intervening plate 7#ajab471 fig4 #ic1 was arranged so that the distance between the plates in the third cell could be increased to six or eight inches1 or diminished to the thickness of a piece of intervening bibulous paper4 ,still the result was the same in both cases1 the effect not being sensibly greater1 when the plates were merely separated by the paper1 than when a great way apart2 so that the principal opposition to the current in this case does not depend upon the quantity of intervening electrolytic conductor1 but on the relation of its elements to the intensity of the current1 or to the chemical nature of the electrodes and the surrounding fluids4 #ajbf4 ,when the acid was sulphuric acid1 increasing its strength in any of the cells1 caused no change in the effects2 it did not produce a more intense current in the exciting cells 7#ijh471 or cause the current produced to traverse the decomposing cells more freely4 ,but if to very weak sulphuric acid a few drops of nitric acid were added1 then either one or other of those effects could be produced2 and1 as might be expected in a case like this1 where the exciting or conducting action bore a direct reference to the acid itself1 increasing the strength of this 7the nitric acid71 also increased its powers4 #ajbg4 ,the nature of the interposed plate was now varied to show its relation to the phenomena either of excitation or retardation1 and amalgamated zinc was first substituted for platina4 ,on employing one voltaic pair and one interposed zinc plate1 fig4 #ajj1 there was as powerful a current1 apparently1 as if the interposed zinc plate was away4 ,hydrogen was evolved against ,p in cell ii1 and against the side of the second zinc in cell i2 but no gas appeared against the side of the zinc in cell ii1 nor against the zinc in cell i4 #ajbh4 ,on interposing two amalgamated zinc plates1 fig4 #aja1 instead of one1 there was still a powerful current1 but interference had taken place4 ,on using three intermediate zinc plates1 fig4 #ajb1 there was still further retardation1 though a good current of electricity passed4 #ajbi4 ,considering the retardation as due to the inaction of the amalgamated zinc upon the dilute acid1 in consequence of the slight though general effect of diminished chemical power produced by the mercury on the surface1 and viewing this inaction as the circumstance which rendered it necessary that each plate should have its tendency to decompose water assisted slightly by the electric current1 it was expected that plates of the metal in the unamalgamated state would probably not require such assistance1 and would offer no sensible impediment to the passing of the current4 ,this expectation was fully realized in the use of two and three interposed unamalgamated plates4 ,the electric current passed through them as freely as if there had been no such plates in the way4 ,they offered no obstacle1 because they could decompose water without the current2 and the latter had only to give direction to a part of the forces1 which would have been active whether it had passed or not4 #ajcj4 ,interposed plates of copper were then employed4 ,these seemed at first to occasion no obstruction1 but after a few minutes the current almost entirely ceased4 ,this effect appears due to the surfaces taking up that peculiar condition 7#ajaj47 by which they tend to produce a reverse current2 for when one or more of the plates were turned round1 which could easily be effected with the couronne des tasses form of experiment1 fig4 #ij1 then the current was powerfully renewed for a few moments1 and then again ceased4 ,plates of platina and copper1 arranged as a voltaic pile with dilute sulphuric acid1 could not form a voltaic trough competent to act for more than a few minutes1 because of this peculiar counteracting effect4 #ajca4 ,all these effects of retardation1 exhibited by decomposition against surfaces for which the evolved elements have more or less affinity1 or are altogether deficient in attraction1 show generally1 though beautifully1 the chemical relations and source of the current1 and also the balanced state of the affinities at the places of excitation and decomposition4 ,in this way they add to the mass of evidence in favour of the identity of the two2 for they demonstrate1 as it were1 the antagonism of the chemical powers at the electromotive part with the chemical powers at the interposed parts2 they show that the first are producing electric effects1 and the second opposing them2 they bring the two into direct relation2 they prove that either can determine the other1 thus making what appears to be cause and effect convertible1 and thereby demonstrating that both chemical and electrical action are merely two exhibitions of one single agent or power 7#iaf4 c474 #ajcb4 ,it is quite evident1 that as water and other electrolytes can conduct electricity without suffering decomposition 7#ihf471 when the electricity is of sufficiently low intensity1 it may not be asserted as absolutely true in all cases1 that whenever electricity passes through an electrolyte1 it produces a definite effect of decomposition4 ,but the quantity of electricity which can pass in a given time through an electrolyte without causing decomposition1 is so small as to bear no comparison to that required in a case of very moderate decomposition1 and with electricity above the intensity required for electrolyzation1 ,i have found no sensible departure as yet from the law of definite electrolytic action developed in the preceding series of these ,researches 7#ghc4 c474 #ajcc4 ,i cannot dismiss this division of the present ,paper without making a reference to the important experiments of ,m4 ,aug4 ,de la ,rive on the effects of interposed plates,a4 ,as ,i have had occasion to consider such plates merely as giving rise to new decompositions1 and in that way only causing obstruction to the passage of the electric current1 ,i was freed from the necessity of considering the peculiar effects described by that philosopher4 ,i was the more willing to avoid for the present touching upon these1 as ,i must at the same time have entered into the views of ,sir ,humphry ,davy upon the same subject,b and also those of ,marianini,c and ,hitter,d1 which are connected with it4 ,a ,annales de ,chimie1 tom4 xxviii4 p #aij2 and ,mmoires de ,gnve4 ,b ,philosophical ,transactions1 #ahbf1 p4 #dac4 ,c ,annales de ,chimie1 tom4 xxxiii4 pp4 #aag1 #aai1 c4 ,d ,journal de ,physique1 tom4 lvii4 pp4 #cai1 #cej4 v4 ,general ,remarks on the active ,voltaic ,battery4 #ajcd4 ,when the ordinary voltaic battery is brought into action1 its very activity produces certain effects1 which re-act upon it1 and cause serious deterioration of its power4 ,these render it an exceedingly inconstant instrument as to the quantity of effect which it is capable of producing4 ,they are already1 in part1 known and understood2 but as their importance1 and that of certain other coincident results1 will be more evident by reference to the principles and experiments already stated and described1 ,i have thought it would be useful1 in this investigation of the voltaic pile1 to notice them briefly here4 #ajce4 ,when the battery is in action1 it causes such substances to be formed and arranged in contact with the plates as very much weaken its power1 or even tend to produce a counter current4 ,they are considered by ,sir ,humphry ,davy as sufficient to account for the phenomena of ,ritter's secondary piles1 and also for the effects observed by ,m4,a4 ,de la ,rive with interposed platina plates,a4 ,a ,philosophical ,transactions1 #ahbf1 p4 #aac4 #ajcf4 ,i have already referred to this consequence 7#ajjc471 as capable1 in some cases1 of lowering the force of the current to one-eighth or one-tenth of what it was at the first moment1 and have met with instances in which its interference was very great4 ,in an experiment in which one voltaic pair and one interposed platina plate were used with dilute sulphuric acid in the cells fig4 #ajc1 the wires of communication were so arranged1 that the end of that marked #c could be placed at pleasure upon paper moistened in the solution of iodide of potassium at x1 or directly upon the platina plate there4 ,if1 after an interval during which the circuit had not been complete1 the wire #c were placed upon the paper1 there was evidence of a current1 decomposition ensued1 and the galvanometer was affected4 ,if the wire #c were made to touch the metal of p1 a comparatively strong sudden current was produced1 affecting the galvanometer1 but lasting only for a moment2 the effect at the galvanometer ceased1 and if the wire #c were placed on the paper at x1 no signs of decomposition occurred4 ,on raising the wire #c1 and breaking the circuit altogether for a while1 the apparatus resumed its first power1 requiring1 however1 from five to ten minutes for this purpose2 and then1 as before1 on making contact between #c and p1 there was again a momentary current1 and immediately all the effects apparently ceased4 #ajcg4 ,this effect ,i was ultimately able to refer to the state of the film of fluid in contact with the zinc plate in cell i4 ,the acid of that film is instantly neutralized by the oxide formed2 the oxidation of the zinc cannot1 of course1 go on with the same facility as before2 and the chemical action being thus interrupted1 the voltaic action diminishes with it4 ,the time of the rest was required for the diffusion of the liquid1 and its replacement by other acid4 ,from the serious influence of this cause in experiments with single pairs of plates of different metals1 in which ,i was at one time engaged1 and the extreme care required to avoid it1 ,i cannot help feeling a strong suspicion that it interferes more frequently and extensively than experimenters are aware of1 and therefore direct their attention to it4 #ajch4 ,in considering the effect in delicate experiments of this source of irregularity of action1 in the voltaic apparatus1 it must be remembered that it is only that very small portion of matter which is directly in contact with the oxidizable metal which has to be considered with reference to the change of its nature2 and this portion is not very readily displaced from its position upon the surface of the metal 7#ehb4 #fje471 especially if that metal be rough and irregular4 ,in illustration of this effect1 ,i will quote a remarkable experiment4 ,a burnished platina plate 7#efi47 was put into hot strong sulphuric acid for an instant only3 it was then put into distilled water1 moved about in it1 taken out1 and wiped dry3 it was put into a second portion of distilled water1 moved about in it1 and again wiped3 it was put into a third portion of distilled water1 in which it was moved about for nearly eight seconds2 it was then1 without wiping1 put into a fourth portion of distilled water1 where it was allowed to remain five minutes4 ,the two latter portions of water were then tested for sulphuric acid2 the third gave no sensible appearance of that substance1 but the fourth gave indications which were not merely evident1 but abundant for the circumstances under which it had been introduced4 ,the result sufficiently shows with what difficulty that portion of the substance which is in contact with the metal leaves it2 and as the contact of the fluid formed against the plate in the voltaic circuit must be as intimate and as perfect as possible1 it is easy to see how quickly and greatly it must vary from the general fluid in the cells1 and how influential in diminishing the force of the battery this effect must be4 #ajci4 ,in the ordinary voltaic pile1 the influence of this effect will occur in all variety of degrees4 ,the extremities of a trough of twenty pairs of plates of ,wollaston's construction were connected with the volta-electrometer1 fig4 #ff4 7#gaa471 of the ,seventh ,series of these ,researches1 and after five minutes the number of bubbles of gas issuing from the extremity of the tube1 in consequence of the decomposition of the water1 noted4 ,without moving the plates1 the acid between the copper and zinc was agitated by the introduction of a feather4 ,the bubbles were immediately evolved more rapidly1 above twice the number being produced in the same portion of time as before4 ,in this instance it is very evident that agitation by a feather must have been a very imperfect mode of restoring the acid in the cells against the plates towards its first equal condition2 and yet imperfect as the means were1 they more than doubled the power of the battery4 ,the first effect of a battery which is known to be so superior to the degree of action which the battery can sustain1 is almost entirely due to the favourable condition of the acid in contact with the plates4 #ajdj4 ,a second cause of diminution in the force of the voltaic battery1 consequent upon its own action1 is that extraordinary state of the surfaces of the metals 7#ifi47 which was first described1 ,i believe1 by ,ritter,a1 to which he refers the powers of his secondary piles1 and which has been so well experimented upon by ,marianini1 and also by ,a4 ,de la ,rive4 ,if the apparatus1 fig4 #ajc4 7#ajif471 be left in action for an hour or two1 with the wire #c in contact with the plate p1 so as to allow a free passage for the current1 then1 though the contact be broken for ten or twelve minutes1 still1 upon its renewal1 only a feeble current will pass1 not at all equal in force to what might be expected4 ,further1 if ,p#a and ,p#b be connected by a metal wire1 a powerful momentary current will pass from ,p#b to ,p#a through the acid1 and therefore in the reverse direction to that produced by the action of the zinc in the arrangement2 and after this has happened1 the general current can pass through the whole of the system as at first1 but by its passage again restores the plates ,p#b and ,p#a into the former opposing condition4 ,this1 generally1 is the fact described by ,ritter1 ,marianini1 and ,de la ,rive4 ,it has great opposing influence on the action of a pile1 especially if the latter consist of but a small number of alternations1 and has to pass its current through many interpositions4 ,it varies with the solution in which the interposed plates are immersed1 with the intensity of the current1 the strength of the pile1 the time of action1 and especially with accidental discharges of the plates by inadvertent contacts or reversions of the plates during experiments1 and must be carefully watched in every endeavour to trace the source1 strength1 and variations of the voltaic current4 ,its effect was avoided in the experiments already described 7#ajcf4 c471 by making contact between the plates ,p#a and ,p#b before the effect dependent upon the state of the solution in contact with the zinc plate was observed1 and by other precautions4 ,a ,journal de ,physique1 lvii4 p4 #cdi4 #ajda4 ,when an apparatus like fig4 #ih4 7#ajag47 with several platina plates was used1 being connected with a battery able to force a current through them1 the power which they acquired1 of producing a reversed current1 was very considerable4 #ajdb4 ,weak and exhausted charges should never be used at the same time with strong and fresh ones in the different cells of a trough1 or the different troughs of a battery3 the fluid in all the cells should be alike1 else the plates in the weaker cells1 in place of assisting1 retard the passage of the electricity generated in1 and transmitted across1 the stronger cells4 ,each zinc plate so circumstanced has to be assisted in decomposing power before the whole current can pass between it and the liquid4 ,so1 that1 if in a battery of fifty pairs of plates1 ten of the cells contain a weaker charge than the others1 it is as if ten decomposing plates were opposed to the transit of the current of forty pairs of generating plates 7#ajca474 ,hence a serious loss of force1 and hence the reason why1 if the ten pairs of plates were removed1 the remaining forty pairs would be much more powerful than the whole fifty4 #ajdc4 ,five similar troughs1 of ten pairs of plates each1 were prepared1 four of them with a good uniform charge of acid1 and the fifth with the partially neutralized acid of a used battery4 ,being arranged in right order1 and connected with a volta-electrometer 7#gaa471 the whole fifty pairs of plates yielded #a4a cubic inch of oxygen and hydrogen in one minute3 but on moving one of the connecting wires so that only the four well-charged troughs should be included in the circuit1 they produced with the same volta-electrometer #h4d cubical inches of gas in the same time4 ,nearly seven-eighths of the power of the four troughs had been lost1 therefore1 by their association with the fifth trough4 #ajdd4 ,the same battery of fifty pairs of plates1 after being thus used1 was connected with a volta-electrometer 7#gaa471 so that by quickly shifting the wires of communication1 the current of the whole of the battery1 or of any portion of it1 could be made to pass through the instrument for given portions of time in succession4 ,the whole of the battery evolved #j4i of a cubic inch of oxygen and hydrogen in half a minute2 the forty plates evolved #d4f cubic inches in the same time2 the whole then evolved #a cubic inch in the half-minute2 the ten weakly charged evolved #j4d of a cubic inch in the time given3 and finally the whole evolved #a4ae cubic inch in the standard time4 ,the order of the observations was that given3 the results sufficiently show the extremely injurious effect produced by the mixture of strong and weak charges in the same battery,a4 ,a ,the gradual increase in the action of the whole fifty pairs of plates was due to the elevation of temperature in the weakly charged trough by the passage of the current1 in consequence of which the exciting energies of the fluid within were increased4 #ajde4 ,in the same manner associations of strong and weak pairs of plates should be carefully avoided4 ,a pair of copper and platina plates arranged in accordance with a pair of zinc and platina plates in dilute sulphuric acid1 were found to stop the action of the latter1 or even of two pairs of the latter1 as effectually almost as an interposed plate of platina 7#ajaa471 or as if the copper itself had been platina4 ,it1 in fact1 became an interposed decomposing plate1 and therefore a retarding instead of an assisting pair4 #ajdf4 ,the reversal1 by accident or otherwise1 of the plates in a battery has an exceedingly injurious effect4 ,it is not merely the counteraction of the current which the reversed plates can produce1 but their effect also in retarding even as indifferent plates1 and requiring decomposition to be effected upon their surface1 in accordance with the course of the current1 before the latter can pass4 ,they oppose the current1 therefore1 in the first place1 as interposed platina plates would do 7#ajaa-ajah472 and to this they add a force of opposition as counter-voltaic plates4 ,i find that1 in a series of four pairs of zinc and platina plates in dilute sulphuric acid1 if one pair be reversed1 it very nearly neutralizes the power of the whole4 #ajdg4 ,there are many other causes of reaction1 retardation1 and irregularity in the voltaic battery4 ,amongst them is the not unusual one of precipitation of copper upon the zinc in the cells1 the injurious effect of which has before been adverted to 7#ajjf474 ,but their interest is not perhaps sufficient to justify any increase of the length of this paper1 which is rather intended to be an investigation of the theory of the voltaic pile than a particular account of its practical application,a4 ,a ,for further practical results relating to these points of the philosophy of the voltaic battery1 see ,series ,x4 #ag4 #aafc4--aafj4--;,dec4 #ahch4 ,note4--,many of the views and experiments in this ,series of my ,experimental ,researches will be seen at once to be corrections and extensions of the theory of electro-chemical decomposition1 given in the ,fifth and ,seventh ,series of these ,researches4 ,the expressions ,i would now alter are those which concern the independence of the evolved elements in relation to the poles or electrodes1 and the reference of their evolution to powers entirely internal 7#ebd4 #ecg4 #ffa474 ,the present paper fully shows my present views2 and ,i would refer to paragraphs #hia4 #ijd4 #iaj4 #iag4 #iah4 #idg4 #ifc4 #ajjg4 #ajca4 c41 as stating what they are4 ,i hope this note will be considered as sufficient in the way of correction at present2 for ,i would rather defer revising the whole theory of electro-chemical decomposition until ,i can obtain clearer views of the way in which the power under consideration can appear at one time as associated with particles giving them their chemical attraction1 and at another as free electricity 7#dic4 #ieg474--,m4,f4 ,royal ,institution1 ,march #cast1 #ahcd4 ,,ninth ,,series4 #ae4 ,on the influence by induction of an ,electric ,current on itself3--and on the inductive action of ,electric ,currents generally4 ,received ,december #ah1 #ahcd1--,read ,january #bi1 #ahce4 #ajdh4 ,the following investigations relate to a very remarkable inductive action of electric currents1 or of the different parts of the same current 7#gd471 and indicate an immediate connexion between such inductive action and the direct transmission of electricity through conducting bodies1 or even that exhibited in the form of a spark4 #ajdi4 ,the inquiry arose out of a fact communicated to me by ,mr4 ,jenkin1 which is as follows4 ,if an ordinary wire of short length be used as the medium of communication between the two plates of an electromotor consisting of a single pair of metals1 no management will enable the experimenter to obtain an electric shock from this wire2 but if the wire which surrounds an electro-magnet be used1 a shock is felt each time the contact with the electromotor is broken1 provided the ends of the wire be grasped one in each hand4 #ajej4 ,another effect is observed at the same time1 which has long been known to philosophers1 namely1 that a bright electric spark occurs at the place of disjunction4 #ajea4 ,a brief account of these results1 with some of a corresponding character which ,i had observed in using long wires1 was published in the ,philosophical ,magazine for #ahcd;,a2 and ,i added to them some observations on their nature4 ,further investigations led me to perceive the inaccuracy of my first notions1 and ended in identifying these effects with the phenomena of induction which ,i had been fortunate enough to develop in the ,first ,series of these ,experimental ,researches 7#a4-ei47;,b4 ,notwithstanding this identity1 the extension and the results supply1 lead me to believe that they will be found worthy of the attention of the ,royal ,society4 ,a ,vol4 v4 pp4 #cdi1 #ddd4 ,b ,philosophical ,transactions1 #ahcb1 p4 #abf4 #ajeb4 ,the electromotor used consisted of a cylinder of zinc introduced between the two parts of a double cylinder of copper1 and preserved from metallic contact in the usual way by corks4 ,the zinc cylinder was eight inches high and four inches in diameter4 ,both it and the copper cylinder were supplied with stiff wires1 surmounted by cups containing mercury2 and it was at these cups that the contacts of wires1 helices1 or electro-magnets1 used to complete the circuit1 were made or broken4 ,these cups ,i will call ,g and ,e throughout the rest of this paper 7#ajgi474 #ajec4 ,certain helices were constructed1 some of which it will be necessary to describe4 ,a pasteboard tube had four copper wires1 one twenty-fourth of an inch in thickness1 wound round it1 each forming a helix in the same direction from end to end3 the convolutions of each wire were separated by string1 and the superposed helices prevented from touching by intervening calico4 ,the lengths of the wires forming the helices were #dh1 #di4e1 #dh1 and #de feet4 ,the first and third wires were united together so as to form one consistent helix of #if feet in length2 and the second and fourth wires were similarly united to form a second helix1 closely interwoven with the first1 and #id4e feet in length4 ,these helices may be distinguished by the numbers i and ii4 ,they were carefully examined by a powerful current of electricity and a galvanometer1 and found to have no communication with each other4 #ajed4 ,another helix was constructed upon a similar pasteboard tube1 two lengths of the same copper wire being used1 each forty-six feet long4 ,these were united into one consistent helix of ninety-two feet1 which therefore was nearly equal in value to either of the former helices1 but was not in close inductive association with them4 ,it may be distinguished by the number iii4 #ajee4 ,a fourth helix was constructed of very thick copper wire1 being one-fifth of an inch in diameter2 the length of wire used was seventy-nine feet1 independent of the straight terminal portions4 #ajef4 ,the principal electro-magnet employed consisted of a cylindrical bar of soft iron twenty-five inches long1 and one inch and three quarters in diameter1 bent into a ring1 so that the ends nearly touched1 and surrounded by three coils of thick copper wire1 the similar ends of which were fastened together2 each of these terminations was soldered to a copper rod1 serving as a conducting continuation of the wire4 ,hence any electric current sent through the rods was divided in the helices surrounding the ring1 into three parts1 all of which1 however1 moved in the same direction4 ,the three wires may therefore be considered as representing one wire1 of thrice the thickness of the wire really used4 #ajeg4 ,other electro-magnets could be made at pleasure by introducing a soft iron rod into any of the helices described 7#ajec1 c474 #ajeh4 ,the galvanometer which ,i had occasion to use was rough in its construction1 having but one magnetic needle1 and not at all delicate in its indications4 #ajei4 ,the effects to be considered depend on the conductor employed to complete the communication between the zinc and copper plates of the electromotor2 and ,i shall have to consider this conductor under four different forms3 as the helix of an electro-magnet 7#ajef72 as an ordinary helix 7#ajec1 c472 as a long extended wire1 having its course such that the parts can exert little or no mutual influence2 and as a short wire4 ,in all cases the conductor was of copper4 #ajfj4 ,the peculiar effects are best shown by the electro-magnet 7#ajef474 ,when it was used to complete the communication at the electromotor1 there was no sensible spark on making contact1 but on breaking contact there was a very large and bright spark1 with considerable combustion of the mercury4 ,then1 again1 with respect to the shock3 if the hands were moistened in salt and water1 and good contact between them and the wires retained1 no shock could be felt upon making contact at the electromotor1 but a powerful one on breaking contact4 #ajfa4 ,when the helix i or iii 7#ajec1 c47 was used as the connecting conductor1 there was also a good spark on breaking contact1 but none 7sensibly7 on making contact4 ,on trying to obtain the shock from these helices1 ,i could not succeed at first4 ,by joining the similar ends of i and ii so as to make the two helices equivalent to one helix1 having wire of double thickness1 ,i could just obtain the sensation4 ,using the helix of thick wire 7#ajee47 the shock was distinctly obtained4 ,on placing the tongue between two plates of silver connected by wires with the parts which the hands had heretofore touched 7#ajfd471 there was a powerful shock on breaking contact1 but none on making contact4 #ajfb4 ,the power of producing these phenomena exists therefore in the simple helix1 as in the electro-magnet1 although by no means in the same high degree4 #ajfc4 ,on putting a bar of soft iron into the helix1 it became an electro-magnet 7#ajeg471 and its power was instantly and greatly raised4 ,on putting a bar of copper into the helix1 no change was produced1 the action being that of the helix alone4 ,the two helices i and ii1 made into one helix of twofold length of wire1 produced a greater effect than either i or ii alone4 #ajfd4 ,on descending from the helix to the mere long wire1 the following effects were obtained1 ,a copper wire1 #j4ah of an inch in diameter1 and #acb feet in length1 was laid out upon the floor of the laboratory1 and used as the connecting conductor 7#ajei472 it gave no sensible spark on making contact1 but produced a bright one on breaking contact1 yet not so bright as that from the helix 7#ajfa47 ,on endeavouring to obtain the electric shock at the moment contact was broken1 ,i could not succeed so as to make it pass through the hands2 but by using two silver plates fastened by small wires to the extremity of the principal wire used1 and introducing the tongue between those plates1 ,i succeeded in obtaining powerful shocks upon the tongue and gums1 and could easily convulse a flounder1 an eel1 or a frog4 ,none of these effects could be obtained directly from the electromotor1 i4e4 when the tongue1 frog1 or fish was in a similar1 and therefore comparative manner1 interposed in the course of the communication between the zinc and copper plates1 separated everywhere else by the acid used to excite the combination1 or by air4 ,the bright spark and the shock1 produced only on breaking contact1 are therefore effects of the same kind as those produced in a higher degree by the helix1 and in a still higher degree by the electro-magnet4 #ajfe4 ,in order to compare an extended wire with a helix1 the helix i1 containing ninety-six feet1 and ninety-six feet of the same-sized wire lying on the floor of the laboratory1 were used alternately as conductors3 the former gave a much brighter spark at the moment of disjunction than the latter4 ,again1 twenty-eight feet of copper wire were made up into a helix1 and being used gave a good spark on disjunction at the electromotor2 being then suddenly pulled out and again employed1 it gave a much smaller spark than before1 although nothing but its spiral arrangement had been changed4 #ajff4 ,as the superiority of a helix over a wire is important to the philosophy of the effect1 ,i took particular pains to ascertain the fact with certainty4 ,a wire of copper sixty-seven feet long was bent in the middle so as to form a double termination which could be communicated with the electromotor2 one of the halves of this wire was made into a helix and the other remained in its extended condition4 ,when these were used alternately as the connecting wire1 the helix half gave by much the strongest spark4 ,it even gave a stronger spark than when it and the extended wire were used conjointly as a double conductor4 #ajfg4 ,when a short wire is used1 all these effects disappear4 ,if it be only two or three inches long1 a spark can scarcely be perceived on breaking the junction4 ,if it be ten or twelve inches long and moderately thick1 a small spark may be more easily obtained4 ,as the length is increased1 the spark becomes proportionately brighter1 until from extreme length the resistance offered by the metal as a conductor begins to interfere with the principal result4 #ajfh4 ,the effect of elongation was well shown thus3 #aad feet of copper wire1 one-eighteenth of an inch in diameter1 were extended on the floor and used as a conductor2 it remained cold1 but gave a bright spark on breaking contact4 ,being crossed so that the two terminations were in contact near the extremities1 it was again used as a conductor1 only twelve inches now being included in the circuit3 the wire became very hot from the greater quantity of electricity passing through it1 and yet the spark on breaking contact was scarcely visible4 ,the experiment was repeated with a wire one-ninth of an inch in diameter and thirty-six feet long with the same results4 #ajfi4 ,that the effects1 and also the action1 in all these forms of the experiment are identical1 is evident from the manner in which the former can be gradually raised from that produced by the shortest wire to that of the most powerful electro-magnet3 and this capability of examining what will happen by the most powerful apparatus1 and then experimenting for the same results1 or reasoning from them1 with the weaker arrangements1 is of great advantage in making out the true principles of the phenomena4 #ajgj4 ,the action is evidently dependent upon the wire which serves as a conductor2 for it varies as that wire varies in its length or arrangement4 ,the shortest wire may be considered as exhibiting the full effect of spark or shock which the electromotor can produce by its own direct power2 all the additional force which the arrangements described can excite being due to some affection of the current1 either permanent or momentary1 in the wire itself4 ,that it is a momentary effect1 produced only at the instant of breaking contact1 will be fully proved 7#ajhi4 #aajj474 #ajga4 ,no change takes place in the quantity or intensity of the current during the time the latter is continued1 from the moment after contact is made1 up to that previous to disunion1 except what depends upon the increased obstruction offered to the passage of the electricity by a long wire as compared to a short wire4 ,to ascertain this point with regard to quantity1 the helix i 7#ajec47 and the galvanometer 7#ajee47 were both made parts of the metallic circuit used to connect the plates of a small electromotor1 and the deflection at the galvanometer was observed2 then a soft iron core was put into the helix1 and as soon as the momentary effect was over1 and the needle had become stationary1 it was again observed1 and found to stand exactly at the same division as before4 ,thus the quantity passing through the wire when the current was continued was the same either with or without the soft iron1 although the peculiar effects occurring at the moment of disjunction were very different in degree under such variation of circumstances4 #ajgb4 ,that the quality of intensity belonging to the constant current did not vary with the circumstances favouring the peculiar results under consideration1 so as to yield an explanation of those results1 was ascertained in the following manner4 ,the current excited by an electromotor was passed through short wires1 and its intensity tried by subjecting different substances to its electrolyzing power 7#iab4 #iff4 c472 it was then passed through the wires of the powerful electro-magnet 7#ajef471 and again examined with respect to its intensity by the same means and found unchanged4 ,again1 the constancy of the quantity passed in the above experiment 7#ajga47 adds further proof that the intensity could not have varied2 for had it been increased upon the introduction of the soft iron1 there is every reason to believe that the quantity passed in a given time would also have increased4 #ajgc4 ,the fact is1 that under many variations of the experiments1 the permanent current loses in force as the effects upon breaking contact become exalted4 ,this is abundantly evident in the comparative experiments with long and short wires 7#ajfh472 and is still more strikingly shown by the following variation4 ,solder an inch or two in length of fine platina wire 7about one-hundredth of an inch in diameter7 on to one end of the long communicating wire1 and also a similar length of the same platina wire on to one end of the short communication2 then1 in comparing the effects of these two communications1 make and break contact between the platina terminations and the mercury of the cup ,g or ,e 7#ajgi474 ,when the short wire is used1 the platina will be ignited by the constant current1 because of the quantity of electricity1 but the spark on breaking contact will be hardly visible2 on using the longer communicating wire1 which by obstructing will diminish the current1 the platina will remain cold whilst the current passes1 but give a bright spark at the moment it ceases3 thus the strange result is obtained of a diminished spark and shock from the strong current1 and increased effects from the weak one4 ,hence the spark and shock at the moment of disjunction1 although resulting from great intensity and quantity1 of the current at that moment1 are no direct indicators or measurers of the intensity or quantity of the constant current previously passing1 and by which they are ultimately produced4 99 99 99 99 99 #ajgd4 ,it is highly important in using the spark as an indication1 by its relative brightness1 of these effects1 to bear in mind certain circumstances connected with its production and appearance 7#ieh474 ,an ordinary electric spark is understood to be the bright appearance of electricity passing suddenly through an interval of air1 or other badly conducting matter4 ,a voltaic spark is sometimes of the same nature1 but1 generally1 is due to the ignition and even combustion of a minute portion of a good conductor2 and that is especially the case when the electromotor consists of but one or few pairs of plates4 ,this can be very well observed if either or both of the metallic surfaces intended to touch be solid and pointed4 ,the moment they come in contact the current passes2 it heats1 ignites1 and even burns the touching points1 and the appearance is as if the spark passed on making contact1 whereas it is only a case of ignition by the current1 contact being previously made1 and is perfectly analogous to the ignition of a fine platina wire connecting the extremities of a voltaic battery4 #ajge4 ,when mercury constitutes one or both of the surfaces used1 the brightness of the spark is greatly increased4 ,but as this effect is due to the action on1 and probable combustion of1 the metal1 such sparks must only be compared with other sparks also taken from mercurial surfaces1 and not with such as may be taken1 for instance1 between surfaces of platina or gold1 for then the appearances are far less bright1 though the same quantity of electricity be passed4 ,it is not at all unlikely that the commonly occurring circumstance of combustion may affect even the duration of the light2 and that sparks taken between mercury1 copper1 or other combustible bodies1 will continue for a period sensibly longer than those passing between platina or gold4 #ajgf4 ,when the end of a short clean copper wire1 attached to one plate of an electromotor1 is brought down carefully upon a surface of mercury connected with the other plate1 a spark1 almost continuous1 can be obtained4 ,this ,i refer to a succession of effects of the following nature3 first1 contact1--then ignition of the touching points1--recession of the mercury from the mechanical results of the heat produced at the place of contact1 and the electro-magnetic condition of the parts at the moment,a1 --breaking of the contact and the production of the peculiar intense effect dependent thereon1--renewal of the contact by the returning surface of the undulating mercury1--and then a repetition of the same series of effects1 and that with such rapidity as to present the appearance of a continued discharge4 ,if a long wire or an electro-magnet be used as the connecting conductor instead of a short wire1 a similar appearance may be produced by tapping the vessel containing the mercury and making it vibrate2 but the sparks do not usually follow each other so rapidly as to produce an apparently continuous spark1 because of the time required1 when the long wire or electro-magnet is used1 both for the full development of the current 7#aaja4 #aajf47 and for its complete cessation4 ,a ,quarterly ,journal of ,science1 vol4 xii1 p4 #dbj4 #ajgg4 ,returning to the phenomena in question1 the first thought that arises in the mind is1 that the electricity circulates with something like momentum or inertia in the wire1 and that thus a long wire produces effects at the instant the current is stopped1 which a short wire cannot produce4 ,such an explanation is1 however1 at once set aside by the fact1 that the same length of wire produces the effects in very different degrees1 according as it is simply extended1 or made into a helix1 or forms the circuit of an electro-magnet 7#ajfi474 ,the experiments to be adduced 7#ajhi47 will still more strikingly show that the idea of momentum cannot apply4 #ajgh4 ,the bright spark at the electromotor1 and the shock in the arms1 appeared evidently to be due to one current in the long wire1 divided into two parts by the double channel afforded through the body and through the electromotor2 for that the spark was evolved at the place of disjunction with the electromotor1 not by any direct action of the latter1 but by a force immediately exerted in the wire of communication1 seemed to be without doubt 7#ajgj474 ,it followed1 therefore1 that by using a better conductor in place of the human body1 the whole of this extra current might be made to pass at that place2 and thus be separated from that which the electromotor could produce by its immediate action1 and its direction be examined apart from any interference of the original and originating current4 ,this was found to be true2 for on connecting the ends of the principal wire together by a cross wire two or three feet in length1 applied just where the hands had felt the shock1 the whole of the extra current passed by the new channel1 and then no better spark than one producible by a short wire was obtained on disjunction at the electromotor4 #ajgi4 ,the current thus separated was examined by galvanometers and decomposing apparatus introduced into the course of this wire4 ,i will always speak of it as the current in the cross wire or wires1 so that no mistake1 as to its place or origin1 may occur4 ,in the wood-cut1 ,z and ,c represent the zinc and copper plates of the electromotor2 ,g and ,e the cups of mercury where contact is made or broken 7#ajeb472 ,a and ,b the terminations of ,d1 the long wire1 the helix or the electro-magnet1 used to complete the circuit2 ,n and ,p are the cross wires1 which can either be brought into contact at x1 or else have a galvanometer 7#ajeh47 or an electrolyzing apparatus 7#cab4 #caf47 interposed there4 ,illustration ,the production of the shock from the current in the cross wire1 whether ,d was a long extended wire1 or a helix1 or an electro-magnet1 has been already described 7#ajfj4 #ajfa4 #ajfd474 #ajhj4 ,the spark of the cross-wire current could be produced at x in the following manner3 ,d was made an electro-magnet2 the metallic extremities at x were held close together1 or rubbed lightly against each other1 whilst contact was broken at ,g or ,e4 ,when the communication was perfect at x1 little or no spark appeared at ,g or ,e4 ,when the condition of vicinity at x was favourable for the result required1 a bright spark would pass there at the moment of disjunction1 none occurring at ,g and ,e3 this spark was the luminous passage of the extra current through the cross-wires4 ,when there was no contact or passage of current at x1 then the spark appeared at ,g or ,e1 the extra current forcing its way through the electromotor itself4 ,the same results were obtained by the use of the helix or the extended wire at ,d in place of the electro-magnet4 #ajha4 ,on introducing a fine platina wire at x1 and employing the electro-magnet at ,d1 no visible effects occurred as long as contact was continued2 but on breaking contact at ,g or ,e1 the fine wire was instantly ignited and fused4 ,a longer or thicker wire could be so adjusted at x as to show ignition1 without fusion1 every time the contact was broken at ,g or ,e4 #ajhb4 ,it is rather difficult to obtain this effect with helices or wires1 and for very simple reasons3 with the helices i1 ii1 or iii1 there was such retardation of the electric current1 from the length of wire used1 that a full inch of platina wire one-fiftieth of an inch in diameter could be retained ignited at the cross-wires during the continuance of contact1 by the portion of electricity passing through it4 ,hence it was impossible to distinguish the particular effects at the moments of making or breaking contact from this constant effect4 ,on using the thick wire helix 7#ajee471 the same results ensued4 #ajhc4 ,proceeding upon the known fact that electric currents of great quantity but low intensity1 though able to ignite thick wires1 cannot produce that effect upon thin ones1 ,i used a very fine platina wire at x1 reducing its diameter until a spark appeared at ,g or ,e1 when contact was broken there4 ,a quarter of an inch of such wire might be introduced at x without being ignited by the continuance of contact at ,g or ,e2 but when contact was broken at either place1 this wire became red-hot2 proving1 by this method1 the production of the induced current at that moment4 #ajhd4 ,chemical decomposition was next effected by the cross-wire current1 an electro-magnet being used at ,d1 and a decomposing apparatus1 with solution of iodide of potassium in paper 7#ajgi471 employed at x4 ,the conducting power of the connecting system ,a ,b ,d was sufficient to carry all the primary current1 and consequently no chemical action took place at x during the continuance of contact at ,g and ,e2 but when contact was broken1 there was instantly decomposition at x4 ,the iodine appeared against the wire ,n1 and not against the wire ,p2 thus demonstrating that the current through the cross-wires1 when contact was broken1 was in the reverse direction to that marked by the arrow1 or that which the electromotor would have sent through it4 #ajhe4 ,in this experiment a bright spark occurs at the place of disjunction1 indicating that only a small part of the extra current passed the apparatus at x1 because of the small conducting power of the latter4 #ajhf4 ,i found it difficult to obtain the chemical effects with the simple helices and wires1 in consequence of the diminished inductive power of these arrangements1 and because of the passage of a strong constant current at x whenever a very active electromotor was used 7#ajhb74 #ajhg4 ,the most instructive set of results was obtained1 however1 when the galvanometer was introduced at x4 ,using an electro-magnet at ,d1 and continuing contact1 a current was then indicated by the deflection1 proceeding from ,p to ,n1 in the direction of the arrow2 the cross-wire serving to carry one part of the electricity excited by the electromotor1 and that part of the arrangement marked ,a ,b ,d1 the other and far greater part1 as indicated by the arrows4 ,the magnetic needle was then forced back1 by pins applied upon opposite sides of its two extremities1 to its natural position when uninfluenced by a current2 after which1 contact being broken at ,g or ,e1 it was deflected strongly in the opposite direction2 thus showing1 in accordance with the chemical effects 7#ajhd71 that the extra current followed a course in the cross-wires contrary to that indicated by the arrow1 i4 e4 contrary to the one produced by the direct action of the electromotor,a4 ,a ,it was ascertained experimentally1 that if a strong current was passed through the galvanometer only1 and the needle restrained in one direction as above in its natural position1 when the current was stopped1 no vibration of the needle in the opposite direction took place4 #ajhh4 ,with the helix only 7#ajfa471 these effects could scarcely be observed1 in consequence of the smaller inductive force of this arrangement1 the opposed action from induction in the galvanometer wire itself1 the mechanical condition and tension of the needle from the effect of blocking 7#ajhg47 whilst the current due to continuance of contact was passing round it2 and because of other causes4 ,with the extended wire 7#ajfd47 all these circumstances had still greater influence1 and therefore allowed less chance of success4 #ajhi4 ,these experiments1 establishing as they did1 by the quantity1 intensity1 and even direction1 a distinction between the primary or generating current and the extra current1 led me to conclude that the latter was identical with the induced current described 7#f4 #bf4 #gd47 in the ,first ,series of these ,researches2 and this opinion ,i was soon able to bring to proof1 and at the same times obtained not the partial 7#ajgh47 but entire separation of one current from the other4 #ajij4 ,the double helix 7#ajec47 was arranged so that it should form the connecting wire between the plates of the electromotor1 in being out of the current1 and its ends unconnected4 ,in this condition it acted very well1 and gave a good spark at the time and place of disjunction4 ,the opposite ends of ii were then connected together so as to form an endless wire1 i remaining unchanged3 but now no spark1 or one scarcely sensible1 could be obtained from the latter at the place of disjunction4 ,then1 again1 the ends of ii were held so nearly together that any current running round that helix should be rendered visible as a spark2 and in this manner a spark was obtained from ii when the junction of i with the electromotor was broken1 in place of appearing at the disjoined extremity of i itself4 #ajia4 ,by introducing a galvanometer or decomposing apparatus into the circuit formed by the helix ii1 ,i could easily obtain the deflections and decomposition occasioned by the induced current due to the breaking contact at helix i1 or even to that occasioned by making contact of that helix with the electromotor2 the results in both cases indicating the contrary directions of the two induced currents thus produced 7#bf474 #ajib4 ,all these effects1 except those of decomposition1 were reproduced by two extended long wires1 not having the form of helices1 but placed close to each other2 and thus it was proved that the extra current could be removed from the wire carrying the original current to a neighbouring wire1 and was at the same time identified1 in direction and every other respect1 with the currents producible by induction 7#ajhi474 ,the case1 therefore1 of the bright spark and shock on disjunction may now be stated thus3 ,if a current be established in a wire1 and another wire1 forming a complete circuit1 be placed parallel to the first1 at the moment the current in the first is stopped it induces a current in the same direction in the second1 the first exhibiting then but a feeble spark2 but if the second wire be away1 disjunction of the first wire induces a current in itself in the same direction1 producing a strong spark4 ,the strong spark in the single long wire or helix1 at the moment of disjunction1 is therefore the equivalent of the current which would be produced in a neighbouring wire if such second current were permitted4 #ajic4 ,viewing the phenomena as the results of the induction of electrical currents1 many of the principles of action1 in the former experiments1 become far more evident and precise4 ,thus the different effects of short wires1 long wires1 helices1 and electro-magnets 7#ajfi47 may be comprehended4 ,if the inductive action of a wire a foot long upon a collateral wire also a foot in length1 be observed1 it will be found very small2 but if the same current be sent through a wire fifty feet long1 it will induce in a neighbouring wire of fifty feet a far more powerful current at the moment of making or breaking contact1 each successive foot of wire adding to the sum of action2 and by parity of reasoning1 a similar effect should take place when the conducting wire is also that in which the induced current is formed 7#gd473 hence the reason why a long wire gives a brighter spark on breaking contact than a short one 7#ajfh471 although it carries much less electricity4 #ajid4 ,if the long wire be made into a helix1 it will then be still more effective in producing sparks and shocks on breaking contact2 for by the mutual inductive action of the convolutions each aids its neighbour1 and will be aided in turn1 and the sum of effect will be very greatly increased4 #ajie4 ,if an electro-magnet be employed1 the effect will be still more highly exalted2 because the iron1 magnetized by the power of the continuing current1 will lose its magnetism at the moment the current ceases to pass1 and in so doing will tend to produce an electric current in the wire around it 7#cg4 #ch471 in conformity with that which the cessation of current in the helix itself also tends to produce4 #ajif4 ,by applying the laws of the induction of electric currents formerly developed 7#f4 c471 various new conditions of the experiments could be devised1 which by their results should serve as tests of the accuracy of the view just given4 ,thus1 if a long wire be doubled1 so that the current in the two halves shall have opposite actions1 it ought not to give a sensible spark at the moment of disjunction3 and this proved to be the case1 for a wire forty feet long1 covered with silk1 being doubled and tied closely together to within four inches of the extremities1 when used in that state1 gave scarcely a perceptible spark2 but being opened out and the parts separated1 it gave a very good one4 ,the two helices i and ii being joined at their similar ends1 and then used at their other extremities to connect the plates of the electromotor1 thus constituted one long helix1 of which one half was opposed in direction to the other half3 under these circumstances it gave scarcely a sensible spark1 even when the soft iron core was within1 although containing nearly two hundred feet of wire4 ,when it was made into one consistent helix of the same length of wire it gave a very bright spark4 #ajig4 ,similar proofs can be drawn from the mutual inductive action of two separate currents 7#aaaj472 and it is important for the general principles that the consistent action of two such currents should be established4 ,thus1 two currents going in the same direction should1 if simultaneously stopped1 aid each other by their relative influence2 or if proceeding in contrary directions1 should oppose each other under similar circumstances4 ,i endeavoured at first to obtain two currents from two different electromotors1 and passing them through the helices i and ii1 tried to effect the disjunctions mechanically at the same moment4 ,but in this ,i could not succeed2 one was always separated before the other1 and in that case produced little or no spark1 its inductive power being employed in throwing a current round the remaining complete circuit 7#ajij473 the current which was stopped last always gave a bright spark4 ,if it were ever to become needful to ascertain whether two junctions were accurately broken at the same moment1 these sparks would afford a test for the purpose1 having an infinitesimal degree of perfection4 #ajih4 ,i was able to prove the points by other expedients4 ,two short thick wires were selected to serve as terminations1 by which contact could be made or broken with the electromotor4 ,the compound helix1 consisting of i and ii 7#ajec471 was adjusted so that the extremities of the two helices could be placed in communication with the two terminal wires1 in such a manner that the current moving through the thick wires should be divided into two equal portions in the two helices1 these portions travelling1 according to the mode of connexion1 either in the same direction or in contrary directions at pleasure4 ,in this manner two streams could be obtained1 both of which could be stopped simultaneously1 because the disjunction could be broken at ,g or ,f by removing a single wire4 ,when the helices were in contrary directions1 there was scarcely a sensible spark at the place of disjunction2 but when they were in accordance there was a very bright one4 #ajii4 ,the helix i was now used constantly1 being sometimes associated1 as above1 with helix ii in an according direction1 and sometimes with helix iii1 which was placed at a little distance4 ,the association i and ii1 which presented two currents able to affect each other by induction1 because of their vicinity1 gave a brighter spark than the association i and iii1 where the two streams could not exert their mutual influence2 but the difference was not so great as ,i expected4 #aajj4 ,thus all the phenomena tend to prove that the effects are due to an inductive action1 occurring at the moment when the principal current is stopped4 ,i at one time thought they were due to an action continued during the whole time of the current1 and expected that a steel magnet would have an influence according to its position in the helix1 comparable to that of a soft iron bar1 in assisting the effect4 ,this1 however1 is not the case2 for hard steel1 or a magnet in the helix1 is not so effectual as soft iron2 nor does it make any difference how the magnet is placed in the helix1 and for very simple reasons1 namely1 that the effect does not depend upon a permanent state of the core1 but a change of state2 and that the magnet or hard steel cannot sink through such a difference of state as soft iron1 at the moment contact ceases1 and therefore cannot produce an equal effect in generating a current of electricity by induction 7#cd4 #cg474 99 99 99 99 99 #aaja4 ,as an electric current acts by induction with equal energy at the moment of its commencement as at the moment of its cessation 7#aj4 #bf471 but in a contrary direction1 the reference of the effects under examination to an inductive action1 would lead to the conclusion that corresponding effects of an opposite nature must occur in a long wire1 a helix1 or an electro-magnet1 every time that contact is made with the electromotor4 ,these effects will tend to establish a resistance for the first moment in the long conductor1 producing a result equivalent to the reverse of a shock or a spark4 ,now it is very difficult to devise means fit for the recognition of such negative results2 but as it is probable that some positive effect is produced at the time1 if we knew what to expect1 ,i think the few facts bearing upon this subject with which ,i am acquainted are worth recording4 #aajb4 ,the electro-magnet was arranged with an electrolyzing apparatus at x1 as before described 7#ajhd471 except that the intensity of the chemical action at the electromotor was increased until the electric current was just able to produce the feeblest signs of decomposition whilst contact was continued at ,g and ,e 7#ajgi472 7the iodine of course appearing against the end of the cross wire ,p27 the wire ,n was also separated from ,a at r1 so that contact there could be made or broken at pleasure4 ,under these circumstances the following set of actions was repeated several times3 contact was broken at r1 then broken at ,g1 next made at r1 and lastly renewed at ,g2 thus any current from ,n to ,p due to breaking of contact was avoided1 but any additional force to the current from ,p to ,n due to making contact could be observed4 ,in this way it was found1 that a much greater decomposing effect 7causing the evolution of iodine against ,p7 could be obtained by a few completions of contact than by the current which could pass in a much longer time if the contact was continued4 ,this ,i attribute to the act of induction in the wire ,,abd at the moment of contact rendering that wire a worse conductor1 or rather retarding the passage of the electricity through it for the instant1 and so throwing a greater quantity of the electricity which the electromotor could produce1 through the cross wire passage ,,np4 ,the instant the induction ceased1 ,,abd resumed its full power of carrying a constant current of electricity1 and could have it highly increased1 as we know by the former experiments 7#ajfj47 by the opposite inductive action brought into activity at the moment contact at ,z or ,c was broken4 #aajc4 ,a galvanometer was then introduced at x1 and the deflection of the needle noted whilst contact was continued at ,g and ,e3 the needle was then blocked as before in one direction 7#ajhg471 so that it should not return when the current ceased1 but remain in the position in which the current could retain it4 ,contact at ,g or ,e was broken1 producing of course no visible effect2 it was then renewed1 and the needle was instantly deflected1 passing from the blocking pins to a position still further from its natural place than that which the constant current could give1 and thus showing1 by the temporary excess of current in this cross communication1 the temporary retardation in the circuit ,,abd4 #aajd4 ,on adjusting a platina wire at x 7#ajha47 so that it should not be ignited by the current passing through it whilst contact at ,g and ,e was continued1 and yet become red-hot by a current somewhat more powerful1 ,i was readily able to produce its ignition upon making contact1 and again upon breaking contact4 ,thus the momentary retardation in ,,abd on making contact was again shown by this result1 as well also as the opposite result upon breaking contact4 ,the two ignitions of the wire at x were of course produced by electric currents moving in opposite directions4 #aaje4 ,using the helix only1 ,i could not obtain distinct deflections at x1 due to the extra effect on making contact1 for the reasons already mentioned 7#ajhh474 ,by using a very fine platina wire there 7#ajhc471 ,i did succeed in obtaining the igniting effect for making contact in the same manner1 though by no means to the same degree1 as with the electro-magnet 7#aajd74 #aajf4 ,we may also consider and estimate the effect on making contact1 by transferring the force of induction from the wire carrying the original current to a lateral wire1 as in the cases described 7#ajij472 and we then are sure1 both by the chemical and galvanometrical results 7#ajia471 that the forces upon making and breaking contact1 like action and reaction1 are equal in their strength but contrary in their direction4 ,if1 therefore1 the effect on making contact resolves itself into a mere retardation of the current at the first moment of its existence1 it must be1 in its degree1 equivalent to the high exaltation of that same current at the moment contact is broken4 #aajg4 ,thus the case1 under the circumstances1 is1 that the intensity and quantity of electricity moving in a current are smaller when the current commences or is increased1 and greater when it diminishes or ceases1 than they would be if the inductive action occurring at these moments did not take place2 or than they are in the original current wire if the inductive action be transferred from that wire to a collateral one 7#ajij474 #aajh4 ,from the facility of transference to neighbouring wires1 and from the effects generally1 the inductive forces appear to be lateral1 i4e4 exerted in a direction perpendicular to the direction of the originating and produced currents3 and they also appear to be accurately represented by the magnetic curves1 and closely related to1 if not identical with1 magnetic forces4 #aaji4 ,there can be no doubt that the current in one part of a wire can act by induction upon other parts of the same wire which are lateral to the first1 i4e4 in the same vertical section 7#gd471 or in the parts which are more or less oblique to it 7#aaab471 just as it can act in producing a current in a neighbouring wire or in a neighbouring coil of the same wire4 ,it is this which gives the appearance of the current acting upon itself3 but all the experiments and all analogy tend to show that the elements 7if ,i may so say7 of the currents do not act upon themselves1 and so cause the effect in question1 but produce it by exciting currents in conducting matter which is lateral to them4 #aaaj4 ,it is possible that some of the expressions ,i have used may seem to imply1 that the inductive action is essentially the action of one current upon another1 or of one element of a current upon another element of the same current4 ,to avoid any such conclusion ,i must explain more distinctly my meaning4 ,if an endless wire be taken1 we have the means of generating a current in it which shall run round the circuit without adding any electricity to what was previously in the wire4 ,as far as we can judge1 the electricity which appears as a current is the same as that which before was quiescent in the wire2 and though we cannot as yet point out the essential condition of difference of the electricity at such times1 we can easily recognize the two states4 ,now when a current acts by induction upon conducting matter lateral to it1 it probably acts upon the electricity in that conducting matter whether it be in the form of a current or quiescent1 in the one case increasing or diminishing the current according to its direction1 in the other producing a current1 and the amount of the inductive action is probably the same in both cases4 ,hence1 to say that the action of induction depended upon the mutual relation of two or more currents1 would1 according to the restricted sense in which the term current is understood at present 7#bhc4 #eag4 #ffg471 be an error4 #aaaa4 ,several of the effects1 as1 for instances1 those with helices7#ajff471 with according or counter currents 7#ajig4 #ajih471 and those on the production of lateral currents 7#ajij471 appeared to indicate that a current could produce an effect of induction in a neighbouring wire more readily than in its own carrying wire1 in which case it might be expected that some variation of result would be produced if a bundle of wires were used as a conductor instead of a single wire4 ,in consequence the following experiments were made4 ,a copper wire one twenty-third of an inch in diameter was cut into lengths of five feet each1 and six of these being laid side by side in one bundle1 had their opposite extremities soldered to two terminal pieces of copper4 ,this arrangement could be used as a discharging wire1 but the general current could be divided into six parallel streams1 which might be brought close together1 or1 by the separation of the wires1 be taken more or less out of each other's influence4 ,a somewhat brighter spark was1 ,i think1 obtained on breaking contact when the six wires were close together than when held asunder4 #aaab4 ,another bundle1 containing twenty of these wires1 was eighteen feet long3 the terminal pieces were one-fifth of an inch in diameter1 and each six inches long4 ,this was compared with nineteen feet in length of copper wire one-fifth of an inch in diameter4 ,the bundle gave a smaller spark on breaking contact than the latter1 even when its strands were held together by string3 when they were separated1 it gave a still smaller spark4 ,upon the whole1 however1 the diminution of effect was not such as ,i expected3 and ,i doubt whether the results can be considered as any proof of the truth of the supposition which gave rise to them4 #aaac4 ,the inductive force by which two elements of one current 7#aaji4 #aaaj47 act upon each other1 appears to diminish as the line joining them becomes oblique to the direction of the current and to vanish entirely when it is parallel4 ,i am led by some results to suspect that it then even passes into the repulsive force noticed by ,ampre,a2 which is the cause of the elevations in mercury described by ,sir ,humphry ,davy,b1 and which again is probably directly connected with the quality of intensity4 ,a ,recueil d',observations ,electro-,dynamiques1 p4 #bhe4 ,b ,philosophical ,transactions1 #ahbc1 p4 #aee4 #aaad4 ,notwithstanding that the effects appear only at the making and breaking of contact1 7the current remaining unaffected1 seemingly1 in the interval17 ,i cannot resist the impression that there is some connected and correspondent effect produced by this lateral action of the elements of the electric stream during the time of its continuance 7#fj4 #bdb474 ,an action of this kind1 in fact1 is evident in the magnetic relations of the parts of the current4 ,but admitting 7as we may do for the moment7 the magnetic forces to constitute the power which produces such striking and different results at the commencement and termination of a current1 still there appears to be a link in the chain of effects1 a wheel in the physical mechanism of the action1 as yet unrecognised4 ,if we endeavour to consider electricity and magnetism as the results of two forces of a physical agent1 or a peculiar condition of matter1 exerted in determinate directions perpendicular to each other1 then1 it appears to me1 that we must consider these two states or forces as convertible into each other in a greater or smaller degree2 i4e4 that an element of an electric current has not a determinate electric force and a determinate magnetic force constantly existing in the same ratio1 but that the two forces are1 to a certain degree1 convertible by a process or change of condition at present unknown to us4 ,how else can a current of a given intensity and quantity be able1 by its direct action1 to sustain a state which1 when allowed to react1 7at the cessation of the original current17 shall produce a second current1 having an intensity and quantity far greater than the generating one8 ,this cannot result from a direct reaction of the electric force2 and if it result from a change of electrical into magnetic force1 and a reconversion back again1 it will show that they differ in something more than mere direction1 as regards that agent in the conducting wire which constitutes their immediate cause4 #aaae4 ,with reference to the appearance1 at different times1 of the contrary effects produced by the making and breaking contact1 and their separation by an intermediate and indifferent state1 this separation is probably more apparent than real4 ,if the conduction of electricity be effected by vibrations 7#bhc471 or by any other mode in which opposite forces are successively and rapidly excited and neutralized1 then we might expect a peculiar and contrary development of force at the commencement and termination of the periods during which the conducting action should last 7somewhat in analogy with the colours produced at the outside of an imperfectly developed solar spectrum73 and the intermediate actions1 although not sensible in the same way1 may be very important and1 for instance1 perhaps constitute the very essence of conductibility4 ,it is by views and reasons such as these1 which seem to me connected with the fundamental laws and facts of electrical science1 that ,i have been induced to enter1 more minutely than ,i otherwise should have done1 into the experimental examination of the phenomena described in this paper4 #aaaf4 ,before concluding1 ,i may briefly remark1 that on using a voltaic battery of fifty pairs of plates instead of a single pair 7#ajeb471 the effects were exactly of the same kind4 ,the spark on making contact1 for the reasons before given1 was very small 7#aaja4 #aajg472 that on breaking contact1 very excellent and brilliant4 ,the continuous discharge did not seem altered in character1 whether a short wire or the powerful electro-magnet were used as a connecting discharger4 #aaag4 ,the effects produced at the commencement and end of a current1 7which are separated by an interval of time when that current is supplied from a voltaic apparatus17 must occur at the same moment when a common electric discharge is passed through a long wire4 ,whether1 if happening accurately at the same moment1 they would entirely neutralize each other1 or whether they would not still give some definite peculiarity to the discharge1 is a matter remaining to be examined2 but it is very probable that the peculiar character and pungency of sparks drawn from a long wire depend in part upon the increased intensity given at the termination of the discharge by the inductive action then occurring4 #aaah4 ,in the wire of the helix of magneto-electric machines1 7as1 for instance1 in ,mr4 ,saxton's beautiful arrangement17 an important influence of these principles of action is evidently shown4 ,from the construction of the apparatus the current is permitted to move in a complete metallic circuit of great length during the first instants of its formation3 it gradually rises in strength1 and is then suddenly stopped by the breaking of the metallic circuit2 and thus great intensity is given by induction to the electricity1 which at that moment passes 7#ajfd4 #ajfj474 ,this intensity is not only shown by the brilliancy of the spark and the strength of the shock1 but also by the necessity which has been experienced of well-insulating the convolutions of the helix1 in which the current is formed3 and it gives to the current a force at these moments very far above that which the apparatus could produce if the principle which forms the subject of this paper were not called into play4 ,royal ,institution1 ,december #hth1 #ahcd4 ,,tenth ,,series4 #af4 ,on an improved form of the ,voltaic ,battery4 #ag4 ,some practical results respecting the construction and use of the ,voltaic ,battery4 ,received ,june #af1--,read ,june #ah1 #ahce4 #aaai4 ,i ,have lately had occasion to examine the voltaic trough practically1 with a view to improvements in its construction and use2 and though ,i do not pretend that the results have anything like the importance which attaches to the discovery of a new law or principle1 ,i still think they are valuable1 and may therefore1 if briefly told1 and in connexion with former papers1 be worthy the approbation of the ,royal ,society4 #af4 ,on an improved form of the ,voltaic ,battery4 #aabj4 ,in a simple voltaic circuit 7and the same is true of the battery7 the chemical forces which1 during their activity1 give power to the instrument1 are generally divided into two portions2 one of these is exerted locally1 whilst the other is transferred round the circle 7#idg4 #iif472 the latter constitutes the electric current of the instrument1 whilst the former is altogether lost or wasted4 ,the ratio of these two portions of power may be varied to a great extent by the influence of circumstances3 thus1 in a battery not closed1 all the action is local2 in one of the ordinary construction1 much is in circulation when the extremities are in communication3 and in the perfect one1 which ,i have described 7#ajja471 all the chemical power circulates and becomes electricity4 ,by referring to the quantity of zinc dissolved from the plates 7#hfe4 #aabj471 and the quantity of decomposition effected in the volta-electrometer 7#gaa4 #aabf17 or elsewhere1 the proportions of the local and transferred actions under any particular circumstances can be ascertained1 and the efficacy of the voltaic arrangement1 or the waste of chemical power at its zinc plates1 be accurately determined4 #aaba4 ,if a voltaic battery were constructed of zinc and platina1 the latter metal surrounding the former1 as in the double copper arrangement1 and the whole being excited by dilute sulphuric acid1 then no insulating divisions of glass1 porcelain or air would be required between the contiguous platina surfaces2 and1 provided these did not touch metallically1 the same acid which1 being between the zinc and platina1 would excite the battery into powerful action1 would1 between the two surfaces of platina1 produce no discharge of the electricity1 nor cause any diminution of the power of the trough4 ,this is a necessary consequence of the resistance to the passage of the current which ,i have shown occurs at the place of decomposition 7#ajjg4 #ajaa472 for that resistance is fully able to stop the current1 and therefore acts as insulation to the electricity of the contiguous plates1 inasmuch as the current which tends to pass between them never has a higher intensity than that due to the action of a single pair4 #aabb4 ,if the metal surrounding the zinc be copper 7#ajde471 and if the acid be nitro-sulphuric acid 7#ajbj471 then a slight discharge between the two contiguous coppers does take place1 provided there be no other channel open by which the forces may circulate2 but when such a channel is permitted1 the return or back discharge of which ,i speak is exceedingly diminished1 in accordance with the principles laid down in the ,eighth ,series of these ,researches4 #aabc4 ,guided by these principles ,i was led to the construction of a voltaic trough1 in which the coppers1 passing round both surfaces of the zincs1 as in ,wollaston's construction1 should not be separated from each other except by an intervening thickness of paper1 or in some other way1 so as to prevent metallic contact1 and should thus constitute an instrument compact1 powerful1 economical1 and easy of use4 ,on examining1 however1 what had been done before1 ,i found that the new trough was in all essential respects the same as that invented and described by ,dr4 ,hare1 ,professor in the ,university of ,pennsylvania1 to whom ,i have great pleasure in referring it4 #aabd4 ,dr4 ,hare has fully described his trough,a4 ,in it the contiguous copper plates are separated by thin veneers of wood1 and the acid is poured on to1 or off1 the plates by a quarter revolution of an axis1 to which both the trough containing the plates1 and another trough to collect and hold the liquid1 are fixed4 ,this arrangement ,i have found the most convenient of any1 and have therefore adopted it4 ,my zinc plates were cut from rolled metal1 and when soldered to the copper plates had the form delineated1 fig4 #a4 ,these were then bent over a gauge into the form fig4 #b1 and when packed in the wooden box constructed to receive them1 were arranged as in fig4 #c;,b1 little plugs of cork being used to keep the zinc plates from touching the copper plates1 and a single or double thickness of cartridge paper being interposed between the contiguous surfaces of copper to prevent them from coming in contact4 ,such was the facility afforded by this arrangement1 that a trough of forty pairs of plates could be unpacked in five minutes1 and repacked again in half an hour2 and the whole series was not more than fifteen inches in length4 ,illustration3 ,fig4 #a4 ,illustration3 ,fig4 #b4 ,illustration3 ,fig4 #c4 ,a ,philosophical ,magazine1 #ahbd1 vol4 lxiii4 p4 #bda2 or ,silliman's ,journal1 vol4 vii4 ,see also a previous paper by ,dr4 ,hare1 ,annals of ,philosophy1 #ahba1 vol4 i4 p4 #cbi1 in which he speaks of the non-necessity of insulation between the coppers4 ,b ,the papers between the coppers are1 for the sake of distinctness1 omitted in the figure4 #aabe4 ,this trough1 of forty pairs of plates three inches square1 was compared1 as to the ignition of a platina wire1 the discharge between points of charcoal1 the shock on the human frame1 c41 with forty pairs of four-inch plates having double coppers1 and used in porcelain troughs divided into insulating cells1 the strength of the acid employed to excite both being the same4 ,in all these effects the former appeared quite equal to the latter4 ,on comparing a second trough of the new construction1 containing twenty pairs of four-inch plates1 with twenty pairs of four-inch plates in porcelain troughs1 excited by acid of the same strength1 the new trough appeared to surpass the old one in producing these effects1 especially in the ignition of wire4 #aabf4 ,in these experiments the new trough diminished in its energy much more rapidly than the one on the old construction1 and this was a necessary consequence of the smaller quantity of acid used to excite it1 which in the case of the forty pairs of new construction was only one-seventh part of that used for the forty pairs in the porcelain troughs4 ,to compare1 therefore1 both forms of the voltaic trough in their decomposing powers1 and to obtain accurate data as to their relative values1 experiments of the following kind were made4 ,the troughs were charged with a known quantity of acid of a known strength2 the electric current was passed through a volta-electrometer 7#gaa47 having electrodes #d inches long and #b4c inches in width1 so as to oppose as little obstruction as possible to the current2 the gases evolved were collected and measured1 and gave the quantity of water decomposed4 ,then the whole of the charge used was mixed together1 and a known part of it analyzed1 by being precipitated and boiled with excess of carbonate of soda1 and the precipitate well-washed1 dried1 ignited1 and weighed4 ,in this way the quantity of metal oxidized and dissolved by the acid was ascertained2 and the part removed from each zinc plate1 or from all the plates1 could be estimated and compared with the water decomposed in the volta-electrometer4 ,to bring these to one standard of comparison1 ,i have reduced the results so as to express the loss at the plates in equivalents of zinc for the equivalent of water decomposed at the volta-electrometer3 ,i have taken the equivalent number of water as #i1 and of zinc as #cb4e1 and have considered #ajj cubic inches of the mixed oxygen and hydrogen1 as they were collected over a pneumatic trough1 to result from the decomposition of #ab4fh grains of water4 #aabg4 ,the acids used in these experiments were three1--sulphuric1 nitric1 and muriatic4 ,the sulphuric acid was strong oil of vitriol2 one cubical inch of it was equivalent to #dhf grains of marble4 ,the nitric acid was very nearly pure2 one cubical inch dissolved #aej grains of marble4 ,the muriatic acid was also nearly pure1 and one cubical inch dissolved #ajh grains of marble4 ,these were always mixed with water by volumes1 the standard of volume being a cubical inch4 #aabh4 ,an acid was prepared consisting of #bjj parts water1 #d-a_/b parts sulphuric acid1 and #d parts nitric acid2 and with this both my trough containing forty pairs of three-inch plates1 and four porcelain troughs1 arranged in succession1 each containing ten pairs of plates with double coppers four inches square1 were charged4 ,these two batteries were then used in succession1 and the action of each was allowed to continue for twenty or thirty minutes1 until the charge was nearly exhausted1 the connexion with the volta-electrometer being carefully preserved during the whole time1 and the acid in the troughs occasionally mixed together4 ,in this way the former trough acted so well1 that for each equivalent of water decomposed in the volta-electrometer only from #b to #b4e equivalents of zinc were dissolved from each plate4 ,in four experiments the average was #b4ba equivalents for each plate1 or #hh4d for the whole battery4 ,in the experiments with the porcelain troughs1 the equivalents of consumption at each plate were #c4ea1 or #ada4f for the whole battery4 ,in a perfect voltaic battery of forty pairs of plates 7#iia4 #ajja47 the consumption would have been one equivalent for each zinc plate1 or forty for the whole4 #aabi4 ,similar experiments were made with two voltaic batteries1 one containing twenty pairs of four-inch plates1 arranged as ,i have described 7#aabd471 and the other twenty pairs of four-inch plates in porcelain troughs4 ,the average of five experiments with the former was a consumption of #c4g equivalents of zinc from each plate1 or #gd from the whole3 the average of three experiments with the latter was #e4e equivalents from each plate1 or #aaj from the whole3 to obtain this conclusion two experiments were struck out1 which were much against the porcelain troughs1 and in which some unknown deteriorating influence was supposed to be accidentally active4 ,in all the experiments1 care was taken not to compare new and old plates together1 as that would have introduced serious errors into the conclusions 7#aadf474 #aacj4 ,when ten pairs of the new arrangement were used1 the consumption of zinc at each plate was #f4gf equivalents1 or #fg4f for the whole4 ,with ten pairs of the common construction1 in a porcelain trough1 the zinc oxidized was1 upon an average1 #ae4e equivalents each plate1 or #aee for the entire trough4 #aaca4 ,no doubt1 therefore1 can remain of the equality or even the great superiority of this form of voltaic battery over the best previously in use1 namely1 that with double coppers1 in which the cells are insulated4 ,the insulation of the coppers may therefore be dispensed with2 and it is that circumstance which principally permits of such other alterations in the construction of the trough as gives it its practical advantages4 #aacb4 ,the advantages of this form of trough are very numerous and great4 i4 ,it is exceedingly compact1 for #ajj pairs of plates need not occupy a trough of more than three feet in length1 ii4 ,by ,dr4 ,hare's plan of making the trough turn upon copper pivots which rest upon copper bearings1 the latter afford fixed terminations2 and these ,i have found it very convenient to connect with two cups of mercury1 fastened in the front of the stand of the instrument4 ,these fixed terminations give the great advantage of arranging an apparatus to be used in connexion with the battery before the latter is put into action1 iii4 ,the trough is put into readiness for use in an instant1 a single jug of dilute acid being sufficient for the charge of #ajj pairs of four-inch plates1 iv4 ,on making the trough pass through a quarter of a revolution1 it becomes active1 and the great advantage is obtained of procuring for the experiment the effect of the first contact of the zinc and acid1 which is twice or sometimes even thrice that which the battery can produce a minute or two after 7#ajcf4 #aaej474 v4 ,when the experiment is completed1 the acid can be at once poured from between the plates1 so that the battery is never left to waste during an unconnected state of its extremities2 the acid is not unnecessarily exhausted2 the zinc is not uselessly consumed2 and1 besides avoiding these evils1 the charge is mixed and rendered uniform1 which produces a great and good result 7#ajci472 and1 upon proceeding to a second experiment1 the important effect of first contact is again obtained4 vi4 ,the saving of zinc is very great4 ,it is not merely that1 whilst in action1 the zinc performs more voltaic duty 7#aabh4 #aabi471 but all the destruction which takes place with the ordinary forms of battery between the experiments is prevented4 ,this saving is of such extent1 that ,i estimate the zinc in the new form of battery to be thrice as effective as that in the ordinary form4 vii4 ,the importance of this saving of metal is not merely that the value of the zinc is saved1 but that the battery is much lighter and more manageable2 and also that the surfaces of the zinc and copper plates may be brought much nearer to each other when the battery is constructed1 and remain so until it is worn out3 the latter is a very important advantage 7#aadh474 viii4 ,again1 as1 in consequence of the saving1 thinner plates will perform the duty of thick ones1 rolled zinc may be used2 and ,i have found rolled zinc superior to cast zinc in action2 a superiority which ,i incline to attribute to its greater purity 7#aadd474 ix4 ,another advantage is obtained in the economy of the acid used1 which is proportionate to the diminution of the zinc dissolved4 x4 ,the acid also is more easily exhausted1 and is in such small quantity that there is never any occasion to return an old charge into use4 ,the acid of old charges whilst out of use1 often dissolves portions of copper from the black flocculi usually mingled with it1 which are derived from the zinc2 now any portion of copper in solution in the charge does great harm1 because1 by the local action of the acid and zinc1 it tends to precipitate upon the latter1 and diminish its voltaic efficacy 7#aade474 xi4 ,by using a due mixture of nitric and sulphuric acid for the charge 7#aaci471 no gas is evolved from the troughs2 so that a battery of several hundred pairs of plates may1 without inconvenience1 be close to the experimenter4 xii4 ,if1 during a series of experiments1 the acid becomes exhausted1 it can be withdrawn1 and replaced by other acid with the utmost facility2 and after the experiments are concluded1 the great advantage of easily washing the plates is at command4 ,and it appears to me1 that in place of making1 under different circumstances1 mutual sacrifices of comfort1 power1 and economy1 to obtain a desired end1 all are at once obtained by ,dr4 ,hare's form of trough4 #aacc4 ,but there are some disadvantages which ,i have not yet had time to overcome1 though ,i trust they will finally be conquered4 ,one is the extreme difficulty of making a wooden trough constantly water-tight under the alternations of wet and dry to which the voltaic instrument is subject4 ,to remedy this evil1 ,mr4 ,newman is now engaged in obtaining porcelain troughs4 ,the other disadvantage is a precipitation of copper on the zinc plates4 ,it appears to me to depend mainly on the circumstance that the papers between the coppers retain acid when the trough is emptied2 and that this acid slowly acting on the copper1 forms a salt1 which gradually mingles with the next charge1 and is reduced on the zinc plate by the local action 7#aabj473 the power of the whole battery is then reduced4 ,i expect that by using slips of glass or wood to separate the coppers at their edges1 their contact can be sufficiently prevented1 and the space between them be left so open that the acid of a charge can be poured and washed out1 and so be removed from every part of the trough when the experiments in which the latter is used are completed4 #aacd4 ,the actual superiority of the troughs which ,i have constructed on this plan1 ,i believe to depend1 first and principally1 on the closer approximation of the zinc and copper surfaces2--in my troughs they are only one-tenth of an inch apart 7#aadh472--;and1 next1 on the superior quality of the rolled zinc above the cast zinc used in the construction of the ordinary pile4 ,it cannot be that insulation between the contiguous coppers is a disadvantage1 but ,i do not find that it is any advantage2 for when1 with both the forty pairs of three-inch plates and the twenty pairs of four-inch plates1 ,i used papers well-soaked in wax,a1 these being so large that when folded at the edges they wrapped over each other1 so as to make cells as insulating as those of the porcelain troughs1 still no sensible advantage in the chemical action was obtained4 ,a ,a single paper thus prepared could insulate the electricity of a trough of forty pairs of plates4 #aace4 ,as1 upon principle1 there must be a discharge of part of the electricity from the edges of the zinc and copper plates at the sides of the trough1 ,i should prefer1 and intend having1 troughs constructed with a plate or plates of crown glass at the sides of the trough3 the bottom will need none1 though to glaze that and the ends would be no disadvantage4 ,the plates need not be fastened in1 but only set in their places2 nor need they be in large single pieces4 #ag4 ,some practical results respecting the construction and use of the ,voltaic ,battery 7#ajcd4 c474 #aacf4 ,the electro-chemical philosopher is well acquainted with some practical results obtained from the voltaic battery by ,,mm44 ,gay-,lussac and ,thenard1 and given in the first forty-five pages of their ',recherches ,physico-,chimiques'4 ,although the following results are generally of the same nature1 yet the advancement made in this branch of science of late years1 the knowledge of the definite action of electricity1 and the more accurate and philosophical mode of estimating the results by the equivalents of zinc consumed1 will be their sufficient justification4 #aacg4 ,nature and strength of the acid4--,my battery of forty pairs of three-inch plates was charged with acid consisting of #bjj parts water and #i oil of vitriol4 ,each plate lost1 in the average of the experiments1 #d4ff equivalents of zinc for the equivalent of water decomposed in the volta-electrometer1 or the whole battery #ahf4d equivalents of zinc4 ,being charged with a mixture of #bjj water and #af of the muriatic acid1 each plate lost #c4h1 equivalents of zinc for the water decomposed1 or the whole battery #aeb equivalents of zinc4 ,being charged with a mixture of #bjj water and #h nitric acid1 each plate lost #a4he1 equivalents of zinc for one equivalent of water decomposed1 or the whole battery #gd4af equivalents of zinc4 ,the sulphuric and muriatic acids evolved much hydrogen at the plates in the trough2 the nitric acid no gas whatever4 ,the relative strengths of the original acids have already been given 7#aabg472 but a difference in that respect makes no important difference in the results when thus expressed by equivalents 7#aadj474 #aach4 ,thus nitric acid proves to be the best for this purpose2 its superiority appears to depend upon its favouring the electrolyzation of the liquid in the cells of the trough upon the principles already explained 7#ije4 #igc1 #ajbb471 and consequently favouring the transmission of the electricity1 and therefore the production of transferable power 7#aabj474 #aaci4 ,the addition of nitric acid might1 consequently1 be expected to improve sulphuric and muriatic acids4 ,accordingly1 when the same trough was charged with a mixture of #bjj water1 #i oil of vitriol1 and #d nitric acid1 the consumption of zinc was at each plate #b4ghf1 and for the whole battery #aaa4e1 equivalents4 ,when the charge was #bjj water1 #i oil of vitriol1 and #h nitric acid1 the loss per plate was #b4bf1 or for the whole battery #ij4d1 equivalents4 ,when the trough was charged with a mixture of #bjj water1 #af muriatic acid1 and #f nitric acid1 the loss per plate was #b4aa1 or for the whole battery #hd4d1 equivalents4 ,similar results were obtained with my battery of twenty pairs of four-inch plates 7#aabi474 ,hence it is evident that the nitric acid was of great service when mingled with the sulphuric acid2 and the charge generally used after this time for ordinary experiments consisted of #bjj water1 #d-a_/b oil of vitriol1 and #d nitric acid4 #aadj4 ,it is not to be supposed that the different strengths of the acids produced the differences above2 for within certain limits ,i found the electrolytic effects to be nearly as the strengths of the acids1 so as to leave the expression of force1 when given in equivalents1 almost constant4 ,thus1 when the trough was charged with a mixture of #bjj water and #h nitric acid1 each plate lost #a4hed equivalent of zinc4 ,when the charge was #bjj water and #af nitric acid1 the loss per plate was #a4hb equivalent4 ,when it was #bjj water and #cb nitric acid1 the loss was #b4a equivalents4 ,the differences here are not greater than happen from unavoidable irregularities1 depending on other causes than the strength of acid4 #aada4 ,again1 when a charge consisting of #bjj water1 #d-a_/b oil of vitriol1 and #d nitric acid was used1 each zinc plate lost #b4af equivalents2 when the charge with the same battery was #bjj water1 #i oil of vitriol1 and #h nitric acid1 each zinc plate lost #b4bf equivalents4 #aadb4 ,i need hardly say that no copper is dissolved during the regular action of the voltaic trough4 ,i have found that much ammonia is formed in the cells when nitric acid1 either pure or mixed with sulphuric acid1 is used4 ,it is produced in part as a secondary result at the cathodes 7#ffc47 of the different portions of fluid constituting the necessary electrolyte1 in the cells4 #aadc4 ,uniformity of the charge4--,this is a most important point1 as ,i have already shown experimentally 7#ajdb4 c474 ,hence one great advantage of ,dr4 ,hare's mechanical arrangement of his trough4 #aadd4 ,purity of the zinc4--,if pure zinc could be obtained1 it would be very advantageous in the construction of the voltaic apparatus 7#iih474 ,most zincs1 when put into dilute sulphuric acid1 leave more or less of an insoluble matter upon the surface in the form of a crust1 which contains various metals1 as copper1 lead1 zinc1 iron1 cadmium1 c41 in the metallic state4 ,such particles1 by discharging part of the transferable power1 render it1 as to the whole battery1 local2 and so diminish the effect4 ,as an indication connected with the more or less perfect action of the battery1 ,i may mention that no gas ought to rise from the zinc plates4 ,the more gas which is generated upon these surfaces1 the greater is the local action and the less the transferable force4 ,the investing crust is also inconvenient1 by preventing the displacement and renewal of the charge upon the surface of the zinc4 ,such zinc as1 dissolving in the cleanest manner in a dilute acid1 dissolves also the slowest1 is the best2 zinc which contains much copper should especially be avoided4 ,i have generally found rolled ,liege or ,mosselman's zinc the purest2 and to the circumstance of having used such zinc in its construction attribute in part the advantage of the new battery 7#aacd474 #aade4 ,foulness of the zinc plates4--,after use1 the plates of a battery should be cleaned from the metallic powder upon their surfaces1 especially if they are employed to obtain the laws of action of the battery itself4 ,this precaution was always attended to with the porcelain trough batteries in the experiments described 7#aabe1 c474 ,if a few foul plates are mingled with many clean ones1 they make the action in the different cells irregular1 and the transferable power is accordingly diminished1 whilst the local and wasted power is increased4 ,no old charge containing copper should be used to excite a battery4 #aadf4 ,new and old plates4--,i have found voltaic batteries far more powerful when the plates were new than when they have been used two or three times2 so that a new and an used battery cannot be compared together1 or even a battery with itself on the first and after times of use4 ,my trough of twenty pairs of four-inch plates1 charged with acid consisting of #bjj water1 #d-a_/b oil of vitriol1 and #d nitric acid1 lost1 upon the first time of being used1 #b4hb equivalents per plate4 ,when used after the fourth time with the same charge1 the loss was from #c4bf to #d4dg equivalents per plate2 the average being #c4g equivalents4 ,the first time the forty pair of plates 7#aabd47 were used1 the loss at each plate was only #a4fe equivalent2 but afterwards it became #b4af1 #b4ag1 #b4eb4 ,the first time twenty pair of four-inch plates in porcelain troughs were used1 they lost1 per plate1 only #c4g equivalents2 but after that1 the loss was #e4be1 #e4cf1 #e4i equivalents4 ,yet in all these cases the zincs had been well-cleaned from adhering copper1 c41 before each trial of power4 #aadg4 ,with the rolled zinc the fall in force soon appeared to become constant1 i4e4 to proceed no further4 ,but with the cast zinc plates belonging to the porcelain troughs1 it appeared to continue1 until at last1 with the same charge1 each plate lost above twice as much zinc for a given amount of action as at first4 ,these troughs were1 however1 so irregular that ,i could not always determine the circumstances affecting the amount of electrolytic action4 #aadh4 ,vicinity of the copper and zinc4--,the importance of this point in the construction of voltaic arrangements1 and the greater power1 as to immediate action1 which is obtained when the zinc and copper surfaces are near to each other than when removed further apart1 are well known4 ,i find that the power is not only greater on the instant1 but also that the sum of transferable power1 in relation to the whole sum of chemical action at the plates1 is much increased4 ,the cause of this gain is very evident4 ,whatever tends to retard the circulation of the transferable force1 7i4e4 the electricity17 diminishes the proportion of such force1 and increases the proportion of that which is local 7#iif4 #aabj474 ,now the liquid in the cells possesses this retarding power1 and therefore acts injuriously1 in greater or less proportion1 according to the quantity of it between the zinc and copper plates1 i4e4 according to the distances between their surfaces4 ,a trough1 therefore1 in which the plates are only half the distance asunder at which they are placed in another1 will produce more transferable1 and less local1 force than the latter2 and thus1 because the electrolyte in the cells can transmit the current more readily2 both the intensity and quantity of electricity is increased for a given consumption of zinc4 ,to this circumstance mainly ,i attribute the superiority of the trough ,i have described 7#aacd474 #aadi4 ,the superiority of double coppers over single plates also depends in part upon diminishing the resistance offered by the electrolyte between the metals4 ,for1 in fact1 with double coppers the sectional area of the interposed acid becomes nearly double that with single coppers1 and therefore it more freely transfers the electricity4 ,double coppers are1 however1 effective1 mainly because they virtually double the acting surface of the zinc1 or nearly so2 for in a trough with single copper plates and the usual construction of cells1 that surface of zinc which is not opposed to a copper surface is thrown almost entirely out of voltaic action1 yet the acid continues to act upon it and the metal is dissolved1 producing very little more than local effect 7#idg4 #iif74 ,but when by doubling the copper1 that metal is opposed to the second surface of the zinc plate1 then a great part of the action upon the latter is converted into transferable force1 and thus the power of the trough as to quantity of electricity is highly exalted4 #aaej4 ,first immersion of the plates4--,the great effect produced at the first immersion of the plates1 7apart from their being new or used 7#aadf4717 ,i have attributed elsewhere to the unchanged condition of the acid in contact with the zinc plate 7#ajjc4 #ajcg473 as the acid becomes neutralized1 its exciting power is proportionally diminished4 ,hare's form of trough secures much advantage of this kind1 by mingling the liquid1 and bringing what may be considered as a fresh surface of acid against the plates every time it is used immediately after a rest4 #aaea4 ,number of plates4,a--,the most advantageous number of plates in a battery used for chemical decomposition1 depends almost entirely upon the resistance to be overcome at the place of action2 but whatever that resistance may be1 there is a certain number which is more economical than either a greater or a less4 ,ten pairs of four-inch plates in a porcelain trough of the ordinary construction1 acting in the volta-electrometer 7#aabf47 upon dilute sulphuric acid of spec4 grav4 #a4cad1 gave an average consumption of #ae4d equivalents per plate1 or #aed equivalents on the whole4 ,twenty pairs of the same plates1 with the same acid1 gave only a consumption of #e4e per plate1 or #aaj equivalents upon the whole4 ,when forty pairs of the same plates were used1 the consumption was #c4ed equivalents per plate1 or #ada4f upon the whole battery4 ,thus the consumption of zinc arranged as twenty plates was more advantageous than if arranged either as ten or as forty4 ,a ,gay-,lussac and ,thenard1 ,recherches ,physico-,chimiques1 tom4 i4 p4 #bi4 #aaeb4 ,again1 ten pairs of my four-inch plates 7#aabi47 lost #f4gf each1 or the whole ten #fg4f equivalents of zinc1 in effecting decomposition2 whilst twenty pairs of the same plates1 excited by the same acid1 lost #c4g equivalents each1 or on the whole #gd equivalents4 ,in other comparative experiments of numbers1 ten pairs of the three inch-plates1 7#aabe47 lost #c4gbe1 or #cg4be equivalents upon the whole2 whilst twenty pairs lost #b4ec each1 or #ej4f in all2 and forty pairs lost on an average #b4ba1 or #hh4d altogether4 ,in both these cases1 therefore1 increase of numbers had not been advantageous as to the effective production of transferable chemical power from the whole quantity of chemical force active at the surfaces of excitation 7#aabj474 #aaec4 ,but if ,i had used a weaker acid or a worse conductor in the volta-electrometer1 then the number of plates which would produce the most advantageous effect would have risen2 or if ,i had used a better conductor than that really employed in the volta-electrometer1 ,i might have reduced the number even to one2 as1 for instance1 when a thick wire is used to complete the circuit 7#hfe41 c474 ,and the cause of these variations is very evident1 when it is considered that each successive plate in the voltaic apparatus does not add anything to the quantity of transferable power or electricity which the first plate can put into motion1 provided a good conductor be present1 but tends only to exalt the intensity of that quantity1 so as to make it more able to overcome the obstruction of bad conductors 7#iid4 #aaeh474 #aaed4 ,large or small plates4,a--,the advantageous use of large or small plates for electrolyzations will evidently depend upon the facility with which the transferable power of electricity can pass4 ,if in a particular case the most effectual number of plates is known 7#aaea471 then the addition of more zinc would be most advantageously made in increasing the size of the plates1 and not their number4 ,at the same time1 large increase in the size of the plates would raise in a small degree the most favourable number4 ,a ,gay-,lussac and ,thenard1 ,recherches ,physico-,chimiques1 tom1 i4 p4 #bj4 #aaee4 ,large and small plates should not be used together in the same battery3 the small ones occasion a loss of the power of the large ones1 unless they be excited by an acid proportionably more powerful2 for with a certain acid they cannot transmit the same portion of electricity in a given time which the same acid can evolve by action on the larger plates4 #aaef4 ,simultaneous decompositions4--,when the number of plates in a battery much surpasses the most favourable proportion 7#aaea--aaec471 two or more decompositions may be effected simultaneously with advantage4 ,thus my forty pairs of plates 7#aabd47 produced in one volta-electrometer #bb4h cubic inches of gas4 ,being recharged exactly in the same manner1 they produced in each of two volta-electrometers #ba cubical inches4 ,in the first experiment the whole consumption of zinc was #hh4d equivalents1 and in the second only #dh4bh equivalents1 for the whole of the water decomposed in both volta-electrometers4 #aaeg4 ,but when the twenty pairs of four-inch plates 7#aabi47 were tried in a similar manner1 the results were in the opposite direction4 ,with one volta-electrometer #eb cubic inches of gas were obtained2 with two1 only #ad4f cubic inches from each4 ,the quantity of charge was not the same in both cases1 though it was of the same strength2 but on rendering the results comparative by reducing them to equivalents 7#aabf471 it was found that the consumption of metal in the first case was #gd1 and in the second case #ig1 equivalents for the whole of the water decomposed4 ,these results of course depend upon the same circumstances of retardation1 c41 which have been referred to in speaking of the proper number of plates 7#aaea474 #aaeh4 ,that the transferring1 or1 as it is usually called1 conducting1 power of an electrolyte which is to be decomposed1 or other interposed body1 should be rendered as good as possible,a1 is very evident 7#ajbj4 #aabj474 ,with a perfectly good conductor and a good battery1 nearly all the electricity is passed1 i4e4 nearly all the chemical power becomes transferable1 even with a single pair of plates 7#hjg474 ,with an interposed nonconductor none of the chemical power becomes transferable4 ,with an imperfect conductor more or less of the chemical power becomes transferable as the circumstances favouring the transfer of forces across the imperfect conductor are exalted or diminished3 these circumstances are1 actual increase or improvement of the conducting power1 enlargement of the electrodes1 approximation of the electrodes1 and increased intensity of the passing current4 ,a ,gay-,lussac and ,thenard1 ,recherches ,physico-,chimiques1 tom4 i4 pp4 #ac1 #ae1 #bb4 #aaei4 ,the introduction of common spring water in place of one of the volta-electrometers used with twenty pairs of four-inch plates 7#aaef47 caused such obstruction as not to allow one-fifteenth of the transferable force to pass which would have circulated without it4 ,thus fourteen-fifteenths of the available force of the battery were destroyed1 local force1 7which was rendered evident by the evolution of gas from the being converted into zincs17 and yet the platina electrodes in the water were three inches long1 nearly an inch wide1 and not a quarter of an inch apart4 #aafj4 ,these points1 i4e4 the increase of conducting power1 the enlargement of the electrodes1 and their approximation1 should be especially attended to in volta-electrometers4 ,the principles upon which their utility depend are so evident that there can be no occasion for further development of them here4 ,royal ,institution1 ,october #aa1 #ahcd4 ,,eleventh ,,series4 #ah4 ,on ,induction4 i4 ,induction an action of contiguous particles4 ii4 ,absolute charge of matter4 iii4 ,electrometer and inductive apparatus employed4 iv4 ,induction in curved lines4 v4 ,specific inductive capacity4 vi4 ,general results as to induction4 ,received ,november #cj1--,read ,december #ba1 #ahcg4 i4 ,induction an action of contiguous particles4 #aafa4 ,the science of electricity is in that state in which every part of it requires experimental investigation2 not merely for the discovery of new effects1 but what is just now of far more importance1 the development of the means by which the old effects are produced1 and the consequent more accurate determination of the first principles of action of the most extraordinary and universal power in nature3--and to those philosophers who pursue the inquiry zealously yet cautiously1 combining experiment with analogy1 suspicious of their preconceived notions1 paying more respect to a fact than a theory1 not too hasty to generalize1 and above all things1 willing at every step to cross-examine their own opinions1 both by reasoning and experiment1 no branch of knowledge can afford so fine and ready a field for discovery as this4 ,such is most abundantly shown to be the case by the progress which electricity has made in the last thirty years3 ,chemistry and ,magnetism have successively acknowledged its over-ruling influence2 and it is probable that every effect depending upon the powers of inorganic matter1 and perhaps most of those related to vegetable and animal life1 will ultimately be found subordinate to it4 #aafb4 ,amongst the actions of different kinds into which electricity has conventionally been subdivided1 there is1 ,i think1 none which excels1 or even equals in importance1 that called ,induction4 ,it is of the most general influence in electrical phenomena1 appearing to be concerned in every one of them1 and has in reality the character of a first1 essential1 and fundamental principle4 ,its comprehension is so important1 that ,i think we cannot proceed much further in the investigation of the laws of electricity without a more thorough understanding of its nature2 how otherwise can we hope to comprehend the harmony and even unity of action which doubtless governs electrical excitement by friction1 by chemical means1 by heat1 by magnetic influence1 by evaporation1 and even by the living being8 #aafc4 ,in the long-continued course of experimental inquiry in which ,i have been engaged1 this general result has pressed upon me constantly1 namely1 the necessity of admitting two forces1 or two forms or directions of a force 7#eaf4 #eag471 combined with the impossibility of separating these two forces 7or electricities7 from each other1 either in the phenomena of statical electricity or those of the current4 ,in association with this1 the impossibility under any circumstances1 as yet1 of absolutely charging matter of any kind with one or the other electricity only1 dwelt on my mind1 and made me wish and search for a clearer view than any that ,i was acquainted with1 of the way in which electrical powers and the particles of matter are related2 especially in inductive actions1 upon which almost all others appeared to rest4 #aafd4 ,when ,i discovered the general fact that electrolytes refused to yield their elements to a current when in the solid state1 though they gave them forth freely if in the liquid condition 7#chj4 #cid4 #djb471 ,i thought ,i saw an opening to the elucidation of inductive action1 and the possible subjugation of many dissimilar phenomena to one law4 ,for let the electrolyte be water1 a plate of ice being coated with platina foil on its two surfaces1 and these coatings connected with any continued source of the two electrical powers1 the ice will charge like a ,leyden arrangement1 presenting a case of common induction1 but no current will pass4 ,if the ice be liquefied1 the induction will fall to a certain degree1 because a current can now pass2 but its passing is dependent upon a peculiar molecular arrangement of the particles consistent with the transfer of the elements of the electrolyte in opposite directions1 the degree of discharge and the quantity of elements evolved being exactly proportioned to each other 7#cgg4 #ghc474 ,whether the charging of the metallic coating be effected by a powerful electrical machine1 a strong and large voltaic battery1 or a single pair of plates1 makes no difference in the principle1 but only in the degree of action 7#cfj74 ,common induction takes place in each case if the electrolyte be solid1 or if fluid1 chemical action and decomposition ensue1 provided opposing actions do not interfere2 and it is of high importance occasionally thus to compare effects in their extreme degrees1 for the purpose of enabling us to comprehend the nature of an action in its weak state1 which may be only sufficiently evident to us in its stronger condition 7#dea474 ,as1 therefore1 in the electrolytic action1 induction appeared to be the first step1 and decomposition the second 7the power of separating these steps from each other by giving the solid or fluid condition to the electrolyte being in our hands72 as the induction was the same in its nature as that through air1 glass1 wax1 c4 produced by any of the ordinary means2 and as the whole effect in the electrolyte appeared to be an action of the particles thrown into a peculiar or polarized state1 ,i was led to suspect that common induction itself was in all cases an action of contiguous particles,a1 and that electrical action at a distance 7i4e4 ordinary inductive action7 never occurred except through the influence of the intervening matter4 ,a ,the word contiguous is perhaps not the best that might have been used here and elsewhere2 for as particles do not touch each other it is not strictly correct4 ,i was induced to employ it1 because in its common acceptation it enabled me to state the theory plainly and with facility4 ,by contiguous particles ,i mean those which are next4--,dec4 #ahch4 #aafe4 ,the respect which ,i entertain towards the names of ,epinus1 ,cavendish1 ,poisson1 and other most eminent men1 all of whose theories ,i believe consider induction as an action at a distance and in straight lines1 long indisposed me to the view ,i have just stated2 and though ,i always watched for opportunities to prove the opposite opinion1 and made such experiments occasionally as seemed to bear directly on the point1 as1 for instance1 the examination of electrolytes1 solid and fluid1 whilst under induction by polarized light 7#iea4 #iee471 it is only of late1 and by degrees1 that the extreme generality of the subject has urged me still further to extend my experiments and publish my view4 ,at present ,i believe ordinary induction in all cases to be an action of contiguous particles consisting in a species of polarity1 instead of being an action of either particles or masses at sensible distances2 and if this be true1 the distinction and establishment of such a truth must be of the greatest consequence to our further progress in the investigation of the nature of electric forces4 ,the linked condition of electrical induction with chemical decomposition2 of voltaic excitement with chemical action2 the transfer of elements in an electrolyte2 the original cause of excitement in all cases2 the nature and relation of conduction and insulation of the direct and lateral or transverse action constituting electricity and magnetism2 with many other things more or less incomprehensible at present1 would all be affected by it1 and perhaps receive a full explication in their reduction under one general law4 #aaff4 ,i searched for an unexceptionable test of my view1 not merely in the accordance of known facts with it1 but in the consequences which would flow from it if true2 especially in those which would not be consistent with the theory of action at a distance4 ,such a consequence seemed to me to present itself in the direction in which inductive action could be exerted4 ,if in straight lines only1 though not perhaps decisive1 it would be against my view2 but if in curved lines also1 that would be a natural result of the action of contiguous particles1 but1 as ,i think1 utterly incompatible with action at a distance1 as assumed by the received theories1 which1 according to every fact and analogy we are acquainted with1 is always in straight lines4 #aafg4 ,again1 if induction be an action of contiguous particles1 and also the first step in the process of electrolyzation 7#aafd4 #iai471 there seemed reason to expect some particular relation of it to the different kinds of matter through which it would be exerted1 or something equivalent to a specific electric induction for different bodies1 which1 if it existed1 would unequivocally prove the dependence of induction on the particles2 and though this1 in the theory of ,poisson and others1 has never been supposed to be the case1 ,i was soon led to doubt the received opinion1 and have taken great pains in subjecting this point to close experimental examination4 #aafh4 ,another ever-present question on my mind has been1 whether electricity has an actual and independent existence as a fluid or fluids1 or was a mere power of matter1 like what we conceive of the attraction of gravitation4 ,if determined either way it would be an enormous advance in our knowledge2 and as having the most direct and influential bearing on my notions1 ,i have always sought for experiments which would in any way tend to elucidate that great inquiry4 ,it was in attempts to prove the existence of electricity separate from matter1 by giving an independent charge of either positive or negative power only1 to some one substance1 and the utter failure of all such attempts1 whatever substance was used or whatever means of exciting or evolving electricity were employed1 that first drove me to look upon induction as an action of the particles of matter1 each having both forces developed in it in exactly equal amount4 ,it is this circumstance1 in connection with others1 which makes me desirous of placing the remarks on absolute charge first1 in the order of proof and argument1 which ,i am about to adduce in favour of my view1 that electric induction is an action of the contiguous particles of the insulating medium or dielectric,a4 ,a ,i use the word dielectric to express that substance through or across which the electric forces are acting4--,dec4 #ahch4 ii4 ,on the absolute charge of matter4 #aafi4 ,can matter1 either conducting or non-conducting1 be charged with one electric force independently of the other1 in any degree1 either in a sensible or latent state8 #aagj4 ,the beautiful experiments of ,coulomb upon the equality of action of conductors1 whatever their substance1 and the residence of all the electricity upon their surfaces,a1 are sufficient1 if properly viewed1 to prove that conductors cannot be bodily charged2 and as yet no means of communicating electricity to a conductor so as to place its particles in relation to one electricity1 and not at the same time to the other in exactly equal amount1 has been discovered4 ,a ,mmoires de l',acadmie1 #aghf1 pp4 #fg4 #fi4 #gb2 #aghg1 p4 #deb4 #aaga4 ,with regard to electrics or non-conductors1 the conclusion does not at first seem so clear4 ,they may easily be electrified bodily1 either by communication 7#abdg47 or excitement2 but being so charged1 every case in succession1 when examined1 came out to be a case of induction1 and not of absolute charge4 ,thus1 glass within conductors could easily have parts not in contact with the conductor brought into an excited state2 but it was always found that a portion of the inner surface of the conductor was in an opposite and equivalent state1 or that another part of the glass itself was in an equally opposite state1 an inductive charge and not an absolute charge having been acquired4 #aagb4 ,well-purified oil of turpentine1 which ,i find to be an excellent liquid insulator for most purposes1 was put into a metallic vessel1 and1 being insulated1 an endeavour was made to charge its particles1 sometimes by contact of the metal with the electrical machine1 and at others by a wire dipping into the fluid within2 but whatever the mode of communication1 no electricity of one kind only was retained by the arrangement1 except what appeared on the exterior surface of the metal1 that portion being present there only by an inductive action through the air to the surrounding conductors4 ,when the oil of turpentine was confined in glass vessels1 there were at first some appearances as if the fluid did receive an absolute charge of electricity from the charging wire1 but these were quickly reduced to cases of common induction jointly through the fluid1 the glass1 and the surrounding air4 #aagc4 ,i carried these experiments on with air to a very great extent4 ,i had a chamber built1 being a cube of twelve feet4 ,a slight cubical wooden frame was constructed1 and copper wire passed along and across it in various directions1 so as to make the sides a large net-work1 and then all was covered in with paper1 placed in close connexion with the wires1 and supplied in every direction with bands of tin foil1 that the whole might be brought into good metallic communication1 and rendered a free conductor in every part4 ,this chamber was insulated in the lecture-room of the ,royal ,institution2 a glass tube about six feet in length was passed through its side1 leaving about four feet within and two feet on the outside1 and through this a wire passed from the large electrical machine 7#bij47 to the air within4 ,by working the machine1 the air in this chamber could be brought into what is considered a highly electrified state 7being1 in fact1 the same state as that of the air of a room in which a powerful machine is in operation71 and at the same time the outside of the insulated cube was everywhere strongly charged4 ,but putting the chamber in communication with the perfect discharging train described in a former series 7#bib471 and working the machine so as to bring the air within to its utmost degree of charge if ,i quickly cut off the connexion with the machine1 and at the same moment or instantly after insulated the cube1 the air within had not the least power to communicate a further charge to it4 ,if any portion of the air was electrified1 as glass or other insulators may be charged 7#aaga471 it was accompanied by a corresponding opposite action within the cube1 the whole effect being merely a case of induction4 ,every attempt to charge air bodily and independently with the least portion of either electricity failed4 #aagd ,i put a delicate gold-leaf electrometer within the cube1 and then charged the whole by an outside communication1 very strongly1 for some time together2 but neither during the charge or after the discharge did the electrometer or air within show the least signs of electricity4 ,i charged and discharged the whole arrangement in various ways1 but in no case could ,i obtain the least indication of an absolute charge2 or of one by induction in which the electricity of one kind had the smallest superiority in quantity over the other4 ,i went into the cube and lived in it1 and using lighted candles1 electrometers1 and all other tests of electrical states1 ,i could not find the least influence upon them1 or indication of any thing particular given by them1 though all the time the outside of the cube was powerfully charged1 and large sparks and brushes were darting off from every part of its outer surface4 ,the conclusion ,i have come to is1 that non-conductors1 as well as conductors1 have never yet had an absolute and independent charge of one electricity communicated to them1 and that to all appearance such a state of matter is impossible4 #aage4 ,there is another view of this question which may be taken under the supposition of the existence of an electric fluid or fluids4 ,it may be impossible to have one fluid or state in a free condition without its producing by induction the other1 and yet possible to have cases in which an isolated portion of matter in one condition being uncharged1 shall1 by a change of state1 evolve one electricity or the other3 and though such evolved electricity might immediately induce the opposite state in its neighbourhood1 yet the mere evolution of one electricity without the other in the first instance1 would be a very important fact in the theories which assume a fluid or fluids2 these theories as ,i understand them assigning not the slightest reason why such an effect should not occur4 #aagf4 ,but on searching for such cases ,i cannot find one4 ,evolution by friction1 as is well known1 gives both powers in equal proportion4 ,so does evolution by chemical action1 notwithstanding the great diversity of bodies which may be employed1 and the enormous quantity of electricity which can in this manner be evolved 7#cga4 #cgf4 #hfa4 #hfh4 #ifa474 ,the more promising cases of change of state1 whether by evaporation1 fusion1 or the reverse processes1 still give both forms of the power in equal proportion2 and the cases of splitting of mica and other crystals1 the breaking of sulphur1 c41 are subject to the same law of limitation4 #aagg4 ,as far as experiment has proceeded1 it appears1 therefore1 impossible either to evolve or make disappear one electric force without equal and corresponding change in the other4 ,it is also equally impossible experimentally to charge a portion of matter with one electric force independently of the other4 ,charge always implies induction1 for it can in no instance be effected without2 and also the presence of the two forms of power1 equally at the moment of the development and afterwards4 ,there is no absolute charge of matter with one fluid2 no latency of a single electricity4 ,this though a negative result is an exceedingly important one1 being probably the consequence of a natural impossibility1 which will become clear to us when we understand the true condition and theory of the electric power4 #aagh4 ,the preceding considerations already point to the following conclusions3 bodies cannot be charged absolutely1 but only relatively1 and by a principle which is the same with that of induction4 ,all charge is sustained by induction4 ,all phenomena of intensity include the principle of induction4 ,all excitation is dependent on or directly related to induction4 ,all currents involve previous intensity and therefore previous induction4 ,,induction appears to be the essential function both the first development and the consequent phenomena of electricity4 iii4 ,electrometer and inductive apparatus employed4 #aagi4 ,leaving for a time the further consideration of the preceding facts until they can be collated with other results bearing directly on the great question of the nature of induction1 ,i will now describe the apparatus ,i have had occasion to use2 and in proportion to the importance of the principles sought to be established is the necessity of doing this so clearly1 as to leave no doubt of the results behind4 #aahj4 ,electrometer4--,the measuring instrument ,i have employed has been the torsion balance electrometer of ,coulomb1 constructed1 generally1 according to his directions,a1 but with certain variations and additions1 which ,i will briefly describe4 ,the lower part was a glass cylinder eight inches in height and eight inches in diameter2 the tube for the torsion thread was seventeen inches in length4 ,the torsion thread itself was not of metal1 but glass1 according to the excellent suggestion of the late ,dr4 ,ritchie,b4 ,it was twenty inches in length1 and of such tenuity that when the shell-lac lever and attached ball1 c4 were connected with it1 they made about ten vibrations in a minute4 ,it would bear torsion through four revolutions or #addj1 and yet1 when released1 return accurately to its position2 probably it would have borne considerably more than this without injury4 ,the repelled ball was of pith1 gilt1 and was #j4c of an inch in diameter4 ,the horizontal stem or lever supporting it was of shell-lac1 according to ,coulomb's direction1 the arm carrying the ball being #b4d inches long1 and the other only #a4b inches3 to this was attached the vane1 also described by ,coulomb1 which ,i found to answer admirably its purpose of quickly destroying vibrations4 ,that the inductive action within the electrometer might be uniform in all positions of the repelled ball and in all states of the apparatus1 two bands of tin foil1 about an inch wide each1 were attached to the inner surface of the glass cylinder1 going entirely round it1 at the distance of #j4d of an inch from each other1 and at such a height that the intermediate clear surface was in the same horizontal plane with the lever and ball4 ,these bands were connected with each other and with the earth1 and1 being perfect conductors1 always exerted a uniform influence on the electrified balls within1 which the glass surface1 from its irregularity of condition at different times1 ,i found1 did not4 ,for the purpose of keeping the air within the electrometer in a constant state as to dryness1 a glass dish1 of such size as to enter easily within the cylinder1 had a layer of fused potash placed within it1 and this being covered with a disc of fine wire-gauze to render its inductive action uniform at all parts1 was placed within the instrument at the bottom and left there4 ,a ,mmoires de l',acadmie1 #aghe1 p4 #egj4 ,b ,philosophical ,transactions1 #ahcj4 #aaha4 ,the moveable ball used to take and measure the portion of electricity under examination1 and which may be called the repelling1 or the carrier1 ball1 was of soft alder wood1 well and smoothly gilt4 ,it was attached to a fine shell-lac stem1 and introduced through a hole into the electrometer according to ,coulomb's method3 the stem was fixed at its upper end in a block or vice1 supported on three short feet2 and on the surface of the glass cover above was a plate of lead with stops on it1 so that when the carrier ball was adjusted in its right position1 with the vice above bearing at the same time against these stops1 it was perfectly easy to bring away the carrier-ball and restore it to its place again very accurately1 without any loss of time4 #aahb4 ,it is quite necessary to attend to certain precautions respecting these balls4 ,if of pith alone they are bad2 for when very dry1 that substance is so imperfect a conductor that it neither receives nor gives a charge freely1 and so1 after contact with a charged conductor1 it is liable to be in an uncertain condition4 ,again1 it is difficult to turn pith so smooth as to leave the ball1 even when gilt1 so free from irregularities of form1 as to retain its charge undiminished for a considerable length of time4 ,when1 therefore1 the balls are finally prepared and gilt they should be examined2 and being electrified1 unless they can hold their charge with very little diminution for a considerable time1 and yet be discharged instantly and perfectly by the touch of an uninsulated conductor1 they should be dismissed4 #aahc4 ,it is1 perhaps1 unnecessary to refer to the graduation of the instrument1 further than to explain how the observations were made4 ,on a circle or ring of paper on the outside of the glass cylinder1 fixed so as to cover the internal lower ring of tinfoil1 were marked four points corresponding to angles of #ij2 four other points exactly corresponding to these points being marked on the upper ring of tinfoil within4 ,by these and the adjusting screws on which the whole instrument stands1 the glass torsion thread could be brought accurately into the centre of the instrument and of the graduations on it4 ,from one of the four points on the exterior of the cylinder a graduation of #ij was set off1 and a corresponding graduation was placed upon the upper tinfoil on the opposite side of the cylinder within2 and a dot being marked on that point of the surface of the repelled ball nearest to the side of the electrometer1 it was easy1 by observing the line which this dot made with the lines of the two graduations just referred to1 to ascertain accurately the position of the ball4 ,the upper end of the glass thread was attached1 as in ,coulomb's original electrometer1 to an index1 which had its appropriate graduated circle1 upon which the degree of torsion was ultimately to be read off4 #aahd4 ,after the levelling of the instrument and adjustment of the glass thread1 the blocks which determine the place of the carrier ball are to be regulated 7#aaha47 so that1 when the carrier arrangement is placed against them1 the centre of the ball may be in the radius of the instrument corresponding to #j on the lower graduation or that on the side of the electrometer1 and at the same level and distance from the centre as the repelled ball on the suspended torsion lever4 ,then the torsion index is to be turned until the ball connected with it 7the repelled ball7 is accurately at #cj1 and finally the graduated arc belonging to the torsion index is to be adjusted so as to bring #j upon it to the index4 ,this state of the instrument was adopted as that which gave the most direct expression of the experimental results1 and in the form having fewest variable errors2 the angular distance of #cj being always retained as the standard distance to which the balls were in every case to be brought1 and the whole of the torsion being read off at once on the graduated circle above4 ,under these circumstances the distance of the balls from each other was not merely the same in degree1 but their position in the instrument1 and in relation to every part of it1 was actually the same every time that a measurement was made2 so that all irregularities arising from slight difference of form and action in the instrument and the bodies around were avoided4 ,the only difference which could occur in the position of anything within1 consisted in the deflexion of the torsion thread from a vertical position1 more or less1 according to the force of repulsion of the balls2 but this was so slight as to cause no interfering difference in the symmetry of form within the instrument1 and gave no error in the amount of torsion force indicated on the graduation above4 #aahe4 ,although the constant angular distance of #cj between the centres of the balls was adopted1 and found abundantly sensible1 for all ordinary purposes1 yet the facility of rendering the instrument far more sensible by diminishing this distance was at perfect command2 the results at different distances being very easily compared with each other either by experiment1 or1 as they are inversely as the squares of the distances1 by calculation4 #aahf4 ,the ,coulomb balance electrometer requires experience to be understood2 but ,i think it a very valuable instrument in the hands of those who will take pains by practice and attention to learn the precautions needful in its use4 ,its insulating condition varies with circumstances1 and should be examined before it is employed in experiments4 ,in an ordinary and fair condition1 when the balls were so electrified as to give a repulsive torsion force of #ajj at the standard distance of #cj1 it took nearly four hours to sink to #ej at the same distance2 the average loss from #djj to #cjj being at the rate of #b4g per minute1 from #cjj to #bjj of #a4g per minute1 from #bjj to #ajj of #a4c per minute1 and from #ajj to #ej of #j4hg per minute4 ,as a complete measurement by the instrument may be made in much less than a minute1 the amount of loss in that time is but small1 and can easily be taken into account4 #aahg4 ,the inductive apparatus4--,my object was to examine inductive action carefully when taking place through different media1 for which purpose it was necessary to subject these media to it in exactly similar circumstances1 and in such quantities as should suffice to eliminate any variations they might present4 ,the requisites of the apparatus to be constructed were1 therefore1 that the inducing surfaces of the conductors should have a constant form and state1 and be at a constant distance from each other2 and that either solids1 fluids1 or gases might be placed and retained between these surfaces with readiness and certainty1 and for any length of time4 #aahh4 ,the apparatus used may be described in general terms as consisting of two metallic spheres of unequal diameter1 placed1 the smaller within the larger1 and concentric with it2 the interval between the two being the space through which the induction was to take place4 ,a section of it is given 7,plate ,,vii4 fig4 #ajd47 on a scale of one-half3 a1 a are the two halves of a brass sphere1 with an air-tight joint at b1 like that of the ,magdeburg hemispheres1 made perfectly flush and smooth inside so as to present no irregularity2 c is a connecting piece by which the apparatus is joined to a good stop-cock d1 which is itself attached either to the metallic foot e1 or to an air-pump4 ,the aperture within the hemisphere at f is very small3 g is a brass collar fitted to the upper hemisphere1 through which the shell-lac support of the inner ball and its stem passes2 h is the inner ball1 also of brass2 it screws on to a brass stem i1 terminated above by a brass ball ,b1 l1 l is a mass of shell-lac1 moulded carefully on to i1 and serving both to support and insulate it and its balls h1 ,b4 ,the shell-lac stem l is fitted into the socket g1 by a little ordinary resinous cement1 more fusible than shell-lac1 applied at mm in such a way as to give sufficient strength and render the apparatus air-tight there1 yet leave as much as possible of the lower part of the shell-lac stem untouched1 as an insulation between the ball h and the surrounding sphere a1 a4 ,the ball h has a small aperture at n1 so that when the apparatus is exhausted of one gas and filled with another1 the ball h may itself also be exhausted and filled1 that no variation of the gas in the interval o may occur during the course of an experiment4 #aahi4 ,it will be unnecessary to give the dimensions of all the parts1 since the drawing is to a scale of one-half3 the inner ball has a diameter #b4cc inches1 and the surrounding sphere an internal diameter of #c4eg inches4 ,hence the width of the intervening space1 through which the induction is to take place1 is #j4fb of an inch2 and the extent of this place or plate1 i4e4 the surface of a medium sphere1 may be taken as twenty-seven square inches1 a quantity considered as sufficiently large for the comparison of different substances4 ,great care was taken in finishing well the inducing surfaces of the ball h and sphere a1 a2 and no varnish or lacquer was applied to them1 or to any part of the metal of the apparatus4 #aaij4 ,the attachment and adjustment of the shell-lac stem was a matter requiring considerable care1 especially as1 in consequence of its cracking1 it had frequently to be renewed4 ,the best lac was chosen and applied to the wire i1 so as to be in good contact with it everywhere1 and in perfect continuity throughout its own mass4 ,it was not smaller than is given by scale in the drawing1 for when less it frequently cracked within a few hours after it was cold4 ,i think that very slow cooling or annealing improved its quality in this respect4 ,the collar g was made as thin as could be1 that the lac might be as wide there as possible4 ,in order that at every re-attachment of the stem to the upper hemisphere the ball h might have the same relative position1 a gauge p 7fig4 #aje47 was made of wood1 and this being applied to the ball and hemisphere whilst the cement at m was still soft1 the bearings of the ball at qq1 and the hemisphere at rr1 were forced home1 and the whole left until cold4 ,thus all difficulty in the adjustment of the ball in the sphere was avoided4 #aaia4 ,i had occasion at first to attach the stem to the socket by other means1 as a band of paper or a plugging of white silk thread2 but these were very inferior to the cement1 interfering much with the insulating power of the apparatus4 #aaib4 ,the retentive power of this apparatus was1 when in good condition1 better than that of the electrometer 7#aahf471 i4e4 the proportion of loss of power was less4 ,thus when the apparatus was electrified1 and also the balls in the electrometer1 to such a degree1 that after the inner ball had been in contact with the top k of the ball of the apparatus1 it caused a repulsion indicated by #fjj of torsion force1 then in falling from #fjj to #djj the average loss was #h4f per minute2 from #djj to #cjj the average loss was #b4f per minute2 from #cjj to #bjj it was #a4g per minute2 from #bjj to #agj it was #a per minute4 ,this was after the apparatus had been charged for a short time2 at the first instant of charging there is an apparent loss of electricity1 which can only be comprehended hereafter 7#abjg4 #abej474 #aaic4 ,when the apparatus loses its insulating power suddenly1 it is almost always from a crack near to or within the brass socket4 ,these cracks are usually transverse to the stem4 ,if they occur at the part attached by common cement to the socket1 the air cannot enter1 and thus constituting vacua1 they conduct away the electricity and lower the charge1 as fast almost as if a piece of metal had been introduced there4 ,occasionally stems in this state1 being taken out and cleared from the common cement1 may1 by the careful application of the heat of a spirit-lamp1 be so far softened and melted as to restore the perfect continuity of the parts2 but if that does not succeed in replacing things in a good condition1 the remedy is a new shell-lac stem4 #aaid4 ,the apparatus when in order could easily be exhausted of air and filled with any given gas2 but when that gas was acid or alkaline1 it could not properly be removed by the air-pump1 and yet required to be perfectly cleared away4 ,in such cases the apparatus was opened and emptied of gas2 and with respect to the inner ball h1 it was washed out two or three times with distilled water introduced at the screw-hole1 and then being heated above #bab1 air was blown through to render the interior perfectly dry4 #aaie4 ,the inductive apparatus described is evidently a ,leyden phial1 with the advantage1 however1 of having the dielectric or insulating medium changed at pleasure4 ,the balls h and ,b1 with the connecting wire i1 constitute the charged conductor1 upon the surface of which all the electric force is resident by virtue of induction 7#aagh474 ,now though the largest portion of this induction is between the ball h and the surrounding sphere aa1 yet the wire i and the ball ,b determine a part of the induction from their surfaces towards the external surrounding conductors4 ,still1 as all things in that respect remain the same1 whilst the medium within at oo1 may be varied1 any changes exhibited by the whole apparatus will in such cases depend upon the variations made in the interior2 and these were the changes ,i was in search of1 the negation or establishment of such differences being the great object of my inquiry4 ,i considered that these differences1 if they existed1 would be most distinctly set forth by having two apparatus of the kind described1 precisely similar in every respect2 and then1 different insulating media being within1 to charge one and measure it1 and after dividing the charge with the other1 to observe what the ultimate conditions of both were4 ,if insulating media really had any specific differences in favouring or opposing inductive action through them1 such differences1 ,i conceived1 could not fail of being developed by such a process4 #aaif4 ,i will wind up this description of the apparatus1 and explain the precautions necessary to their use1 by describing the form and order of the experiments made to prove their equality when both contained common air4 ,in order to facilitate reference ,i will distinguish the two by the terms ,app4 i4 and ,app4 ii4 #aaig4 ,the electrometer is first to be adjusted and examined 7#aahd471 and the app4 i4 and ii4 are to be perfectly discharged4 ,a ,leyden phial is to be charged to such a degree that it would give a spark of about one-sixteenth or one-twentieth of an inch in length between two balls of half an inch diameter2 and the carrier ball of the electrometer being charged by this phial1 is to be introduced into the electrometer1 and the lever ball brought by the motion of the torsion index against it2 the charge is thus divided between the balls1 and repulsion ensues4 ,it is useful then to bring the repelled ball to the standard distance of #cj by the motion of the torsion index1 and observe the force in degrees required for this purpose2 this force will in future experiments be called repulsion of the balls4 #aaih4 ,one of the inductive apparatus1 as1 for instance1 app4 i41 is now to be charged from the ,leyden phial1 the latter being in the state it was in when used to charge the balls2 the carrier ball is to be brought into contact with the top of its upper ball 7k1 fig4 #ajd471 then introduced into the electrometer1 and the repulsive force 7at the distance of #cj7 measured4 ,again1 the carrier should be applied to the app4 i4 and the measurement repeated2 the apparatus i4 and ii4 are then to be joined1 so as to divide the charge1 and afterwards the force of each measured by the carrier ball1 applied as before1 and the results carefully noted4 ,after this both i4 and ii4 are to be discharged2 then app4 ii4 charged1 measured1 divided with app4 i41 and the force of each again measured and noted4 ,if in each case the half charges of app4 i4 and ii4 are equal1 and are together equal to the whole charge before division1 then it may be considered as proved that the two apparatus are precisely equal in power1 and fit to be used in cases of comparison between different insulating media or dielectrics4 #aaii4 ,but the precautions necessary to obtain accurate results are numerous4 ,the apparatus i4 and ii4 must always be placed on a thoroughly uninsulating medium4 ,a mahogany table1 for instance1 is far from satisfactory in this respect1 and therefore a sheet of tinfoil1 connected with an extensive discharging train 7#bib471 is what ,i have used4 ,they must be so placed also as not to be too near each other1 and yet equally exposed to the inductive influence of surrounding objects2 and these objects1 again1 should not be disturbed in their position during an experiment1 or else variations of induction upon the external ball ,b of the apparatus may occur1 and so errors be introduced into the results4 ,the carrier ball1 when receiving its portion of electricity from the apparatus1 should always be applied at the same part of the ball1 as1 for instance1 the summit k1 and always in the same way2 variable induction from the vicinity of the head1 hands1 c4 being avoided1 and the ball after contact being withdrawn upwards in a regular and constant manner4 #abjj4 ,as the stem had occasionally to be changed 7#aaij471 and the change might occasion slight variations in the position of the ball within1 ,i made such a variation purposely1 to the amount of an eighth of an inch 7which is far more than ever could occur in practice71 but did not find that it sensibly altered the relation of the apparatus1 or its inductive condition as a whole4 ,another trial of the apparatus was made as to the effect of dampness in the air1 one being filled with very dry air1 and the other with air from over water4 ,though this produced no change in the result1 except an occasional tendency to more rapid dissipation1 yet the precaution was always taken when working with gases 7#abij47 to dry them perfectly4 #abja4 ,it is essential that the interior of the apparatus should be perfectly free from dust or small loose particles1 for these very rapidly lower the charge and interfere on occasions when their presence and action would hardly be expected4 ,to breathe on the interior of the apparatus and wipe it out quietly with a clean silk handkerchief1 is an effectual way of removing them2 but then the intrusion of other particles should be carefully guarded against1 and a dusty atmosphere should for this and several other reasons be avoided4 #abjb4 ,the shell-lac stem requires occasionally to be well-wiped1 to remove1 in the first instance1 the film of wax and adhering matter which is upon it2 and afterwards to displace dirt and dust which will gradually attach to it in the course of experiments4 ,i have found much to depend upon this precaution1 and a silk handkerchief is the best wiper4 #abjc4 ,but wiping and some other circumstances tend to give a charge to the surface of the shell-lac stem4 ,this should be removed1 for1 if allowed to remain1 it very seriously affects the degree of charge given to the carrier ball by the apparatus 7#abcb474 ,this condition of the stem is best observed by discharging the apparatus1 applying the carrier ball to the stem1 touching it with the finger1 insulating and removing it1 and examining whether it has received any charge 7by induction7 from the stem2 if it has1 the stem itself is in a charged state4 ,the best method of removing the charge ,i have found to be1 to cover the finger with a single fold of a silk handkerchief1 and breathing on the stem1 to wipe it immediately after with the finger2 the ball ,b and its connected wire1 c4 being at the same time uninsulated3 the wiping place of the silk must not be changed2 it then becomes sufficiently damp not to excite the stem1 and is yet dry enough to leave it in a clean and excellent insulating condition4 ,if the air be dusty1 it will be found that a single charge of the apparatus will bring on an electric state of the outside of the stem1 in consequence of the carrying power of the particles of dust2 whereas in the morning1 and in a room which has been left quiet1 several experiments can be made in succession without the stem assuming the least degree of charge4 #abjd4 ,experiments should not be made by candle or lamp light except with much care1 for flames have great and yet unsteady powers of affecting and dissipating electrical charges4 #abje4 ,as a final observation on the state of the apparatus1 they should retain their charges well and uniformly1 and alike for both1 and at the same time allow of a perfect and instantaneous discharge1 giving afterwards no charge to the carrier ball1 whatever part of the ball ,b it may be applied to 7#abah474 #abjf4 ,with respect to the balance electrometer1 all the precautions that need be mentioned1 are1 that the carrier ball is to be preserved during the first part of an experiment in its electrified state1 the loss of electricity which would follow upon its discharge being avoided2 and that in introducing it into the electrometer through the hole in the glass plate above1 care should be taken that it do not touch1 or even come near to1 the edge of the glass4 #abjg4 ,when the whole charge in one apparatus is divided between the two1 the gradual fall1 apparently from dissipation1 in the apparatus which has received the half charge is greater than in the one originally charged4 ,this is due to a peculiar effect to be described hereafter 7#abej4 #abea471 the interfering influence of which may be avoided to a great extent by going through the steps of the process regularly and quickly2 therefore1 after the original charge has been measured1 in app4 i4 for instance1 i4 and ii4 are to be symmetrically joined by their balls ,b1 the carrier touching one of these balls at the same time2 it is first to be removed1 and then the apparatus separated from each other2 app4 ii4 is next quickly to be measured by the carrier1 then app4 i42 lastly1 ii4 is to be discharged1 and the discharged carrier applied to it to ascertain whether any residual effect is present 7#abje471 and app4 i4 being discharged is also to be examined in the same manner and for the same purpose4 #abjh4 ,the following is an example of the division of a charge by the two apparatus1 air being the dielectric in both of them4 ,the observations are set down one under the other in the order in which they were taken1 the left-hand numbers representing the observations made on app4 i41 and the right-hand numbers those on app4 ii4 ,app4 i4 is that which was originally charged1 and after two measurements1 the charge was divided with app4 ii4 ,app4 i4 ,app4 ii4 ,balls #afj 4 4 4 4 #j #bed 4 4 4 4 #bej 4 4 4 4 divided and instantly taken 4 4 4 4 #abb #abd 4 4 4 4 #a 4 4 4 4 after being discharged4 4 4 4 4 #b after being discharged4 #abji4 ,without endeavouring to allow for the loss which must have been gradually going on during the time of the experiment1 let us observe the results of the numbers as they stand4 ,as #a remained in app4 i4 in an undischargeable state1 #bdi may be taken as the utmost amount of the transferable or divisible charge1 the half of which is #abd4e4 ,as app4 ii4 was free of charge in the first instance1 and immediately after the division was found with #abb1 this amount at least may be taken as what it had received4 ,on the other hand #abd minus #a1 or #abc1 may be taken as the half of the transferable charge retained by app4 i4 ,now these do not differ much from each other1 or from #abd4e1 the half of the full amount of transferable charge2 and when the gradual loss of charge evident in the difference between #bed and #bej of app4 i4 is also taken into account1 there is every reason to admit the result as showing an equal division of charge1 unattended by any disappearance of power except that due to dissipation4 #abaj4 ,i will give another result1 in which app4 ii4 was first charged1 and where the residual action of that apparatus was greater than in the former case4 ,app4 i4 ,app4 ii4 ,balls #aej 4 4 4 4 #aeb 4 4 4 4 #adh divided and instantly taken #gj 4 4 4 4 4 4 4 4 #gh 4 4 4 4 #e immediately after discharge4 #j 4 4 4 4 immediately after discharge4 #abaa4 ,the transferable charge being #adh - #e1 its half is #ga4e1 which is not far removed from #gj1 the half charge of i42 or from #gc1 the half charge of ii43 these half charges again making up the sum of #adc1 or just the amount of the whole transferable charge4 ,considering the errors of experiment1 therefore1 these results may again be received as showing that the apparatus were equal in inductive capacity1 or in their powers of receiving charges4 #abab4 ,the experiments were repeated with charges of negative electricity with the same general results4 #abac4 ,that ,i might be sure of the sensibility and action of the apparatus1 ,i made such a change in one as ought upon principle to increase its inductive force1 i4e4 ,i put a metallic lining into the lower hemisphere of app4 i41 so as to diminish the thickness of the intervening air in that part1 from #j4fb to #j4dce of an inch3 this lining was carefully shaped and rounded so that it should not present a sudden projection within at its edge1 but a gradual transition from the reduced interval in the lower part of the sphere to the larger one in the upper4 #abad4 ,this change immediately caused app4 i4 to produce effects indicating that it had a greater aptness or capacity for induction than app4 ii4 ,thus1 when a transferable charge in app4 ii4 of #dfi was divided with app4 i41 the former retained a charge of #bbe1 whilst the latter showed one of #bbg1 i4e4 the former had lost #bdd in communicating #bbg to the latter3 on the other hand1 when app4 i4 had a transferable charge in it of #cha divided by contact with app4 ii41 it lost #aha only1 whilst it gave to app4 ii4 as many as #aid3--the sum of the divided forces being in the first instance less1 and in the second instance greater than the original undivided charge4 ,these results are the more striking1 as only one-half of the interior of app4 i4 was modified1 and they show that the instruments are capable of bringing out differences in inductive force from amongst the errors of experiment1 when these differences are much less than that produced by the alteration made in the present instance4 iv4 ,induction in curved lines4 #abae4 ,amongst those results deduced from the molecular view of induction 7#aaff471 which1 being of a peculiar nature1 are the best tests of the truth or error of the theory1 the expected action in curved lines is1 ,i think1 the most important at present2 for1 if shown to take place in an unexceptionable manner1 ,i do not see how the old theory of action at a distance and in straight lines can stand1 or how the conclusion that ordinary induction is an action of contiguous particles can be resisted4 #abaf4 ,there are many forms of old experiments which might be quoted as favourable to1 and consistent with the view ,i have adopted4 ,such are most cases of electro-chemical decomposition1 electrical brushes1 auras1 sparks1 c42 but as these might be considered equivocal evidence1 inasmuch as they include a current and discharge1 7though they have long been to me indications of prior molecular action 7#abcj477 ,i endeavoured to devise such experiments for first proofs as should not include transfer1 but relate altogether to the pure simple inductive action of statical electricity4 #abag4 ,it was also of importance to make these experiments in the simplest possible manner1 using not more than one insulating medium or dielectric at a time1 lest differences of slow conduction should produce effects which might erroneously be supposed to result from induction in curved lines4 ,it will be unnecessary to describe the steps of the investigation minutely2 ,i will at once proceed to the simplest mode of proving the facts1 first in air and then in other insulating media4 #abah4 ,a cylinder of solid shell-lac1 #j4i of an inch in diameter and seven inches in length1 was fixed upright in a wooden foot 7fig4 #ajf473 it was made concave or cupped at its upper extremity so that a brass ball or other small arrangement could stand upon it4 ,the upper half of the stem having been excited negatively by friction with warm flannel1 a brass ball1 ,b1 #a inch in diameter1 was placed on the top1 and then the whole arrangement examined by the carrier ball and ,coulomb's electrometer 7#aahj4 c474 ,for this purpose the balls of the electrometer were charged positively to about #cfj1 and then the carrier being applied to various parts of the ball ,b1 the two were uninsulated whilst in contact or in position1 then insulated,a1 separated1 and the charge of the carrier examined as to its nature and force4 ,its electricity was always positive1 and its force at the different positions a1 b1 c1 d1 c4 7figs4 #ajf4 and #ajg47 observed in succession1 was as follows3 at a above #ajjj b it was #adi c #bgj d #eab b #acj ,a ,it can hardly be necessary for me to say here1 that whatever general state the carrier ball acquired in any place where it was uninsulated and then insulated1 it retained on removal from that place1 notwithstanding that it might pass through other places that would have given to it1 if uninsulated1 a different condition4 #abai4 ,to comprehend the full force of these results1 it must first be understood1 that all the charges of the ball ,b and the carrier are charges by induction1 from the action of the excited surface of the shell-lac cylinder2 for whatever electricity the ball ,b received by communication from the shell-lac1 either in the first instance or afterwards1 was removed by the uninsulating contacts1 only that due to induction remaining2 and this is shown by the charges taken from the ball in this its uninsulated state being always positive1 or of the contrary character to the electricity of the shell-lac4 ,in the next place1 the charges at a1 c1 and d were of such a nature as might be expected from an inductive action in straight lines1 but that obtained at b is not so3 it is clearly a charge by induction1 but induction in a curved line2 for the carrier ball whilst applied to b1 and after its removal to a distance of six inches or more from ,b1 could not1 in consequence of the size of ,b1 be connected by a straight line with any part of the excited and inducing shell-lac4 #abbj4 ,to suppose that the upper part of the uninsulated ball ,b1 should in some way be retained in an electrified state by that portion of the surface of the ball which is in sight of the shell-lac1 would be in opposition to what we know already of the subject4 ,electricity is retained upon the surface of conductors only by induction 7#aagh472 and though some persons may not be prepared as yet to admit this with respect to insulated conductors1 all will as regards uninsulated conductors like the ball ,b2 and to decide the matter we have only to place the carrier ball at e 7fig4 #ajg471 so that it shall not come in contact with ,b1 uninsulate it by a metallic rod descending perpendicularly1 insulate it1 remove it1 and examine its state2 it will be found charged with the same kind of electricity as1 and even to a higher degree 7#abbd47 than1 if it had been in contact with the summit of ,b4 #abba4 ,to suppose1 again1 that induction acts in some way through or across the metal of the ball1 is negatived by the simplest considerations2 but a fact in proof will be better4 ,if instead of the ball ,b a small disc of metal be used1 the carrier may be charged at1 or above the middle of its upper surface3 but if the plate be enlarged to about #a-a_/b or #b inches in diameter1 ,c 7fig4 #ajh471 then no charge will be given to the carrier at f1 though when applied nearer to the edge at g1 or even above the middle at h1 a charge will be obtained2 and this is true though the plate may be a mere thin film of gold-leaf4 ,hence it is clear that the induction is not through the metal1 but through the surrounding air or dielectric1 and that in curved lines4 #abbb4 ,i had another arrangement1 in which a wire passing downwards through the middle of the shell-lac cylinder to the earth1 was connected with the ball ,b 7fig4 #aji47 so as to keep it in a constantly uninsulated state4 ,this was a very convenient form of apparatus1 and the results with it were the same as those just described4 #abbc4 ,in another case the ball ,b was supported by a shell-lac stem1 independently of the excited cylinder of shell-lac1 and at half an inch distance from it2 but the effects were the same4 ,then the brass ball of a charged ,leyden jar was used in place of the excited shell-lac to produce induction2 but this caused no alteration of the phenomena4 ,both positive and negative inducing charges were tried with the same general results4 ,finally1 the arrangement was inverted in the air for the purpose of removing every possible objection to the conclusions1 but they came out exactly the same4 #abbd4 ,some results obtained with a brass hemisphere instead of the ball ,b were exceedingly interesting1 ,it was #a4cf of an inch in diameter1 7fig4 #aaj471 and being placed on the top of the excited shell-lac cylinder1 the carrier ball was applied1 as in the former experiments 7#abah471 at the respective positions delineated in the figure4 ,at i the force was #aab1 at k #ajh1 at l #fe1 at m #ce2 the inductive force gradually diminishing1 as might have been expected1 to this point4 ,but on raising the carrier to the position n1 the charge increased to #hg2 and on raising it still higher to o1 the charge still further increased to #aje3 at a higher point still1 p1 the charge taken was smaller in amount1 being #ih1 and continued to diminish for more elevated positions4 ,here the induction fairly turned a corner4 ,nothing1 in fact1 can better show both the curved lines or courses of the inductive action1 disturbed as they are from their rectilineal form by the shape1 position1 and condition of the metallic hemisphere2 and also a lateral tension1 so to speak1 of these lines on one another3--all depending1 as ,i conceive1 on induction being an action of the contiguous particles of the dielectric1 which being thrown into a state of polarity and tension1 are in mutual relation by their forces in all directions4 #abbe4 ,as another proof that the whole of these actions were inductive ,i may state a result which was exactly what might be expected1 namely1 that if uninsulated conducting matter was brought round and near to the excited shell-lac stem1 then the inductive force was directed towards it1 and could not be found on the top of the hemisphere4 ,removing this matter the lines of force resumed their former direction4 ,the experiment affords proofs of the lateral tension of these lines1 and supplies a warning to remove such matter in repeating the above investigation4 #abbf4 ,after these results on curved inductive action in air ,i extended the experiments to other gases1 using first carbonic acid and then hydrogen3 the phenomena were precisely those already described4 ,in these experiments ,i found that if the gases were confined in vessels they required to be very large1 for whether of glass or earthenware1 the conducting power of such materials is so great that the induction of the excited shell-lac cylinder towards them is as much as if they were metal2 and if the vessels be small1 so great a portion of the inductive force is determined towards them that the lateral tension or mutual repulsion of the lines of force before spoken of1 7#abbd47 by which their inflexion is caused1 is so much relieved in other directions1 that no inductive charge will be given to the carrier ball in the positions k1 l1 m1 n1 o1 p 7fig4 #aaj474 ,a very good mode of making the experiment is to let large currents of the gases ascend or descend through the air1 and carry on the experiments in these currents4 #abbg4 ,these experiments were then varied by the substitution of a liquid dielectric1 namely1 oil of turpentine1 in place of air and gases4 ,a dish of thin glass well-covered with a film of shell-lac 7#abgb471 which was found by trial to insulate well1 had some highly rectified oil of turpentine put into it to the depth of half an inch1 and being then placed upon the top of the brass hemisphere 7fig4 #aaj471 observations were made with the carrier ball as before 7#abbd474 ,the results were the same1 and the circumstance of some of the positions being within the fluid and some without1 made no sensible difference4 #abbh4 ,lastly1 ,i used a few solid dielectrics for the same purpose1 and with the same results4 ,these were shell-lac1 sulphur1 fused and cast borate of lead1 flint glass well-covered with a film of lac1 and spermaceti4 ,the following was the form of experiment with sulphur1 and all were of the same kind4 ,a square plate of the substance1 two inches in extent and #j4f of an inch in thickness1 was cast with a small hole or depression in the middle of one surface to receive the carrier ball4 ,this was placed upon the surface of the metal hemisphere 7fig4 #aab47 arranged on the excited lac as in former cases1 and observations were made at n1 o1 p1 and q4 ,great care was required in these experiments to free the sulphur or other solid substance from any charge it might previously have received4 ,this was done by breathing and wiping 7#abjc471 and the substance being found free from all electrical excitement1 was then used in the experiment2 after which it was removed and again examined1 to ascertain that it had received no charge1 but had acted really as a dielectric4 ,with all these precautions the results were the same3 and it is thus very satisfactory to obtain the curved inductive action through solid bodies1 as any possible effect from the translation of charged particles in fluids or gases1 which some persons might imagine to be the case1 is here entirely negatived4 #abbi4 ,in these experiments with solid dielectrics1 the degree of charge assumed by the carrier ball at the situations n1 o1 p 7fig4 #aab471 was decidedly greater than that given to the ball at the same places when air only intervened between it and the metal hemisphere4 ,this effect is consistent with what will hereafter be found to be the respective relations of these bodies1 as to their power of facilitating induction through them 7#abfi4 #abgc4 #abgg474 #abcj4 ,i might quote many other forms of experiment1 some old and some new1 in which induction in curved or contorted lines takes place1 but think it unnecessary after the preceding results2 ,i shall therefore mention but two4 ,if a conductor ,a1 7fig4 #aaa47 be electrified1 and an uninsulated metallic ball ,b1 or even a plate1 provided the edges be not too thin1 be held before it1 a small electrometer at c or at d1 uninsulated1 will give signs of electricity1 opposite in its nature to that of ,a1 and therefore caused by induction1 although the influencing and influenced bodies cannot be joined by a right line passing through the air4 ,or if1 the electrometers being removed1 a point be fixed at the back of the ball in its uninsulated state as at ,c1 this point will become luminous and discharge the conductor ,a4 ,the latter experiment is described by ,nicholson,a1 who1 however1 reasons erroneously upon it4 ,as to its introduction here1 though it is a case of discharge1 the discharge is preceded by induction1 and that induction must be in curved lines4 ,a ,encyclopdia ,britannica1 vol4 vi4 p4 #ejd4 #abca4 ,as argument against the received theory of induction and in favour of that which ,i have ventured to put forth1 ,i cannot see how the preceding results can be avoided4 ,the effects are clearly inductive effects produced by electricity1 not in currents but in its statical state1 and this induction is exerted in lines of force which1 though in many experiments they may be straight1 are here curved more or less according to circumstances4 ,i use the term line of inductive force merely as a temporary conventional mode of expressing the direction of the power in cases of induction2 and in the experiments with the hemisphere 7#abbd471 it is curious to see how1 when certain lines have terminated on the under surface and edge of the metal1 those which were before lateral to them expand and open out from each other1 some bending round and terminating their action on the upper surface of the hemisphere1 and others meeting1 as it were1 above in their progress outwards1 uniting their forces to give an increased charge to the carrier ball1 at an increased distance from the source of power1 and influencing each other so as to cause a second flexure in the contrary direction from the first one4 ,all this appears to me to prove that the whole action is one of contiguous particles1 related to each other1 not merely in the lines which they may be conceived to form through the dielectric1 between the inductric and the inducteous surfaces 7#adhc471 but in other lateral directions also4 ,it is this which gives an effect equivalent to a lateral repulsion or expansion in the lines of force ,i have spoken of1 and enables induction to turn a corner 7#acjd474 ,the power1 instead of being like that of gravity1 which causes particles to act on each other through straight lines1 whatever other particles may be between them1 is more analogous to that of a series of magnetic needles1 or to the condition of the particles considered as forming the whole of a straight or a curved magnet4 ,so that in whatever way ,i view it1 and with great suspicion of the influence of favourite notions over myself1 ,i cannot perceive how the ordinary theory applied to explain induction can be a correct representation of that great natural principle of electrical action4 #abcb4 ,i have had occasion in describing the precautions necessary in the use of the inductive apparatus1 to refer to one founded on induction in curved lines 7#abjc472 and after the experiments already described1 it will easily be seen how great an influence the shell-lac stem may exert upon the charge of the carrier ball when applied to the apparatus 7#abah471 unless that precaution be attended to4 #abcc4 ,i think it expedient1 next in the course of these experimental researches1 to describe some effects due to conduction1 obtained with such bodies as glass1 lac1 sulphur1 c41 which had not been anticipated4 ,being understood1 they will make us acquainted with certain precautions necessary in investigating the great question of specific inductive capacity4 #abcd4 ,one of the inductive apparatus already described 7#aahg1 c47 had a hemispherical cup of shell-lac introduced1 which being in the interval between the inner bull and the lower hemisphere1 nearly occupied the space there2 consequently when the apparatus was charged1 the lac was the dielectric or insulating medium through which the induction took place in that part4 ,when this apparatus was first charged with electricity 7#aaih47 up to a certain intensity1 as #djj1 measured by the ,,coulomb',s electrometer 7#aahj471 it sank much faster from that degree than if it had been previously charged to a higher point1 and had gradually fallen to #djj2 or than it would do if the charge were1 by a second application1 raised up again to #djj2 all other things remaining the same4 ,again1 if after having been charged for some time1 as fifteen or twenty minutes1 it was suddenly and perfectly discharged1 even the stem having all electricity removed from it 7#abjc471 then the apparatus being left to itself1 would gradually recover a charge1 which in nine or ten minutes would rise up to #ej or #fj1 and in one instance to #hj4 #abce4 ,the electricity1 which in these cases returned from an apparently latent to a sensible state1 was always of the same kind as that which had been given by the charge4 ,the return took place at both the inducing surfaces2 for if after the perfect discharge of the apparatus the whole was insulated1 as the inner ball resumed a positive state the outer sphere acquired a negative condition4 #abcf4 ,this effect was at once distinguished from that produced by the excited stem acting in curved lines of induction 7#abjc4 #abcb471 by the circumstance that all the returned electricity could be perfectly and instantly discharged4 ,it appeared to depend upon the shell-lac within1 and to be1 in some way1 due to electricity evolved from it in consequence of a previous condition into which it had been brought by the charge of the metallic coatings or balls4 #abcg4 ,to examine this state more accurately1 the apparatus1 with the hemispherical cup of shell-lac in it1 was charged for about forty-five minutes to above #fjj with positive electricity at the balls h and ,b4 7fig4 #ajd47 above and within4 ,it was then discharged1 opened1 the shell-lac taken out1 and its state examined2 this was done by bringing the carrier ball near the shell-lac1 uninsulating it1 insulating it1 and then observing what charge it had acquired4 ,as it would be a charge by induction1 the state of the ball would indicate the opposite state of electricity in that surface of the shell-lac which had produced it4 ,at first the lac appeared quite free from any charge2 but gradually its two surfaces assumed opposite states of electricity1 the concave surface1 which had been next the inner and positive ball2 assuming a positive state1 and the convex surface1 which had been in contact with the negative coating1 acquiring a negative state2 these states gradually increased in intensity for some time4 #abch4 ,as the return action was evidently greatest instantly after the discharge1 ,i again put the apparatus together1 and charged it for fifteen minutes as before1 the inner ball positively4 ,i then discharged it1 instantly removing the upper hemisphere with the interior ball1 and1 leaving the shell-lac cup in the lower uninsulated hemisphere1 examined its inner surface by the carrier ball as before 7#abcg474 ,in this way ,i found the surface of the shell-lac actually negative1 or in the reverse state to the ball which had been in it2 this state quickly disappeared1 and was succeeded by a positive condition1 gradually increasing in intensity for some time1 in the same manner as before4 ,the first negative condition of the surface opposite the positive charging ball is a natural consequence of the state of things1 the charging ball being in contact with the shell-lac only in a few points4 ,it does not interfere with the general result and peculiar state now under consideration1 except that it assists in illustrating in a very marked manner the ultimate assumption by the surfaces of the shell-lac of an electrified condition1 similar to that of the metallic surfaces opposed to or against them4 #abci4 ,glass was then examined with respect to its power of assuming this peculiar state4 ,i had a thick flint-glass hemispherical cup formed1 which would fit easily into the space o of the lower hemisphere 7#aahh4 #aahi472 it had been heated and varnished with a solution of shell-lac in alcohol1 for the purpose of destroying the conducting power of the vitreous surface 7#abed474 ,being then well-warmed and experimented with1 ,i found it could also assume the same state1 but not apparently to the same degree1 the return action amounting in different cases to quantities from #f to #ah4 #abdj4 ,spermaceti experimented with in the same manner gave striking results4 ,when the original charge had been sustained for fifteen or twenty minutes at about #ejj1 the return charge was equal to #ie or #ajj1 and was about fourteen minutes arriving at the maximum effect4 ,a charge continued for not more than two or three seconds was here succeeded by a return charge of #ej or #fj4 ,the observations formerly made 7#abcd47 held good with this substance4 ,spermaceti1 though it will insulate a low charge for some time1 is a better conductor than shell-lac1 glass1 and sulphur2 and this conducting power is connected with the readiness with which it exhibits the particular effect under consideration4 #abda4 ,sulphur4--,i was anxious to obtain the amount of effect with this substance1 first1 because it is an excellent insulator1 and in that respect would illustrate the relation of the effect to the degree of conducting power possessed by the dielectric 7#abdg472 and in the next place1 that ,i might obtain that body giving the smallest degree of the effect now under consideration for the investigation of the question of specific inductive capacity 7#abgg474 #abdb4 ,with a good hemispherical cup of sulphur cast solid and sound1 ,i obtained the return charge1 but only to an amount of #ag or #ah4 ,thus glass and sulphur1 which are bodily very bad conductors of electricity1 and indeed almost perfect insulators1 gave very little of this return charge4 #abdc4 ,i tried the same experiment having air only in the inductive apparatus4 ,after a continued high charge for some time ,i could obtain a little effect of return action1 but it was ultimately traced to the shell-lac of the stem4 #abdd4 ,i sought to produce something like this state with one electric power and without induction2 for upon the theory of an electric fluid or fluids1 that did not seem impossible1 and then ,i should have obtained an absolute charge 7#aafi4 #aagg471 or something equivalent to it4 ,in this ,i could not succeed4 ,i excited the outside of a cylinder of shell-lac very highly for some time1 and then quickly discharging it 7#abjc471 waited and watched whether any return charge would appear1 but such was not the case4 ,this is another fact in favour of the inseparability of the two electric forces 7#aagg471 and another argument for the view that induction and its concomitant phenomena depend upon a polarity of the particles of matter4 #abde4 ,although inclined at first to refer these effects to a peculiar masked condition of a certain portion of the forces1 ,i think ,i have since correctly traced them to known principles of electrical action4 ,the effects appear to be due to an actual penetration of the charge to some distance within the electric1 at each of its two surfaces1 by what we call conduction2 so that1 to use the ordinary phrase1 the electric forces sustaining the induction are not upon the metallic surfaces only1 but upon and within the dielectric also1 extending to a greater or smaller depth from the metal linings4 ,let c 7fig4 #aac47 be the section of a plate of any dielectric1 a and b being the metallic coatings2 let b be uninsulated1 and a be charged positively2 after ten or fifteen minutes1 if a and b be discharged1 insulated1 and immediately examined1 no electricity will appear in them2 but in a short time1 upon a second examination1 they will appear charged in the same way1 though not to the same degree1 as they were at first4 ,now suppose that a portion of the positive force has1 under the coercing influence of all the forces concerned1 penetrated the dielectric and taken up its place at the line p1 a corresponding portion of the negative force having also assumed its position at the line n2 that in fact the electric at these two parts has become charged positive and negative2 then it is clear that the induction of these two forces will be much greater one towards the other1 and less in an external direction1 now that they are at the small distance np from each other1 than when they were at the larger interval ab4 ,then let a and b be discharged2 the discharge destroys or neutralizes all external induction1 and the coatings are therefore found by the carrier ball unelectrified2 but it also removes almost the whole of the forces by which the electric charge was driven into the dielectric1 and though probably a part of that charge goes forward in its passage and terminates in what we call discharge1 the greater portion returns on its course to the surfaces of c1 and consequently to the conductors a and b1 and constitutes the recharge observed4 #abdf4 ,the following is the experiment on which ,i rest for the truth of this view4 ,two plates of spermaceti1 d and1 f 7fig4 #aad471 were put together to form the dielectric1 a and b being the metallic coatings of this compound plate1 as before4 ,the system was charged1 then discharged1 insulated1 examined1 and found to give no indications of electricity to the carrier ball4 ,the plates d and fwere then separated from each other1 and instantly a with d was found in a positive state1 and b with f in a negative state1 nearly all the electricity being in the linings a and b4 ,hence it is clear that1 of the forces sought for1 the positive was in one-half of the compound plate and the negative in the other half2 for when removed bodily with the plates from each other's inductive influence1 they appeared in separate places1 and resumed of necessity their power of acting by induction on the electricity of surrounding bodies4 ,had the effect depended upon a peculiar relation of the contiguous particles of matter only1 then each half-plate1 d and f1 should have shown positive force on one surface and negative on the other4 #abdg4 ,thus it would appear that the best solid insulators1 such as shell-lac1 glass1 and sulphur1 have conductive properties to such an extent1 that electricity can penetrate them bodily1 though always subject to the overruling condition of induction 7#aagh474 ,as to the depth to which the forces penetrate in this form of charge of the particles1 theoretically1 it should be throughout the mass1 for what the charge of the metal does for the portion of dielectric next to it1 should be close by the charged dielectric for the portion next beyond it again2 but probably in the best insulators the sensible charge is to a very small depth only in the dielectric1 for otherwise more would disappear in the first instance whilst the original charge is sustained1 less time would be required for the assumption of the particular state1 and more electricity would re-appear as return charge4 #abdh4 ,the condition of time required for this penetration of the charge is important1 both as respects the general relation of the cases to conduction1 and also the removal of an objection that might otherwise properly be raised to certain results respecting specific inductive capacities1 hereafter to be given 7#abfi4 #abgg47 #abdi4 ,it is the assumption for a time of this charged state of the glass between the coatings in the ,leyden jar1 which gives origin to a well-known phenomenon1 usually referred to the diffusion of electricity over the uncoated portion of the glass1 namely1 the residual charge4 ,the extent of charge which can spontaneously be recovered by a large battery1 after perfect uninsulation of both surfaces1 is very considerable1 and by far the largest portion of this is due to the return of electricity in the manner described4 ,a plate of shell-lac six inches square1 and half an inch thick1 or a similar plate of spermaceti an inch thick1 being coated on the sides with tinfoil as a ,leyden arrangement1 will show this effect exceedingly well4 99 99 99 99 99 #abej4 ,the peculiar condition of dielectrics which has now been described1 is evidently capable of producing an effect interfering with the results and conclusions drawn from the use of the two inductive apparatus1 when shell-lac1 glass1 c4 is used in one or both of them 7#aaib4 #abjg471 for upon dividing the charge in such cases according to the method described 7#aaih4 #abjg471 it is evident that the apparatus just receiving its half charge must fall faster in its tension than the other4 ,for suppose app4 i4 first charged1 and app4 ii4 used to divide with it2 though both may actually lose alike1 yet app4 i41 which has been diminished one-half1 will be sustained by a certain degree of return action or charge 7#abcd471 whilst app4 ii4 will sink the more rapidly from the coming on of the particular state4 ,i have endeavoured to avoid this interference by performing the whole process of comparison as quickly as possible1 and taking the force of app4 ii4 immediately after the division1 before any sensible diminution of the tension arising from the assumption of the peculiar state could be produced2 and ,i have assumed that as about three minutes pass between the first charge of app4 i4 and the division1 and three minutes between the division and discharge1 when the force of the non-transferable electricity is measured1 the contrary tendencies for those periods would keep that apparatus in a moderately steady and uniform condition for the latter portion of time4 #abea4 ,the particular action described occurs in the shell-lac of the stems1 as well as in the dielectric used within the apparatus4 ,it therefore constitutes a cause by which the outside of the stems may in some operations become charged with electricity1 independent of the action of dust or carrying particles 7#abjc474 v4 ,on specific induction1 or specific inductive capacity4 #abeb4 ,i now proceed to examine the great question of specific inductive capacity1 i4e4 whether different dielectric bodies actually do possess any influence over the degree of induction which takes place through them4 ,if any such difference should exist1 it appeared to me not only of high importance in the further comprehension of the laws and results of induction1 but an additional and very powerful argument for the theory ,i have ventured to put forth1 that the whole depends upon a molecular action1 in contradistinction to one at sensible distances4 ,the question may be stated thus3 suppose ,a an electrified plate of metal suspended in the air1 and ,b and ,c two exactly similar plates1 placed parallel to and on each side of ,a at equal distances and uninsulated2 ,a will then induce equally towards ,b and ,c4 ,if in this position of the plates some other dielectric than air1 as shell-lac1 be introduced between ,a and ,c1 will the induction between them remain the same8 ,will the relation of ,c and ,b to ,a be unaltered1 notwithstanding the difference of the dielectrics interposed between them8,a ,a ,refer for the practical illustration of this statement to the supplementary note commencing #acjg1 c4--,dec4 #ahch4 #abec4 ,as far as ,i recollect1 it is assumed that no change will occur under such variation of circumstances1 and that the relations of ,b find ,c to ,a depend entirely upon their distance4 ,i only remember one experimental illustration of the question1 and that is by ,coulomb,a1 in which he shows that a wire surrounded by shell-lac took exactly the same quantity of electricity from a charged body as the same wire in air4 ,the experiment offered to me no proof of the truth of the supposition3 for it is not the mere films of dielectric substances surrounding the charged body which have to be examined and compared1 but the whole mass between that body and the surrounding conductors at which the induction terminates4 ,charge depends upon induction 7#aaga4 #aagh472 and if induction is related to the particles of the surrounding dielectric1 then it is related to all the particles of that dielectric inclosed by the surrounding conductors1 and not merely to the few situated next to the charged body4 ,whether the difference ,i sought for existed or not1 ,i soon found reason to doubt the conclusion that might be drawn from ,coulomb's result2 and therefore had the apparatus made1 which1 with its use1 has been already described 7#aahg1 c471 and which appears to me well-suited for the investigation of the question4 ,a ,mmoires de l',acadmie1 #aghg1 pp4 #deb1 #dec4 #abed4 ,glass1 and many bodies which might at first be considered as very fit to test the principle1 proved exceedingly unfit for that purpose4 ,glass1 principally in consequence of the alkali it contains1 however well-warmed and dried it may be1 has a certain degree of conducting power upon its surface1 dependent upon the moisture of the atmosphere1 which renders it unfit for a test experiment4 ,resin1 wax1 naphtha1 oil of turpentine1 and many other substances were in turn rejected1 because of a slight degree of conducting power possessed by them2 and ultimately shell-lac and sulphur were chosen1 after many experiments1 as the dielectrics best fitted for the investigation4 ,no difficulty can arise in perceiving how the possession of a feeble degree of conducting power tends to make a body produce effects1 which would seem to indicate that it had a greater capability of allowing induction through it than another body perfect in its insulation4 ,this source of error has been that which ,i have found most difficult to obviate in the proving experiments4 99 99 99 99 99 #abee4 ,induction through shell-lac4--,as a preparatory experiment1 ,i first ascertained generally that when a part of the surface of a thick plate of shell-lac was excited or charged1 there was no sensible difference in the character of the induction sustained by that charged part1 whether exerted through the air in the one direction1 or through the shell-lac of the plate in the other2 provided the second surface of the plate had not1 by contact with conductors1 the action of dust1 or any other means1 become charged 7#abjc474 ,its solid condition enabled it to retain the excited particles in a permanent position1 but that appeared to be all2 for these particles acted just as freely through the shell-lac on one side as through the air on the other4 ,the same general experiment was made by attaching a disc of tinfoil to one side of the shell-lac plate1 and electrifying it1 and the results were the same4 ,scarcely any other solid substance than shell-lac and sulphur1 and no liquid substance that ,i have tried1 will bear this examination4 ,glass in its ordinary state utterly fails2 yet it was essentially necessary to obtain this prior degree of perfection in the dielectric used1 before any further progress could be made in the principal investigation4 #abef4 ,shell-lac and air were compared in the first place4 ,for this purpose a thick hemispherical cup of shell-lac was introduced into the lower hemisphere of one of the inductive apparatus 7#aahg1 c471 so as nearly to fill the lower half of the space o1 o 7fig4 #ajd47 between it and the inner ball2 and then charges were divided in the manner already described 7#aaih4 #abjg471 each apparatus being used in turn to receive the first charge before its division by the other4 ,as the apparatus were known to have equal inductive power when air was in both 7#abji4 #abaa471 any differences resulting from the introduction of the shell-lac would show a peculiar action in it1 and if unequivocally referable to a specific inductive influence1 would establish the point sought to be sustained4 ,i have already referred to the precautions necessary in making the experiments 7#aaii1 c472 and with respect to the error which might be introduced by the assumption of the peculiar state1 it was guarded against1 as far as possible1 in the first place1 by operating quickly 7#abdh72 and1 afterwards1 by using that dielectric as glass or sulphur1 which assumed the peculiar state most slowly1 and in the least degree 7#abci4 #abda474 #abeg4 ,the shell-lac hemisphere was put into app4 i41 and app4 ii4 left filled with air4 ,the results of an experiment in which the charge through air was divided and reduced by the shell-lac app4 were as follows3 ,app4 i4 ,lac4 ,app4 ii4 ,air4 ,balls #bee4 #j 4 4 4 4 4 4 4 4 #cjd 4 4 4 4 #big ,charge divided4 #aac 4 4 4 4 4 4 4 4 #aba #j 4 4 4 4 after being discharged4 4 4 4 4 #g after being discharged4 #abeh4 ,here #big1 minus #g1 or #bij1 may be taken as the divisible charge of app4 ii4 7the #g being fixed stem action 7#abjc4 #abcb4771 of which #ade is the half4 ,the lac app4 i4 gave #aac as the power or tension it had acquired after division2 and the air app4 ii4 gave #aba1 minus #g1 or #aad1 as the force it possessed from what it retained of the divisible charge of #bij4 ,these two numbers should evidently be alike1 and they are very nearly so1 indeed far within the errors of experiment and observation1 but these numbers differ very much from #ade1 or the force which the half charge would have had if app4 i4 had contained air instead of shell-lac2 and it appears that whilst in the division the induction through the air has lost #agf of force1 that through the lac has only gained #aac4 #abei4 ,if this difference be assumed as depending entirely on the greater facility possessed by shell-lac of allowing or causing inductive action through its substance than that possessed by air1 then this capacity for electric induction would be inversely as the respective loss and gain indicated above2 and assuming the capacity of the air apparatus as #a1 that of the shell-lac apparatus would be #agf_/aac or #a4ee4 #abfj4 ,this extraordinary difference was so unexpected in its amount1 as to excite the greatest suspicion of the general accuracy of the experiment1 though the perfect discharge of app4 i4 after the division1 showed that the #aac had been taken and given up readily4 ,it was evident that1 if it really existed1 it ought to produce corresponding effects in the reverse order2 and that when induction through shell-lac was converted into induction through air1 the force or tension of the whole ought to be increased4 ,the app4 i4 was therefore charged in the first place1 and its force divided with app4 ii4 ,the following were the results3 ,app4 i4 ,lac4 ,app4 ii4 ,air4 4 4 4 4 #j #bae 4 4 4 4 #bjd 4 4 4 4 ,charge divided4 4 4 4 4 #aah #aah 4 4 4 4 4 4 4 4 #j after being discharged4 #j 4 4 4 4 after being discharged4 #abfa4 ,here #bjd must be the utmost of the divisible charge4 ,the app4 i4 and app4 ii4 present #aah as their respective forces2 both now much above the half of the first force1 or #ajb1 whereas in the former case they were below it4 ,the lac app4 i4 has lost only #hf1 yet it has given to the air app4 ii4 #aah1 so that the lac still appears much to surpass the air1 the capacity of the lac app4 i4 to the air app4 ii4 being as #a4cg to #a4 #abfb4 ,the difference of #a4ee and #a4cg as the expression of the capacity for the induction of shell-lac seems considerable1 but is in reality very admissible under the circumstances1 for both are in error in contrary directions4 ,thus in the last experiment the charge fell from #bae to #bjd by the joint effects of dissipation and absorption 7#aaib4 #abej471 during the time which elapsed in the electrometer operations1 between the applications of the carrier ball required to give those two results4 ,nearly an equal time must have elapsed between the application of the carrier which gave the #bjd result1 and the division of the charge between the two apparatus2 and as the fall in force progressively decreases in amount 7#aaib471 if in this case it be taken at #f only1 it will reduce the whole transferable charge at the time of division to #aih instead of #bjd2 this diminishes the loss of the shell-lac charge to #hj instead of #hf2 and then the expression of specific capacity for it is increased1 and1 instead of #a4cg1 is #a4dg times that of air4 #abfc4 ,applying the same correction to the former experiment in which air was first charged1 the result is of the contrary kind4 ,no shell-lac hemisphere was then in the apparatus1 and therefore the loss would be principally from dissipation1 and not from absorption3 hence it would be nearer to the degree of loss shown by the numbers #cjd and #big1 and being assumed as #f would reduce the divisible charge to #bhd4 ,in that case the air would have lost #agj1 and communicated only #aac to the shell-lac2 and the relative specific capacity of the latter would appear to be #a4ej1 which is very little indeed removed from #a4dg1 the expression given by the second experiment when corrected in the same way4 #abfd4 ,the shell-lac was then removed from app4 i4 and put into app4 ii4 and the experiments of division again made4 ,i give the results1 because ,i think the importance of the point justifies and even requires them4 ,app4 i4 ,air4 ,app4 ii4 ,lac4 ,balls #bjj4 4 4 4 4 #j4 #bhf 4 4 4 4 #bhc 4 4 4 4 ,charge divided4 4 4 4 4 #aaj #aji 4 4 4 4 4 4 4 4 #j4be after discharge4 ,trace 4 4 4 4 after discharge4 ,here app4 i4 retained #aji1 having lost #agd in communicating #aaj to app4 ii42 and the capacity of the air app4 is to the lac app41 therefore1 as #a to #a4eh4 ,if the divided charge be corrected for an assumed loss of only #c1 being the amount of previous loss in the same time1 it will make the capacity of the shell-lac app4 #a4ee only4 #abfe4 ,then app4 ii4 was charged1 and the charge divided thus3 ,app4 i4 ,air4 ,app4 ii4 ,lac1 #j 4 4 4 4 4 4 4 4 #bej 4 4 4 4 #bea ,charge divided4 #adf 4 4 4 4 4 4 4 4 #adi a little 4 4 4 4 after discharge4 4 4 4 4 a little after discharge4 ,here app4 i4 acquired a charge of #adf1 while app4 ii4 lost only #ajb in communicating that amount of force2 the capacities being1 therefore1 to each other as #a to #a4dc4 ,if the whole transferable charge be corrected for a loss of #d previous to division1 it gives the expression of l4#di for the capacity of the shell-lac apparatus4 #abff4 ,these four expressions of #a4dg1 #a4ej1 #a4ee1 and #a4di for the power of the shell-lac apparatus1 through the different variations of the experiment1 are very near to each other2 the average is close upon #a4e1 which may hereafter be used as the expression of the result4 ,it is a very important result2 and1 showing for this particular piece of shell-lac a decided superiority over air in allowing or causing the act of induction1 it proved the growing necessity of a more close and rigid examination of the whole question4 #abfg4 ,the shell-lac was of the best quality1 and had been carefully selected and cleaned2 but as the action of any conducting particles in it would tend1 virtually1 to diminish the quantity or thickness of the dielectric used1 and produce effects as if the two inducing surfaces of the conductors in that apparatus were nearer together than in the one with air only1 ,i prepared another shell-lac hemisphere1 of which the material had been dissolved in strong spirit of wine1 the solution filtered1 and then carefully evaporated4 ,this is not an easy operation1 for it is difficult to drive off the last portions of alcohol without injuring the lac by the heat applied2 and unless they be dissipated1 the substance left conducts too well to be used in these experiments4 ,i prepared two hemispheres this way1 one of them unexceptionable2 and with it ,i repeated the former experiments with all precautions4 ,the results were exactly of the same kind2 the following expressions for the capacity of the shell-lac apparatus1 whether it were app4 i4 or ii41 being given directly by the experiments1 #a4df1 #a4ej1 #a4eb1 #a4ea2 the average of these and several others being very nearly #a4e4 #abfh4 ,as a final check upon the general conclusion1 ,i then actually brought the surfaces of the air apparatus1 corresponding to the place of the shell-lac in its apparatus1 nearer together1 by putting a metallic lining into the lower hemisphere of the one not containing the lac 7#abac474 ,the distance of the metal surface from the carrier ball was in this way diminished from #j4fb of an inch to #j4dce of an inch1 whilst the interval occupied by the lac in the other apparatus remained ,o4#fb of an inch as before4 ,notwithstanding this change1 the lac apparatus showed its former superiority2 and whether it or the air apparatus was charged first1 the capacity of the lac apparatus to the air apparatus was by the experimental results as #a4de to #a4 #abfi4 ,from all the experiments ,i have made1 and their constant results1 ,i cannot resist the conclusion that shell-lac does exhibit a case of specific inductive capacity4 ,i have tried to check the trials in every way1 and if not remove1 at least estimate1 every source of error4 ,that the final result is not due to common conduction is shown by the capability of the apparatus to retain the communicated charge2 that it is not due to the conductive power of inclosed small particles1 by which they could acquire a polarized condition as conductors1 is shown by the effects of the shell-lac purified by alcohol2 and1 that it is not due to any influence of the charged state1 formerly described 7#abej471 first absorbing and then evolving electricity1 is indicated by the instantaneous assumption and discharge of those portions of the power which are concerned in the phenomena1 that instantaneous effect occurring in these cases1 as in all others of ordinary induction1 by charged conductors4 ,the latter argument is the more striking in the case where the air apparatus is employed to divide the charge with the lac apparatus1 for it obtains its portion of electricity in an instant1 and yet is charged far above the mean4 #abgj4 ,admitting for the present the general fact sought to be proved2 then #a4e1 though it expresses the capacity of the apparatus containing the hemisphere of shell-lac1 by no means expresses the relation of lac to air4 ,the lac only occupies one-half of the space o1 o1 of the apparatus containing it1 through which the induction is sustained2 the rest is filled with air1 as in the other apparatus2 and if the effect of the two upper halves of the globes be abstracted1 then the comparison of the shell-lac powers in the lower half of the one1 with the power of the air in the lower half of the other1 will be as #b3a2 and even this must be less than the truth1 for the induction of the upper part of the apparatus1 i4e4 of the wire and ball ,b4 7fig4 #ajd47 to external objects1 must be the same in both1 and considerably diminish the difference dependent upon1 and really producible by1 the influence of the shell-lac within4 99 99 99 99 99 #abga4 ,glass4--,i next worked with glass as the dielectric4 ,it involved the possibility of conduction on its surface1 but it excluded the idea of conducting particles within its substance 7#abfg47 other than those of its own mass4 ,besides this it does not assume the charged state 7#abci47 so readily1 or to such an extent1 as shell-lac4 #abgb4 ,a thin hemispherical cup of glass being made hot was covered with a coat of shell-lac dissolved in alcohol1 and after being dried for many hours in a hot place1 was put into the apparatus and experimented with4 ,it exhibited effects so slight1 that1 though they were in the direction indicating a superiority of glass over air1 they were allowed to pass as possible errors of experiment2 and the glass was considered as producing no sensible effect4 #abgc4 ,i then procured a thick hemispherical flint glass cup resembling that of shell-lac 7#abci471 but not filling up the space o1 o1 so well4 ,its average thickness was #j4d of an inch1 there being an additional thickness of air1 averaging #j4bb of an inch1 to make up the whole space of #j4fb of an inch between the inductive metallic surfaces4 ,it was covered with a film of shell-lac as the former was1 7#abgb47 and being made very warm1 was introduced into the apparatus1 also warmed1 and experiments made with it as in the former instances 7#abeg4 c474 ,the general results were the same as with shell-lac1 i4e4 glass surpassed air in its power of favouring induction through it4 ,the two best results as respected the state of the apparatus for retention of charge1 c41 gave1 when the air apparatus was charged first #a4ccf1 and when the glass apparatus was charged first #a4de1 as the specific inductive capacity for glass1 both being without correction4 ,the average of nine results1 four with the glass apparatus first charged1 and five with the air apparatus first charged1 gave #a4ch as the power of the glass apparatus2 #a4bb and #a4df being the minimum and maximum numbers with all the errors of experiment upon them4 ,in all the experiments the glass apparatus took up its inductive charge instantly1 and lost it as readily 7#abfi472 and during the short time of each experiment1 acquired the peculiar state in a small degree only1 so that the influence of this state1 and also of conduction upon the results1 must have been small4 #abgd4 ,allowing specific inductive capacity to be proved and active in this case1 and #a4ch as the expression for the glass apparatus1 then the specific inductive capacity of flint glass will be above #a4gf1 not forgetting that this expression is for a piece of glass of such thickness as to occupy not quite two-thirds of the space through which the induction is sustained 7#abec4 #abgc474 99 99 99 99 99 #abge4 ,sulphur4--,the same hemisphere of this substance was used in app4 ii4 as was formerly referred to 7#abdb474 ,the experiments were well made1 i4e4 the sulphur itself was free from charge both before and after each experiment1 and no action from the stem appeared 7#abjc4 #abcb471 so that no correction was required on that account4 ,the following are the results when the air apparatus was first charged and divided3 ,app4 i4 ,air1 ,app4 ii4 ,sulphur4 ,balls #bhj4 #j 4 4 4 4 4 4 4 4 #j #dch 4 4 4 4 #dcd 4 4 4 4 ,charge divided4 4 4 4 4 #afb #afd 4 4 4 4 4 4 4 4 #afj #afb 4 4 4 4 4 4 4 4 #j after discharge4 #j 4 4 4 4 after discharge4 ,here app4 i4 retained #afd1 having lost #bgf in communicating #afb to app4 ii41 and the capacity of the air apparatus is to that of the sulphur apparatus as #a to #a4ff4 #abgf4 ,then the sulphur apparatus was charged first1 thus3 4 4 4 4 #j #j 4 4 4 4 4 4 4 4 #cie 4 4 4 4 #chh ,charge divided4 #bcg 4 4 4 4 4 4 4 4 #bch #j 4 4 4 4 after discharge4 4 4 4 4 #j after discharge4 ,here app4 ii4 retained #bch1 and gave up #aej in communicating a charge of #bcg to app4 i41 and the capacity of the air apparatus is to that of the sulphur apparatus as #a to #a4eh4 ,these results are very near to each other1 and we may take the mean #a4fb as representing the specific inductive capacity of the sulphur apparatus2 in which case the specific inductive capacity of sulphur itself as compared to air #a 7#abgj47 will be about or above #b4bd4 #abgg4 ,this result with sulphur ,i consider as one of the most unexceptionable4 ,the substance when fused was perfectly clear1 pellucid1 and free from particles of dirt 7#abfg471 so that no interference of small conducting bodies confused the result4 ,the substance when solid is an excellent insulator1 and by experiment was found to take up1 with great slowness1 that state 7#abdd4 #abdb47 which alone seemed likely to disturb the conclusion4 ,the experiments themselves1 also1 were free from any need of correction4 ,yet notwithstanding these circumstances1 so favourable to the exclusion of error1 the result is a higher specific inductive capacity for sulphur than for any other body as yet tried2 and though this may in part be clue to the sulphur being in a better shape1 i4e4 filling up more completely the space o1 o1 7fig4 #ajd47 than the cups of shell-lac and glass1 still ,i feel satisfied that the experiments altogether fully prove the existence of a difference between dielectrics as to their power of favouring an inductive action through them2 which difference may1 for the present1 be expressed by the term specific inductive capacity4 #abgh4 ,having thus established the point in the most favourable cases that ,i could anticipate1 ,i proceeded to examine other bodies amongst solids1 liquids1 and gases4 ,these results ,i shall give with all convenient brevity4 99 99 99 99 99 #abgi4 ,spermaceti4--,a good hemisphere of spermaceti being tried as to conducting power whilst its two surfaces were still in contact with the tinfoil moulds used in forming it1 was found to conduct sensibly even whilst warm4 ,on removing it from the moulds and using it in one of the apparatus1 it gave results indicating a specific inductive capacity between #a4c and #a4f for the apparatus containing it4 ,but as the only mode of operation was to charge the air apparatus1 and then after a quick contact with the spermaceti apparatus1 ascertain what was left in the former 7#abha471 no great confidence can be placed in the results4 ,they are not in opposition to the general conclusion1 but cannot be brought forward as argument in favour of it4 99 99 99 99 99 #abhj4 ,i endeavoured to find some liquids which would insulate well1 and could be obtained in sufficient quantity for these experiments4 ,oil of turpentine1 native naphtha rectified1 and the condensed oil gas fluid1 appeared by common experiments to promise best as to insulation4 ,being left in contact with fused carbonate of potassa1 chloride of lime1 and quick lime for some days and then filtered1 they were found much injured in insulating power2 but after distillation acquired their best state1 though even then they proved to be conductors when extensive metallic contact was made with them4 #abha4 ,oil of turpentine rectified4--,i filled the lower half of app4 i4 with the fluid3 and as it would not hold a charge sufficiently to enable me first to measure and then divide it1 ,i charged app4 ii4 containing air1 and dividing its charge with app4 i4 by a quick contact1 measured that remaining in app4 ii43 for1 theoretically1 if a quick contact would divide up to equal tension between the two apparatus1 yet without sensible loss from the conducting power of app4 i42 and app4 ii4 were left charged to a degree of tension above half the original charge1 it would indicate that oil of turpentine had less specific inductive capacity than air2 or1 if left charged below that mean state of tension1 it would imply that the fluid had the greater inductive capacity4 ,in an experiment of this kind1 app4 ii4 gave as its charge #cij before division with app4 i41 and #age afterwards1 which is less than the half of #cij4 ,again1 being at #agf before division1 it was #gi after1 which is also less than half the divided charge4 ,being at #gi1 it was a third time divided1 and then fell to #cf1 less than the half of #gi4 ,such are the best results ,i could obtain2 they are not inconsistent with the belief that oil of turpentine has a greater specific capacity than air1 but they do not prove the fact1 since the disappearance of more than half the charge may be due to the conducting power merely of the fluid4 #abhb4 ,naphtha4--,this liquid gave results similar in their nature and direction to those with oil of turpentine4 99 99 99 99 99 #abhc4 ,a most interesting class of substances1 in relation to specific inductive capacity1 now came under review1 namely1 the gases or ariform bodies4 ,these are so peculiarly constituted1 and are bound together by so many striking physical and chemical relations1 that ,i expected some remarkable results from them3 air in various states was selected for the first experiments4 #abhd4 ,air1 rare and dense4--,some experiments of division 7#abjh47 seemed to show that dense and rare air were alike in the property under examination4 ,a simple and better process was to attach one of the apparatus to an air-pump1 to charge it1 and then examine the tension of the charge when the air within was more or less rarefied4 ,under these circumstances it was found1 that commencing with a certain charge1 that charge did not change in its tension or force as the air was rarefied1 until the rarefaction was such that discharge across the space o1 o 7fig4 #ajd47 occurred4 ,this discharge was proportionate to the rarefaction2 but having taken place1 and lowered the tension to a certain degree1 that degree was not at all affected by restoring the pressure and density of the air to their first quantities4 inches of mercury4 ,thus at a pressure of #cj the charge was #hh ,again #cj the charge was #hh ,again #cj the charge was #hg ,reduced to #aa the charge was #hg ,raised again to #cj the charge was #hf ,being now reduced to #c4d the charge fell to #ha ,raised again to #cj the charge was still #ha #abhe4 ,the charges were low in these experiments1 first that they might not pass off at low pressure1 and next that little loss by dissipation might occur4 ,i now reduced them still lower1 that ,i might rarefy further1 and for this purpose in the following experiment used a measuring interval in the electrometer of only #ae 7#aahe474 ,the pressure of air within the apparatus being reduced to #a4i inches of mercury1 the charge was found to be #bi2 then letting in air till the pressure was #cj inches1 the charge was still #bi4 #abhf4 ,these experiments were repeated with pure oxygen with the same consequences4 #abhg4 ,this result of no variation in the electric tension being produced by variation in the density or pressure of the air1 agrees perfectly with those obtained by ,mr4 ,harris,a1 and described in his beautiful and important investigations contained in the ,philosophical ,transactions2 namely that induction is the same in rare and dense air1 and that the divergence of an electrometer under such variations of the air continues the same1 provided no electricity pass away from it4 ,the effect is one entirely independent of that power which dense air has of causing a higher charge to be retained upon the surface of conductors in it than can be retained by the same conductors in rare air2 a point ,i propose considering hereafter4 ,a ,philosophical ,transactions1 #ahcd1 pp4 #bbc1 #bbd1 #bcg1 #bdd4 #abhh4 ,i then compared hot and cold air together1 by raising the temperature of one of the inductive apparatus as high as it could be without injury1 and then dividing charges between it and the other apparatus containing cold air4 ,the temperatures were about #ej and #bjj1 ,still the power or capacity appeared to be unchanged2 and when ,i endeavoured to vary the experiment1 by charging a cold apparatus and then warming it by a spirit lamp1 ,i could obtain no proof that the inductive capacity underwent any alteration4 #abhi4 ,i compared damp and dry air together1 but could find no difference in the results4 99 99 99 99 99 #abij4 ,gases4--,a very long series of experiments was then undertaken for the purpose of comparing different gases one with another4 ,they were all found to insulate well1 except such as acted on the shell-lac of the supporting stem2 these were chlorine1 ammonia1 and muriatic acid4 ,they were all dried by appropriate means before being introduced into the apparatus4 ,it would have been sufficient to have compared each with air2 but1 in consequence of the striking result which came out1 namely1 that all had the same power of or capacity for1 sustaining induction through them1 7which perhaps might have been expected after it was found that no variation of density or pressure produced any effect17 ,i was induced to compare them1 experimentally1 two and two in various ways1 that no difference might escape me1 and that the sameness of result might stand in full opposition to the contrast of property1 composition1 and condition which the gases themselves presented4 #abia4 ,the experiments were made upon the following pairs of gases4 #a4 ,nitrogen and ,oxygen4 #b4 ,oxygen ,air4 #c4 ,hydrogen ,air4 #d4 ,muriatic acid gas ,air4 #e4 ,oxygen ,hydrogen4 #e4 ,oxygen ,carbonic acid4 #g4 ,oxygen ,olefiant gas4 #h4 ,oxygen ,nitrous gas4 #i4 ,oxygen ,sulphurous acid4 #aj4 ,oxygen ,ammonia4 #aa4 ,hydrogen ,carbonic acid4 #ab ,hydrogen ,olefiant gas4 #ac4 ,hydrogen ,sulphurous acid4 #ad4 ,hydrogen ,fluo-silicic acid4 #ae4 ,hydrogen ,ammonia4 #af1 ,hydrogen ,arseniuretted hydrogen4 #ag4 ,hydrogen ,sulphuretted hydrogen4 #ah1 ,nitrogen ,olefiant gas4 #ai4 ,nitrogen ,nitrous gas4 #bj4 ,nitrogen ,nitrous oxide4 #ba4 ,nitrogen ,ammonia4 #bb4 ,carbonic oxide ,carbonic acid4 #bc4 ,carbonic oxide ,olefiant gas4 #bd4 ,nitrous oxide ,nitrous gas4 #be4 ,ammonia ,sulphurous acid4 #abib4 ,notwithstanding the striking contrasts of all kinds which these gases present of property1 of density1 whether simple or compound1 anions or cations 7#ffe471 of high or low pressure 7#abhd4 #abhf471 hot or cold 7#abhh471 not the least difference in their capacity to favour or admit electrical induction through them could be perceived4 ,considering the point established1 that in all these gases induction takes place by an action of contiguous particles1 this is the more important1 and adds one to the many striking relations which hold between bodies having the gaseous condition and form4 ,another equally important electrical relation1 which will be examined in the next paper,a1 is that which the different gases have to each other at the same pressure of causing the retention of the same or different degrees of charge upon conductors in them4 ,these two results appear to bear importantly upon the subject of electrochemical excitation and decomposition2 for as all these phenomena1 different as they seem to be1 must depend upon the electrical forces of the particles of matter1 the very distance at which they seem to stand from each other will do much1 if properly considered1 to illustrate the principle by which they are held in one common bond1 and subject1 as they must be1 to one common law4 ,a ,see in relation to this point #achb4 c4--,dec4 #ahch4 #abic4 ,it is just possible that the gases may differ from each other in their specific inductive capacity1 and yet by quantities so small as not to be distinguished in the apparatus ,i have used4 ,it must be remembered1 however1 that in the gaseous experiments the gases occupy all the space o1 o1 7fig4 #ajd47 between the inner and the outer ball1 except the small portion filled by the stem2 and the results1 therefore1 are twice as delicate as those with solid dielectrics4 #abid4 ,the insulation was good in all the experiments recorded1 except ,nos4 #aj1 #ae1 #ba1 and #be1 being those in which ammonia was compared with other gases4 ,when shell-lac is put into ammoniacal gas its surface gradually acquires conducting power1 and in this way the lac part of the stem within was so altered1 that the ammonia apparatus could not retain a charge with sufficient steadiness to allow of division4 ,in these experiments1 therefore1 the other apparatus was charged2 its charge measured and divided with the ammonia apparatus by a quick contact1 and what remained untaken away by the division again measured 7#abha474 ,it was so nearly one-half of the original charge1 as to authorize1 with this reservation1 the insertion of ammoniacal gas amongst the other gases1 as having equal power with them4 vi4 ,general results as to induction4 #abie4 ,thus induction appears to be essentially an action of contiguous particles1 through the intermediation of which the electric force1 originating or appearing at a certain place1 is propagated to or sustained at a distance1 appearing there as a force of the same kind exactly equal in amount1 but opposite in its direction and tendencies 7#aafd474 ,induction requires no sensible thickness in the conductors which may be used to limit its extent2 an uninsulated leaf of gold may be made very highly positive on one surface1 and as highly negative on the other1 without the least interference of the two states whilst the inductions continue4 ,nor is it affected by the nature of the limiting conductors1 provided time be allowed1 in the case of those which conduct slowly1 for them to assume their final state 7#aagj474 #abif4 ,but with regard to the dielectrics or insulating media1 matters are very different 7#aafg474 ,their thickness has an immediate and important influence on the degree of induction4 ,as to their quality1 though all gases and vapours are alike1 whatever their state2 yet amongst solid bodies1 and between them and gases1 there are differences which prove the existence of specific inductive capacities1 these differences being in some cases very great4 #abig4 ,the direct inductive force1 which may be conceived to be exerted in lines between the two limiting and charged conducting surfaces1 is accompanied by a lateral or transverse force equivalent to a dilatation or repulsion of these representative lines 7#abbd472 or the attractive force which exists amongst the particles of the dielectric in the direction of the induction is accompanied by a repulsive or a diverging force in the transverse direction 7#acjd474 #abih4 ,induction appears to consist in a certain polarized state of the particles1 into which they are thrown by the electrified body sustaining the action1 the particles assuming positive and negative points or parts1 which are symmetrically arranged with respect to each other and the inducting surfaces or particles,a4 ,the state must be a forced one1 for it is originated and sustained only by force1 and sinks to the normal or quiescent state when that force is removed4 ,it can be continued only in insulators by the same portion of electricity1 because they only can retain this state of the particles 7#acjd74 ,a ,the theory of induction which ,i am stating does not pretend to decide whether electricity be a fluid or fluids1 or a mere power or condition of recognized matter4 ,that is a question which ,i may be induced to consider in the next or following series of these researches4 #abii4 ,the principle of induction is of the utmost generality in electric action4 ,it constitutes charge in every ordinary case1 and probably in every case2 it appears to be the cause of all excitement1 and to precede every current4 ,the degree to which the particles are affected in this their forced state1 before discharge of one kind or another supervenes1 appears to constitute what we call intensity4 #acjj4 ,when a ,leyden jar is charged1 the particles of the glass are forced into this polarized and constrained condition by the electricity of the charging apparatus4 ,discharge is the return of these particles to their natural state from their state of tension1 whenever the two electric forces are allowed to be disposed of in some other direction4 #acja4 ,all charge of conductors is on their surface1 because being essentially inductive1 it is there only that the medium capable of sustaining the necessary inductive state begins4 ,if the conductors are hollow and contain air or any other dielectric1 still no charge can appear upon that internal surface1 because the dielectric there cannot assume the polarized state throughout1 in consequence of the opposing actions in different directions4 #acjb4 ,the known influence of form is perfectly consistent with the corpuscular view of induction set forth4 ,an electrified cylinder is more affected by the influence of the surrounding conductors 7which complete the condition of charge7 at the ends than at the middle1 because the ends are exposed to a greater sum of inductive forces than the middle2 and a point is brought to a higher condition than a ball1 because by relation to the conductors around1 more inductive force terminates on its surface than on an equal surface of the ball with which it is compared4 ,here too1 especially1 can be perceived the influence of the lateral or transverse force 7#abig471 which1 being a power of the nature of or equivalent to repulsion1 causes such a disposition of the lines of inductive force in their course across the dielectric1 that they must accumulate upon the point1 the end of the cylinder1 or any projecting part4 #acjc4 ,the influence of distance is also in harmony with the same view4 ,there is perhaps no distance so great that induction cannot take place through it,a2 but with the same constraining force 7#abih47 it takes place the more easily1 according as the extent of dielectric through which it is exerted is lessened4 ,and as it is assumed by the theory that the particles of the dielectric1 though tending to remain in a normal state1 are thrown into a forced condition during the induction2 so it would seem to follow that the fewer there are of these intervening particles opposing their tendency to the assumption of the new state1 the greater degree of change will they suffer1 i4e4 the higher will be the condition they assume1 and the larger the amount of inductive action exerted through them4 ,a ,i have traced it experimentally from a ball placed in the middle of the large cube formerly described 7#aagc47 to the sides of the cube six feet distant1 and also from the same ball placed in the middle of our large lecture-room to the walls of the room at twenty-six feet distance1 the charge sustained upon the ball in these cases being solely due to induction through these distances4 #acjd4 ,i have used the phrases lines of inductive force and curved lines of force 7#abca4 #abig4 #abih4 #acjb47 in a general sense only1 just as we speak of the lines of magnetic force4 ,the lines are imaginary1 and the force in any part of them is of course the resultant of compound forces1 every molecule being related to every other molecule in all directions by the tension and reaction of those which are contiguous4 ,the transverse force is merely this relation considered in a direction oblique to the lines of inductive force1 and at present ,i mean no more than that by the phrase4 ,with respect to the term polarity also1 ,i mean at present only a disposition of force by which the same molecule acquires opposite powers on different parts4 ,the particular way in which this disposition is made will come into consideration hereafter1 and probably varies in different bodies1 and so produces variety of electrical relation,a4 ,all ,i am anxious about at present is1 that a more particular meaning should not be attached to the expressions used than ,i contemplate4 ,further inquiry1 ,i trust1 will enable us by degrees to restrict the sense more and more1 and so render the explanation of electrical phenomena day by day more and more definite4 ,a ,see now #afhe4 c4--,dec4 #ahch4 #acje4 ,as a test of the probable accuracy of my views1 ,i have throughout this experimental examination compared them with the conclusions drawn by ,m4 ,poisson from his beautiful mathematical inquiries,a4 ,i am quite unfit to form a judgment of these admirable papers2 but as far as ,i can perceive1 the theory ,i have set forth and the results ,i have obtained are not in opposition to such of those conclusions as represent the final disposition and state of the forces in the limited number of cases be has considered4 ,his theory assumes a very different mode of action in induction to that which ,i have ventured to support1 and would probably find its mathematical test in the endeavour to apply it to cases of induction in curved lines4 ,to my feeling it is insufficient in accounting for the retention of electricity upon the surface of conductors by the pressure of the air1 an effect which ,i hope to show is simple and consistent according to the present view,b2 and it does not touch voltaic electricity1 or in any way associate it and what is called ordinary electricity under one common principle4 ,a ,mmoires de ,l',institut1 #ahaa1 tom4 xii4 the first page #a1 and the second paging #afc4 ,b ,refer to #acgg1 #acgh1 #acgi1 #acih4--;,dec4 #ahch4 ,i have also looked with some anxiety to the results which that indefatigable philosopher ,harris has obtained in his investigation of the laws of induction,a1 knowing that they were experimental1 and having a full conviction of their exactness2 but ,i am happy in perceiving no collision at present between them and the views ,i have taken4 ,a ,philosophical ,transactions1 #ahcd1 p4 #bac4 #acjf4 ,finally1 ,i beg to say that ,i put forth my particular view with doubt and fear1 lest it should not bear the test of general examination1 for unless true it will only embarrass the progress of electrical science4 ,it has long been on my mind1 but ,i hesitated to publish it until the increasing persuasion of its accordance with all known facts1 and the manner in which it linked together effects apparently very different in kind1 urged me to write the present paper4 ,i as yet see no inconsistency between it and nature1 but1 on the contrary1 think ,i perceive much new light thrown by it on her operations2 and my next papers will be devoted to a review of the phenomena of conduction1 electrolyzation1 current1 magnetism1 retention1 discharge1 and some other points1 with an application of the theory to these effects1 and an examination of it by them4 ,royal ,institution1 ,november #af1 #ahcg4 99 99 99 99 99 ,supplementary ,note to ,experimental ,researches in ,electricity4 ,eleventh ,series4 ,received ,march #bi1 #ahch4 #acjg4 ,i have recently put into an experimental form that general statement of the question of specific inductive capacity which is given at ,no4 #abeb of ,series ,,xi41 and the result is such as to lead me to hope the ,council of the ,royal ,society will authorize its addition to the paper in the form of a supplementary note4 ,three circular brass plates1 about five inches in diameter1 were mounted side by side upon insulating pillars2 the middle one1 ,a1 was a fixture1 but the outer plates ,b and ,c were moveable on slides1 so that all three could be brought with their sides almost into contact1 or separated to any required distance4 ,two gold leaves were suspended in a glass jar from insulated wires2 one of the outer plates ,b was connected with one of the gold leaves1 and the other outer plate with the other leaf4 ,the outer plates ,b and ,c were adjusted at the distance of an inch and a quarter from the middle plate ,a1 and the gold leaves were fixed at two inches apart2 ,a was then slightly charged with electricity1 and the plates ,b and ,c1 with their gold leaves1 thrown out of insulation at the same time1 and then left insulated4 ,in this state of things ,a was charged positive inductrically1 and ,b and ,c negative inducteously2 the same dielectric1 air1 being in the two intervals1 and the gold leaves hanging1 of course1 parallel to each other in a relatively unelectrified state4 #acjh4 ,a plate of shell-lac three-quarters of an inch in thickness1 and four inches square1 suspended by clean white silk thread1 was very carefully deprived of all charge 7#abjc47 7so that it produced no effect on the gold leaves if ,a were uncharged7 and then introduced between plates ,a and ,b2 the electric relation of the three plates was immediately altered1 and the gold leaves attracted each other4 ,on removing the shell-lac this attraction ceased2 on introducing it between ,a and ,c it was renewed2 on removing it the attraction again ceased2 and the shell-lac when examined by a delicate ,coulomb electrometer was still without charge4 #acji4 ,as ,a was positive1 ,b and ,c were of course negative2 but as the specific inductive capacity of shell-lac is about twice that of air 7#abgj471 it was expected that when the lac was introduced between ,a and ,b1 ,a would induce more towards ,b than towards ,c2 that therefore ,b would become more negative than before towards ,a1 and consequently1 because of its insulated condition1 be positive externally1 as at its back or at the gold leaves2 whilst ,c would be less negative towards ,a1 and therefore negative outwards or at the gold leaves4 ,this was found to be the case2 for on whichever side of ,a the shell-lac was introduced the external plate at that side was positive1 and the external plate on the other side negative towards each other1 and also to uninsulated external bodies4 #acaj4 ,on employing a plate of sulphur instead of shell-lac1 the same results were obtained2 consistent with the conclusions drawn regarding the high specific inductive capacity of that body already given 7#abgf474 #acaa4 ,these effects of specific inductive capacity can be exalted in various ways1 and it is this capability which makes the great value of the apparatus4 ,thus ,i introduced the shell-lac between ,a and ,b1 and then for a moment connected ,b and ,c1 uninsulated them1 and finally left them in the insulated state2 the gold leaves were of course hanging parallel to each other4 ,on removing the shell-lac the gold leaves attracted each other2 on introducing the shell-lac between ,a and ,c this attraction was increased1 7as had been anticipated from theory17 and the leaves came together1 though not more than four inches long1 and hanging three inches apart4 #acab4 ,by simply bringing the gold leaves nearer to each other ,i was able to show the difference of specific inductive capacity when only thin plates of shell-lac were used1 the rest of the dielectric space being filled with air4 ,by bringing ,b and ,c nearer to ,a another great increase of sensibility was made4 ,by enlarging the size of the plates still further power was gained4 ,by diminishing the extent of the wires1 c4 connected with the gold leaves1 another improvement resulted4 ,so that in fact the gold leaves became1 in this manner1 as delicate a test of specific inductive action as they are1 in ,bennet's and ,singer's electrometers1 of ordinary electrical charge4 #acac4 ,it is evident that by making the three plates the sides of cells1 with proper precautions as regards insulation1 c41 this apparatus may be used in the examination of gases1 with far more effect than the former apparatus 7#aahg4 #abij71 and may1 perhaps1 bring out differences which have as yet escaped me 7#abib4 #abic47 #acad4 ,it is also evident that two metal plates are quite sufficient to form the instrument2 the state of the single inducteous plate when the dielectric is changed1 being examined either by bringing a body excited in a known manner towards its gold leaves1 or1 what ,i think will be better1 employing a carrier ball in place of the leaf1 and examining that ball by the ,coulomb electrometer 7#aahj474 ,the inductive and inducteous surfaces may even be balls2 the latter being itself the carrier ball of the ,coulomb's electrometer 7#aaha4 #abbi474 #acae4 ,to increase the effect1 a small condenser may be used with great advantage4 ,thus if1 when two inducteous plates are used1 a little condenser were put in the place of the gold leaves1 ,i have no doubt the three principal plates might be reduced to an inch or even half an inch in diameter4 ,even the gold leaves act to each other for the time as the plates of a condenser4 ,if only two plates were used1 by the proper application of the condenser the same reduction might take place4 ,this expectation is fully justified by an effect already observed and described 7#abbi474 #acaf4 ,in that case the application of the instrument to very extensive research is evident4 ,comparatively small masses of dielectrics could be examined1 as diamonds and crystals4 ,an expectation1 that the specific inductive capacity of crystals will vary in different directions1 according as the lines of inductive force 7#acjd47 are parallel to1 or in other positions in relation to the axes of the crystals1 can be tested,a3 ,i purpose that these and many other thoughts which arise respecting specific inductive action and the polarity of the particles of dielectric matter1 shall be put to the proof as soon as ,i can find time4 ,a ,refer for this investigation to #afhj-afih4--;,dec4 #ahch4 #acag4 ,hoping that this apparatus will form an instrument of considerable use1 ,i beg to propose for it 7at the suggestion of a friend7 the name of ,differential ,inductometer4 ,royal ,institution1 ,march #bi1 #ahch4 ,,twelfth ,,series4 #ah4 ,on ,induction 7continued74 vii4 ,conduction1 or conductive discharge4 viii4 ,electrolytic discharge4 ix4 ,disruptive discharge--,insulation--,spark--,brush-- ,difference of discharge at the positive and negative surfaces of conductors4 ,received ,january #aa1--,read ,february #h1 #ahch4 #acah4 ,i ,proceed now1 according to my promise1 to examine1 by the great facts of electrical science1 that theory of induction which ,i have ventured to put forth 7#aafe4 #abie4 c474 ,the principle of induction is so universal that it pervades all electrical phenomena2 but the general case which ,i purpose at present to go into consists of insulation traced into and terminating with discharge1 with the accompanying effects4 ,this case includes the various modes of discharge1 and also the condition and characters of a current2 the elements of magnetic action being amongst the latter4 ,i shall necessarily have occasion to speak theoretically1 and even hypothetically2 and though these papers profess to be experimental researches1 ,i hope that1 considering the facts and investigations contained in the last series in support of the particular view advanced1 ,i shall not be considered as taking too much liberty on the present occasion1 or as departing too far from the character which they ought to have1 especially as ,i shall use every opportunity which presents itself of returning to that strong test of truth1 experiment4 #acai4 ,induction has as yet been considered in these papers only in cases of insulation2 opposed to insulation is discharge4 ,the action or effect which may be expressed by the general term discharge1 may take place1 as far as we are aware at present1 in several modes4 ,thus1 that which is called simply conduction involves no chemical action1 and apparently no displacement of the particles concerned4 ,a second mode may be called electrolytic discharge2 in it chemical action does occur1 and particles must1 to a certain degree1 be displaced4 ,a third mode1 namely1 that by sparks or brushes1 may1 because of its violent displacement of the particles of the dielectric in its course1 be called the disruptive discharge2 and a fourth may1 perhaps1 be conveniently distinguished for a time by the words convection1 or carrying discharge1 being that in which discharge is effected either by the carrying power of solid particles1 or those of gases and liquids4 ,hereafter1 perhaps1 all these modes may appear as the result of one common principle1 but at present they require to be considered apart2 and ,i will now speak of the first mode1 for amongst all the forms of discharge1 that which we express by the term conduction appears the most simple and the most directly in contrast with insulation4 vii4 ,conduction1 or conductive discharge4 #acbj4 ,though assumed to be essentially different1 yet neither ,cavendish nor ,poisson attempt to explain by1 or even state in1 their theories1 what the essential difference between insulation and conduction is4 ,nor have ,i anything1 perhaps1 to offer in this respect1 except that1 according to my view of induction1 insulation and conduction depend upon the same molecular action of the dielectrics concerned2 are only extreme degrees of one common condition or effect2 and in any sufficient mathematical theory of electricity must be taken as cases of the same kind4 ,hence the importance of the endeavour to show the connection between them under my theory of the electrical relations of contiguous particles4 #acba4 ,though the action of the insulating dielectric in the charged ,leyden jar1 and that of the wire in discharging it1 may seem very different1 they may be associated by numerous intermediate links1 which carry us on from one to the other1 leaving1 ,i think1 no necessary connection unsupplied4 ,we may observe some of these in succession for information respecting the whole case4 #acbb4 ,spermnceti has been examined and found to be a dielectric1 through which induction can take place 7#abdj4 #abdf471 its specific inductive capacity being about or above #a4h 7#abgi471 and the inductive action has been considered in it1 as in all other substances1 an action of contiguous particles4 #acbc4 ,but spermaceti is also a conductor1 though in so low a degree that we can trace the process of conduction1 as it were1 step by step through the mass 7#abdg472 and even when the electric force has travelled through it to a certain distance1 we can1 by removing the coercitive 7which is at the same time the inductive7 force1 cause it to return upon its path and reappear in its first place 7#abde4 #abdf474 ,here induction appears to be a necessary preliminary to conduction4 ,it of itself brings the contiguous particles of the dielectric into a certain condition1 which1 if retained by them1 constitutes insulation1 but if lowered by the communication of power from one particle to another1 constitutes conduction4 #acbd4 ,if glass or shell-lac be the substances under consideration1 the same capabilities of suffering either induction or conduction through them appear 7#abcc4 #abci4 #abdg471 but not in the same degree4 ,the conduction almost disappears 7#abci4 #abdb472 the induction therefore is sustained1 i4e4 the polarized state into which the inductive force has brought the contiguous particles is retained1 there being little discharge action between them1 and therefore the insulation continues4 ,but1 what discharge there is1 appears to be consequent upon that condition of the particles into which the induction throws them2 and thus it is that ordinary insulation and conduction are closely associated together or rather are extreme cases of one common condition4 #acbe4 ,in ice or water we have a better conductor than spermaceti1 and the phenomena of induction and insulation therefore rapidly disappear1 because conduction quickly follows upon the assumption of the inductive state4 ,but let a plate of cold ice have metallic coatings on its sides1 and connect one of these with a good electrical machine in work1 and the other with the ground1 and it then becomes easy to observe the phenomena of induction through the ice1 by the electrical tension which can be obtained and continued on both the coatings 7#dai4 #dbf474 ,for although that portion of power which at one moment gave the inductive condition to the particles is at the next lowered by the consequent discharge due to the conductive act1 it is succeeded by another portion of force from the machine to restore the inductive state4 ,if the ice be converted into water the same succession of actions can be just as easily proved1 provided the water be distilled1 and 7if the machine be not powerful enough7 a voltaic battery be employed4 #acbf4 ,all these considerations impress my mind strongly with the conviction1 that insulation and ordinary conduction cannot be properly separated when we are examining into their nature2 that is1 into the general law or laws under which their phenomena are produced4 ,they appear to me to consist in an action of contiguous particles dependent on the forces developed in electrical excitement2 these forces bring the particles into a state of tension or polarity1 which constitutes both induction and insulation2 and being in this state1 the continuous particles have a power or capability of communicating their forces one to the other1 by which they are lowered1 and discharge occurs4 ,every body appears to discharge 7#ddd4 #ihg472 but the possession of this capability in a greater or smaller degree in different bodies1 makes them better or worse conductors1 worse or better insulators2 and both induction and conduction appear to be the same in their principle and action 7#acbj471 except that in the latter an effect common to both is raised to the highest degree1 whereas in the former it occurs in the best cases1 in only an almost insensible quantity4 #acbg4 ,that in our attempts to penetrate into the nature of electrical action1 and to deduce laws more general than those we are at present acquainted with1 we should endeavour to bring apparently opposite effects to stand side by side in harmonious arrangement1 is an opinion of long standing1 and sanctioned by the ablest philosophers4 ,i hope1 therefore1 ,i may be excused the attempt to look at the highest cases of conduction as analogous to1 or even the same in kind with1 those of induction and insulation4 #acbh4 ,if we consider the slight penetration of sulphur 7#abda4 #abdb47 or shell-lac 7#abcd47 by electricity1 or the feebler insulation sustained by spermaceti 7#abgi4 #abdj471 as essential consequences and indications of their conducting power1 then may we look on the resistance of metallic wires to the passage of electricity through them as insulating power4 ,of the numerous well-known cases fitted to show this resistance in what are called the perfect conductors1 the experiments of ,professor ,wheatstone best serve my present purpose1 since they were carried to such an extent as to show that time entered as an element into the conditions of conduction,a even in metals4 ,when discharge was made through a copper wire #bfdj feet in length1 and #a_/aeth of an inch in diameter1 so that the luminous sparks at each end of the wire1 and at the middle1 could be observed in the same place1 the latter was found to be sensibly behind the two former in time1 they being by the conditions of the experiment simultaneous4 ,hence a proof of retardation2 and what reason can be given why this retardation should not be of the same kind as that in spermaceti1 or in lac1 or sulphur8 ,but as1 in them1 retardation is insulation1 and insulation is induction1 why should we refuse the same relation to the same exhibitions of force in the metals8 ,a ,philosophical ,transactions1 #ahcd1 p4 #ehc4 #acbi4 ,we learn from the experiment1 that if time be allowed the retardation is gradually overcome2 and the same thing obtains for the spermaceti1 the lac1 and glass 7#abdh472 give but time in proportion to the retardation1 and the latter is at last vanquished4 ,but if that be the case1 and all the results are alike in kind1 the only difference being in the length of time1 why should we refuse to metals the previous inductive action1 which is admitted to occur in the other bodies8 ,the diminution of time is no negation of the action2 nor is the lower degree of tension requisite to cause the forces to traverse the metal1 as compared to that necessary in the cases of water1 spermaceti1 or lac4 ,these differences would only point to the conclusion1 that in metals the particles under induction can transfer their forces when at a lower degree of tension or polarity1 and with greater facility than in the instances of the other bodies4 #accj4 ,let us look at ,mr4 ,wheatstone's beautiful experiment in another point of view1 ,if1 leaving the arrangement at the middle and two ends of the long copper wire unaltered1 we remove the two intervening portions and replace them by wires of iron or platina1 we shall have a much greater retardation of the middle spark than before4 ,if1 removing the iron1 we were to substitute for it only five or six feet of water in a cylinder of the same diameter as the metal1 we should have still greater retardation4 ,if from water we passed to spermaceti1 either directly or by gradual steps through other bodies1 7even though we might vastly enlarge the bulk1 for the purpose of evading the occurrence of a spark elsewhere 7#acca47 than at the three proper intervals17 we should have still greater retardation1 until at last we might arrive1 by degrees so small as to be inseparable from each other1 at actual and permanent insulation4 ,what1 then1 is to separate the principle of these two extremes1 perfect conduction and perfect insulation1 from each other2 since the moment we leave in the smallest degree perfection at either extremity1 we involve the element of perfection at the opposite end8 ,especially too1 as we have not in nature the case of perfection either at one extremity or the other1 either of insulation or conduction4 #acca4 ,again1 to return to this beautiful experiment in the various forms which may be given to it3 the forces are not all in the wire 7after they have left the ,leyden jar7 during the whole time 7#acbh47 occupied by the discharge2 they are disposed in part through the surrounding dielectric under the well-known form of induction2 and if that dielectric be air1 induction takes place from the wire through the air to surrounding conductors1 until the ends of the wire are electrically related through its length1 and discharge has occurred1 i4e4 for the time during which the middle spark is retarded beyond the others4 ,this is well shown by the old experiment1 in which a long wire is so bent that two parts 7,plate ,,viii4 fig4 #aae471 a1 b1 near its extremities shall approach within a short distance1 as a quarter of an inch1 of each other in the air4 ,if the discharge of a ,leyden jar1 charged to a sufficient degree1 be sent through such a wire1 by far the largest portion of the electricity will pass as a spark across the air at the interval1 and not by the metal4 ,does not the middle part of the wire1 therefore1 act here as an insulating medium1 though it be of metal8 and is not the spark through the air an indication of the tension 7simultaneous with induction7 of the electricity in the ends of this single wire8 ,why should not the wire and the air both be regarded as dielectrics2 and the action at its commencement1 and whilst there is tension1 as an inductive action8 ,if it acts through the contorted lines of the wire1 so it also does in curved and contorted lines through air 7#abai1 #abbd1 #abca471 and other insulating dielectrics 7#abbh72 and we can apparently go so far in the analogy1 whilst limiting the case to the inductive action only1 as to show that amongst insulating dielectrics some lead away the lines of force from others 7#abbi471 as the wire will do from worse conductors1 though in it the principal effect is no doubt due to the ready discharge between the particles whilst in a low state of tension4 ,the retardation is for the time insulation2 and it seems to me we may just as fairly compare the air at the interval a1 b 7fig4 #aae47 and the wire in the circuit1 as two bodies of the same kind and acting upon the same principles1 as far as the first inductive phenomena are concerned1 notwithstanding the different forms of discharge which ultimately follow,a1 as we may compare1 according to ,coulomb's investigations,b different lengths of different insulating bodies required to produce the same amount of insulating effect4 ,a ,these will be examined hereafter 7#acdh4 c474 ,b ,mmoires de l',acadmie1 #aghe1 p4 #fab4 or ,ency4 ,britann4 ,first ,supp4 vol4 i4 p4 #fad4 #accb4 ,this comparison is still more striking when we take into consideration the experiment of ,mr4 ,harris1 in which he stretched a fine wire across a glass globe1 the air within being rarefied,a4 ,on sending a charge through the joint arrangement of metal and rare air1 as much1 if not more1 electricity passed by the latter as by the former4 ,in the air1 rarefied as it was1 there can be no doubt the discharge was preceded by induction 7#abhd472 and to my mind all the circumstances indicate that the same was the case with the metal2 that1 in fact1 both substances are dielectrics1 exhibiting the same effects in consequence of the action of the same causes1 the only variation being one of degree in the different substances employed4 ,a ,philosophical ,transactions1 #ahcd1 p1 #bab4 #accc4 ,judging on these principles1 velocity of discharge through the same wire may be varied greatly by attending to the circumstances which cause variations of discharge through spermaceti or sulphur4 ,thus1 for instance1 it must vary with the tension or intensity of the first urging force 7#abcd4 #abdj471 which tension is charge and induction4 ,so if the two ends of the wire1 in ,professor ,wheatstone's experiment1 were immediately connected with two large insulated metallic surfaces exposed to the air1 so that the primary act of induction1 after making the contact for discharge1 might be in part removed from the internal portion of the wire at the first instant1 and disposed for the moment on its surface jointly with the air and surrounding conductors1 then ,i venture to anticipate that the middle spark would be more retarded than before2 and if these two plates were the inner and outer coating of a large jar or a ,leyden battery1 then the retardation of that spark would be still greater4 #accd4 ,cavendish was perhaps the first to show distinctly that discharge was not always by one channel,a1 but1 if several are present1 by many at once4 ,we may make these different channels of different bodies1 and by proportioning their thicknesses and lengths1 may include such substances as air1 lac1 spermaceti1 water1 protoxide of iron1 iron and silver1 and by one discharge make each convey its proportion of the electric force4 ,perhaps the air ought to be excepted1 as its discharge by conduction is questionable at present 7#accf472 but the others may all be limited in their mode of discharge to pure conduction4 ,yet several of them suffer previous induction1 precisely like the induction through the air1 it being a necessary preliminary to their discharging action4 ,how can we therefore separate any one of these bodies from the others1 as to the principles and mode of insulating and conducting1 except by mere degree8 ,all seem to me to be dielectrics acting alike1 and under the same common laws4 ,a ,philosophical ,transactions1 #aggf1 p4 #aig4 #acce4 ,i might draw another argument in favour of the general sameness1 in nature and action1 of good and bad conductors 7and all the bodies ,i refer to are conductors more or less71 from the perfect equipoise in action of very different bodies when opposed to each other in magneto-electric inductive action1 as formerly described 7#bac471 but am anxious to be as brief as is consistent with the clear examination of the probable truth of my views4 #accf4 ,with regard to the possession by the gases of any conducting power of the simple kind now under consideration1 the question is a very difficult one to determine at present4 ,experiments seem to indicate that they do insulate certain low degrees of tension perfectly1 and that the effects which may have appeared to be occasioned by conduction have been the result of the carrying power of the charged particles1 either of the air or of dust1 in it4 ,it is equally certain1 however1 that with higher degrees of tension or charge the particles discharge to one another1 and that is conduction4 ,if the gases possess the power of insulating a certain low degree of tension continuously and perfectly1 such a result may be due to their peculiar physical state1 and the condition of separation under which their particles are placed4 ,but in that1 or in any case1 we must not forget the fine experiments of ,cagniard de la ,tour,a1 in which he has shown that liquids and their vapours can be made to pass gradually into each other1 to the entire removal of any marked distinction of the two states4 ,thus1 hot dry steam and cold water pass by insensible gradations into each other2 yet the one is amongst the gases as an insulator1 and the other a comparatively good conductor4 ,as to conducting power1 therefore1 the transition from metals even up to gases is gradual2 substances make but one series in this respect1 and the various cases must come under one condition and law 7#ddd474 ,the specific differences of bodies as to conducting power only serves to strengthen the general argument1 that conduction1 like insulation1 is a result of induction1 and is an action of contiguous particles4 ,a ,annales de ,chimie1 xxi4 pp4 #abg1 #agh1 or ,quarterly ,journal of ,science1 xv4 #ade4 #accg4 ,i might go on now to consider induction and its concomitant1 conduction1 through mixed dielectrics1 as1 for instance1 when a charged body1 instead of acting across air to a distant uninsulated conductor1 acts jointly through it and an interposed insulated conductor4 ,in such a case1 the air and the conducting body are the mixed dielectrics2 and the latter assumes a polarized condition as a mass1 like that which my theory assumes each particle of the air to possess at the same time 7#afgi74 ,but ,i fear to be tedious in the present condition of the subject1 and hasten to the consideration of other matter4 #acch4 ,to sum up1 in some degree1 what has been said1 ,i look upon the first effect of an excited body upon neighbouring matters to be the production of a polarized state of their particles1 which constitutes induction2 and this arises from its action upon the particles in immediate contact with it1 which again act upon those contiguous to them1 and thus the forces are transferred to a distance4 ,if the induction remain undiminished1 then perfect insulation is the consequence2 and the higher the polarized condition which the particles can acquire or maintain1 the higher is the intensity which may be given to the acting forces4 ,if1 on the contrary1 the contiguous particles1 upon acquiring the polarized state1 have the power to communicate their forces1 then conduction occurs1 and the tension is lowered1 conduction being a distinct act of discharge between neighbouring particles4 ,the lower the state of tension at which this discharge between the particles of a body takes place1 the better conductor is that body4 ,in this view1 insulators may be said to be bodies whose particles can retain the polarized state2 whilst conductors are those whose particles cannot be permanently polarized4 ,if ,i be right in my view of induction1 then ,i consider the reduction of these two effects 7which have been so long held distinct7 to an action of contiguous particles obedient to one common law1 as a very important result2 and1 on the other hand1 the identity of character which the two acquire when viewed by the theory 7#acbf471 is additional presumptive proof in favour of the correctness of the latter4 99 99 99 99 99 #acci4 ,that heat has great influence over simple conduction is well known 7#dde471 its effect being1 in some cases1 almost an entire change of the characters of the body 7#dcb4 #acdj474 ,harris has1 however1 shown that it in no respect affects gaseous bodies1 or at least air,a2 and ,davy has taught us that1 as a class1 metals have their conducting power diminished by it,b4 ,a ,philosophical ,transactions1 #ahcd1 p4 #bcj ,b ,ibid4 #ahba1 p4 #dca4 #acdj4 ,i formerly described a substance1 sulphuret of silver1 whose conducting power was increased by heat 7#dcc4 #dcg4 #dch472 and ,i have since then met with another as strongly affected in the same way3 this is fluoride of lead4 ,when a piece of that substance1 which had been fused and cooled1 was introduced into the circuit of a voltaic battery1 it stopped the current4 ,being heated1 it acquired conducting powers before it was visibly red-hot in daylight2 and even sparks could be taken against it whilst still solid4 ,the current alone then raised its temperature 7as in the case of sulphuret of silver7 until it fused1 after which it seemed to conduct as well as the metallic vessel containing it2 for whether the wire used to complete the circuit touched the fused fluoride only1 or was in contact with the platina on which it was supported1 no sensible difference in the force of the current was observed4 ,during all the time there was scarcely a trace of decomposing action of the fluoride1 and what did occur1 seemed referable to the air and moisture of the atmosphere1 and not to electrolytic action4 #acda4 ,i have now very little doubt that periodide of mercury 7#dad4 #ddh4 #fia47 is a case of the same kind1 and also corrosive sublimate 7#fib474 ,i am also inclined to think1 since making the above experiments1 that the anomalous action of the protoxide of antimony1 formerly observed and described 7#fic4 #hja471 may be referred in part to the same cause4 #acdb4 ,i have no intention at present of going into the particular relation of heat and electricity1 but we may hope hereafter to discover by experiment the law which probably holds together all the above effects with those of the evolution and the disappearance of heat by the current1 and the striking and beautiful results of thermo-electricity1 in one common bond4 viii4 ,electrolytic discharge4 #acdc4 ,i have already expressed in a former paper 7#aafd471 the view by which ,i hope to associate ordinary induction and electrolyzation4 ,under that view1 the discharge of electric forces by electrolyzation is rather an effect superadded1 in a certain class of bodies1 to those already described as constituting induction and insulation1 than one independent of and distinct from these phenomena4 #acdd4 ,electrolytes1 as respects their insulating and conducting forces1 belong to the general category of bodies 7#acbj4 #accd472 and if they are in the solid state 7as nearly all can assume that state71 they retain their place1 presenting then no new phenomenon 7#dbf4 c472 or if one occur1 being in so small a proportion as to be almost unimportant4 ,when liquefied1 they also belong to the same list whilst the electric intensity is below a certain degree2 but at a given intensity 7#iaj4 #iab4 #ajjg471 fixed for each1 and very low in all known cases1 they play a new part1 causing discharge in proportion 7#ghc47 to the development of certain chemical effects of combination and decomposition2 and at this point1 move out from the general class of insulators and conductors1 to form a distinct one by themselves4 ,the former phenomena have been considered 7#acbj4 #acch472 it is the latter which have now to be revised1 and used as a test of the proposed theory of induction4 #acde4 ,the theory assumes1 that the particles of the dielectric 7now an electrolyte7 are in the first instance brought1 by ordinary inductive action1 into a polarized state1 and raised to a certain degree of tension or intensity before discharge commences2 the inductive state being1 in fact1 a necessary preliminary to discharge4 ,by taking advantage of those circumstances which bear upon the point1 it is not difficult to increase the tension indicative of this state of induction1 and so make the state itself more evident4 ,thus1 if distilled water be employed1 and a long narrow portion of it placed between the electrodes of a powerful voltaic battery1 we have at once indications of the intensity which can be sustained at these electrodes by the inductive action through the water as a dielectric1 for sparks may be obtained1 gold leaves diverged1 and ,leyden bottles charged at their wires4 ,the water is in the condition of the spermaceti 7#acbb4 #acbc47 a bad conductor and a bad insulator2 but what it does insulate is by virtue of inductive action1 and that induction is the preparation for and precursor of discharge 7#acch474 #acdf4 ,the induction and tension which appear at the limits of the portion of water in the direction of the current1 are only the sums of the induction and tension of the contiguous particles between those limits2 and the limitation of the inductive tension1 to a certain degree shows 7time entering in each case as an important element of the result71 that when the particles have acquired a certain relative state1 discharge1 or a transfer of forces equivalent to ordinary conduction1 takes place4 #acdg4 ,in the inductive condition assumed by water before discharge comes on1 the particles polarized are the particles of the water that being the dielectric used,a2 but the discharge between particle and particle is not1 as before1 a mere interchange of their powers or forces at the polar parts1 but an actual separation of them into their two elementary particles1 the oxygen travelling in one direction1 and carrying with it its amount of the force it had acquired during the polarization1 and the hydrogen doing the same thing in the other direction1 until they each meet the next approaching particle1 which is in the same electrical state with that they have left1 and by association of their forces with it1 produce what constitutes discharge4 ,this part of the action may be regarded as a carrying one 7#acai4 #aegb4 #afbb471 performed by the constituent particles of the dielectric4 ,the latter is always a compound body 7#ffd4 #hbc472 and by those who have considered the subject and are acquainted with the philosophical view of transfer which was first put forth by ,grotthuss,b1 its particles may easily be compared to a series of metallic conductors under inductive action1 which1 whilst in that state1 are divisible into these elementary moveable halves4 ,a ,see #afii-agjh4--;,dec4 #ahch ,b ,annales de ,chimie1 lviii4 #fj4 and lxiii1 #bj4 #acdh4 ,electrolytic discharge depends1 of necessity1 upon the non-conduction of the dielectric as a whole1 and there are two steps or acts in the process3 first a polarization of the molecules of the substance and then a lowering of the forces by the separation1 advance in opposite directions1 and recombination of the elements of the molecules1 these being1 as it were1 the halves of the originally polarized conductors or particles4 #acdi4 ,these views of the decomposition of electrolytes and the consequent effect of discharge1 which1 as to the particular case1 are the same with those of ,grotthuss 7#dha47 and ,davy 7#dhb471 though they differ from those of ,biot 7#dhg471 ,de la ,rive 7#dij471 and others1 seem to me to be fully in accordance not merely with the theory ,i have given of induction generally 7#aafe471 but with all the known facts of common induction1 conduction1 and electrolytic discharge2 and in that respect help to confirm in my mind the truth of the theory set forth4 ,the new mode of discharge which electrolyzation presents must surely be an evidence of the action of contiguous particles2 and as this appears to depend directly upon a previous inductive state1 which is the same with common induction1 it greatly strengthens the argument which refers induction in all cases to an action of contiguous particles also 7#abie1 c474 #acej4 ,as an illustration of the condition of the polarized particles in a dielectric under induction1 ,i may describe an experiment4 ,put into a glass vessel some clear rectified oil of turpentine1 and introduce two wires passing through glass tubes where they coincide with the surface of the fluid1 and terminating either in balls or points4 ,cut some very clean dry white silk into small particles1 and put these also into the liquid3 then electrify one of the wires by an ordinary machine and discharge by the other4 ,the silk will immediately gather from all parts of the liquid1 and form a band of particles reaching from wire to wire1 and if touched by a glass rod will show considerable tenacity2 yet the moment the supply of electricity ceases1 the band will fall away and disappear by the dispersion of its parts4 ,the conduction by the silk is in this case very small2 and after the best examination ,i could give to the effects1 the impression on my mind is1 that the adhesion of the whole is due to the polarity which each filament acquires1 exactly as the particles of iron between the poles of a horse-shoe magnet are held together in one mass by a similar disposition of forces4 ,the particles of silk therefore represent to me the condition of the molecules of the dielectric itself1 which ,i assume to be polar1 just as that of the silk is4 ,in all cases of conductive discharge the contiguous polarized particles of the body are able to effect a neutralization of their forces with greater or less facility1 as the silk does also in a very slight degree4 ,further we are not able to carry the parallel1 except in imagination2 but if we could divide each particle of silk into two halves1 and let each half travel until it met and united with the next half in an opposite state1 it would then exert its carrying power 7#acdg471 and so far represent electrolytic discharge4 #acea4 ,admitting that electrolytic discharge is a consequence of previous induction1 then how evidently do its numerous cases point to induction in curved lines 7#eba4 #abaf471 and to the divergence or lateral action of the lines of inductive force 7#abca471 and so strengthen that part of the general argument in the former paper6 ,if two balls of platina1 forming the electrodes of a voltaic battery1 are put into a large vessel of dilute sulphuric acid1 the whole of the surfaces are covered with the respective gases in beautifully regulated proportions1 and the mind has no difficulty in conceiving the direction of the curved lines of discharge1 and even the intensity of force of the different lines1 by the quantity of gas evolved upon the different parts of the surface4 ,from this condition of the lines of inductive force arise the general effects of diffusion2 the appearance of the anions or cathions round the edges and on the further side of the electrodes when in the form of plates2 and the manner in which the current or discharge will follow all the forms of the electrolyte1 however contorted4 ,hence1 also1 the effects which ,nobili has so well examined and described,a in his papers on the distribution of currents in conducting masses4 ,all these effects indicate the curved direction of the currents or discharges which occur in and through the dielectrics1 and these are in every case preceded by equivalent inductive actions of the contiguous particles4 ,a ,bibliothque ,universelle1 #ahce1 lix4 #bfc4 #daf4 #aceb4 ,hence also the advantage1 when the exciting forces are weak or require assistance1 of enlarging the mass of the electrolyte2 of increasing the size of the electrodes2 of making the coppers surround the zincs3--all is in harmony with the view of induction which ,i am endeavouring to examine2 ,i do not perceive as yet one fact against it4 #acec4 ,there are many points of electrolytic discharge which ultimately will require to be very closely considered1 though ,i can but slightly touch upon them4 ,it is not that1 as far as ,i have investigated them1 they present any contradiction to the view taken 7for ,i have carefully1 though unsuccessfully1 sought for such cases71 but simply want of time as yet to pursue the inquiry1 which prevents me from entering upon them here4 #aced4 ,one point is1 that different electrolytes or dielectrics require different initial intensities for their decomposition 7#iab474 ,this may depend upon the degree of polarization which the particles require before electrolytic discharge commences4 ,it is in direct relation to the chemical affinity of the substances concerned2 and will probably be found to have a relation or analogy to the specific inductive capacity of different bodies 7#abeb4 #abif474 ,it thus promises to assist in causing the great truths of those extensive sciences1 which are occupied in considering the forces of the particles of matter1 to fall into much closer order and arrangement than they have heretofore presented4 #acee4 ,another point is the facilitation of electrolytic conducting power or discharge by the addition of substances to the dielectric employed4 ,this effect is strikingly shown where water is the body whose qualities are improved1 but1 as yet1 no general law governing all the phenomena has been detected4 ,thus some acids1 as the sulphuric1 phosphoric1 oxalic1 and nitric1 increase the power of water enormously2 whilst others1 as the tartaric and citric acids1 give but little power2 and others1 again1 as the acetic and boracic acids1 do not produce a change sensible to the voltameter 7#gci474 ,ammonia produces no effect1 but its carbonate does4 ,the caustic alkalies and their carbonates produce a fair effect4 ,sulphate of soda1 nitre 7#gec471 and many soluble salts produce much effect4 ,percyanide of mercury and corrosive sublimate produce no effect2 nor does iodine1 gum1 or sugar1 the test being a voltameter4 ,in many cases the added substance is acted on either directly or indirectly1 and then the phenomena are more complicated2 such substances are muriatic acid 7#geh471 the soluble protochlorides 7#gff471 and iodides 7#gfi471 nitric acid 7#geb471 c4 ,in other cases the substance added is not1 when alone1 subject to or a conductor of the powers of the voltaic battery1 and yet both gives and receives power when associated with water4 ,m4 de la ,rive has pointed this result out in sulphurous acid,a1 iodine and bromine,b2 the chloride of arsenic produces the same effect4 ,a far more striking case1 however1 is presented by that very influential body sulphuric acid 7#fha473 and probably phosphoric acid also is in the same peculiar relation4 ,a ,quarterly ,journal1 xxvii4 #djg4 or ,bibliothque ,universelle1 xl4 #bje4 ,kemp says sulphurous acid is a very good conductor1 ,quarterly ,journal1 #ahca1 p4 #fac4 ,b ,quarterly ,journal1 xxiv1 #dfe4 or ,annales de ,chimie1 xxxv4 #afa4 #acef4 ,it would seem in the cases of those bodies which suffer no change themselves1 as sulphuric acid 7and perhaps in all71 that they affect water in its conducting power only as an electrolyte2 for whether little or much improved1 the decomposition is proportionate to the quantity of electricity passing 7#gbg4 #gcj471 and the transfer is therefore due to electrolytic discharge4 ,this is in accordance with the fact already stated as regards water 7#ihd471 that the conducting power is not improved for electricity of force below the electrolytic intensity of the substance acting as the dielectric2 but both facts 7and some others7 are against the opinion which ,i formerly gave1 that the power of salts1 c4 might depend upon their assumption of the liquid state by solution in the water employed 7#daj474 ,it occurs to me that the effect may perhaps be related to1 and have its explanation in differences of specific inductive capacities4 #aceg4 ,i have described in the last paper1 cases1 where shell-lac was rendered a conductor by absorption of ammonia 7#abid474 ,the same effect happens with muriatic acid2 yet both these substances1 when gaseous1 are non-conductors2 and the ammonia1 also when in strong solution 7#gah474 ,mr4 ,harris has mentioned instances,a in which the conducting power of metals is seriously altered by a very little alloy4 ,these may have no relation to the former cases1 but nevertheless should not be overlooked in the general investigation which the whole question requires4 ,a ,philosophical ,transactions1 #ahbg1 p4 #bb4 #aceh4 ,nothing is perhaps more striking in that class of dielectrics which we call electrolytes1 than the extraordinary and almost complete suspension of their peculiar mode of effecting discharge when they are rendered solid 7#chj1 c471 even though the intensity of the induction acting through them may be increased a hundredfold or more 7#dai474 ,it not only establishes a very general relation between the physical properties of these bodies and electricity acting by induction through them1 but draws both their physical and chemical relations so near together1 as to make us hope we shall shortly arrive at the full comprehension of the influence they mutually possess over each other4 ix4 ,disruptive discharge and insulation4 #acei4 ,the next form of discharge has been distinguished by the adjective disruptive 7#acai471 as it in every case displaces more or less the particles amongst and across which it suddenly breaks4 ,i include under it1 discharge in the form of sparks1 brushes1 and glow 7#adje471 but exclude the cases of currents of air1 fluids1 c41 which1 though frequently accompanying the former1 are essentially distinct in their nature4 #acfj4 ,the conditions requisite for the production of an electric spark in its simplest form are well-known4 ,an insulating dielectric must be interposed between two conducting surfaces in opposite states of electricity1 and then if the actions be continually increased in strength1 or otherwise favoured1 either by exalting the electric state of the two conductors1 or bringing them nearer to each other1 or diminishing the density of the dielectric1 a spark at last appears1 and the two forces are for the time annihilated1 for discharge has occurred4 #acfa4 ,the conductors 7which may be considered as the termini of the inductive action7 are in ordinary cases most generally metals1 whilst the dielectrics usually employed are common air and glass4 ,in my view of induction1 however1 every dielectric becomes of importance1 for as the results are considered essentially dependent on these bodies1 it was to be expected that differences of action never before suspected would be evident upon close examination1 and so at once give fresh confirmation of the theory1 and open new doors of discovery into the extensive and varied fields of our science4 ,this hope was especially entertained with respect to the gases1 because of their high degree of insulation1 their uniformity in physical condition1 and great difference in chemical properties4 #acfb4 ,all the effects prior to the discharge are inductive2 and the degree of tension which it is necessary to attain before the spark passes is therefore1 in the examination ,i am now making of the new view of induction1 a very important point4 ,it is the limit of the influence which the dielectric exerts in resisting discharge2 it is a measure1 consequently1 of the conservative power of the dielectric1 which in its turn may be considered as becoming a measure1 and therefore a representative of the intensity of the electric forces in activity4 #acfc4 ,many philosophers have examined the circumstances of this limiting action in air1 but1 as far as ,i know1 none have come near ,mr4 ,harris as to the accuracy with1 and the extent to1 which he has carried on his investigations,a4 ,some of his results ,i must very briefly notice1 premising that they are all obtained with the use of air as the dielectric between the conducting surfaces4 ,a ,philosophical ,transactions1 #ahcd1 p4 #bbe4 #acfd4 ,first as to the distance between the two balls used1 or in other words1 the thickness of the dielectric across which the induction was sustained4 ,the quantity of electricity1 measured by a unit jar1 or otherwise on the same principle with the unit jar1 in the charged or inductive ball1 necessary to produce spark discharge1 was found to vary exactly with the distance between the balls1 or between the discharging points1 and that under very varied and exact forms of experiment,a4 ,a ,philosophical ,transactions1 #ahcd1 p4 #bbe4 #acfe4 ,then with respect to variation in the pressure or density of the air4 ,the quantities of electricity required to produce discharge across a constant interval varied exactly with variations of the density2 the quantity of electricity and density of the air being in the same simple ratio4 ,or1 if the quantity was retained the same1 whilst the interval and density of the air were varied1 then these were found in the inverse simple ratio of each other1 the same quantity passing across twice the distance with air rarefied to one-half,a4 ,a ,philosophical ,transactions1 #ahcd1 p4#bbi4 #acff4 ,it must be remembered that these effects take place without any variation of the inductive force by condensation or rarefaction of the air4 ,that force remains the same in air,a1 and in all gases 7#abhd4 #abib471 whatever their rarefaction may be4 ,a ,philosophical ,transactions1 #ahcd1 p4 #bcg1 #bdd4 #acfg4 ,variation of the temperature of the air produced no variation of the quantity of electricity required to cause discharge across a given interval,a4 ,a ,philosophical ,transactions1 #ahcd1 p4 #bcj ,such are the general results1 which ,i have occasion for at present1 obtained by ,mr4 ,harris1 and they appear to me to be unexceptionable4 #acfh4 ,in the theory of induction founded upon a molecular action of the dielectric1 we have to look to the state of that body principally for the cause and determination of the above effects4 ,whilst the induction continues1 it is assumed that the particles of the dielectric are in a certain polarized state1 the tension of this state rising higher in each particle as the induction is raised to a higher degree1 either by approximation of the inducing surfaces1 variation of form1 increase of the original force1 or other means2 until at last1 the tension of the particles having reached the utmost degree which they can sustain without subversion of the whole arrangement1 discharge immediately after takes place4 #acfi4 ,the theory does not assume1 however1 that all the particles of the dielectric subject to the inductive action are affected to the same amount1 or acquire the same tension4 ,what has been called the lateral action of the lines of inductive force 7#abca4 #abig471 and the diverging and occasionally curved form of these lines1 is against such a notion4 ,the idea is1 that any section taken through the dielectric across the lines of inductive force1 and including all of them1 would be equal1 in the sum of the forces1 to the sum of the forces in any other section2 and that1 therefore1 the whole amount of tension for each such section would be the same4 #acgj4 ,discharge probably occurs1 not when all the particles have attained to a certain degree of tension1 but when that particle which is most affected has been exalted to the subverting or turning point 7#adaj474 ,for though all the particles in the line of induction resist charge1 and are associated in their actions so as to give a sum of resisting force1 yet when any one is brought up to the overturning point1 all must give way in the case of a spark between ball and ball4 ,the breaking down of that one must of necessity cause the whole barrier to be overturned1 for it was at its utmost degree of resistance when it possessed the aiding power of that one particle1 in addition to the power of the rest1 and the power of that one is now lost4 ,hence tension or intensity,a may1 according to the theory1 be considered as represented by the particular condition of the particles1 or the amount in them of forced variation from their normal state 7#abih4 #acfh474 ,a ,see ,harris on proposed particular meaning of these terms1 ,philosophical ,transactions1 #ahcd1 p4 #bbb4 #acga4 ,the whole effect produced by a charged conductor on a distant conductor1 insulated or not1 is by my theory assumed to be due to an action propagated from particle to particle of the intervening and insulating dielectric1 all the particles being considered as thrown for the time into a forced condition1 from which they endeavour to return to their normal or natural state4 ,the theory1 therefore1 seems to supply an easy explanation of the influence of distance in affecting induction 7#acjc4 #acfd474 ,as the distance is diminished induction increases2 for there are then fewer particles in the line of inductive force to oppose their united resistance to the assumption of the forced or polarized state1 and vice versa4 ,again1 as the distance diminishes1 discharge across happens with a lower charge of electricity2 for if1 as in ,harris's experiments 7#acfd71 the interval be diminished to one-half1 then half the electricity required to discharge across the first interval is sufficient to strike across the second2 and it is evident1 also1 that at that time there are only half the number of interposed molecules uniting their forces to resist the discharge4 #acgb4 ,the effect of enlarging the conducting surfaces which are opposed to each other in the act of induction1 is1 if the electricity be limited in its supply1 to lower the intensity of action2 and this follows as a very natural consequence from the increased area of the dielectric across which the induction is effected4 ,for by diffusing the inductive action1 which at first was exerted through one square inch of sectional area of the dielectric1 over two or three square inches of such area1 twice or three times the number of molecules of the dielectric are brought into the polarized condition1 and employed in sustaining the inductive action1 and consequently the tension belonging to the smaller number on which the limited force was originally accumulated1 must fall in a proportionate degree4 #acgc4 ,for the same reason diminishing these opposing surfaces must increase the intensity1 and the effect will increase until the surfaces become points4 ,but in this case1 the tension of the particles of the dielectric next the points is higher than that of particles midway1 because of the lateral action and consequent bulging1 as it were1 of the lines of inductive force at the middle distance 7#acfi474 #acgd4 ,the more exalted effects of induction on a point p1 or any small surface1 as the rounded end of a rod1 when it is opposed to a large surface1 as that of a ball or plate1 rather than to another point or end1 the distance being in both cases the same1 fall into harmonious relation with my theory 7#acjb474 ,for in the latter case1 the small surface p is affected only by those particles which are brought into the inductive condition by the equally small surface of the opposed conductor1 whereas when that is a ball or plate the lines of inductive force from the latter are concentrated1 as it were1 upon the end p4 ,now though the molecules of the dielectric against the large surface may have a much lower state of tension than those against the corresponding smaller surface1 yet they are also far more numerous1 and1 as the lines of inductive force converge towards a point1 are able to communicate to the particles contained in any cross section 7#acfi47 nearer the small surface an amount of tension equal to their own1 and consequently much higher for each individual particle2 so that1 at the surface of the smaller conductor1 the tension of a particle rises much1 and if that conductor were to terminate in a point1 the tension would rise to an infinite degree1 except that it is limited1 as before 7#acfh471 by discharge4 ,the nature of the discharge from small surfaces and points under induction will be resumed hereafter 7#adbe4 c47 #acge4 ,rarefaction of the air does not alter the intensity of inductive action 7#abhd4 #abhg472 nor is there any reason1 as far as ,i can perceive1 why it should4 ,if the quantity of electricity and the distance remain the same1 and the air be rarefied one-half1 then1 though one-half of the particles of the dielectric are removed1 the other half assume a double degree of tension in their polarity1 and therefore the inductive forces are balanced1 and the result remains unaltered as long as the induction and insulation are sustained4 ,but the case of discharge is very different2 for as there are only half the number of dielectric particles in the rarefied atmosphere1 so these are brought up to the discharging intensity by half the former quantity of electricity2 discharge1 therefore1 ensues1 and such a consequence of the theory is in perfect accordance with ,mr4 ,harris's results 7#acfe474 #acgf4 ,the increase of electricity required to cause discharge over the same distance1 when the pressure of the air or its density is increased1 flows in a similar manner1 and on the same principle 7#acge471 from the molecular theory4 #acgg4 ,here ,i think my view of induction has a decided advantage over others1 especially over that which refers the retention of electricity on the surface of conductors in air to the pressure of the atmosphere 7#acje474 ,the latter is the view which1 being adopted by ,poisson and ,biot,a1 is also1 ,i believe1 that generally received2 and it associates two such dissimilar things1 as the ponderous air and the subtile and even hypothetical fluid or fluids of electricity1 by gross mechanical relations2 by the bonds of mere static pressure4 ,my theory1 on the contrary1 sets out at once by connecting the electric forces with the particles of matter2 it derives all its proofs1 and even its origin in the first instance1 from experiment2 and then1 without any further assumption1 seems to offer at once a full explanation of these and many other singular1 peculiar1 and1 ,i think1 heretofore unconnected effects4 ,a ,encyclopdia ,britannica1 ,supplement1 vol4 iv4 ,article ,electricity1 pp4 #gf1 #ha4 c4 #acgh4 ,an important assisting experimental argument may here be adduced1 derived from the difference of specific inductive capacity of different dielectrics 7#abfi4 #abgd4 #abgh474 ,consider an insulated sphere electrified positively and placed in the centre of another and larger sphere uninsulated1 a uniform dielectric1 as air1 intervening4 ,the case is really that of my apparatus 7#aahg471 and also1 in effect1 that of any ball electrified in a room and removed to some distance from irregularly-formed conductors4 ,whilst things remain in this state the electricity is distributed 7so to speak7 uniformly over the surface of the electrified sphere4 ,but introduce such a dielectric as sulphur or lac1 into the space between the two conductors on one side only1 or opposite one part of the inner sphere1 and immediately the electricity on the latter is diffused unequally 7#abbi4 #abgj4 #acji471 although the form of the conducting surfaces1 their distances1 and the pressure of the atmosphere remain perfectly unchanged4 #acgi4 ,fusinieri took a different view from that of ,poisson1 ,biot1 and others1 of the reason why rarefaction of air caused easy diffusion of electricity4 ,he considered the effect as due to the removal of the obstacle which the air presented to the expansion of the substances from which the electricity passed,a4 ,but platina balls show the phenomena in vacuo as well as volatile metals and other substances2 besides which1 when the rarefaction is very considerable1 the electricity passes with scarcely any resistance1 and the production of no sensible heat2 so that ,i think ,fusinieri's view of the matter is likely to gain but few assents4 ,a ,bib4 ,univ4 #ahca1 xlviii4 #cge4 #achj4 ,i have no need to remark upon the discharging or collecting power of flame or hot air4 ,i believe1 with ,harris1 that the mere heat does nothing 7#acfg471 the rarefaction only being influential4 ,the effect of rarefaction has been already considered generally 7#acge472 and that caused by the heat of a burning light1 with the pointed form of the wick1 and the carrying power of the carbonaceous particles which for the time are associated with it1 are fully sufficient to account for all the effects4 #acha4 ,we have now arrived at the important question1 how will the inductive tension requisite for insulation and disruptive discharge be sustained in gases1 which1 having the same physical state and also the same pressure and the same temperature as air1 differ from it in specific gravity1 in chemical qualities1 and it may be in peculiar relations1 which not being as yet recognized1 are purely electrical 7#acfa478 #achb4 ,into this question ,i can enter now only as far as is essential for the present argument1 namely1 that insulation and inductive tension do not depend merely upon the charged conductors employed1 but also1 and essentially1 upon the interposed dielectric1 in consequence of the molecular action of its particles 7#abib474 #achc4 ,a glass vessel a 7fig4 #abg47;,a was ground at the top and bottom so as to be closed by two ground brass plates1 b and c2 b carried a stuffing-box1 with a sliding rod d terminated by a brass ball s below1 and a ring above4 ,the lower plate was connected with a foot1 stop-cock1 and socket1 e1 f and g2 and also with a brass ball l1 which by means of a stem attached to it and entering the socket g1 could be fixed at various heights4 ,the metallic parts of this apparatus were not varnished1 but the glass was well-covered with a coat of shell-lac previously dissolved in alcohol4 ,on exhausting the vessel at the air-pump it could be filled with any other gas than air1 and1 in such cases1 the gas so passed in was dried whilst entering by fused chloride of calcium4 ,a ,the drawing is to a scale of #a_/f4 #achd4 ,the other part of the apparatus consisted of two insulating pillars1 h and i1 to which were fixed two brass balls1 and through these passed two sliding rods1 k and m1 terminated at each end by brass balls2 n is the end of an insulated conductor1 which could be rendered either positive or negative from an electrical machine2 o and p are wires connecting it with the two parts previously described1 and q is a wire which1 connecting the two opposite sides of the collateral arrangements1 also communicates with a good discharging train r 7#bib474 #ache4 ,it is evident that the discharge from the machine electricity may pass either between s and l1 or ,s and ,l4 ,the regulation adopted in the first experiments was to keep s and l with their distance unchanged1 but to introduce first one gas and then another into the vessel a1 and then balance the discharge at the one place against that at the other2 for by making the interval at a sufficiently small1 all the discharge would pass there1 or making it sufficiently large it would all occur at the interval v in the receiver4 ,on principle it seemed evident1 that in this way the varying interval u might be taken as a measure1 or rather indication of the resistance to discharge through the gas at the constant interval v4 ,the following are the constant dimensions4 ,ball s #j4ic of an inch4 ,ball ,s #j4if of an inch4 ,ball l #b4jb of an inch4 ,ball ,l #j4fb of an inch4 ,interval v #j4fb of an inch4 #achf4 ,on proceeding to experiment it was found that when air or any gas was in the receiver a1 the interval u was not a fixed one2 it might be altered through a certain range of distance1 and yet sparks pass either there or at v in the receiver4 ,the extremes were therefore noted1 i4e4 the greatest distance short of that at which the discharge always took place at v in the gas1 and the least distance short of that at which it always took place at u in the air4 ,thus1 with air in the receiver1 the extremes at u were #j4ef and #j4gi of an inch1 the range of #j4bc between these distances including intervals at which sparks passed occasionally either at one place or the other4 #achg4 ,the small balls s and ,s could be rendered either positive or negative from the machine1 and as gases were expected and were found to differ from each other in relation to this change 7#acii471 the results obtained under these differences of charge were also noted4 #achh4 ,the following is a ,table of results2 the gas named is that in the vessel a4 ,the smallest1 greatest1 and mean interval at u in air is expressed in parts of an inch1 the interval v being constantly #j4fb of an inch4 ,smallest4 ,greatest4 ,mean4 ,air1 s and ,s1 pos4 #j4fj #j4gi #j4fie ,air1 s and ,s1 neg4 #j4ei #j4fh #j4fce ,oxygen1 s and ,s1 pos4 #j4da #j4fj #j4eje ,oxygen1 s and ,s1 neg4 #j4ej #j4eb #j4eaj ,nitrogen1 s and ,s1 pos4 #j4ee #j4fh #j4fae ,nitrogen1 s and ,s1 neg4 #j4ei #j4gj #j4fde ,hydrogen1 s and ,s1 pos4 #j4cj #j4dd #j4cgj ,hydrogen1 s and ,s1 neg4 #j4be #j4cj #j4bge ,carbonic acid1 s and ,s1 pos4 #j4ef #j4gb #j4fdj ,carbonic acid1 s and ,s1 neg4 #j4eh #j4fj #j4eij ,olefiant gas1 s and ,s1 pos4 #j4fd #j4hf #j4gej ,olefiant gas1 s and ,s1 neg4 #j4fi #j4gg #j4gcj ,coal gas1 s and ,s1 pos4 #j4cg #j4fa #j4dij ,coal gas1 s and ,s1 neg4 #j4dg #j4eh #j4ebe ,muriatic acid gas1 s and ,s1 pos4 #j4hi #a4cb #a4aje ,muriatic acid gas1 s and ,s1 neg4 #j4fg #j4ge #j4gaj #achi4 ,the above results were all obtained at one time4 ,on other occasions other experiments were made1 which gave generally the same results as to order1 though not as to numbers4 ,thus3 ,hydrogen1 s and ,s1 pos4 #j4bc #j4eg #j4djj ,carbonic acid1 s and ,s1 pos4 #j4ea #a4je #j4ghj ,olefiant gas1 s and ,s1 pos4 #j4ff #a4bg #j4ife ,i did not notice the difference of the barometer on the days of experiment,a4 ,a ,similar experiments in different gases are described at #aejg4 #aejh4--;,dec4 #ahch4 #acij4 ,one would have expected only two distances1 one for each interval1 for which the discharge might happen either at one or the other2 and that the least alteration of either would immediately cause one to predominate constantly over the other4 ,but that under common circumstances is not the case4 ,with air in the receiver1 the variation amounted to #j4b of an inch nearly on the smaller interval of #j4f1 and with muriatic acid gas1 the variation was above #j4d on the smaller interval of #j4i4 ,why is it that when a fixed interval 7the one in the receiver7 will pass a spark that cannot go across #j4f of air at one time1 it will immediately after1 and apparently under exactly similar circumstances1 not pass a spark that can go across #j4h of air8 #acia4 ,it is probable that part of this variation will be traced to particles of dust in the air drawn into and about the circuit 7#aefh474 ,i believe also that part depends upon a variable charged condition of the surface of the glass vessel a4 ,that the whole of the effect is not traceable to the influence of circumstances in the vessel a1 may be deduced from the fact1 that when sparks occur between balls in free air they frequently are not straight1 and often pass otherwise than by the shortest distance4 ,these variations in air itself1 and at different parts of the very same balls1 show the presence and influence of circumstances which are calculated to produce effects of the kind now under consideration4 #acib4 ,when a spark had passed at either interval1 then1 generally1 more tended to appear at the same interval1 as if a preparation had been made for the passing of the latter sparks4 ,so also on continuing to work the machine quickly the sparks generally followed at the same place4 ,this effect is probably due in part to the warmth of the air heated by the preceding spark1 in part to dust1 and ,i suspect in part1 to something unperceived as yet in the circumstances of discharge4 #acic4 ,a very remarkable difference1 which is constant in its direction1 occurs when the electricity communicated to the balls s and ,s is changed from positive to negative1 or in the contrary direction4 ,it is that the range of variation is always greater when the small bulls are positive than when they are negative4 ,this is exhibited in the following ,table1 drawn from the former experiments4 ,pos4 ,neg4 ,in ,air the range was #j4ai #j4ji ,oxygen #j4ai #j4jb ,nitrogen #j4ah #j4aa ,hydrogen #j4ad #j4je ,carbonic acid #j4af #j4jb ,olefiant gas #j4bb #j4jh ,coal gas #j4bd #j4ab ,muriatic acid #j4dc #j4jh ,i have no doubt these numbers require considerable correction1 but the general result is striking1 and the differences in several cases very great4 99 99 99 99 99 #acid4 ,though1 in consequence of the variation of the striking distance 7#achf471 the interval in air fails to be a measure1 as yet1 of the insulating or resisting power of the gas in the vessel1 yet we may for present purposes take the mean interval as representing in some degree that power4 ,on examining these mean intervals as they are given in the third column 7#achh471 it will be very evident1 that gases1 when employed as dielectrics1 have peculiar electrical relations to insulation1 and therefore to induction1 very distinct from such as might be supposed to depend upon their mere physical qualities of specific gravity or pressure4 #acie4 ,first1 it is clear that at the same pressure they are not alike1 the difference being as great as #cg and #aaj4 ,when the small balls are charged positively1 and with the same surfaces and the same pressure1 muriatic acid gas has three times the insulating or restraining power 7#acfb47 of hydrogen gas1 and nearly twice that of oxygen1 nitrogen1 or air4 #acif4 ,yet it is evident that the difference is not due to specific gravity1 for though hydrogen is the lowest1 and therefore lower than oxygen1 oxygen is much beneath nitrogen1 or olefiant gas2 and carbonic acid gas1 though considerably heavier than olefiant gas or muriatic acid gas1 is lower than either4 ,oxygen as a heavy1 and olefiant as a light gas1 are in strong contrast with each other2 and if we may reason of olefiant gas from ,harris's results with air 7#acfe471 then it might be rarefied to two-thirds its usual density1 or to a specific gravity of #i4c 7hydrogen being #a71 and having neither the same density nor pressure as oxygen1 would have equal insulating powers with it1 or equal tendency to resist discharge4 #acig4 ,experiments have already been described 7#abia4 #abib47 which show that the gases are sensibly alike in their inductive capacity4 ,this result is not in contradiction with the existence of great differences in their restraining power4 ,the same point has been observed already in regard to dense and rare air 7#acge474 #acih4 ,hence arises a new argument proving that it cannot be mere pressure of the atmosphere which prevents or governs discharge 7#acgg4 #acgh471 but a specific electric quality or relation of the gaseous medium4 ,hence also additional argument for the theory of molecular inductive action4 #acii4 ,other specific differences amongst the gases may be drawn from the preceding series of experiments1 rough and hasty as they are4 ,thus the positive and negative series of mean intervals do not give the same differences4 ,it has been already noticed that the negative numbers are lower than the positive 7#acic471 but1 besides that1 the order of the positive and negative results is not the same4 ,thus1 on comparing the mean numbers 7which represent for the present insulating tension17 it appears that in air1 hydrogen1 carbonic acid1 olefiant gas and muriatic acid1 the tension rose higher when the smaller ball was made positive than when rendered negative1 whilst in oxygen1 nitrogen1 and coal gas1 the reverse was the case4 ,now though the numbers cannot be trusted as exact1 and though air1 oxygen1 and nitrogen should probably be on the same side1 yet some of the results1 as1 for instance1 those with muriatic acid1 fully show a peculiar relation and difference amongst gases in this respect4 ,this was further proved by making the interval in air #j4h of an inch whilst muriatic acid gas was in the vessel a2 for on charging the small balls s and ,s positively1 all the discharge took place through the air2 but on charging them negatively1 all the discharge took place through the muriatic acid gas4 #adjj4 ,so also1 when the conductor n was connected only with the muriatic acid gas apparatus1 it was found that the discharge was more facile when the small ball s was negative than when positive2 for in the latter case1 much of the electricity passed off as brush discharge through the air from the connecting wire p but in the former case1 it all seemed to go through the muriatic acid4 #adja4 ,the consideration1 however1 of positive and negative discharge across air and other gases will be resumed in the further part of this1 or in the next paper 7#adfe4 #aebe474 #adjb4 ,here for the present ,i must leave this part of the subject1 which had for its object only to observe how far gases agreed or differed as to their power of retaining a charge on bodies acting by induction through them4 ,all the results conspire to show that ,induction is an action of contiguous molecules 7#abie4 c472 but besides confirming this1 the first principle placed for proof in the present inquiry1 they greatly assist in developing the specific properties of each gaseous dielectric1 at the same time showing that further and extensive experimental investigation is necessary1 and holding out the promise of new discovery as the reward of the labour required4 99 99 99 99 99 #adjc4 ,when we pass from the consideration of dielectrics like the gases to that of bodies having the liquid and solid condition1 then our reasonings in the present state of the subject assume much more of the character of mere supposition4 ,still ,i do not perceive anything adverse to the theory1 in the phenomena which such bodies present4 ,if we take three insulating dielectrics1 as air1 oil of turpentine1 and shell-lac1 and use the same balls or conductors at the same intervals in these three substances1 increasing the intensity of the induction until discharge take place1 we shall find that it must be raised much higher in the fluid than for the gas1 and higher still in the solid than for the fluid4 ,nor is this inconsistent with the theory2 for with the liquid1 though its molecules are free to move almost as easily as those of the gas1 there are many more particles introduced into the given interval2 and such is also the case when the solid body is employed4 ,besides that with the solid1 the cohesive force of the body used will produce some effect2 for though the production of the polarized states in the particle of a solid may not be obstructed1 but1 on the contrary1 may in some cases be even favoured 7#aafd4 #acdd47 by its solidity or other circumstances1 yet solidity may well exert an influence on the point of final subversion1 7just as it prevents discharge in an electrolyte17 and so enable inductive intensity to rise to a much higher degree4 #adjd4 ,in the cases of solids and liquids too1 bodies may1 and most probably do1 possess specific differences as to their ability of assuming the polarized state1 and also as to the extent to which that polarity must rise before discharge occurs4 ,an analogous difference exists in the specific inductive capacities already pointed out in a few substances 7#abgh47 in the last paper4 ,such a difference might even account for the various degrees of insulating and conducting power possessed by different bodies1 and1 if it should be found to exist1 would add further strength to the argument in favour of the molecular theory of inductive action4 99 99 99 99 99 #adje4 ,having considered these various cases of sustained insulation in non-conducting dielectrics up to the highest point which they can attain1 we find that they terminate at last in disruptive discharge2 the peculiar condition of the molecules of the dielectric which was necessary to the continuous induction1 being equally essential to the occurrence of that effect which closes all the phenomena4 ,this discharge is not only in its appearance and condition different to the former modes by which the lowering of the powers was effected 7#acbj4 #acdc471 but1 whilst really the same in principle1 varies much from itself in certain characters1 and thus presents us with the forms of spark1 brush1 and glow 7#acei474 ,i will first consider the spark1 limiting it for the present to the case of discharge between two oppositely electrified conducting surfaces4 ,the electric spark or flash4 #adjf4 ,the spark is consequent upon a discharge or lowering of the polarized inductive state of many dielectric particles1 by a particular action of a few of the particles occupying a very small and limited space2 all the previously polarized particles returning to their first or normal condition in the inverse order in which they left it1 and uniting their powers meanwhile to produce1 or rather to continue1 7#adag4--adcf47 the discharge effect in the place where the subversion of force first occurred4 ,my impression is1 that the few particles situated where discharge occurs are not merely pushed apart1 but assume a peculiar state1 a highly exulted condition for the time1 i4e4 have thrown upon them all the surrounding forces in succession1 and rising up to a proportionate intensity of condition1 perhaps equal to that of chemically combining atoms1 discharge the powers1 possibly in the same manner as they do theirs1 by some operation at present unknown to us2 and so the end of the whole4 ,the ultimate effect is exactly as if a metallic wire had been put into the place of the discharging particles2 and it does not seem impossible that the principles of action in both cases1 may1 hereafter1 prove to be the same4 #adjg4 ,the path of the spark1 or of the discharge1 depends on the degree of tension acquired by the particles in the line of discharge1 circumstances1 which in every common case are very evident and by the theory easy to understand1 rendering it higher in them than in their neighbours1 and1 by exalting them first to the requisite condition1 causing them to determine the course of the discharge4 ,hence the selection of the path1 and the solution of the wonder which ,harris has so well described,a as existing under the old theory4 ,all is prepared amongst the molecules beforehand1 by the prior induction1 for the path either of the electric spark or of lightning itself4 ,a ,nautical ,magazine1 #ahcd1 p #bbi4 #adjh4 ,the same difficulty is expressed as a principle by ,nobili for voltaic electricity1 almost in ,mr4 ,harris's words1 namely,a1 electricity directs itself towards the point where it can most easily discharge itself1 and the results of this as a principle he has well wrought out for the case of voltaic currents4 ,but the solution of the difficulty1 or the proximate cause of the effects1 is the same2 induction brings the particles up to or towards a certain degree of tension 7#acgj472 and by those which first attain it1 is the discharge first and most efficiently performed4 ,a ,bibliothque ,universelle1 #ahce1 lix4 #bge4 #adji4 ,the moment of discharge is probably determined by that molecule of the dielectric which1 from the circumstances1 has its tension most quickly raised up to the maximum intensity4 ,in all cases where the discharge passes from conductor to conductor this molecule must be on the surface of one of them2 but when it passes between a conductor and a nonconductor1 it is1 perhaps1 not always so 7#adec474 ,when this particle has acquired its maximum tension1 then the whole barrier of resistance is broken down in the line or lines of inductive action originating at it1 and disruptive discharge occurs 7#acgj473 and such an inference1 drawn as it is from the theory1 seems to me in accordance with ,mr4 ,harris's facts and conclusions respecting the resistance of the atmosphere1 namely1 that it is not really greater at any one discharging distance than another,a4 ,a ,philosophical ,transactions1 #ahcd1 pp4 #bbg1 #bbi4 #adaj4 ,it seems probable1 that the tension of a particle of the same dielectric1 as air1 which is requisite to produce discharge1 is a constant quantity1 whatever the shape of the part of the conductor with which it is in contact1 whether ball or point2 whatever the thickness or depth of dielectric throughout which induction is exerted2 perhaps1 even1 whatever the state1 as to rarefaction or condensation of the dielectric2 and whatever the nature of the conductor1 good or bad1 with which the particle is for the moment associated4 ,in saying so much1 ,i do not mean to exclude small differences which may be caused by the reaction of neighbouring particles on the deciding particle1 and indeed1 it is evident that the intensity required in a particle must be related to the condition of those which are contiguous4 ,but if the expectation should be found to approximate to truth1 what a generality of character it presents6 and1 in the definiteness of the power possessed by a particular molecule1 may we not hope to find an immediate relation to the force which1 being electrical1 is equally definite and constitutes chemical affinity8 #adaa4 ,theoretically it would seem that1 at the moment of discharge by the spark in one line of inductive force1 not merely would all the other lines throw their forces into this one 7#adjf471 but the lateral effect1 equivalent to a repulsion of these lines 7#abbd4 #abig471 would be relieved and1 perhaps1 followed by a contrary action1 amounting to a collapse or attraction of these parts4 ,having long sought for some transverse force in statical electricity1 which should be the equivalent to magnetism or the transverse force of current electricity1 and conceiving that it might be connected with the transverse action of the lines of inductive force1 already described 7#abig471 ,i was desirous1 by various experiments1 of bringing out the effect of such a force1 and making it tell upon the phenomena of electro-magnetism and magneto-electricity,a4 ,a ,see further investigations of this subject1 #afeh-afff4 #agji-agce4--;,dec4 #ahch4 #adab4 ,amongst other results1 ,i expected and sought for the mutual affection1 or even the lateral coalition of two similar sparks1 if they could be obtained simultaneously side by side1 and sufficiently near to each other4 ,for this purpose1 two similar ,leyden jars were supplied with rods of copper projecting from their balls in a horizontal direction1 the rods being about #j4b of an inch thick1 and rounded at the ends4 ,the jars were placed upon a sheet of tinfoil1 and so adjusted that their rods1 a and b1 were near together1 in the position represented in plan at fig4 #aaf3 c and d were two brass balls connected by a brass rod and insulated3 e was also a brass ball connected1 by a wire1 with the ground and with the tinfoil upon which the ,leyden jars were placed4 ,by laying an insulated metal rod across from a to b1 charging the jars1 and removing the rod1 both the jars could be brought up to the same intensity of charge 7#acgj474 ,then1 making the ball e approach the ball d1 at the moment the spark passed there1 two sparks passed between the rods n1 o1 and the ball c2 and as far as the eye could judge1 or the conditions determine1 they were simultaneous4 #adac4 ,under these circumstances two modes of discharge took place2 either each end had its own particular spark to the ball1 or else one end only was associated by a spark with the ball1 but was at the same time related to the other end by a spark between the two4 #adad4 ,when the ball c was about an inch in diameter1 the ends n and o1 about half an inch from it1 and about #j4d of an inch from each other1 the two sparks to the ball could be obtained4 ,when for the purpose of bringing the sparks nearer together1 the ends1 n and o1 were brought closer to each other1 then1 unless very carefully adjusted1 only one end had a spark with the ball1 the other having a spark to it2 and the least variation of position would cause either n or o to be the end which1 giving the direct spark to the ball1 was also the one through1 or by means of which1 the other discharged its electricity4 #adae4 ,on making the ball c smaller1 ,i found that then it was needful to make the interval between the ends n and o larger in proportion to the distance between them and the ball c4 ,on making c larger1 ,i found ,i could diminish the interval1 and so bring the two simultaneous separate sparks closer together1 until1 at last1 the distance between them was not more at the widest part than #j4f of their whole length4 #adaf4 ,numerous sparks were then passed and carefully observed4 ,they were very rarely straight1 but either curved or bent irregularly4 ,in the average of cases they were1 ,i think1 decidedly convex towards each other2 perhaps two-thirds presented more or less of this effect1 the rest bulging more or less outwards4 ,i was never able1 however1 to obtain sparks which1 separately leaving the ends of the wires n and o1 conjoined into one spark before they reached or communicated with the ball c4 ,at present1 therefore1 though ,i think ,i saw a tendency in the sparks to unite1 ,i cannot assert it as a fact4 #adag4 ,but there is one very interesting effect here1 analogous to1 and it may be in part the same with1 that ,i was searching for3 ,i mean the increased facility of discharge where the spark passes4 ,for instance1 in the cases where one end1 as n1 discharged the electricity of both ends to the ball c1 fig4 #aaf1 the electricity of the other end o1 had to pass through an interval of air #a4e times as great as that which it might have taken1 by its direct passage between the end and the ball itself4 ,in such cases1 the eye could not distinguish1 even by the use of ,wheatstone's means,a1 that the spark from the end n1 which contained both portions of electricity1 was a double spark4 ,it could not have consisted of two sparks taking separate courses1 for such an effect would have been visible to the eye2 but it is just possible1 that the spark of the first end n and its jar1 passing at the smallest interval of time before that of the other o had heated and expanded the air in its course1 and made it so much more favourable to discharge1 that the electricity of the end o preferred leaping across to it and taking a very circuitous route1 rather than the more direct one to the ball4 ,it must1 however1 be remarked1 in answer to this supposition1 that the one spark between d and e would1 by its influence1 tend to produce simultaneous discharges at n and o1 and certainly did so1 when no preponderance was given to one wire over the other1 as to the previous inductive effect 7#adad474 ,a ,philosophical ,transactions1 #ahcd1 pp4 #ehd1 #ehe4 #adah4 ,the fact1 however1 is1 that disruptive discharge is favourable to itself4 ,it is at the outset a case of tottering equilibrium3 and if time be an element in discharge1 in however minute a proportion 7#adcf471 then the commencement of the act at any point favours its continuance and increase there1 and portions of power will be discharged by a course which they would not otherwise have taken4 #adai4 ,the mere heating and expansion of the air itself by the first portion of electricity which passes1 must have a great influence in producing this result4 #adbj4 ,as to the result itself1 we see its effect in every electric spark2 for it is not the whole quantity which passes that determines the discharge1 but merely that small portion of force which brings the deciding molecule 7#acgj47 up to its maximum tension2 then1 when its forces are subverted and discharge begins1 all the rest passes by the same course1 from the influence of the favouring circumstances just referred to2 and whether it be the electricity on a square inch1 or a thousand square inches of charged glass1 the discharge is complete4 ,hereafter we shall find the influence of this effect in the formation of brushes 7#adce472 and it is not impossible that we may trace it producing the jagged spark and the forked lightning4 99 99 99 99 99 #adba4 ,the characters of the electric spark in different gases vary1 and the variation may be due simply to the effect of the heat evolved at the moment4 ,but it may also be due to that specific relation of the particles and the electric forces which ,i have assumed as the basis of a theory of induction2 the facts do not oppose such a view2 and in that view the variation strengthens the argument for molecular action1 as it would seem to show the influence of the latter in every part of the electrical effect 7#adbc4 #aded474 #adbb4 ,the appearances of the sparks in different gases have often been observed and recorded,a1 but ,i think it not out of place to notice briefly the following results2 they were obtained with balls of brass1 7platina surfaces would have been better17 and at common pressures4 ,in air1 the sparks have that intense light and bluish colour which are so well known1 and often have faint or dark parts in their course1 when the quantity of electricity passing is not great4 ,in nitrogen1 they are very beautiful1 having the same general appearance as in air1 but have decidedly more colour of a bluish or purple character1 and ,i thought were remarkably sonorous4 ,in oxygen1 the sparks were whiter than in air or nitrogen1 and ,i think not so brilliant4 ,in hydrogen1 they had a very fine crimson colour1 not due to its rarity1 for the character passed away as the atmosphere was rarefied 7#adei47;,b4 ,very little sound was produced in this gas2 but that is a consequence of its physical condition,c4 ,in carbonic acid gas1 the colour was similar to that of the spark in air1 but with a little green in it3 the sparks were remarkably irregular in form1 more so than in common air3 they could also1 under similar circumstances as to size of ball1 c41 be obtained much longer than in air1 the gas showing a singular readiness to cause the discharge in the form of spark4 ,in muriatic acid gas1 the spark was nearly white3 it was always bright throughout1 never presenting those dark parts which happen in air1 nitrogen1 and some other gases4 ,the gas was dry1 and during the whole experiment the surface of the glass globe within remained quite dry and bright4 ,in coal gas1 the spark was sometimes green1 sometimes red1 and occasionally one part was green and another red3 black parts also occur very suddenly in the line of the spark1 i4e4 they are not connected by any dull part with bright portions1 but the two seem to join directly one with the other4 ,a ,see ,van ,marum's description of the ,teylerian machine1 vol4 i4 p4 #aab1 and vol4 ii4 p4 #aif2 also ,ency4 ,britan41 vol4 vi41 ,article ,electricity1 pp4 #eje1 #ejg4 ,b ,van ,marum says they are about four times as large in hydrogen as in air4 vol4 i4 p4 #abb4 ,c ,leslie4 ,cambridge ,phil4 ,transactions1 #bfg4 #adbc4 ,these varieties of character impress my mind with a feeling1 that they are due to a direct relation of the electric powers to the particles of the dielectric through which the discharge occurs1 and are not the mere results of a casual ignition or a secondary kind of action of the electricity1 upon the particles which it finds in its course and thrusts aside in its passage 7#aded474 #adbd4 ,the spark may be obtained in media which are far denser than air1 as in oil of turpentine1 olive oil1 resin1 glass1 c43 it may also be obtained in bodies which being denser likewise approximate to the condition of conductors1 as spermaceti1 water1 c4 ,but in these cases1 nothing occurs which1 as far as ,i can perceive1 is at all hostile to the general views ,i have endeavoured to advocate4 ,the electrical brush4 #adbe4 ,the brush is the next form of disruptive discharge which ,i shall consider4 ,there are many ways of obtaining it1 or rather of exalting its characters2 and all these ways illustrate the principles upon which it is produced4 ,if an insulated conductor1 connected with the positive conductor of an electrical machine1 have a metal rod #j4c of an inch in diameter projecting from it outwards from the machine1 and terminating by a rounded end or a small ball1 it will generally give good brushes2 or1 if the machine be not in good action1 then many ways of assisting the formation of the brush can be resorted to2 thus1 the hand or any large conducting surface may be approached towards the termination to increase inductive force 7#acgd473 or the termination may be smaller and of badly conducting matter1 as wood3 or sparks may be taken between the prime conductor of the machine and the secondary conductor to which the termination giving brushes belongs3 or1 which gives to the brushes exceedingly fine characters and great magnitude1 the air around the termination may be rarefied more or less1 either by heat or the air-pump2 the former favourable circumstances being also continued4 #adbf4 ,the brush when obtained by a powerful machine on a ball about #j4g of an inch in diameter1 at the end of a long brass rod attached to the positive prime conductor1 had the general appearance as to form represented in fig4 #aag3 a short conical bright part or root appeared at the middle part of the ball projecting directly from it1 which1 at a little distance from the ball1 broke out suddenly into a wide brush of pale ramifications having a quivering motion1 and being accompanied at the same time with a low dull chattering sound4 #adbg4 ,at first the brush seems continuous1 but ,professor ,wheatstone has shown that the whole phenomenon consists of successive intermitting discharges,a4 ,if the eye be passed rapidly1 not by a motion of the head1 but of the eyeball itself1 across the direction of the brush1 by first looking steadfastly about #aj or #ae above1 and then instantly as much below it1 the general brush will be resolved into a number of individual brushes1 standing in a row upon the line which the eye passed over2 each elementary brush being the result of a single discharge1 and the space between them representing both the time during which the eye was passing over that space1 and that which elapsed between one discharge and another4 ,a ,philosophical ,transactions1 #ahcd1 p4 #ehf4 #adbh4 ,the single brushes could easily be separated to eight or ten times their own width1 but were not at the same time extended1 i4e4 they did not become more indefinite in shape1 but1 on the contrary1 less so1 each being more distinct in form1 ramification1 and character1 because of its separation from the others1 in its effects upon the eye4 ,each1 therefore1 was instantaneous in its existence 7#adcf474 ,each had the conical root complete 7#adbf474 #adbi4 ,on using a smaller ball1 the general brush was smaller1 and the sound1 though weaker1 more continuous4 ,on resolving the brush into its elementary parts1 as before1 these were found to occur at much shorter intervals of time than in the former case1 but still the discharge was intermitting4 #adcj4 ,employing a wire with a round end1 the brush was still smaller1 but1 as before1 separable into successive discharges4 ,the sound1 though feebler1 was higher in pitch1 being a distinct musical note4 #adca4 ,the sound is1 in fact1 due to the recurrence of the noise of each separate discharge1 and these1 happening at intervals nearly equal under ordinary circumstances1 cause a definite note to be heard1 which1 rising in pitch with the increased rapidity and regularity of the intermitting discharges1 gives a ready and accurate measure of the intervals1 and so may be used in any case when the discharge is heard1 even though the appearances may not be seen1 to determine the element of time4 ,so when1 by bringing the hand towards a projecting rod or ball1 the pitch of the tone produced by a brushy discharge increases1 the effect informs us that we have increased the induction 7#acgd471 and by that means increased the rapidity of the alternations of charge and discharge4 #adcb4 ,by using wires with finer terminations1 smaller brushes were obtained1 until they could hardly be distinguished as brushes2 but as long as sound was heard1 the discharge could be ascertained by the eye to be intermitting2 and when the sound ceased1 the light became continuous as a glow 7#acei4 #adje4 #aebf-aedc474 #adcc4 ,to those not accustomed to use the eye in the manner ,i have described1 or1 in cases where the recurrence is too quick for any unassisted eye1 the beautiful revolving mirror of ,professor ,wheatstone,a will be useful for such developments of condition as those mentioned above4 ,another excellent process is to produce the brush or other luminous phenomenon on the end of a rod held in the hand opposite to a charged positive or negative conductor1 and then move the rod rapidly from side to side whilst the eye remains still4 ,the successive discharges occur of course in different places1 and the state of things before1 at1 and after a single coruscation or brush can be exceedingly well separated4 ,a ,philosophical ,transactions1 #ahcd1 pp4 #eha1 #ehe4 #adcd4 ,the brush is in reality a discharge between a bad or a non-conductor and either a conductor or another non-conductor4 ,under common circumstances1 the brush is a discharge between a conductor and air1 and ,i conceive it to take place in something like the following manner4 ,when the end of an electrified rod projects into the middle of a room1 induction takes place between it and the walls of the room1 across the dielectric1 air2 and the lines of inductive force accumulate upon the end in greater quantity than elsewhere1 or the particles of air at the end of the rod are more highly polarized than those at any other part of the rod1 for the reasons already given 7#acgd474 ,the particles of air situated in sections across these lines of force are least polarized in the sections towards the walls and most polarized in those nearer to the end of the wires 7#acfi473 thus1 it may well happen1 that a particle at the end of the wire is at a tension that will immediately terminate in discharge1 whilst in those even only a few inches off1 the tension is still beneath that point4 ,but suppose the rod to be charged positively1 a particle of air ,a1 fig4 #aah1 next it1 being polarized1 and having of course its negative force directed towards the rod and its positive force outwards2 the instant that discharge takes place between the positive force of the particle of the rod opposite the air and the negative force of the particle of air towards the rod1 the whole particle of air becomes positively electrified2 and when1 the next instant1 the discharged part of the rod resumes its positive state by conduction from the surface of metal behind1 it not only acts on the particles beyond ,a1 by throwing ,a into a polarized state again1 but ,a itself1 because of its charged state1 exerts a distinct inductive act towards these further particles1 and the tension is consequently so much exalted between ,a and ,b1 that discharge takes place there also1 as well as again between the metal and ,a4 #adce4 ,in addition to this effect1 it has been shown1 that1 the act of discharge having once commenced1 the whole operation1 like a case of unstable equilibrium1 is hastened to a conclusion 7#acgj4 #adah471 the rest of the act being facilitated in its occurrence1 and other electricity than that which caused the first necessary tension hurrying to the spot4 ,when1 therefore1 disruptive discharge has once commenced at the root of a brush1 the electric force which has been accumulating in the conductor attached to the rod1 finds a more ready discharge there than elsewhere1 and will at once follow the course marked out as it were for it1 thus leaving the conductor in a partially discharged state1 and the air about the end of the wire in a charged condition2 and the time necessary for restoring the full charge of the conductor1 and the dispersion of the charged air in a greater or smaller degree1 by the joint forces of repulsion from the conductor and attraction towards the walls of the room1 to which its inductive action is directed1 is just that time which forms the interval between brush and brush 7#adbj4 #adbg4 #adca4 #addg474 #adcf4 ,the words of this description are long1 but there is nothing in the act or the forces on which it depends to prevent the discharge being instantaneous1 as far as we can estimate and measure it4 ,the consideration of time is1 however1 important in several points of view 7#adah471 and in reference to disruptive discharge1 it seemed from theory far more probable that it might be detected in a brush than in a spark2 for in a brush1 the particles in the line through which the discharge passes are in very different states as to intensity1 and the discharge is already complete in its act at the root of the brush1 before the particles at the extremity of the ramifications have yet attained their maximum intensity4 #adcg4 ,i consider brush discharge as probably a successive effect in this way4 ,discharge begins at the root 7#adbf4 #aeec471 and1 extending itself in succession to all parts of the single brush1 continues to go on at the root and the previously formed parts until the whole brush is complete2 then1 by the fall in intensity and power at the conductor1 it ceases at once in all parts1 to be renewed1 when that power has risen again to a sufficient degree4 ,but in a spark1 the particles in the line of discharge being1 from the circumstances1 nearly alike in their intensity of polarization1 suffer discharge so nearly at the same moment as to make the time quite insensible to us4 #adch4 ,mr4 ,wheatstone has already made experiments which fully illustrate this point4 ,he found that the brush generally had a sensible duration1 but that with his highest capabilities he could not detect any such effect in the spark,a4 ,i repeated his experiment on the brush1 though with more imperfect means1 to ascertain whether ,i could distinguish a longer duration in the stem or root of the brush than in the extremities1 and the appearances were such as to make me think an effect of this kind was produced4 ,a ,philosophical ,transactions1 #ahcf1 pp4 #ehf1 #eij4 #adci4 ,that the discharge breaks into several ramifications1 and by them passes through portions of air alike1 or nearly alike1 as to polarization and the degree of tension the particles there have acquired1 is a very natural result of the previous state of things1 and rather to be expected than that the discharge should continue to go straight out into space in a single line amongst those particles which1 being at a distance from the end of the rod1 are in a lower state of tension than those which are near3 and whilst we cannot but conclude1 that those parts where the branches of a single brush appear1 are more favourably circumstanced for discharge than the darker parts between the ramifications1 we may also conclude1 that in those parts where the light of concomitant discharge is equal1 there the circumstances are nearly equal also4 ,the single successive brushes are by no means of the same particular shape even when they are observed without displacement of the rod or surrounding objects 7#adbg4 #adcc471 and the successive discharges may be considered as taking place into the mass of air around1 through different roads at each brush1 according as minute circumstances1 such as dust1 c4 7#acia4 #acib471 may have favoured the course by one set of particles rather than another4 #addj4 ,brush discharge does not essentially require any current of the medium in which the brush appears3 the current almost always occurs1 but is a consequence of the brush1 and will be considered hereafter 7#aefb-afaj474 ,on holding a blunt point positively charged towards uninsulated water1 a star or glow appeared on the point1 a current of air passed from it1 and the surface of the water was depressed2 but on bringing the point so near that sonorous brushes passed1 then the current of air instantly ceased1 and the surface of the water became level4 #adda4 ,the discharge by a brush is not to all the particles of air that are near the electrified conductor from which the brush issues2 only those parts where the ramifications pass are electrified3 the air in the central dark parts between them receives no charge1 and1 in fact1 at the time of discharge1 has its electric and inductive tension considerably lowered4 ,for consider fig4 #abh to represent a single positive brush2--the induction before the discharge is from the end of the rod outwards1 in diverging lines towards the distant conductors1 as the walls of the room1 c41 and a particle at a has polarity of a certain degree of tension1 and tends with a certain force to become charged2 but at the moment of discharge1 the air in the ramifications b and d1 acquiring also a positive state1 opposes its influence to that of the positive conductor on a1 and the tension of the particle at a is therefore diminished rather than increased4 ,the charged particles at b and d are now inductive bodies1 but their lines of inductive action are still outwards towards the walls of the room2 the direction of the polarity and the tendency of other particles to charge from these1 being governed by1 or in conformity with1 these lines of force4 #addb4 ,the particles that are charged are probably very highly charged1 but1 the medium being a non-conductor1 they cannot communicate that state to their neighbours4 ,they travel1 therefore1 under the influence of the repulsive and attractive forces1 from the charged conductor towards the nearest uninsulated conductor1 or the nearest body in a different state to themselves1 just as charged particles of dust would travel1 and are then discharged2 each particle acting1 in its course1 as a centre of inductive force upon any bodies near which it may come4 ,the travelling of these charged particles when they are numerous1 causes wind and currents1 but these will come into consideration under carrying discharge 7#acai4 #aefb4 c474 #addc4 ,when air is said to be electrified1 and it frequently assumes this state near electrical machines1 it consists1 according to my view1 of a mixture of electrified and unelectrified particles1 the latter being in very large proportion to the former4 ,when we gather electricity from air1 by a flame or by wires1 it is either by the actual discharge of these particles1 or by effects dependent on their inductive action1 a case of either kind being produceable at pleasure4 ,that the law of equality between the two forces or forms of force in inductive action is as strictly preserved in these as in other cases1 is fully shown by the fact1 formerly stated 7#aagc4 #aagd471 that1 however strongly air in a vessel might be charged positively1 there was an exactly equal amount of negative force on the inner surface of the vessel itself1 for no residual portion of either the one or the other electricity could be obtained4 #addd4 ,i have nowhere said1 nor does it follow1 that the air is charged only where the luminous brush appears4 ,the charging may extend beyond those parts which are visible1 i4e4 particles to the right or left of the lines of light may receive electricity1 the parts which are luminous being so only because much electricity is passing by them to other parts 7#adcg472 just as in a spark discharge the light is greater as more electricity passes1 though it has no necessary relation to the quantity required to commence discharge 7#acgj4 #adbj474 ,hence the form we see in a brush may by no means represent the whole quantity of air electrified2 for an invisible portion1 clothing the visible form to a certain depth1 may1 at the same time1 receive its charge 7#aeeb474 #adde4 ,several effects which ,i have met with in muriatic acid gas tend to make me believe1 that that gaseous body allows of a dark discharge4 ,at the same time1 it is quite clear from theory1 that in some gases1 the reverse of this may occur1 i4e4 that the charging of the air may not extend even so far as the light4 ,we do not know as yet enough of the electric light to be able to state on what it depends1 and it is very possible that1 when electricity bursts forth into air1 all the particles of which are in a state of tension1 light may be evolved by such as1 being very near to1 are not of1 those which actually receive a charge at the time4 #addf4 ,the further a brush extends in a gas1 the further no doubt is the charge or discharge carried forward2 but this may vary between different gases1 and yet the intensity required for the first moment of discharge not vary in the same1 but in some other proportion4 ,thus with respect to nitrogen and muriatic acid gases1 the former1 as far as my experiments have proceeded1 produces far finer and larger brushes than the latter 7#adeh4 #adfb471 but the intensity required to commence discharge is much higher for the muriatic acid than the nitrogen 7#acie474 ,here again1 therefore1 as in many other qualities1 specific differences are presented by different gaseous dielectrics1 and so prove the special relation of the latter to the act and the phenomena of induction4 #addg4 ,to sum up these considerations respecting the character and condition of the brush1 ,i may state that it is a spark to air2 a diffusion of electric force to matter1 not by conduction1 but disruptive discharge1 a dilute spark which1 passing to very badly conducting matter1 frequently discharges but a small portion of the power stored up in the conductor2 for as the air charged reacts on the conductor1 whilst the conductor1 by loss of electricity1 sinks in its force 7#adce471 the discharge quickly ceases1 until by the dispersion of the charged air and the renewal of the excited conditions of the conductor1 circumstances have risen up to their first effective condition1 again to cause discharge1 and again to fall and rise1 #addh4 ,the brush and spark gradually pass into one another1 ,making a small ball positive by a good electrical machine with a large prime conductor1 and approaching a large uninsulated discharging ball towards it1 very beautiful variations from the spark to the brush may be obtained4 ,the drawings of long and powerful sparks1 given by ,van ,marum,a1 ,harris,b1 and others1 also indicate the same phenomena4 ,as far as ,i have observed1 whenever the spark has been brushy in air of common pressures1 the whole of the electricity has not been discharged1 but only portions of it1 more or less according to circumstances2 whereas1 whenever the effect has been a distinct spark throughout the whole of its course1 the discharge has been perfect1 provided no interruption had been made to it elsewhere1 in the discharging circuit1 than where the spark occurred4 ,a ,description of the ,teylerian machine1 vol4 i4 pp4 #bh4 #cb42 vol4 ii4 p4 #bbf1 c4 ,b ,philosophical ,transactions1 #ahcd1 p4 #bac4 #addi4 ,when an electrical brush from an inch to six inches in length or more is issuing into free air1 it has the form given1 fig4 #aag4 ,but if the hand1 a ball1 of any knobbed conductor be brought near1 the extremities of the coruscations turn towards it and each other1 and the whole assumes various forms according to circumstances1 as in figs4 #aai1 #abj1 and #aba4 ,the influence of the circumstances in each case is easily traced1 and ,i might describe it here1 but that ,i should be ashamed to occupy the time of the ,society in things so evident4 ,but how beautifully does the curvature of the ramifications illustrate the curved form of the lines of inductive force existing previous to the discharge6 for the former are consequences of the latter1 and take their course1 in each discharge1 where the previous inductive tension had been raised to the proper degree4 ,they represent these curves just as well as iron filings represent magnetic curves1 the visible effects in both cases being the consequences of the action of the forces in the places where the effects appear4 ,the phenomena1 therefore1 constitute additional and powerful testimony 7#abaf4 #abcj47 to that already given in favour both of induction through dielectrics in curved lines 7#abca471 and of the lateral relation of these lines1 by an effect equivalent to a repulsion producing divergence1 or1 as in the cases figured1 the bulging form4 #adej4 ,in reference to the theory of molecular inductive action1 ,i may also add1 the proof deducible from the long brushy ramifying spark which1 may be obtained between a small ball on the positive conductor of an electrical machine1 and a larger one at a distance 7#addh4 #aejd474 ,what a fine illustration that spark affords of the previous condition of all the particles of the dielectric between the surfaces of discharge1 and how unlike the appearances are to any which would be deduced from the theory which assumes inductive action to be action at a distance1 in straight lines only2 and charge1 as being electricity retained upon the surface of conductors by the mere pressure of the atmosphere6 99 99 99 99 99 #adea4 ,when the brush is obtained in rarefied air1 the appearances vary greatly1 according to circumstances1 and are exceedingly beautiful4 ,sometimes a brush may be formed of only six or seven branches1 these being broad and highly luminous1 of a purple colour1 and in some parts an inch or more apart3 by a spark discharge at the prime conductor 7#adee47 single brushes may be obtained at pleasure4 ,discharge in the form of a brush is favoured by rarefaction of the air1 in the same manner and for the same reason as discharge in the form of a spark 7#acge472 but in every case there is previous induction and charge through the dielectric1 and polarity of its particles 7#adcg471 the induction being1 as in any other instance1 alternately raised by the machine and lowered by the discharge4 ,in certain experiments the rarefaction was increased to the utmost degree1 and the opposed conducting surfaces brought as near together as possible without producing glow 7#aebi473 the brushes then contracted in their lateral dimensions1 and recurred so rapidly as to form an apparently continuous arc of light from metal to metal4 ,still the discharge could be observed to intermit 7#adbg471 so that even under these high conditions1 induction preceded each single brush1 and the tense polarized condition of the contiguous particles was a necessary preparation for the discharge itself4 #adeb4 ,the brush form of disruptive discharge may be obtained not only in air and gases1 but also in much denser media4 ,i procured it in oil of turpentine from the end of a wire going through a glass tube into the fluid contained in a metal vessel4 ,the brush was small and very difficult to obtain2 the ramifications were simple1 and stretched out from each other1 diverging very much4 ,the light was exceedingly feeble1 a perfectly dark room being required for its observation4 ,when a few solid particles1 as of dust or silk1 were in the liquid1 the brush was produced with much greater facility4 #adec4 ,the running together or coalescence of different lines of discharge 7#adab47 is very beautifully shown in the brush in air4 ,this point may present a little difficulty to those who are not accustomed to see in every discharge an equal exertion of power in opposite directions1 a positive brush being considered by such 7perhaps in consequence of the common phrase direction of a current7 as indicating a breaking forth in different directions of the original force1 rather than a tendency to convergence and union in one line of passage4 ,but the ordinary case of the brush may be compared1 for its illustration1 with that in which1 by holding the knuckle opposite to highly excited glass1 a discharge occurs1 the ramifications of a brush then leading from the glass and converging into a spark on the knuckle4 ,though a difficult experiment to make1 it is possible to obtain discharge between highly excited shell-lac and the excited glass of a machine3 when the discharge passes1 it is1 from the nature of the charged bodies1 brush at each end and spark in the middle1 beautifully illustrating that tendency of discharge to facilitate like action1 which ,i have described in a former page 7#adah474 #aded4 ,the brush has specific characters in different gases1 indicating a relation to the particles of these bodies even in a stronger degree than the spark 7#adbb4 #adbc474 ,this effect is in strong contrast with the non-variation caused by the use of different substances as conductors from which the brushes are to originate4 ,thus1 using such bodies as wood1 card1 charcoal1 nitre1 citric acid1 oxalic acid1 oxide of lead1 chloride of lead1 carbonate of potassa1 potassa fusa1 strong solution of potash1 oil of vitriol1 sulphur1 sulphuret of antimony1 and hmatite1 no variation in the character of the brushes was obtained1 except that 7dependent upon their effect as better or worse conductors7 of causing discharge with more or less readiness and quickness from the machine,a4 ,a ,exception must1 of course1 be made of those cases where the root of the brush1 becoming a spark1 causes a little diffusion or even decomposition of the matter there1 and so gains more or less of a particular colour at that part4 #adee4 ,the following are a few of the effects ,i observed in different gasses at the positively charged surfaces1 and with atmospheres varying in their pressure4 ,the general effect of rarefaction was the same for all the gases3 at first1 sparks passed2 these gradually were converted into brushes1 which became larger and more distinct in their ramifications1 until1 upon further rarefaction1 the latter began to collapse and draw in upon each other1 till they formed a stream across from conductor to conductor3 then a few lateral streams shot out towards the glass of the vessel from the conductors2 these became thick and soft in appearance1 and were succeeded by the full constant glow which covered the discharging wire4 ,the phenomena varied with the size of the vessel 7#adgg471 the degree of rarefaction1 and the discharge of electricity from the machine4 ,when the latter was in successive sparks1 they were most beautiful1 the effect of a spark from a small machine being equal to1 and often surpassing1 that produced by the constant discharge of a far more powerful one4 #adef4 ,air4--,fine positive brushes are easily obtained in air at common pressures1 and possess the well-known purplish light4 ,when the air is rarefied1 the ramifications are very long1 filling the globe 7#adgg472 the light is greatly increased1 and is of a beautiful purple colour1 with an occasional rose tint in it4 #adeg4 ,oxygen4--,at common pressures1 the brush is very close and compressed1 and of a dull whitish colour4 ,in rarefied oxygen1 the form and appearance are better1 the colour somewhat purplish1 but all the characters very poor compared to those in air4 #adeh4 ,nitrogen gives brushes with great facility at the positive surface1 far beyond any other gas ,i have tried3 they are almost always fine in form1 light1 and colour1 and in rarefied nitrogen1 are magnificent4 ,they surpass the discharges in any other gas as to the quantity of light evolved4 #adei4 ,hydrogen1 at common pressures1 gave a better brush than oxygen1 but did not equal nitrogen2 the colour was greenish gray4 ,in rarefied hydrogen1 the ramifications were very fine in form and distinctness1 but pale in colour1 with a soft and velvety appearance1 and not at all equal to those in nitrogen4 ,in the rarest state of the gas1 the colour of the light was a pale gray green4 #adfj4 ,coal gas4--,the brushes were rather difficult to produce1 the contrast with nitrogen being great in this respect4 ,they were short and strong1 generally of a greenish colour1 and possessing much of the spark character3 for1 occurring on both the positive and negative terminations1 often when there was a dark interval of some length between the two brushes1 still the quick1 sharp sound of the spark was produced1 as if the discharge had been sudden through this gas1 and partaking1 in that respect1 of the character of a spark4 ,in rare coal gas1 the brush forms were better1 but the light very poor and the colour gray4 #adfa4 ,carbonic acid gas produces a very poor brush at common pressures1 as regards either size1 light1 or colour2 and this is probably connected with the tendency which this gas has to discharge the electricity as a spark 7#adbb474 ,in rarefied carbonic acid1 the brush is better in form1 but weak as to light1 being of a dull greenish or purplish line1 varying with the pressure and other circumstances4 #adfb4 ,muriatic acid gas4--,it is very difficult to obtain the brush in this gas at common pressures4 ,on gradually increasing the distance of the rounded ends1 the sparks suddenly ceased when the interval was about an inch1 and the discharge1 which was still through the gas in the globe1 was silent and dark4 ,occasionally a very short brush could for a few moments be obtained1 but it quickly disappeared4 ,even when the intermitting spark current 7#adee47 from the machine was used1 still ,i could only with difficulty obtain a brush1 and that very short1 though ,i used rods with rounded terminations 7about #j4be of an inch in diameter7 which had before given them most freely in air and nitrogen4 ,during the time of this difficulty with the muriatic gas1 magnificent brushes were passing off from different parts of the machine into the surrounding air4 ,on rarefying the gas1 the formation of the brush was facilitated1 but it was generally of a low squat form1 very poor in light1 and very similar on both the positive and negative surfaces4 ,on rarefying the gas still more1 a few large ramifications were obtained of a pale bluish colour1 utterly unlike those in nitrogen4 99 99 99 99 99 #adfc4 ,in all the gases1 the different forms of disruptive discharge may be linked together and gradually traced from one extreme to the other1 i4e4 from the spark to the glow 7#adje4 #aebf471 or1 it may be1 to a still further condition to be called dark discharge 7#aedd-aefj472 but it is1 nevertheless1 very surprising to see what a specific character each keeps whilst under the predominance of the general law4 ,thus1 in muriatic acid1 the brush is very difficult to obtain1 and there comes in its place almost a dark discharge1 partaking of the readiness of the spark action4 ,moreover1 in muriatic acid1 ,i have never observed the spark with any dark interval in it4 ,in nitrogen1 the spark readily changes its character into that of brush4 ,in carbonic acid gas1 there seems to be a facility to occasion spark discharge1 whilst yet that gas is unlike nitrogen in the facility of the latter to form brushes1 and unlike muriatic acid in its own facility to continue the spark4 ,these differences add further force1 first to the observations already made respecting the spark in various gases 7#adbb4 #adbc471 and then1 to the proofs deducible from it1 of the relation of the electrical forces to the particles of matter4 #adfd4 ,the peculiar characters of nitrogen in relation to the electric discharge 7#adbb4 #adeh47 must1 evidently1 have an important influence over the form and even the occurrence of lightning4 ,being that gas which most readily produces coruscations1 and1 by them1 extends discharge to a greater distance than any other gas tried1 it is also that which constitutes four-fifths of our atmosphere2 and as1 in atmospheric electrical phenomena1 one1 and sometimes both the inductive forces are resident on the particles of the air1 which1 though probably affected as to conducting power by the aqueous particles in it1 cannot be considered as a good conductor2 so the peculiar power possessed by nitrogen1 to originate and effect discharge in the form of a brush or of ramifications1 has1 probably1 an important relation to its electrical service in nature1 as it most seriously affects the character and condition of the discharge when made4 ,the whole subject of discharge from and through gases is of great interest1 and1 if only in reference to atmospheric electricity1 deserves extensive and close experimental investigation4 ,difference of discharge at the positive and negative conducting surfaces4 #adfe4 ,i have avoided speaking of this well-known phenomenon more than was quite necessary1 that ,i might bring together here what ,i have to say on the subject4 ,when the brush discharge is observed in air at the positive and negative surfaces1 there is a very remarkable difference1 the true and full comprehension of which would1 no doubt1 be of the utmost importance to the physics of electricity2 it would throw great light on our present subject1 i4e4 the molecular action of dielectrics under induction1 and its consequences2 and seems very open to1 and accessible by1 experimental inquiry4 #adff4 ,the difference in question used to be expressed in former times by saying1 that a point charged positively gave brushes into the air1 whilst the same point charged negatively gave a star4 ,this is true only of bad conductors1 or of metallic conductors charged intermittingly1 or otherwise controlled by collateral induction4 ,if metallic points project freely into the air1 the positive and negative light upon them differ very little in appearance1 and the difference can be observed only upon close examination4 #adfg4 ,the effect varies exceedingly under different circumstances1 but1 as we must set out from some position1 may perhaps be stated thus3 if a metallic wire with a rounded termination in free air be used to produce the brushy discharge1 then the brushes obtained when the wire is charged negatively are very poor and small1 by comparison with those produced when the charge is positive4 ,or if a large metal ball connected with the electrical machine be charged positively1 and a fine uninsulated point be gradually brought towards it1 a star appears on the point when at a considerable distance1 which1 though it becomes brighter1 does not change its form of a star until it is close up to the ball3 whereas1 if the ball be charged negatively1 the point at a considerable distance has a star on it as before2 but when brought nearer1 7in my case to the distance of #a-a_/b inch17 a brush formed on it1 extending to the negative ball2 and when still nearer1 7at #a_/h of an inch distance17 the brush ceased1 and bright sparks passed4 ,these variations1 ,i believe1 include the whole series of differences1 and they seem to show at once1 that the negative surface tends to retain its discharging character unchanged1 whilst the positive surface1 under similar circumstances1 permits of great variation4 #adfh4 ,there are several points in the character of the negative discharge to air which it is important to observe4 ,a metal rod1 #j4c of an inch in diameter1 with a rounded end projecting into the air1 was charged negatively1 and gave a short noisy brush 7fig4 #abb474 ,it was ascertained both by sight 7#adbg4 #adcc47 and sound 7#adca471 that the successive discharges were very rapid in their recurrence1 being seven or eight times more numerous in the same period1 than those produced when the rod was charged positively to an equal degree4 ,when the rod was positive1 it was easy1 by working the machine a little quicker1 to replace the brush by a glow 7#adje4 #adfc471 but when it was negative no efforts could produce this change4 ,even by bringing the hand opposite the wire1 the only effect was to increase the number of brush discharges in a given period1 raising at the same time the sound to a higher pitch4 #adfi4 ,a point opposite the negative brush exhibited a star1 and as it was approximated caused the size and sound of the negative brush to diminish1 and1 at last1 to cease1 leaving the negative end silent and dark1 yet effective as to discharge4 #adgj4 ,when the round end of a smaller wire 7fig4 #abc47 was advanced towards the negative brush1 it 7becoming positive by induction7 exhibited the quiet glow at #h inches distance1 the negative brush continuing4 ,when nearer1 the pitch of the sound of the negative brush rose1 indicating quicker intermittences 7#adca472 still nearer1 the positive end threw off ramifications and distinct brushes2 at the same time1 the negative brush contracted in its lateral directions and collected together1 giving a peculiar narrow longish brush1 in shape like a hair pencil1 the two brushes existing at once1 but very different in their form and appearance1 and especially in the more rapid recurrence of the negative discharges than of the positive4 ,on using a smaller positive wire for the same experiment1 the glow first appeared on it1 and then the brush1 the negative brush being affected at the same time2 and the two at one distance became exceedingly alike in appearance1 and the sounds1 ,i thought1 were in unison2 at all events they were in harmony1 so that the intermissions of discharge were either isochronous1 or a simple ratio existed between the intervals4 ,with a higher action of the machine1 the wires being retained unaltered1 the negative surface became dark and silent1 and a glow appeared on the positive one4 ,a still higher action changed the latter into a spark4 ,finer positive wires gave other variations of these effects1 the description of which ,i must not allow myself to go into here4 #adga4 ,a thinner rod was now connected with the negative conductor in place of the larger one 7#adfh471 its termination being gradually diminished to a blunt point1 as in fig4 #abd2 and it was beautiful to observe that1 notwithstanding the variation of the brush1 the same general order of effects was produced4 ,the end gave a small sonorous negative brush1 which the approach of the hand or a large conducting surface did not alter1 until it was so near as to produce a spark4 ,a fine point opposite to it was luminous at a distance2 being nearer it did not destroy the light and sound of the negative brush1 but only tended to have a brush produced on itself1 which1 at a still less distance1 passed into a spark joining the two surfaces4 #adgb4 ,when the distinct negative and positive brushes are produced simultaneously in relation to each other in air1 the former almost always has a contracted form1 as in fig4 #abe1 very much indeed resembling the figure which the positive brush itself has when influenced by the lateral vicinity of positive parts acting by induction4 ,thus a brush issuing from a point in the re-entering angle of a positive conductor has the same compressed form 7fig4 #abf474 #adgc4 ,the character of the negative brush is not affected by the chemical nature of the substances of the conductors 7#aded471 but only by their possession of the conducting power in a greater or smaller degree4 #adgd4 ,rarefaction of common air about a negative ball or blunt point facilitated the development of the negative brush1 the effect being1 ,i think1 greater than on a positive brush1 though great on both4 ,extensive ramifications could be obtained from a ball or end electrified negatively to the plate of the air-pump on which the jar containing it stood4 #adge4 ,a very important variation of the relative forms and conditions of the positive and negative brush takes place on varying the dielectric in which they are produced4 ,the difference is so very great that it points to a specific relation of this form of discharge to the particular gas in which it takes place1 and opposes the idea that gases are but obstructions to the discharge1 acting one like another and merely in proportion to their pressure 7#acgg474 #adgf4 ,in air1 the superiority of the positive brush is well known 7#adfg4 #adgb474 ,in nitrogen1 it is as great or even greater than in air 7#adeh474 ,in hydrogen1 the positive brush loses a part of its superiority1 not being so good as in nitrogen or air2 whilst the negative brush does not seem injured 7#adei474 ,in oxygen1 the positive brush is compressed and poor 7#adeg72 whilst the negative did not become less3 the two were so alike that the eye frequently could not tell one from the other1 and this similarity continued when the oxygen was gradually rarefied4 ,in coal gas1 the brushes are difficult of production as compared to nitrogen 7#adfj471 and the positive not much superior to the negative in its character1 either at common or low pressures4 ,in carbonic acid gas1 this approximation of character also occurred4 ,in muriatic acid gas1 the positive brush was very little better than the negative1 and both difficult to produce 7#adfb47 as compared with the facility in nitrogen or air4 #adgg4 ,these experiments were made with rods of brass about a quarter of an inch thick having rounded ends1 these being opposed in a glass globe #g inches in diameter1 containing the gas to be experimented with4 ,the electric machine was used to communicate directly1 sometimes the positive1 and sometimes the negative state1 to the rod in connection with it4 #adgh4 ,thus we see that1 notwithstanding there is a general difference in favour of the superiority of the positive brush over the negative1 that difference is at its maximum in nitrogen and air2 whilst in carbonic acid1 muriatic acid1 coal gas1 and oxygen1 it diminishes1 and at last almost disappears4 ,so that in this particular effect1 as in all others yet examined1 the evidence is in favour of that view which refers the results to a direct relation of the electric forces with the molecules of the matter concerned in the action 7#adba4 #adbc4 #adfc474 ,even when special phenomena arise under the operation of the general law1 the theory adopted seems fully competent to meet the case4 #adgi4 ,before ,i proceed further in tracing the probable cause of the difference between the positive and negative brush discharge1 ,i wish to know the results of a few experiments which are in course of preparation3 and thinking this ,series of ,researches long enough1 ,i shall here close it with the expectation of being able in a few weeks to renew the inquiry1 and entirely redeem my pledge 7#acjf474 ,royal ,institution1 ,dec4 #bcrd1 #ahcg4 ,,thirteenth ,,series4 #ah4 ,on ,induction 7continued74 ix4 ,disruptive discharge 7continued7--,peculiarities of positive and negative discharge either as spark or brush--,glow discharge--,dark discharge4 x4 ,convection1 or carrying discharge4 xi4 ,relation of a vacuum to electrical phenomena4 #ai4 ,nature of the electrical current4 ,received ,february #bb1--,read ,march #ae1 #ahch4 ix4 ,disruptive discharge 7continued74 #adhj4 ,let us now direct our attention to the general difference of the positive and negative disruptive discharge1 with the object of tracing1 as far as possible1 the cause of that difference1 and whether it depends on the charged conductors principally1 or on the interposed dielectric2 and as it appears to be great in air and nitrogen 7#adgf471 let us observe the phenomena in air first4 #adha4 ,the general case is best understood by a reference to surfaces of considerable size rather than to points1 which involve 7as a secondary effect7 the formation of currents 7#aefb74 ,my investigation1 therefore1 was carried on with balls and terminations of different diameters1 and the following are some of the principal results4 #adhb4 ,if two balls of very different dimensions1 as for instance one-half an inch1 and the other three inches in diameter1 be arranged at the ends of rods so that either can be electrified by a machine and made to discharge by sparks to the other1 which is at the same time uninsulated2 then1 as is well known1 far longer sparks are obtained when the small ball is positive and the large ball negative1 than when the small ball is negative and the large ball positive4 ,in the former case1 the sparks are #aj or #ab inches in length2 in the latter1 an inch or an inch and a half only4 99 99 99 99 99 #adhc4 ,but previous to the description of further experiments1 ,i will mention two words1 for which with many others ,i am indebted to a friend1 and which ,i think it would be expedient to introduce and use4 ,it is important in ordinary inductive action1 to distinguish at which charged surface the induction originates and is sustained3 i4e4 if two or more metallic balls1 or other masses of matter1 are in inductive relation1 to express which are charged originally1 and which are brought by them into the opposite electrical condition4 ,i propose to call those bodies which are originally charged1 inductric bodies2 and those which assume the opposite state1 in consequence of the induction1 inducteous bodies4 ,this distinction is not needful because there is any difference between the sums of the inductric and the inducteous forces2 but principally because1 when a ball ,a is inductric1 it not merely brings a ball ,b1 which is opposite to it1 into an inducteous state1 but also many other surrounding conductors1 though some of them may be a considerable distance off1 and the consequence is1 that the balls do not bear the same precise relation to each other when1 first one1 and then the other1 is made the inductric ball2 though1 in each case1 the same ball be made to assume the same state4 #adhd1 ,another liberty which ,i may also occasionally take in language ,i will explain and limit4 ,it is that of calling a particular spark or brush1 positive or negative1 according as it may be considered as originating at a positive or a negative surface4 ,we speak of the brush as positive or negative when it shoots out from surfaces previously in those states2 and the experiments of ,mr4 ,wheatstone go to prove that it really begins at the charged surface1 and from thence extends into the air 7#adcg4 #adch47 or other dielectric4 ,according to my view1 sparks also originate or are determined at one particular spot 7#acgj471 namely1 that where the tension first rises up to the maximum degree2 and when this can be determined1 as in the simultaneous use of large and small balls1 in which case the discharge begins or is determined by the latter1 ,i would call that discharge which passes at once1 a positive spark1 if it was at the positive surface that the maximum intensity was first obtained2 or a negative spark1 if that necessary intensity was first obtained at the negative surface4 99 99 99 99 99 #adhe4 ,an apparatus was arranged1 as in fig4 #abi4 7,plate ,,viii473 ,a and ,b were brass balls of very different diameters attached to metal rods1 moving through sockets on insulating pillars1 so that the distance between the balls could be varied at pleasure4 ,the large ball ,a1 #b inches in diameter1 was connected with an insulated brass conductor1 which could be rendered positive or negative directly from a cylinder machine3 the small ball ,b1 #j4be of an inch in diameter1 was connected with a discharging train 7#bib47 and perfectly uninsulated4 ,the brass rods sustaining the balls were #j4b of an inch in thickness4 #adhf4 ,when the large ball was positive and inductric 7#adhc471 negative sparks occurred until the interval was #j4di of an inch2 then mixed brush and spark between that and #j4ea2 and from #j4eb and upwards1 negative brush alone4 ,when the large ball was made negative and inductric1 then positive spark alone occurred until the interval was as great as #a4ae inches2 spark and brush from that up to #a4ee2 and to have the positive brush alone1 it required an interval of at least #a4fe inches4 #adhg4 ,the balls ,a and ,b were now changed for each other4 ,then making the small ball ,b inductric positively1 the positive sparks alone continued only up to #j4fg2 spark and brush occurred from #j4fh up to #j4gb2 and positive brush alone from #j4gd and upwards4 ,rendering the small ball ,b inductric and negative1 negative sparks alone occurred up to #j4dj2 then spark and brush at #j4db2 whilst from #j4dd and upwards the noisy negative brush alone took place4 #adhh4 ,we thus find a great difference as the balls are rendered inductric or inducteous2 the small ball rendered positive inducteously giving a spark nearly twice as long as that produced when it was charged positive inductrically1 and a corresponding difference1 though not1 under the circumstances1 to the same extent1 was manifest1 when it was rendered negative,a4 ,a ,for similar experiments on different gases1 see #aeah4--;,dec4 #ahch4 #adhi4 ,other results are1 that the small ball rendered positive gives a much longer spark than when it is rendered negative1 and that the small ball rendered negative gives a brush more readily than when positive1 in relation to the effect produced by increasing the distance between the two balls4 #adij4 ,when the interval was below #j4d of an inch1 so that the small ball should give sparks1 whether positive or negative1 ,i could not observe that there was any constant difference1 either in their ready occurrence or the number which passed in a given time4 ,but when the interval was such that the small ball when negative gave a brush1 then the discharges from it1 as separate negative brushes1 were far more numerous than the corresponding discharges from it when rendered positive1 whether those positive discharges were as sparks or brushes4 #adia4 ,it is1 therefore1 evident that1 when a ball is discharging electricity in the form of brushes1 the brushes are far more numerous1 and each contains or carries off far less electric force when the electricity so discharged is negative1 than when it is positive4 #adib4 ,in all such experiments as those described1 the point of change from spark to brush is very much governed by the working state of the electrical machine and the size of the conductor connected with the discharging ball4 ,if the machine be in strong action and the conductor large1 so that much power is accumulated quickly for each discharge1 then the interval is greater at which the sparks are replaced by brushes2 but the general effect is the same,a4 ,a ,for similar experiments in different gases1 see #aeaj-aeag4--;,dec4 #ahch4 #adic4 ,these results1 though indicative of very striking and peculiar relations of the electric force or forces1 do not show the relative degrees of charge which the small ball acquires before discharge occurs1 i4e4 they do not tell whether it acquires a higher condition in the negative1 or in the positive state1 immediately preceding that discharge4 ,to illustrate this important point ,i arranged two places of discharge as represented1 fig #acj4 ,a and ,d are brass balls #b inches diameter1 ,b and ,c are smaller brass balls #j4be of an inch in diameter2 the forks ,l and ,r supporting them were of brass wire #j4b of an inch in diameter2 the space between the large and small ball on the same fork was #e inches1 that the two places of discharge n and o might be sufficiently removed from each other's influence4 ,the fork ,l was connected with a projecting cylindrical conductor1 which could be rendered positive or negative at pleasure1 by an electrical machine1 and the fork ,r was attached to another conductor1 but thrown into an uninsulated state by connection with a discharging train 7#bib474 ,the two intervals or places of discharge n and o could be varied at pleasure1 their extent being measured by the occasional introduction of a diagonal scale4 ,it is evident1 that1 as the balls ,a and ,b connected with the same conductor are always charged at once1 and that discharge may take place to either of the balls connected with the discharging train1 the intervals of discharge n and o may be properly compared to each other1 as respects the influence of large and small balls when charged positively and negatively in air4 #adid4 ,when the intervals n and o were each made #j4i of an inch1 and the balls ,a and ,b inductric positively1 the discharge was all at n from the small ball of the conductor to the large ball of the discharging train1 and mostly by positive brush1 though once by a spark4 ,when the balls ,a and ,b were made inductric negatively1 the discharge was still from the same small ball1 at n1 by a constant negative brush4 #adie4 ,i diminished the intervals n and o to #j4f of an inch4 ,when ,a and ,b were inductric positively1 all the discharge was at n as a positive brush3 when ,a and ,b were inductric negatively1 still all the discharge was at n1 as a negative brush4 #adif4 ,the facility of discharge at the positive and negative small balls1 therefore1 did not appear to be very different4 ,if a difference had existed1 there were always two small balls1 one in each state1 that the discharge might happen at that most favourable to the effect4 ,the only difference was1 that one was in the inductric1 and the other in the inducteous state1 but whichsoever happened for the time to be in that state1 whether positive or negative1 had the advantage4 #adig4 ,to counteract this interfering influence1 ,i made the interval n #j4gi and interval o #j4eh of an inch4 ,then1 when the balls ,a and ,b were inductric positive1 the discharge was about equal at both intervals4 ,when1 on the other hand1 the balls ,a and ,b were inductric negative1 there was discharge1 still at both1 but most at n1 as if the small ball negative could discharge a little easier than the same ball positive4 #adih4 ,the small balls and terminations used in these and similar experiments may very correctly be compared1 in their action1 to the same balls and ends when electrified in free air at a much greater distance from conductors1 than they were in those cases from each other4 ,in the first place1 the discharge1 even when as a spark1 is1 according to my view1 determined1 and1 so to speak1 begins at a spot on the surface of the small ball 7#acgd471 occurring when the intensity there has risen up to a certain maximum degree 7#acgj472 this determination of discharge at a particular spot first1 being easily traced from the spark into the brush1 by increasing the distance1 so as1 at last1 even to render the time evident which is necessary for the production of the effect 7#adcf4 #adch474 ,in the next place1 the large balls which ,i have used might be replaced by larger balls at a still greater distance1 and so1 by successive degrees1 may be considered as passing into the sides of the rooms2 these being under general circumstances the inducteous bodies1 whilst the small ball rendered either positive or negative is the inductric body4 #adii4 ,but1 as has long been recognised1 the small ball is only a blunt end1 and1 electrically speaking1 a point only a small ball2 so that when a point or blunt end is throwing out its brushes into the air1 it is acting exactly as the small balls have acted in the experiments already described1 and by virtue of the same properties and relations4 #aejj4 ,it may very properly be said with respect to the experiments1 that the large negative ball is as essential to the discharge as the small positive ball1 and also that the large negative ball shows as much superiority over the large positive ball 7which is inefficient in causing a spark from its opposed small negative ball7 as the small positive ball does over the small negative ball2 and probably when we understand the real cause of the difference1 and refer it rather to the condition of the particles of the dielectric than to the sizes of the conducting balls1 we may find much importance in such an observation4 ,but for the present1 and whilst engaged in investigating the point1 we may admit1 what is the fact1 that the forces are of higher intensity at the surfaces of the smaller balls than at those of the larger 7#acgb4 #acgd472 that the former1 therefore1 determine the discharge1 by first rising up to that exalted condition which is necessary for it2 and that1 whether brought to this condition by induction towards the walls of a room or the large balls ,i have used1 these may fairly be compared one with the other in their influence and actions4 #aeja4 ,the conclusions ,i arrive at are3 first1 that when two equal small conducting surfaces equally placed in air are electrified1 one positively and the other negatively1 that which is negative can discharge to the air at a tension a little lower than that required for the positive ball3 second1 that when discharge does take place1 much more passes at each time from the positive than from the negative surface 7#adia474 ,the last conclusion is very abundantly proved by the optical analysis of the positive and negative brushes already described 7#adfh471 the latter set of discharges being found to recur five or six times oftener than the former,a4 ,a ,a very excellent mode of examining the relation of small positive and negative surfaces would be by the use of drops of gum water1 solutions1 or other liquids4 ,see onwards 7#aeha4 #aeic474 #aejb4 ,if1 now1 a small ball be made to give brushes or brushy sparks by a powerful machine1 we can1 in some measure1 understand and relate the difference perceived when it is rendered positive or negative4 ,it is known to give when positive a much larger and more powerful spark than when negative1 and with greater facility 7#adhb473 in fact1 the spark1 although it takes away so much more electricity at once1 commences at a tension higher only in a small degree1 if at all4 ,on the other hand1 if rendered negative1 though discharge may commence at a lower degree1 it continues but for a very short period1 very little electricity passing away each time4 ,these circumstances are directly related2 for the extent to which the positive spark can reach1 and the size and extent of the positive brush1 are consequences of the capability which exists of much electricity passing off at one discharge from the positive surface 7#adfh4 #aeja474 #aejc4 ,but to refer these effects only to the form and size of the conductor1 would1 according to my notion of induction1 be a very imperfect mode of viewing the whole question 7#aebc4 #afjj474 ,i apprehend that the effects are due altogether to the mode in which the particles of the interposed dielectric polarize1 and ,i have already given some experimental indications of the differences presented by different electrics in this respect 7#adge4 #adgf474 ,the modes of polarization1 as ,i shall have occasion hereafter to show1 may be very diverse in different dielectrics4 ,with respect to common air1 what seems to be the consequence of a superiority in the positive force at the surface of the small ball1 may be due to the more exalted condition of the negative polarity of the particles of air1 or of the nitrogen in it 7the negative part being1 perhaps1 more compressed1 whilst the positive part is more diffuse1 or vice versa 7#afhg4 c4772 for such a condition could determine certain effects at the positive ball which would not take place to the same degree at the negative ball1 just as well as if the positive ball had possessed some special and independent power of its own4 #aejd4 ,the opinion1 that the effects are more likely to be dependent upon the dielectric than the ball1 is supported by the character of the two discharges4 ,if a small positive ball be throwing off brushes with ramifications ten inches long1 how can the ball affect that part of a ramification which is five inches from it8 ,yet the portion beyond that place has the same character as that preceding it1 and no doubt has that character impressed by the same general principle and law4 ,looking upon the action of the contiguous particles of a dielectric as fully proved1 ,i see1 in such a ramification1 a propagation of discharge from particle to particle1 each doing for the one next it what was done for it by the preceding particle1 and what was done for the first particle by the charged metal against which it was situated4 #aeje4 ,with respect to the general condition and relations of the positive and negative brushes in dense or rare air1 or in other media and gases1 if they are produced at different times and places they are of course independent of each other4 ,but when they are produced from opposed ends or balls at the same time1 in the same vessel of gas 7#adgj4 #adgg471 they are frequently related2 and circumstances may be so arranged that they shall be isochronous1 occurring in equal numbers in equal times2 or shall occur in multiples1 i4e4 with two or three negatives to one positive2 or shall alternate1 or be quite irregular4 ,all these variations ,i have witnessed2 and when it is considered that the air in the vessel1 and also the glass of the vessel1 can take a momentary charge1 it is easy to comprehend their general nature and cause4 99 99 99 99 99 #aejf4 ,similar experiments to those in air 7#adhe4 #adic47 were made in different gases1 the results of which ,i will describe as briefly as possible4 ,the apparatus is represented fig4 #aca1 consisting of a bell-glass eleven inches in diameter at the widest part1 and ten and a half inches high up to the bottom of the neck4 ,the balls are lettered1 as in fig4 #acj1 and are in the same relation to each other2 but ,a and ,b were on separate sliding wires1 which1 however1 were generally joined by a cross wire1 w1 above1 and that connected with the brass conductor1 which received its positive or negative charge from the machine4 ,the rods of ,a and ,b were graduated at the part moving through the stuffing-box1 so that the application of a diagonal scale applied there1 told what was the distance between these balls and those beneath them4 ,as to the position of the balls in the jar1 and their relation to each other1 ,c and ,d were three and a quarter inches apart1 their height above the pump plate five inches1 and the distance between any of the balls and the glass of the jar one inch and three quarters at least1 and generally more4 ,the balls ,a and ,d were two inches in diameter1 as before 7#adic472 the balls ,b and ,c only #j4ae of an inch in diameter4 ,another apparatus was occasionally used in connection with that just described1 being an open discharger 7fig4 #acb471 by which a comparison of the discharge in air and that in gases could be obtained4 ,the balls ,e and ,f1 each #j4f of an inch in diameter1 were connected with sliding rods and other balls1 and were insulated4 ,when used for comparison1 the brass conductor was associated at the same time with the balls ,a and ,b of figure #aca and ball ,e of this apparatus 7fig4 #acb472 whilst the balls ,c1 ,d and ,f were connected with the discharging train4 #aejg4 ,i will first tabulate the results as to the restraining power of the gases over discharge4 ,the balls ,a and ,c 7fig4 #aca47 were thrown out of action by distance1 and the effects at ,b and ,d1 or the interval n in the gas1 compared with those at the interval p in the air1 between ,e and ,f 7fig4 #acb474 ,the ,table sufficiently explains itself4 ,it will be understood that all discharge was in the air1 when the interval there was less than that expressed in the first or third columns of figures2 and all the discharge in the gas1 when the interval in air was greater than that in the second or fourth column of figures4 ,at intermediate distances the discharge was occasionally at both places1 i4e4 sometimes in the air1 sometimes in the gas4 ,interval p in parts of an inch ,when the small ball ,b ,when the small ball ,b ,constant inter- was inductric and was inductric and val n between positive the negative the ,b and ,d #a discharge was all discharge was all inch at p in at n in at p in at n in air before the gas air before the gas after after p p p p ,in ,air #j4aj #j4ej #j4bh #j4cc ,in ,nitrogen #j4cj #j4fe #j4ca #j4dj ,in ,oxygen #j4cc #j4eb #j4bg #j4cj ,in ,hydrogen #j4bj #j4aj #j4bb #j4bd ,in ,coal ,gas #j4bj #j4ij #j4bj #j4bg ,in ,carbonic ,acid #j4fa #a4cj #j4cj #j4ae #aejh4 ,these results are the same generally1 as far as they go1 as those of the like nature in the last series 7#achh471 and confirm the conclusion that different gases restrain discharge in very different proportions4 ,they are probably not so good as the former ones1 for the glass jar not being varnished1 acted irregularly1 sometimes taking a certain degree of charge as a non-conductor1 and at other times acting as a conductor in the conveyance and derangement of that charge4 ,another cause of difference in the ratios is1 no doubt1 the relative sizes of the discharge balls in air2 in the former case they were of very different size1 here they were alike4 #aeji4 ,in future experiments intended to have the character of accuracy1 the influence of these circumstances ought to be ascertained1 and1 above all things1 the gases themselves ought to be contained in vessels of metal1 and not of glass4 99 99 99 99 99 #aeaj4 ,the next set of results are those obtained when the intervals n and o 7fig4 #aca47 were made equal to each other1 and relate to the greater facility of discharge at the small ball1 when rendered positive or negative 7#adic474 #aeaa4 ,in air1 with the intervals #j4d of an inch1 ,a and ,b being inductric and positive1 discharge was nearly equal at n and o2 when ,a and ,b were inductric and negative1 the discharge was mostly at n by negative brush4 ,when the intervals were #j4h of an inch1 with ,a and ,b inductric positively1 all discharge was at n by positive brush2 with ,a and ,b inductric negatively1 all the discharge was at n by a negative brush4 ,it is doubtful1 therefore1 from these results1 whether the negative ball has any greater facility than the positive4 #aeab4 ,nitrogen4--,intervals n and o #j4d of an inch3 ,a1 ,b inductric positive1 discharge at both intervals1 most at n1 by positive sparks2 ,a1 ,b inductric negative1 discharge equal at n and o4 ,the intervals made #j4h of an inch3 ,a1 ,b inductric positive1 discharge all at n by positive brush2 ,a1 ,b inductric negative1 discharge most at o by positive brush4 ,in this gas1 therefore1 though the difference is not decisive1 it would seem that the positive small ball caused the most ready discharge4 #aeac4 ,oxygen4--,intervals n and o #j4d of an inch3 ,a1 ,b inductric positive1 discharge nearly equal2 inductric negative1 discharge mostly at n by negative brush4 ,made the intervals #j4h of an inch3 ,a1 ,b inductric positive1 discharge both at n and o2 inductric negative1 discharge all at o by negative brush4 ,so here the negative small ball seems to give the most ready discharge4 #aead4 ,hydrogen4--,intervals n and o #j4d of an inch3 ,a1 ,b inductric positive1 discharge nearly equal3 inductric negative1 discharge mostly at o4 ,intervals #j4h of an inch3 ,a and ,b inductric positive1 discharge mostly at n1 as positive brush2 inductric negative1 discharge mostly at o1 as positive brush4 ,here the positive discharge seems most facile4 #aeae4 ,coal gas4--n and o #j4d of an inch3 ,a1 ,b inductric positive1 discharge nearly all at o by negative spark3 ,a1 ,b inductric negative1 discharge nearly all at n by negative spark4 ,intervals #j4h of an inch1 and ,a1 ,b inductric positive1 discharge mostly at o by negative brush3 ,a1 ,b inductric negative1 discharge all at n by negative brush4 ,here the negative discharge most facile4 #aeaf4 ,carbonic acid gas4--n and o #j4a of an inch3 ,a1 ,b inductric positive1 discharge nearly all at o1 or negative3 ,a1 ,b inductric negative1 discharge nearly all at n1 or negative4 ,intervals #j4h of an inch3 ,a1 ,b inductric positive1 discharge mostly at o1 or negative4 ,a1 ,b inductric negative1 discharge all at n1 or negative4 ,in this case the negative had a decided advantage in facility of discharge4 #aeag4 ,thus1 if we may trust this form of experiment1 the negative small ball has a decided advantage in facilitating disruptive discharge over the positive small ball in some gases1 as in carbonic acid gas and coal gas 7#acii471 whilst in others that conclusion seems more doubtful2 and in others1 again1 there seems a probability that the positive small ball may be superior4 ,all these results were obtained at very nearly the same pressure of the atmosphere4 99 99 99 99 99 #aeah4 ,i made some experiments in these gases whilst in the air jar 7fig4 #aca471 as to the change from spark to brush1 analogous to those in the open air already described 7#adhf4 #adhg474 ,i will give1 in a ,table1 the results as to when brush began to appear mingled with the spark2 but the after results were so varied1 and the nature of the discharge in different gases so different1 that to insert the results obtained without further investigation1 would be of little use4 ,at intervals less than those expressed the discharge was always by spark4 ,discharge between ,discharge between balls ,b and ,d4 balls ,a and ,c4 ,small ball ,small ball ,large ball ,large ball ,b inductric ,b inductric ,a inductric ,a inductric pos4 neg4 pos4 neg4 ,air #j4ee #j4cj #j4dj #j4ge ,nitrogen #j4cj #j4dj #j4eb #j4da ,oxygen #j4gj #j4cj #j4de #j4hb ,hydrogen #j4bj #j4aj ,coal gas #j4ac #j4cj #j4cj #j4dd ,carbonic acid #j4hb #j4dc #a4fj above #a4hj2 had not space47 #aeai4 ,it is to be understood that sparks occurred at much higher intervals than these2 the table only expresses that distance beneath which all discharge was as spark4 ,some curious relations of the different gases to discharge are already discernible1 but it would be useless to consider them until illustrated by further experiments4 99 99 99 99 99 #aebj4 ,i ought not to omit noticing here1 that ,professor ,belli of ,milan has published a very valuable set of experiments on the relative dissipation of positive and negative electricity in the air,a2 he finds the latter far more ready1 in this respect1 than the former4 ,a ,bibliothque ,universelle1 #ahcf1 ,september1 p4 #aeb4 #aeba4 ,i made some experiments of a similar kind1 but with sustained high charges2 the results were less striking than those of ,signore ,belli1 and ,i did not consider them as satisfactory4 ,i may be allowed to mention1 in connexion with the subject1 an interfering effect which embarrassed me for a long time4 ,when ,i threw positive electricity from a given point into the air1 a certain intensity was indicated by an electrometer on the conductor connected with the point1 but as the operation continued this intensity rose several degrees2 then making the conductor negative with the same point attached to it1 and all other things remaining the same1 a certain degree of tension was observed in the first instance1 which also gradually rose as the operation proceeded4 ,returning the conductor to the positive state1 the tension was at first low1 but rose as before2 and so also when again made negative4 #aebb4 ,this result appeared to indicate that the point which had been giving off one electricity1 was1 by that1 more fitted for a short time to give off the other4 ,but on closer examination ,i found the whole depended upon the inductive reaction of that air1 which being charged by the point1 and gradually increasing in quantity before it1 as the positive or negative issue was continued1 diverted and removed a part of the inductive action of the surrounding wall1 and thus apparently affected the powers of the point1 whilst really it was the dielectric itself that was causing the change of tension4 99 99 99 99 99 #aebc4 ,the results connected with the different conditions of positive and negative discharge will have a far greater influence on the philosophy of electrical science than we at present imagine1 especially if1 as ,i believe1 they depend on the peculiarity and degree of polarized condition which the molecules of the dielectrics concerned acquire 7#aejc4 #afjj474 ,thus1 for instance1 the relation of our atmosphere and the earth within it1 to the occurrence of spark or brush1 must be especial and not accidental 7#adfd474 ,it would not else consist with other meteorological phenomena1 also of course dependent on the special properties of the air1 and which being themselves in harmony the most perfect with the functions of animal and vegetable life1 are yet restricted in their actions1 not by loose regulations1 but by laws the most precise4 #aebd4 ,even in the passage through air of the voltaic current we see the peculiarities of positive and negative discharge at the two charcoal points2 and if these discharges are made to take place simultaneously to mercury1 the distinction is still more remarkable1 both as to the sound and the quantity of vapour produced4 #aebe4 ,it seems very possible that the remarkable difference recently observed and described by my friend ,professor ,daniell,a1 namely1 that when a zinc and a copper ball1 the same in size1 were placed respectively in copper and zinc spheres1 also the same in size1 and excited by electrolytes or dielectrics of the same strength and nature1 the zinc ball far surpassed the zinc sphere in action1 may also be connected with these phenomena2 for it is not difficult to conceive how the polarity of the particles shall be affected by the circumstance of the positive surface1 namely the zinc1 being the larger or the smaller of the two inclosing the electrolyte4 ,it is even possible1 that with different electrolytes or dielectrics the ratio may be considerably varied1 or in some cases even inverted4 ,a ,philosophical ,transactions1 #ahch1 p4 #dg4 99 99 99 99 99 ,glow discharge4 #aebf4 ,that form of disruptive discharge which appears as a glow 7#acei4 #adje471 is very peculiar and beautiful3 it seems to depend on a quick and almost continuous charging of the air close to1 and in contact with1 the conductor4 #aebg4 ,diminution of the charging surface will produce it4 ,thus1 when a rod #j4c of an inch in diameter1 with a rounded termination1 was rendered positive in free air1 it gave fine brushes from the extremity1 but occasionally these disappeared1 and a quiet phosphorescent continuous glow took their place1 covering the whole of the end of the wire1 and extending a very small distance from the metal into the air4 ,with a rod #j4b of an inch in diameter the glow was more readily produced4 ,with still smaller rods1 and also with blunt conical points1 it occurred still more readily2 and with a fine point ,i could not obtain the brush in free air1 but only this glow4 ,the positive glow and the positive star are1 in fact1 the same4 #aebh4 ,increase of power in the machine tends to produce the glow2 for rounded terminations which will give only brushes when the machine is in weak action1 will readily give the glow when it is in good order4 #aebi4 ,rarefaction of the air wonderfully favours the glow phenomena4 ,a brass ball1 two and a half inches in diameter1 being made positively inductric in an air-pump receiver1 became covered with glow over an area of two inches in diameter1 when the pressure was reduced to #d4d inches of mercury4 ,by a little adjustment the ball could be covered all over with this light4 ,using a brass ball #a4be inches in diameter1 and making it inducteously positive by an inductric negative point1 the phenomena1 at high degrees of rarefaction1 were exceedingly beautiful4 ,the glow came over the positive ball1 and gradually increased in brightness1 until it was at last very luminous2 and it also stood up like a low flame1 half an inch or more in height4 ,on touching the sides of the glass jar this lambent flame was affected1 assumed a ring form1 like a crown on the top of the ball1 appeared flexible1 and revolved with a comparatively slow motion1 i4e4 about four or five times in a second4 ,this ring-shape and revolution are beautifully connected with the mechanical currents 7#aegf47 taking place within the receiver4 ,these glows in rarefied air are often highly exalted in beauty by a spark discharge at the conductor 7#aeea4 ,note474 #aecj4 ,to obtain a negative glow in air at common pressures is difficult4 ,i did not procure it on the rod #j4c of an inch in diameter by my machine1 nor on much smaller rods2 and it is questionable as yet1 whether1 even on fine points1 what is called the negative star is a very reduced and minute1 but still intermitting brush1 or a glow similar to that obtained on a positive point4 #aeca4 ,in rarefied air the negative glow can easily be obtained4 ,if the rounded ends of two metal rods1 about ,o4#b of an inch in diameter1 are introduced into a globe or jar 7the air within being rarefied71 and being opposite to each other1 are about four inches apart1 the glow can be obtained on both rods1 covering not only the ends1 but an inch or two of the part behind4 ,on using balls in the air-pump jar1 and adjusting the distance and exhaustion1 the negative ball could be covered with glow1 whether it were the inductric or the inducteous surface4 #aecb4 ,when rods are used it is necessary to be aware that1 if placed concentrically in the jar or globe1 the light on one rod is often reflected by the sides of the vessel on to the other rod1 and makes it apparently luminous1 when really it is not so4 ,this effect may be detected by shifting the eye at the time of observation1 or avoided by using blackened rods4 #aecc4 ,it is curious to observe the relation of glow1 brush1 and spark to each other1 as produced by positive or negative surfaces2 thus1 beginning with spark discharge1 it passes into brush much sooner when the surface at which the discharge commences 7#adhd47 is negative1 than it does when positive2 but proceeding onwards in the order of change1 we find that the positive brush passes into glow long before the negative brush does4 ,so that1 though each presents the three conditions in the same general order1 the series are not precisely the same4 ,it is probable1 that1 when these points are minutely examined1 as they must be shortly1 we shall find that each different gas or dielectric presents its own peculiar results1 dependent upon the mode in which its particles assume polar electric condition4 #aecd4 ,the glow occurs in all gases in which ,i have looked for it4 ,these are air1 nitrogen1 oxygen1 hydrogen1 coal gas1 carbonic acid1 muriatic acid1 sulphurous acid and ammonia4 ,i thought also that ,i obtained it in oil of turpentine1 but if so it was very dull and small4 #aece4 ,the glow is always accompanied by a wind proceeding either directly out from the glowing part1 or directly towards it2 the former being the most general case4 ,this takes place even when the glow occurs upon a ball of considerable size3 and if matters be so arranged that the ready and regular access of air to a part exhibiting the glow be interfered with or prevented1 the glow then disappears4 #aecf4 ,i have never been able to analyse or separate the glow into visible elementary intermitting discharges 7#adbg4 #adcc471 nor to obtain the other evidence of intermitting action1 namely an audible sound 7#adca474 ,the want of success1 as respects trials made by ocular means1 may depend upon the large size of the glow preventing the separation of the visible images3 and1 indeed1 if it does intermit1 it is not likely that all parts intermit at once with a simultaneous regularity4 #aecg4 ,all the effects tend to show1 that glow is due to a continuous charge or discharge of air2 in the former case being accompanied by a current from1 and in the latter by one to1 the place of the glow4 ,as the surrounding air comes up to the charged conductor1 on attaining that spot at which the tension of the particles is raised to the sufficient degree 7#acgj4 #adaj471 it becomes charged1 and then moves off1 by the joint action of the forces to which it is subject2 and1 at the same time that it makes way for other particles to come and be charged in turn1 actually helps to form that current by which they are brought into the necessary position4 ,thus1 through the regularity of the forces1 a constant and quiet result is produced2 and that result is1 the charging of successive portions of air1 the production of a current1 and of a continuous glow4 #aech4 ,i have frequently been able to make the termination of a rod1 which1 when left to itself1 would produce a brush1 produce in preference a glow1 simply by aiding the formation of a current of air at its extremity2 and1 on the other hand1 it is not at all difficult to convert the glow into brushes1 by affecting the current of air 7#aegd4 #aegi47 or the inductive action near it4 #aeci4 ,the transition from glow1 on the one hand1 to brush and spark1 on the other1 and1 therefore1 their connexion1 may be established in various ways4 ,those circumstances which tend to facilitate the charge of the air by the excited conductor1 and also those which tend to keep the tension at the same degree notwithstanding the discharge1 assist in producing the glow2 whereas those which tend to resist the charge of the air or other dielectric1 and those which favour the accumulation of electric force prior to discharge1 which1 sinking by that act1 has to be exalted before the tension can again acquire the requisite degree1 favour intermitting discharge1 and1 therefore1 the production of brush or spark4 ,thus1 rarefaction of the air1 the removal of large conducting surfaces from the neighbourhood of the glowing termination1 the presentation of a sharp point towards it1 help to sustain or produce the glow3 but the condensation of the air1 the presentation of the hand or other large surface1 the gradual approximation of a discharging ball1 tend to convert the glow into brush or even spark4 ,all these circumstances may be traced and reduced1 in a manner easily comprehensible1 to their relative power of assisting to produce1 either a continuous discharge to the air1 which gives the glow2 or an interrupted one1 which produces the brush1 and1 in a more exalted condition1 the spark4 #aedj4 ,the rounded end of a brass rod1 #j4c of an inch in diameter1 was covered with a positive glow by the working of an electrical machine3 on stopping the machine1 so that the charge of the connected conductor should fall1 the glow changed for a moment into brushes just before the discharge ceased altogether1 illustrating the necessity for a certain high continuous charge1 for a certain sized termination4 ,working the machine so that the intensity should be just low enough to give continual brushes from the end in free air1 the approach of a fine point changed these brushes into a glow4 ,working the machine so that the termination presented a continual glow in free air1 the gradual approach of the hand caused the glow to contract at the very end of the wire1 then to throw out a luminous point1 which1 becoming a foot stalk 7#adbf471 finally produced brushes with large ramifications4 ,all these results are in accordance with what is stated above 7#aeci474 #aeda4 ,greasing the end of a rounded wire will immediately make it produce brushes instead of glow4 ,a ball having a blunt point which can be made to project more or less beyond its surface1 at pleasure1 can be made to produce every gradation from glow1 through brush1 to spark4 #aedb4 ,it is also very interesting and instructive to trace the transition from spark to glow1 through the intermediate condition of stream1 between ends in a vessel containing air more or less rarefied2 but ,i fear to be prolix4 #aedc4 ,all the effects show1 that the glow is in its nature exactly the same as the luminous part of a brush or ramification1 namely a charging of air2 the only difference being1 that the glow has a continuous appearance from the constant renewal of the same action in the same place1 whereas the ramification is due to a momentary1 independent and intermitting action of the same kind4 99 99 99 99 99 ,dark discharge4 #aedd4 ,i will now notice a very remarkable circumstance in the luminous discharge accompanied by negative glow1 which may1 perhaps1 be correctly traced hereafter into discharges of much higher intensity4 ,two brass rods1 #j4c of an inch in diameter1 entering a glass globe on opposite sides1 had their ends brought into contact1 and the air about them very much rarefied4 ,a discharge of electricity from the machine was then made through them1 and whilst that was continued the ends were separated from each other4 ,at the moment of separation a continuous glow came over the end of the negative rod1 the positive termination remaining quite dark4 ,as the distance was increased1 a purple stream or haze appeared on the end of the positive rod1 and proceeded directly outwards towards the negative rod2 elongating as the interval was enlarged1 but never joining the negative glow1 there being always a short dark space between4 ,this space1 of about #a_/afth or #a_/bjth of an inch1 was apparently invariable in its extent and its position1 relative to the negative rod2 nor did the negative glow vary4 ,whether the negative end were inductric or inducteous1 the same effect was produced4 ,it was strange to see the positive purple haze diminish or lengthen as the ends were separated1 and yet this dark space and the negative glow remain unaltered 7fig4 #acc74 #aede4 ,two balls were then used in a large air-pump receiver1 and the air rarefied4 ,the usual transitions in the character of the discharge took place2 but whenever the luminous stream1 which appears after the spark and the brush have ceased1 was itself changed into glow at the balls1 the dark space occurred1 and that whether the one or the other ball was made inductric1 or positive1 or negative4 #aedf4 ,sometimes when the negative ball was large1 the machine in powerful action1 and the rarefaction high1 the ball would be covered over half its surface with glow1 and then1 upon a hasty observation1 would seem to exhibit no dark space3 but this was a deception1 arising from the overlapping of the convex termination of the negative glow and the concave termination of the positive stream4 ,more careful observation and experiment have convinced me1 that when the negative glow occurs1 it never visibly touches the luminous part of the positive discharge1 but that the dark space is always there4 #aedg4 ,this singular separation of the positive and negative discharge1 as far as concerns their luminous character1 under circumstances which one would have thought very favourable to their coalescence1 is probably connected with their differences when in the form of brush1 and is perhaps even dependent on the same cause4 ,further1 there is every likelihood that the dark parts which occur in feeble sparks are also connected with these phenomena,a4 ,to understand them would be very important1 for it is quite clear that in many of the experiments1 indeed in all that ,i have quoted1 discharge is taking place across the dark part of the dielectric to an extent quite equal to what occurs in the luminous part4 ,this difference in the result would seem to imply a distinction in the modes by which the two electric forces are brought into equilibrium in the respective parts2 and looking upon all the phenomena as giving additional proofs1 that it is to the condition of the particles of the dielectric we must refer for the principles of induction and discharge1 so it would be of great importance if we could know accurately in what the difference of action in the dark and the luminous parts consisted4 ,a ,see ,professor ,johnson's experiments4 ,silliman's ,journal1 xxv4 p4 #eg4 #aedh4 ,the dark discharge through air 7#aeeb471 which in the case mentioned is very evident 7#aedd471 leads to the inquiry1 whether the particles of air are generally capable of effecting discharge from one to another without becoming luminous2 and the inquiry is important1 because it is connected with that degree of tension which is necessary to originate discharge 7#acfh4 #acgj474 ,discharge between air and conductors without luminous appearances are very common2 and non-luminous discharges by carrying currents of air and other fluids 7#aefb4 #aeie47 are also common enough3 but these are not cases in point1 for they are not discharges between insulating particles4 #aedi4 ,an arrangement was made for discharge between two balls 7#adhe47 7fig4 #abi47 but1 in place of connecting the inducteous ball directly with the discharging train1 it was put in communication with the inside coating of a ,leyden jar1 and the discharging train with the outside coating4 ,then working the machine1 it was found that whenever sonorous and luminous discharge occurred at the balls ,a ,b1 the jar became charged2 but that when these did not occur1 the jar acquired no charge3 and such was the case when small rounded terminations were used in place of the balls1 and also in whatever manner they were arranged4 ,under these circumstances1 therefore1 discharge even between the air and conductors was always luminous4 #aeej4 ,but in other cases1 the phenomena are such as to make it almost certain1 that dark discharge can take place across air4 ,if the rounded end of a metal rod1 #j4ae of an inch in diameter1 be made to give a good negative brush1 the approach of a smaller end or a blunt point opposite to it will1 at a certain distance1 cause a diminution of the brush1 and a glow will appear on the positive inducteous wire1 accompanied by a current of air passing from it4 ,now1 as the air is being charged both at the positive and negative surfaces1 it seems a reasonable conclusion1 that the charged portions meet somewhere in the interval1 and there discharge to each other1 without producing any luminous phenomena4 ,it is possible1 however1 that the air electrified positively at the glowing end may travel on towards the negative surface1 and actually form that atmosphere into which the visible negative brushes dart1 in which case dark discharge need not1 of necessity1 occur4 ,but ,i incline to the former opinion1 and think1 that the diminution in size of the negative brush1 as the positive glow comes on to the end of the opposed wire1 is in favour of that view4 #aeea4 ,using rarefied air as the dielectric1 it is very easy to obtain luminous phenomena as brushes1 or glow1 upon both conducting balls or terminations1 whilst the interval is dark1 and that1 when the action is so momentary that ,i think we cannot consider currents as effecting discharge across the dark part4 ,thus if two balls1 about an inch in diameter1 and #d or more inches apart1 have the air rarefied about them1 and are then interposed in the course of discharge1 an interrupted or spark current being produced at the machine,a1 each termination may be made to show luminous phenomena1 whilst more or less of the interval is quite dark4 ,the discharge will pass as suddenly as a retarded spark 7#bie4 #ccd471 i4e4 in an interval of time almost inappreciably small1 and in such a case1 ,i think it must have passed across the dark part as true disruptive discharge1 and not by convection4 ,a ,by spark current ,i mean one passing in a series of spark between the conductor of the machine and the apparatus3 by a continuous current one that passes through metallic conductors1 and in that respect without interruption at the same place4 #aeeb4 ,hence ,i conclude that dark disruptive discharge may occur 7#aedg4 #aeej472 and also1 that1 in the luminous brush1 the visible ramifications may not show the full extent of the disruptive discharge 7#addd4 #adeb471 but that each may have a dark outside1 enveloping1 as it were1 every part through which the discharge extends4 ,it is probable1 even1 that there are such things as dark discharges analogous in form to the brush and the spark1 but not luminous in any part 7#adde474 #aeec4 ,the occurrence of dark discharge in any case shows at how low a tension disruptive discharge may occur 7#aedh171 and indicates that the light of the ultimate brush or spark is in no relation to the intensity required 7#acfh4 #acgj474 ,so to speak1 the discharge begins in darkness1 and the light is a mere consequence of the quantity which1 after discharge has commenced1 flows to that spot and there finds its most facile passage 7#adah4 #adce474 ,as an illustration of the growth generally of discharge1 ,i may remark that1 in the experiments on the transition in oxygen of the discharge from spark to brush 7#aeah471 every spark was immediately preceded by a short brush4 #aeed4 ,the phenomena relative to dark discharge in other gases1 though differing in certain characters from those in air1 confirm the conclusions drawn above4 ,the two rounded terminations 7#aedd47 7fig4 #acc471 were placed in muriatic acid gas 7#adde4 #adfc47 at the pressure of #f4e inches of mercury1 and a continuous machine current of electricity sent through the apparatus3 bright sparks occurred until the interval was about or above an inch1 when they were replaced by squat brushy intermitting glows upon both terminations1 with a dark part between4 ,when the current at the machine was in spark1 then each spark caused a discharge across the muriatic acid gas1 which1 with a certain interval1 was bright2 with a larger interval1 was straight across and flamy1 like a very exhausted and sudden1 but not a dense sharp spark2 and with a still larger interval1 produced a feeble brush on the inductric positive end1 and a glow on the inducteous negative end1 the dark part being between 7#aedd472 and at such times1 the spark at the conductor1 instead of being sudden and sonorous1 was dull and quiet 7#ccd474 #aeee4 ,on introducing more muriatic acid gas1 until the pressure was #bi4ig inches1 the same terminations gave bright sparks within at small distances2 but when they were about an inch or more apart1 the discharge was generally with very small brushes and glow1 and frequently with no light at all1 though electricity had passed through the gas4 ,whenever the bright spark did pass through the muriatic acid gas at this pressure1 it was bright throughout1 presenting no dark or dull space4 #aeef4 ,in coal gas1 at common pressures1 when the distance was about an inch1 the discharge was accompanied by short brushes on the ends1 and a dark interval of half an inch or more between them1 notwithstanding the discharge had the sharp quick sound of a dull spark1 and could not have depended in the dark part on convection 7#aefb474 #aeeg4 ,this gas presents several curious points in relation to the bright and dark parts of spark discharge4 ,when bright sparks passed between the rod ends #j4c of an inch in diameter 7#aedd471 very sudden dark parts would occur next to the brightest portions of the spark4 ,again with these ends and also with balls 7#adbb471 the bright sparks would be sometimes red1 sometimes green1 and occasionally green and red in different parts of the same spark4 ,again1 in the experiments described 7#aeah471 at certain intervals a very peculiar pale1 dull1 yet sudden discharge would pass1 which1 though apparently weak1 was very direct in its course1 and accompanied by a sharp snapping noise1 as if quick in its occurrence4 #aeeh4 ,hydrogen frequently gave peculiar sparks1 one part being bright red1 whilst the other was a dull pale gray1 or else the whole spark was dull and peculiar4 #aeei4 ,nitrogen presents a very remarkable discharge1 between two balls of the respective diameters of #j4ae and #b inches 7#aejf4 #aeah471 the smaller one being rendered negative either directly inducteously4 ,the peculiar discharge occurs at intervals between #j4db and #j4fh1 and even at #a4d inches when the large ball was inductric positively2 it consisted of a little brushy part on the small negative ball1 then a dark space1 and lastly a dull straight line on the large positive ball 7fig4 #acd474 ,the position of the dark space was very constant1 and is probably in direct relation to the dark space described when negative glow was produced 7#aedd474 ,when by any circumstance a bright spark was determined1 the contrast with the peculiar spark described was very striking2 for it always had a faint purple part1 but the place of this part was constantly near the positive ball4 #aefj4 ,thus dark discharge appears to be decidedly established4 ,but its establishment is accompanied by proofs that it occurs in different degrees and modes in different gases4 ,hence then another specific action1 added to the many 7#abif4 #acih4 #acii4 #adbc4 #aded4 #aejc47 by which the electrical relations of insulating dielectrics are distinguished and established1 and another argument in favour of that molecular theory of induction1 which is at present under examination,a4 ,a ,i cannot resist referring here by a note to ,biot's philosophical view of the nature of the light of the electric discharge1 ,annales de ,chimie1 liii4 p4 #cba4 99 99 99 99 99 #aefa4 ,what ,i have had to say regarding disruptive discharge has extended to some length1 but ,i hope will be excused in consequence of the importance of the subject4 ,before concluding my remarks1 ,i will again intimate in the form of a query1 whether we have not reason to consider the tension or retention and after discharge in air or other insulating dielectrics1 as the same thing with retardation and discharge in a metal wire1 differing only1 but almost infinitely1 in degree 7#accd4 #accf474 ,in other words1 can we not1 by a gradual chain of association1 carry up discharge from its occurrence in air1 through spermaceti and water1 to solutions1 and then on to chlorides1 oxides and metals1 without any essential change in its character2 and1 at the same time1 connecting the insensible conduction of air1 through muriatic acid gas and the dark discharge1 with the better conduction of spermaceti1 water1 and the all but perfect conduction of the metals1 associate the phenomena at both extremes8 and may it not be1 that the retardation and ignition of a wire are effects exactly correspondent in their nature to the retention of charge and spark in air8 ,if so1 here again the two extremes in property amongst dielectrics will be found to be in intimate relation1 the whole difference probably depending upon the mode and degree in which their particles polarize under the influence of inductive actions 7#acch4 #afjc4 #afaj474 99 99 99 99 99 x4 ,convection1 or carrying discharge4 #aefb4 ,the last kind of discharge which ,i have to consider is that effected by the motion of charged particles from place to place4 ,it is apparently very different in its nature to any of the former modes of discharge 7#acai471 but1 as the result is the same1 may be of great importance in illustrating1 not merely the nature of discharge itself1 but also of what we call the electric current4 ,it often1 as before observed1 in cases of brush and glow 7#addj4 #aece471 joins its effect to that of disruptive discharge1 to complete the act of neutralization amongst the electric forces4 #aefc4 ,the particles which being charged1 then travel1 may be either of insulating or conducting matter1 large or small4 ,the consideration in the first place of a large particle of conducting matter may perhaps help our conceptions4 #aefd4 ,a copper boiler #c feet in diameter was insulated and electrified1 but so feebly1 that dissipation by brushes or disruptive discharge did not occur at its edges or projecting parts in a sensible degree4 ,a brass ball1 #b inches in diameter1 suspended by a clean white silk thread1 was brought towards it1 and it was found that1 if the ball was held for a second or two near any part of the charged surface of the boiler1 at such distance 7two inches more or less7 as not to receive any direct charge from it1 it became itself charged1 although insulated the whole time2 and its electricity was the reverse of that of the boiler4 #aefe4 ,this effect was the strongest opposite the edges and projecting parts of the boiler1 and weaker opposite the sides1 or those extended portions of the surface which1 according to ,coulomb's results1 have the weakest charge4 ,it was very strong opposite a rod projecting a little way from the boiler4 ,it occurred when the copper was charged negatively as well as positively3 it was produced also with small balls down to #j4b of an inch and less in diameter1 and also with smaller charged conductors than the copper4 ,it is1 indeed1 hardly possible in some cases to carry an insulated ball within an inch or two of a charged plane or convex surface without its receiving a charge of the contrary kind to that of the surface4 #aeff4 ,this effect is one of induction between the bodies1 not of communication4 ,the ball1 when related to the positive charged surface by the intervening dielectric1 has its opposite sides brought into contrary states1 that side towards the boiler being negative and the outer side positive4 ,more inductric action is directed towards it than would have passed across the same place if the ball had not been there1 for several reasons2 amongst others1 because1 being a conductor1 the resistance of the particles of the dielectric1 which otherwise would have been there1 is removed 7#abih472 and also1 because the reacting positive surface of the ball being projected further out from the boiler than when there is no introduction of conducting matter1 is more free therefore to act through the rest of the dielectric towards surrounding conductors1 and so favours the exaltation of that inductric polarity which is directed in its course4 ,it is1 as to the exaltation of force upon its outer surface beyond that upon the inductric surface of the boiler1 as if the latter were itself protuberant in that direction4 ,thus it acquires a state like1 but higher than1 that of the surface of the boiler which causes it2 and sufficiently exalted to discharge at its positive surface to the air1 or to affect small particles1 as it is itself affected by the boiler1 and they flying to it1 take a charge and pass off2 and so the ball1 as a whole1 is brought into the contrary inducteous state4 ,the consequence is1 that1 if free to move1 its tendency1 under the influence of all the forces1 to approach the boiler is increased1 whilst it at the same time becomes more and more exalted in its condition1 both of polarity and charge1 until1 at a certain distance1 discharge takes place1 it acquires the same state as the boiler1 is repelled1 and passing to that conductor most favourably circumstanced to discharge it1 there resumes its first indifferent condition4 #aefg4 ,it seems to me1 that the manner in which inductric bodies affect uncharged floating or moveable conductors near them1 is very frequently of this nature1 and generally so when it ends in a carrying operation 7#aefb4 #afjb474 ,the manner in which1 whilst the dominant inductric body cannot give off its electricity to the air1 the inducteous body can effect the discharge of the same kind of force1 is curious1 and1 in the case of elongated or irregularly shaped conductors1 such as filaments or particles of dust1 the effect will often be very ready1 and the consequent attraction immediate4 #aefh4 ,the effect described is also probably influential in causing those variations in spark discharge referred to in the last series 7#achf4 #acij4 #acia473 for if a particle of dust were drawn towards the axis of induction between the balls1 it would tend1 whilst at some distance from that axis1 to commence discharge at itself1 in the manner described 7#aeff471 and that commencement might so far facilitate the act 7#adag4 #adbj47 as to make the complete discharge1 as spark1 pass through the particle1 though it might not be the shortest course from ball to ball4 ,so also1 with equal balls at equal distances1 as in the experiments of comparison already described 7#adic4 #aejf471 a particle being between one pair of balls would cause discharge there in preference2 or even if a particle were between each1 difference of size or shape would give one for the time a predominance over the other4 #aefi4 ,the power of particles of dust to carry off electricity in cases of high tension is well known1 and ,i have already mentioned some instances of the kind in the use of the inductive apparatus 7#abja474 ,the general operation is very well shown by large light objects1 as the toy called the electrical spider2 or1 if smaller ones are wanted for philosophical investigation1 by the smoke of a glowing green wax taper1 which1 presenting a successive stream of such particles1 makes their course visible4 #aegj4 ,on using oil of turpentine as the dielectric1 the action and course of small conducting carrying particles in it can be well observed4 ,a few short pieces of thread will supply the place of carriers1 and their progressive action is exceedingly interesting4 #aega4 ,a very striking effect was produced on oil of turpentine1 which1 whether it was due to the carrying power of the particles in it1 or to any other action of them1 is perhaps as yet doubtful4 ,a portion of that fluid in a glass vessel had a large uninsulated silver dish at the bottom1 and an electrified metal rod with a round termination dipping into it at the top4 ,the insulation was very good1 and the attraction and other phenomena striking4 ,the rod end1 with a drop of gum water attached to it1 was then electrified in the fluid2 the gum water soon spun off in fine threads1 and was quickly dissipated through the oil of turpentine4 ,by the time that four drops had in this way been commingled with a pint of the dielectric1 the latter had lost by far the greatest portion of its insulating power2 no sparks could be obtained in the fluid2 and all the phenomena dependent upon insulation had sunk to a low degree4 ,the fluid was very slightly turbid4 ,upon being filtered through paper only1 it resumed its first clearness1 and now insulated as well as before4 ,the water1 therefore1 was merely diffused through the oil of turpentine1 not combined with or dissolved in it3 but whether the minute particles acted as carriers1 or whether they were not rather gathered together in the line of highest inductive tension 7#acej471 and there1 being drawn into elongated forms by the electric forces1 combined their effects to produce a band of matter having considerable conducting power1 as compared with the oil of turpentine1 is as yet questionable4 #aegb4 ,the analogy between the action of solid conducting carrying particles and that of the charged particles of fluid insulating substances1 acting as dielectrics1 is very evident and simple2 but in the latter case the result is1 necessarily1 currents in the mobile media4 ,particles are brought by inductric action into a polar state2 and the latter1 after rising to a certain tension 7#acgj471 is followed by the communication of a part of the force originally on the conductor2 the particles consequently become charged1 and then1 under the joint influence of the repellent and attractive forces1 are urged towards a discharging place1 or to that spot where these inductric forces are most easily compensated by the contrary inducteous forces4 #aegc4 ,why a point should be so exceedingly favourable to the production of currents in a fluid insulating dielectric1 as air1 is very evident4 ,it is at the extremity of the point that the intensity necessary to charge the air is first acquired 7#acgd472 it is from thence that the charged particle recedes2 and the mechanical force which it impresses on the air to form a current is in every way favoured by the shape and position of the rod1 of which the point forms the termination4 ,at the same time1 the point1 having become the origin of an active mechanical force1 does1 by the very act of causing that force1 namely1 by discharge1 prevent any other part of the rod from acquiring the same necessary condition1 and so preserves and sustains its own predominance4 #aegd4 ,the very varied and beautiful phenomena produced by sheltering or enclosing the point1 illustrate the production of the current exceedingly well1 and justify the same conclusions2 it being remembered that in such cases the effect upon the discharge is of two kinds4 ,for the current may be interfered with by stopping the access of fresh uncharged air1 or retarding the removal of that which has been charged1 as when a point is electrified in a tube of insulating matter closed at one extremity2 or the electric condition of the point itself may be altered by the relation of other parts in its neighbourhood1 also rendered electric1 as when the point is in a metal tube1 by the metal itself1 or when it is in the glass tube1 by a similar action of the charged parts of the glass1 or even by the surrounding air which has been charged1 and which cannot escape4 #aege4 ,whenever it is intended to observe such inductive phenomena in a fluid dielectric as have a direct relation to1 and dependence upon1 the fluidity of the medium1 such1 for instance1 as discharge from points1 or attractions and repulsions1 c41 then the mass of the fluid should be great1 and in such proportion to the distance between the inductric and inducteous surfaces as to include all the lines of inductive force 7#acfi47 between them2 otherwise1 the effects of currents1 attraction1 c41 which are the resultants of all these forces1 cannot be obtained4 ,the phenomena1 which occur in the open air1 or in the middle of a globe filled with oil of turpentine1 will not take place in the same media if confined in tubes of glass1 shell-lac1 sulphur1 or other such substances1 though they be excellent insulating dielectrics2 nor can they be expected3 for in such cases1 the polar forces1 instead of being all dispersed amongst fluid particles1 which tend to move under their influence1 are now associated in many parts with particles that1 notwithstanding their tendency to motion1 are constrained by their solidity to remain quiescent4 #aegf4 ,the varied circumstances under which1 with conductors differently formed and constituted1 currents can occur1 all illustrate the same simplicity of production4 ,a ball1 if the intensity be raised sufficiently on its surface1 and that intensity be greatest on a part consistent with the production of a current of air up to and off from it1 will produce the effect like a point 7#aecg72 such is the case whenever the glow occurs upon a ball1 the current being essential to that phenomenon4 ,if as large a sphere as can well be employed with the production of glow be used1 the glow will appear at the place where the current leaves the ball1 and that will be the part directly opposite to the connection of the ball and rod which supports it2 but by increasing the tension elsewhere1 so as to raise it above the tension upon that spot1 which can easily be effected inductively1 then the place of the glow and the direction of the current will also change1 and pass to that spot which for the time is most favourable for their production 7#aeia474 #aegg4 ,for instance1 approaching the hand towards the ball will tend to cause brush 7#aeci471 but by increasing the supply of electricity the condition of glow may be preserved2 then on moving the hand about from side to side the position of the glow will very evidently move with it4 #aegh4 ,a point brought towards a glowing ball would at twelve or fourteen inches distance make the glow break into brush1 but when still nearer1 glow was reproduced1 probably dependent upon the discharge of wind or air passing from the point to the ball1 and this glow was very obedient to the motion of the point1 following it in every direction4 #aegi4 ,even a current of wind could affect the place of the glow2 for a varnished glass tube being directed sideways towards the ball1 air was sometimes blown through it at the ball and sometimes not4 ,in the former case1 the place of the glow was changed a little1 as if it were blown away by the current1 and this is just the result which might have been anticipated4 ,all these effects illustrate beautifully the general causes and relations1 both of the glow and the current of air accompanying it 7#aegd474 #aehj4 ,flame facilitates the production of a current in the dielectric surrounding it4 ,thus1 if a ball which would not occasion a current in the air have a flame1 whether large or small1 formed on its surface1 the current is produced with the greatest ease2 but not the least difficulty can occur in comprehending the effective action of the flame in this case1 if its relation1 as part of the surrounding dielectric1 to the electrified ball1 be but for a moment considered 7#acge4 #achj474 #aeha4 ,conducting fluid terminations1 instead of rigid points1 illustrate in a very beautiful manner the formation of the currents1 with their effects and influence in exalting the conditions under which they were commenced4 ,let the rounded end of a brass rod1 #j4c of an inch or thereabouts in diameter1 point downwards in free air2 let it be amalgamated1 and have a drop of mercury suspended from it2 and then let it be powerfully electrized4 ,the mercury will present the phenomenon of glow2 a current of air will rush along the rod1 and set off from the mercury directly downwards2 and the form of the metallic drop will be slightly affected1 the convexity at a small part near the middle and lower part becoming greater1 whilst it diminishes all round at places a little removed from this spot4 ,the change is from the form of a 7fig4 #ace47 to that of b1 and is due almost1 if not entirely1 to the mechanical force of the current of air sweeping over its surface4 #aehb4 ,as a comparative observation1 let it be noticed1 that a ball gradually brought towards it converts the glow into brushes1 and ultimately sparks pass from the most projecting part of the mercury4 ,a point does the same1 but at much smaller distances4 #aehc4 ,take next a drop of strong solution of muriate of lime2 being electrified1 a part will probably be dissipated1 but a considerable portion1 if the electricity be not too powerful1 will remain1 forming a conical drop 7fig4 #acf471 accompanied by a strong current4 ,if glow be produced1 the drop will be smooth on the surface4 ,if a short low brush is formed1 a minute tremulous motion of the liquid will be visible2 but both effects coincide with the principal one to be observed1 namely1 the regular and successive charge of air1 the formation of a wind or current1 and the form given by that current to the fluid drop1 if a discharge ball be gradually brought toward the cone1 sparks will at last pass1 and these will be from the apex of the cone to the approached ball1 indicating a considerable degree of conducting power in this fluid4 #aehd4 ,with a drop of water1 the effects were of the same kind1 and were best obtained when a portion of gum water or of syrup hung from a ball 7fig4 #acg474 ,when the machine was worked slowly1 a fine large quiet conical drop1 with concave lateral outline1 and a small rounded end1 was produced1 on which the glow appeared1 whilst a steady wind issued1 in a direction from the point of the cone1 of sufficient force to depress the surface of uninsulated water held opposite to the termination4 ,when the machine was worked more rapidly some of the water was driven off2 the smaller pointed portion left was roughish on the surface1 and the sound of successive brush discharges was heard4 ,with still more electricity1 more water was dispersed2 that which remained was elongated and contracted1 with an alternating motion2 a stronger brush discharge was heard1 and the vibrations of the water and the successive discharges of the individual brushes were simultaneous4 ,when water from beneath was brought towards the drop1 it did not indicate the same regular strong contracted current of air as before2 and when the distance was such that sparks passed1 the water beneath was attracted rather than driven away1 and the current of air ceased4 #aehe4 ,when the discharging ball was brought near the drop in its first quiet glowing state 7#aehb471 it converted that glow into brushes1 and caused the vibrating motion of the drop4 ,when still nearer1 sparks passed1 but they were always from the metal of the rod1 over the surface of the water1 to the point1 and then across the air to the ball4 ,this is a natural consequence of the deficient conducting power of the fluid 7#aehd4 #aehe474 #aehf4 ,why the drop vibrated1 changing its form between the periods of discharging brushes1 so as to be more or less acute at particular instants1 to be most acute when the brush issued forth1 and to be isochronous in its action1 and how the quiet glowing liquid drop1 on assuming the conical form1 facilitated1 as it were1 the first action1 are points1 as to theory1 so evident1 that ,i will not stop to speak of them4 ,the principal thing to observe at present is1 the formation of the carrying current of air1 and the manner in which it exhibits its existence and influence by giving form to the drop4 #aehg4 ,that the drop1 when of water1 or a better conductor than water1 is formed into a cone principally by the current of air1 is shown amongst other ways 7#aeid47 thus4 ,a sharp point being held opposite the conical drop1 the latter soon lost its pointed form2 was retraced and became round2 the current of air from it ceased1 and was replaced by one from the point beneath1 which1 if the latter were held near enough to the drop1 actually blew it aside1 and rendered it concave in form4 #aehh4 ,it is hardly necessary to say what happened with still worse conductors than water1 as oil1 or oil of turpentine2 the fluid itself was then spun out into threads and carried off1 not only because the air rushing over its surface helped to sweep it away1 but also because its insulating particles assumed the same charged state as the particles of air1 and1 not being able to discharge to them in a much greater decree than the air particles themselves could do1 were carried off by the same causes which urged those in their course4 ,a similar effect with melted sealing-wax on a metal point forms an old and well-known experiment4 #aehi4 ,a drop of gum water in the exhausted receiver of the air-pump was not sensibly affected in its form when electrified4 ,when air was let in1 it begun to show change of shape when the pressure was ten inches of mercury4 ,at the pressure of fourteen or fifteen inches the change was more sensible1 and as the air increased in density the effects increased1 until they were the same as those in the open atmosphere4 ,the diminished effect in the rare air ,i refer to the relative diminished energy of its current2 that diminution depending1 in the first place1 on the lower electric condition of the electrified ball in the rarefied medium1 and in the next1 on the attenuated condition of the dielectric1 the cohesive force of water in relation to rarefied air being something like that of mercury to dense air 7#aeha471 whilst that of water in dense air may be compared to that of mercury in oil of turpentine 7#aeig474 #aeij4 ,when a ball is covered with a thick conducting fluid1 as treacle or syrup1 it is easy by inductive action to determine the wind from almost any part of it 7#aegg472 the experiment1 which before was of rather difficult performance1 being rendered facile in consequence of the fluid enabling that part1 which at first was feeble in its action1 to rise into an exalted condition by assuming a pointed form4 #aeia4 ,to produce the current1 the electric intensity must rise and continue at one spot1 namely1 at the origin of the current1 higher than elsewhere1 and then1 air having a uniform and ready access1 the current is produced4 ,if no current be allowed 7#aegd471 then discharge may take place by brush or spark4 ,but whether it be by brush or spark1 or wind1 it seems very probable that the initial intensity or tension at which a particle of a given gaseous dielectric charges1 or commences discharge1 is1 under the conditions before expressed1 always the same 7#adaj474 #aeib4 ,it is not supposed that all the air which enters into motion is electrified2 on the contrary1 much that is not charged is carried on into the stream4 ,the part which is really charged may be but a small proportion of that which is ultimately set in motion 7#addb474 #aeic4 ,when a drop of gum water 7#aehd47 is made negative1 it presents a larger cone than when made positive2 less of the fluid is thrown off1 and yet1 when a ball is approached1 sparks can hardly be obtained1 so pointed is the cone1 and so free the discharge4 ,a point held opposite to it did not cause the retraction of the cone to such an extent as when it was positive4 ,all the effects are so different from those presented by the positive cone1 that ,i have no doubt such drops would present a very instructive method of investigating the difference of positive and negative discharge in air and other dielectrics 7#adhj4 #aeja474 #aeid4 ,that ,i may not be misunderstood 7#aehg471 ,i must observe here that ,i do not consider the cones produced as the result only of the current of air or other insulating dielectric over their surface4 ,when the drop is of badly conducting matter1 a part of the effect is due to the electrified state of the particles1 and this part constitutes almost the whole when the matter is melted sealing-wax1 oil of turpentine1 and similar insulating bodies 7#aehh474 ,but even when the drop is of good conducting matter1 as water1 solutions1 or mercury1 though the effect above spoken of will then be insensible 7#afjg471 still it is not the mere current of air or other dielectric which produces all the change of form2 for a part is due to those attractive forces by which the charged drop1 if free to move1 would travel along the line of strongest induction1 and not being free to move1 has its form elongated until the sum of the different forces tending to produce this form is balanced by the cohesive attraction of the fluid4 ,the effect of the attractive forces are well shown when treacle1 gum water1 or syrup is used2 for the long threads which spin out1 at the same time that they form the axes of the currents of air1 which may still be considered as determined at their points1 are like flexible conductors1 and show by their directions in what way the attractive forces draw them4 #aeie4 ,when the phenomena of currents are observed in dense insulating dielectrics1 they present us with extraordinary degrees of mechanical force4 ,thus1 if a pint of well-rectified and filtered 7#aega47 oil of turpentine be put into a glass vessel1 and two wires be dipped into it in different places1 one leading to the electrical machine1 and the other to the discharging train1 on working the machine the fluid will be thrown into violent motion throughout its whole mass1 whilst at the same time it will rise two1 three or four inches up the machine wire1 and dart off jets from it into the air4 #aeif4 ,if very clean uninsulated mercury be at the bottom of the fluid1 and the wire from the machine be terminated either by a ball or a point1 and also pass through a glass tube extending both above and below the surface of the oil of turpentine1 the currents can be better observed1 and will be seen to rush down the wire1 proceeding directly from it towards the mercury1 and there1 diverging in all directions1 will ripple its surface strongly1 and mounting up at the sides of the vessel1 will return to re-enter upon their course4 #aeig4 ,a drop of mercury being suspended from an amalgamated brass ball1 preserved its form almost unchanged in air 7#aeha472 but when immersed in the oil of turpentine it became very pointed1 and even particles of the metal could be spun out and carried off by the currents of the dielectric4 ,the form of the liquid metal was just like that of the syrup in air 7#aehd471 the point of the cone being quite as fine1 though not so long4 ,by bringing a sharp uninsulated point towards it1 it could also be effected in the same manner as the syrup drop in air 7#aehg471 though not so readily1 because of the density and limited quantity of the dielectric4 #aeih4 ,if the mercury at the bottom of the fluid be connected with the electrical machine1 whilst a rod is held in the hand terminating in a ball three quarters of an inch1 less or more1 in diameter1 and the ball be dipped into the electrified fluid1 very striking appearances ensue4 ,when the ball is raised again so as to be at a level nearly out of the fluid1 large portions of the latter will seem to cling to it 7fig4 #ach474 ,if it be raised higher1 a column of the oil of turpentine will still connect it with that in the basin below 7fig4 #aci474 ,if the machine be excited into more powerful action1 this will become more bulky1 and may then also be raised higher1 assuming the form 7fig4 #adj72 and all the time that these effects continue1 currents and counter-currents1 sometimes running very close together1 may be observed in the raised column of fluid4 #aeii4 ,it is very difficult to decide by sight the direction of the currents in such experiments as these4 ,if particles of silk are introduced they cling about the conductors2 but using drops of water and mercury the course of the fluid dielectric seems well indicated4 ,thus1 if a drop of water be placed at the end of a rod 7#aega47 over the uninsulated mercury1 it is soon swept away in particles streaming downwards towards the mercury4 ,if another drop be placed on the mercury beneath the end of the rod1 it is quickly dispersed in all directions in the form of streaming particles1 the attractive forces drawing it into elongated portions1 and the currents carrying them away4 ,if a drop of mercury be hung from a ball used to raise a column of the fluid 7#aeih471 then the shape of the drop seems to show currents travelling in the fluid in the direction indicated by the arrows 7fig4 #ada474 #afjj4 ,a very remarkable effect is produced on these phenomena1 connected with positive and negative charge and discharge1 namely1 that a ball charged positively raises a much higher and larger column of the oil of turpentine than when charged negatively4 ,there can be no doubt that this is connected with the difference of positive and negative action already spoken of 7#adhj4 #aebe471 and tends much to strengthen the idea that such difference is referable to the particles of the dielectric rather than to the charged conductors1 and is dependent upon the mode in which these particles polarize 7#aejc4 #aebc474 #afja4 ,whenever currents travel in insulating dielectrics they really effect discharge2 and it is important to observe1 though a very natural result1 that it is indifferent which way the current or particles travel1 as with reversed direction their state is reversed4 ,the change is easily made1 either in air or oil of turpentine1 between two opposed rods1 for an insulated ball being placed in connexion with either rod and brought near its extremity1 will cause the current to set towards it from the opposite end4 #afjb4 ,the two currents often occur at once1 as when both terminations present brushes1 and frequently when they exhibit the glow 7#aeca474 ,in such cases1 the charged particles1 or many of them1 meet and mutually discharge each other 7#aeah4 #afab474 ,if a smoking wax taper be held at the end of an insulating rod towards a charged prime conductor1 it will very often happen that two currents will form1 and be rendered visible by its vapour1 one passing as a fine filament of smoky particles directly to the charged conductor1 and the other passing as directly from the same taper wick outwards1 and from the conductor3 the principles of inductric action and charge1 which were referred to in considering the relation of a carrier ball and a conductor 7#aeff471 being here also called into play4 99 99 99 99 99 #afjc4 ,the general analogy and1 ,i think ,i may say1 identity of action found to exist as to insulation and conduction 7#acch4 #aefa47 when bodies1 the best and the worst in the classes of insulators or conductors1 were compared1 led me to believe that the phenomena of convection in badly conducting media were not without their parallel amongst the best conductors1 such even as the metals4 ,upon consideration1 the cones produced by ,davy,a in fluid metals1 as mercury and tin1 seemed to be cases in point1 and probably also the elongation of the metallic medium through which a current of electricity was passing1 described by ,ampre 7#aaac7;,b2 for it is not difficult to conceive1 that the diminution of convective effect1 consequent upon the high conducting power of the metallic media used in these experiments1 might be fully compensated for by the enormous quantity of electricity passing4 ,in fact1 it is impossible not to expect some effect1 whether sensible or not1 of the kind in question1 when such a current is passing through a fluid offering a sensible resistance to the passage of the electricity1 and1 thereby1 giving proof of a certain degree of insulating power 7#acbh474 ,a ,philosophical ,transactions1 #ahbc1 p4 #aee4 ,b ,bibliothque ,universelle1 xxi1 #dag4 #afjd4 ,i endeavoured to connect the convective currents in air1 oil of turpentine1 c4 and those in metals1 by intermediate cases1 but found this not easy to do4 ,on taking bodies1 for instance1 which1 like water1 adds1 solutions1 fused salts or chlorides1 c41 have intermediate conducting powers1 the minute quantity of electricity which the common machine can supply 7#cga4 #hfa47 is exhausted instantly1 so that the cause of the phenomenon is kept either very low in intensity1 or the instant of time during which the effect lasts is so small1 that one cannot hope to observe the result sought for4 ,if a voltaic battery be used1 these bodies are all electrolytes1 and the evolution of gas1 or the production of other changes1 interferes and prevents observation of the effect required4 #afje4 ,there are1 nevertheless1 some experiments which illustrate the connection4 ,two platina wires1 forming the electrodes of a powerful voltaic battery1 were placed side by side1 near each other1 in distilled water1 hermetically sealed up in a strong glass tube1 some minute vegetable fibres being present in the water4 ,when1 from the evolution of gas and the consequent increased pressure1 the bubbles formed on the electrodes were so small as to produce but feebly ascending currents1 then it could be observed that the filaments present were attracted and repelled between the two wires1 as they would have been between two oppositely charged surfaces in air or oil of turpentine1 moving so quickly as to displace and disturb the bubbles and the currents which these tended to form4 ,now ,i think it cannot be doubted1 that under similar circumstances1 and with an abundant supply of electricity1 of sufficient tension also1 convective currents might have been formed2 the attractions and repulsions of the filaments were1 in fact1 the elements of such currents 7#aegb471 and therefore water1 though almost infinitely above air or oil of turpentine as a conductor1 is a medium in which similar currents can take place4 #afjf4 ,i had an apparatus made 7fig4 #adb47 in which a is a plate of shell-lac1 b a fine platina wire passing through it1 and having only the section of the wire exposed above2 c a ring of bibulous paper resting on the shell-lac1 and d distilled water retained by the paper in its place1 and just sufficient in quantity to cover the end of the wire b2 another wire1 e1 touched a piece of tinfoil lying in the water1 and was also connected with a discharging train2 in this way it was easy1 by rendering b either positive or negative1 to send a current of electricity by its extremity into the fluid1 and so away by the wire e4 #afjg4 ,on connecting b with the conductor of a powerful electrical machine1 not the least disturbance of the level of the fluid over the end of the wire during the working of the machine could be observed2 but at the same time there was not the smallest indication of electrical charge about the conductor of the machine1 so complete was the discharge4 ,i conclude that the quantity of electricity passed in a given time had been too small1 when compared with the conducting power of the fluid to produce the desired effect4 #afjh4 ,i then charged a large ,leyden battery 7#bia471 and discharged it through the wire b1 interposing1 however1 a wet thread1 two feet long1 to prevent a spark in the water1 and to reduce what would else have been a sudden violent discharge into one of more moderate character1 enduring for a sensible length of time 7#ccd474 ,i now did obtain a very brief elevation of the water over the end of the wire2 and though a few minute bubbles of gas were at the same time formed there1 so as to prevent me from asserting that the effect was unequivocally the same as that obtained by ,,davy in the metals1 yet1 according to my best judgement1 it was partly1 and ,i believe principally1 of that nature4 #afji4 ,i employed a voltaic battery of #ajj pair of four-inch plates for experiments of a similar nature with electrolytes4 ,in these cases the shell-lac was cupped1 and the wire b #j4b of an inch in diameter4 ,sometimes ,i used a positive amalgamated zinc wire in contact with dilute sulphuric acid2 at others1 a negative copper wire in a solution of sulphate of copper2 but1 because of the evolution of gas1 the precipitation of copper1 c41 ,i was not able to obtain decided results4 ,it is but right to mention1 that when ,i made use of mercury1 endeavouring to repeat ,,davy's experiment1 the battery of #ajj pair was not sufficient to produce the elevations,a4 ,a ,in the experiments at the ,royal ,institution1 ,sir ,h4 ,davy used1 ,i think1 #ejj or #fjj pairs of plates4 ,those at the ,london ,institution were made with the apparatus of ,mr4 ,pepys 7consisting of an enormous single pair of plates71 described in the ,philosophical ,transactions for #ahcb1 p4 #ahg4 #afaj4 ,the latter experiments 7#afji47 may therefore be considered as failing to give the hoped-for proof1 but ,i have much confidence in the former 7#afje4 #afjh471 and in the considerations 7#afjc47 connected with them4 ,if ,i have rightly viewed them1 and we may be allowed to compare the currents at points and surfaces in such extremely different bodies as air and the metals1 and admit that they are effects of the same kind1 differing only in degree and in proportion to the insulating or conducting power of the dielectric used1 what great additional argument we obtain in favour of that theory1 which in the phenomena of insulation and conduction also1 as in these1 would link the same apparently dissimilar substances together 7#accf4 #aefa472 and how completely the general view1 which refers all the phenomena to the direct action of the molecules of matter1 seems to embrace the various isolated phenomena as they successively come under consideration6 99 99 99 99 99 #afaa4 ,the connection of this convective or carrying effect1 which depends upon a certain degree of insulation1 with conduction2 i4e4 the occurrence of both in so many of the substances referred to1 as1 for instance1 the metals1 water1 air1 c41 would lead to many very curious theoretical generalizations1 which ,i must not indulge in here4 ,one point1 however1 ,i shall venture to refer to4 ,conduction appears to be essentially an action of contiguous particles1 and the considerations just stated1 together with others formerly expressed 7#acbf1 #accf1 c471 lead to the conclusion1 that all bodies conduct1 and by the same process1 air as well as metals2 the only difference being in the necessary degree of force or tension between the particles which must exist before the act of conduction or transfer from one particle to another can take place4 #afab4 ,the question then arises1 what is this limiting condition which separates1 as it were1 conduction and insulation from each other8 ,does it consist in a difference between the two contiguous particles1 or the contiguous poles of these particles1 in the nature and amount of positive and negative force1 no communication or discharge occurring unless that difference rises up to a certain degree1 variable for different bodies1 but always the same for the same body8 ,or is it true that1 however small the difference between two such particles1 if time be allowed1 equalization of force will take place1 even with the particles of such bodies as air1 sulphur or lac8 ,in the first case1 insulating power in any particular body would be proportionate to the degree of the assumed necessary difference of force2 in the second1 to the time required to equalize equal degrees of difference in different bodies4 ,with regard to airs1 one is almost led to expect a permanent difference of force2 but in all other bodies1 time seems to be quite sufficient to ensure1 ultimately1 complete conduction4 ,the difference in the modes by which insulation may be sustained1 or conduction effected1 is not a mere fanciful point1 but one of great importance1 as being essentially connected with the molecular theory of induction1 and the manner in which the particles of bodies assume and retain their polarized state4 99 99 99 99 99 xi4 ,relation of a vacuum to electrical phenomena4 #afac4 ,it would seem strange1 if a theory which refers all the phenomena of insulation and conduction1 i4e4 all electrical phenomena1 to the action of contiguous particles1 were to omit to notice the assumed possible case of a vacuum4 ,admitting that a vacuum can be produced1 it would be a very curious matter indeed to know what its relation to electrical phenomena would be2 and as shell-lac and metal are directly opposed to each other1 whether a vacuum would be opposed to them both1 and allow neither of induction or conduction across it4 ,mr4 ,morgan,a has said that a vacuum does not conduct4 ,sir ,h4 ,davy concluded from his investigations1 that as perfect a vacuum as could be made,b did conduct1 but does not consider the prepared spaces which he used as absolute vacua4 ,in such experiments ,i think ,i have observed the luminous discharge to be principally on the inner surface of the glass2 and it does not appear at all unlikely1 that1 if the vacuum refused to conduct1 still the surface of glass next it might carry on that action4 ,a ,philosophical ,transactions1 #aghe1 p4 #bgb ,b ,ibid4 #ahbb1 p4 #fd4 #afad4 ,at one time1 when ,i thought inductive force was exerted in right lines1 ,i hoped to illustrate this important question by making experiments on induction with metallic mirrors 7used only as conducting vessels7 exposed towards a very clear sky at night time1 and of such concavity that nothing but the firmament could be visible from the lowest part of the concave n1 fig4 #adc4 ,such mirrors1 when electrified1 as by connexion with a ,leyden jar1 and examined by a carrier ball1 readily gave electricity at the lowest part of their concavity if in a room2 but ,i was in hopes of finding that1 circumstanced as before stated1 they would give little or none at the same spot1 if the atmosphere above really terminated in a vacuum4 ,i was disappointed in the conclusion1 for ,i obtained as much electricity there as before2 but on discovering the action of induction in curved lines 7#abca471 found a full and satisfactory explanation of the result4 #afae4 ,my theory1 as far as ,i have ventured it1 does not pretend to decide upon the consequences of a vacuum4 ,it is not at present limited sufficiently1 or rendered precise enough1 either by experiments relating to spaces void of matter1 or those of other kinds1 to indicate what would happen in the vacuum case4 ,i have only as yet endeavoured to establish1 what all the facts seem to prove1 that when electrical phenomena1 as those of induction1 conduction1 insulation and discharge occur1 they depend on1 and are produced by the action of contiguous particles of matter1 the next existing particle being considered as the contiguous one2 and ,i have further assumed1 that these particles are polarized2 that each exhibits the two forces1 or the force in two directions 7#abie4 #abih472 and that they act at a distance1 only by acting on the contiguous and intermediate particles4 #afaf4 ,but assuming that a perfect vacuum were to intervene in the course of the lines of inductive action 7#acjd471 it does not follow from this theory1 that the particles on opposite sides of such a vacuum could not act on each other4 ,suppose it possible for a positively electrified particle to be in the centre of a vacuum an inch in diameter1 nothing in my present views forbids that the particle should act at the distance of half an inch on all the particles forming the inner superficies of the bounding sphere1 and with a force consistent with the well-known law of the squares of the distance4 ,but suppose the sphere of an inch were full of insulating matter1 the electrified particle would not then1 according to my notion1 act directly on the distant particles1 but on those in immediate association with it1 employing all its power in polarizing them2 producing in them negative force equal in amount to its own positive force and directed towards the latter1 and positive force of equal amount directed outwards and acting in the same manner upon the layer of particles next in succession4 ,so that ultimately1 those particles in the surface of a sphere of half an inch radius1 which were acted on directly when that sphere was a vacuum1 will now be acted on indirectly as respects the central particle or source of action1 i4e4 they will be polarized in the same way1 and with the same amount of force4 #ai4 ,nature of the electric current4 #afag4 ,the word current is so expressive in common language1 that when applied in the consideration of electrical phenomena we can hardly divest it sufficiently of its meaning1 or prevent our minds from being prejudiced by it 7#bhc4 #eaa474 ,i shall use it in its common electrical sense1 namely1 to express generally a certain condition and relation of electrical forces supposed to be in progression4 #afah4 ,a current is produced both by excitement and discharge2 and whatsoever the variation of the two general causes may be1 the effect remains the same4 ,thus excitement may occur in many ways1 as by friction1 chemical action1 influence of heat1 change of condition1 induction1 c42 and discharge has the forms of conduction1 electrolyzation1 disruptive discharge1 and convection2 yet the current connected with these actions1 when it occurs1 appears in all cases to be the same4 ,this constancy in the character of the current1 notwithstanding the particular and great variations which may be made in the mode of its occurrence1 is exceedingly striking and important2 and its investigation and development promise to supply the most open and advantageous road to a true and intimate understanding of the nature of electrical forces4 #afai4 ,as yet the phenomena of the current have presented nothing in opposition to the view ,i have taken of the nature of induction as an action of contiguous particles4 ,i have endeavoured to divest myself of prejudices and to look for contradictions1 but ,i have not perceived any in conductive1 electrolytic1 convective1 or disruptive discharge4 #afbj4 ,looking at the current as a cause1 it exerts very extraordinary and diverse powers1 not only in its course and on the bodies in which it exists1 but collaterally1 as in inductive or magnetic phenomena4 #afba4 ,electrolytic action4--,one of its direct actions is the exertion of pure chemical force1 this being a result which has now been examined to a considerable extent4 ,the effect is found to be constant and definite for the quantity of electric force discharged 7#ghc4 c472 and beyond that1 the intensity required is in relation to the intensity of the affinity or forces to be overcome 7#ijd4 #ijf4 #iaa474 ,the current and its consequences are here proportionate2 the one may be employed to represent the other2 no part of the effect of either is lost or gained2 so that the case is a strict one1 and yet it is the very case which most strikingly illustrates the doctrine that induction is an action of contiguous particles 7#aafd4 #acdc474 #afbb4 ,the process of electrolytic discharge appears to me to be in close analogy1 and perhaps in its nature identical with another process of discharge1 which at first seems very different from it1 ,i mean convection 7#acdg4 #aegb474 ,in the latter case the particles may travel for yards across a chamber2 they may produce strong winds in the air1 so as to move machinery2 and in fluids1 as oil of turpentine1 may even shake the hand1 and carry heavy metallic bodies about,a2 and yet ,i do not see that the force1 either in kind or action1 is at all different to that by which a particle of hydrogen leaves one particle of oxygen to go to another1 or by which a particle of oxygen travels in the contrary direction4 ,a ,if a metallic vessel three or four inches deep1 containing oil of turpentine1 be insulated and electrified1 and a rod with a ball 7an inch or more in diameter7 at the end have the ball immersed in the fluid whilst the end is held in the hand1 the mechanical force generated when the ball is moved to and from the sides of the vessel will soon be evident to the experimenter4 #afbc4 ,travelling particles of the air can effect chemical changes just as well as the contact of a fixed platina electrode1 or that of a combining electrode1 or the ions of a decomposing electrolyte 7#dec4 #dga472 and in the experiment formerly described1 where eight places of decomposition were rendered active by one current 7#dfi471 and where charged particles of air in motion were the only electrical means of connecting these parts of the current1 it seems to me that the action of the particles of the electrolyte and of the air were essentially the same4 ,a particle of air was rendered positive2 it travelled in a certain determinate direction1 and coming to an electrolyte1 communicated its powers2 an equal amount of positive force was accordingly acquired by another particle 7the hydrogen71 and the latter1 so charged1 travelled as the former did1 and in the same direction1 until it came to another particle1 and transferred its power and motion1 making that other particle active4 ,now1 though the particle of air travelled over a visible and occasionally a large space1 whilst the particle of the electrolyte moved over an exceedingly small one2 though the air particle might be oxygen1 nitrogen1 or hydrogen1 receiving its charge from force of high intensity1 whilst the electrolytic particle of hydrogen had a natural aptness to receive the positive condition with extreme facility2 though the air particle might be charged with very little electricity at a very high intensity by one process1 whilst the hydrogen particle might be charged with much electricity at a very low intensity by another process2 these are not differences of kind1 as relates to the final discharging action of these particles1 but only of degree2 not essential differences which make things unlike1 but such differences as give to things1 similar in their nature1 that great variety which fits them for their office in the system of the universe4 #afbd4 ,so when a particle of air1 or of dust in it1 electrified at a negative point1 moves on through the influence of the inductive forces 7#aegb47 to the next positive surface1 and after discharge passes away1 it seems to me to represent exactly that particle of oxygen which1 having been rendered negative in the electrolyte1 is urged by the same disposition of inductive forces1 and going to the positive platina electrode1 is there discharged1 and then passes away1 as the air or dust did before it4 #afbe4 ,heat is another direct effect of the current upon substances in which it occurs1 and it becomes a very important question1 as to the relation of the electric and heating forces1 whether the latter is always definite in amount,a4 ,there are many cases1 even amongst bodies which conduct without change1 that at present are irreconcileable with the assumption that it is,b2 but there are also many which indicate that1 when proper limitations are applied1 the heat produced is definite4 ,harris has shown this for a given length of current in a metallic wire1 using common electricity,c2 and ,de la ,rive has proved the same point for voltaic electricity by his beautiful application of ,breguet's thermometer,d4 ,a ,see ,de la ,rive's ,researches1 ,bib4 ,universelle1 #ahbi1 xl4 p4 #dj4 ,b ,amongst others1 ,davy1 ,philosophical ,transactions1 #ahba1 p4 #dch4 ,pelletier's important results1 ,annales de ,chimie1 #ahcd1 lvi4 p4 #cga4 and ,becquerel's non-heating current1 ,bib4 ,universelle1 #ahce1 lx4 #bah4 ,c ,philosophical ,transactions1 #ahbd1 pp4 #bbe4 #bbh4 ,d ,annales de ,chimie1 #ahcf1 lxii4 #agg4 #afbf4 ,when the production of heat is observed in electrolytes under decomposition1 the results are still more complicated4 ,but important steps have been taken in the investigation of this branch of the subject by ,de la ,rive,a and others2 and it is more than probable that1 when the right limitations are applied1 constant and definite results will here also be obtained4 ,a ,bib4 ,universelle1 #ahbi1 xl4 #di2 and ,ritchie1 ,phil4 ,trans4 #ahcb4 p4 #bif4 99 99 99 99 99 #afbg4 ,it is a most important part of the character of the current1 and essentially connected with its very nature1 that it is always the same4 ,the two forces are everywhere in it4 ,there is never one current of force or one fluid only4 ,any one part of the current may1 as respects the presence of the two forces there1 be considered as precisely the same with any other part2 and the numerous experiments which imply their possible separation1 as well as the theoretical expressions which1 being used daily1 assume it1 are1 ,i think1 in contradiction with facts 7#eaa1 c474 ,it appears to me to be as impossible to assume a current of positive or a current of negative force alone1 or of the two at once with any predominance of one over the other1 as it is to give an absolute charge to matter 7#eaf4 #aafi4 #aagg474 #afbh4 ,the establishment of this truth1 if1 as ,i think1 it be a truth1 or on the other hand the disproof of it1 is of the greatest consequence4 ,if1 as a first principle1 we can establish1 that the centres of the two forces1 or elements of force1 never can be separated to any sensible distance1 or at all events not further than the space between two contiguous particles 7#afae471 or if we can establish the contrary conclusion1 how much more clear is our view of what lies before us1 and how much less embarrassed the ground over which we have to pass in attaining to it1 than if we remain halting between two opinions6 ,and if1 with that feeling1 we rigidly test every experiment which bears upon the point1 as far as our prejudices will let us 7#aafa471 instead of permitting them with a theoretical expression to pass too easily away1 are we not much more likely to attain the real truth1 and from that proceed with safety to what is at present unknown8 #afbi4 ,i say these things1 not1 ,i hope1 to advance a particular view1 but to draw the strict attention of those who are able to investigate and judge of the matter1 to what must be a turning point in the theory of electricity2 to a separation of two roads1 one only of which can be right3 and ,i hope ,i may be allowed to go a little further into the facts which have driven me to the view ,i have just given4 #afcj4 ,when a wire in the voltaic circuit is heated1 the temperature frequently rises first1 or most at one end4 ,if this effect were due to any relation of positive or negative as respects the current1 it would be exceedingly important4 ,i therefore examined several such cases2 but when1 keeping the contacts of the wire and its position to neighbouring things unchanged1 ,i altered the direction of the current1 ,i found that the effect remained unaltered1 showing that it depended1 not upon the direction of the current1 but on other circumstances4 ,so there is here no evidence of a difference between one part of the circuit and another4 #afca4 ,the same point1 i4e4 uniformity in every part1 may be illustrated by what may be considered as the inexhaustible nature of the current when producing particular effects2 for these effects depend upon transfer only1 and do not consume the power4 ,thus a current which will heat one inch of platina wire will heat a hundred inches 7#hec4 note74 ,if a current be sustained in a constant state1 it will decompose the fluid in one voltameter only1 or in twenty others if they be placed in the circuit1 in each to an amount equal to that in the single one4 #afcb4 ,again1 in cases of disruptive discharge1 as in the spark1 there is frequently a dark part 7#adbb47 which1 by ,professor ,johnson1 has been called the neutral point,a2 and this has given rise to the use of expressions implying that there are two electricities existing separately1 which1 passing to that spot1 there combine and neutralize each other,b4 ,but if such expressions are understood as correctly indicating that positive electricity alone is moving between the positive ball and that spot1 and negative electricity only between the negative ball and that spot1 then what strange conditions these parts must be in2 conditions1 which to my mind are every way unlike those which really occur6 ,in such a case1 one part of a current would consist of positive electricity only1 and that moving in one direction2 another part would consist of negative electricity only1 and that moving in the other direction2 and a third part would consist of an accumulation of the two electricities1 not moving in either direction1 but mixing up together6 and being in a relation to each other utterly unlike any relation which could be supposed to exist in the two former portions of the discharge4 ,this does not seem to me to be natural4 ,in a current1 whatever form the discharge may take1 or whatever part of the circuit or current is referred to1 as much positive force as is there exerted in one direction1 so much negative force is there exerted in the other4 ,if it were not so we should have bodies electrified not merely positive and negative1 but on occasions in a most extraordinary manner1 one being charged with five1 ten1 or twenty times as much of both positive and negative electricity in equal quantities as another4 ,at present1 however1 there is no known fact indicating such states4 ,a ,silliman's ,journal1 #ahcd1 xxv4 p4 #eg4 ,b ,thomson on ,heat and ,electricity1 p4 #aga4 #afcc4 ,even in cases of convection1 or carrying discharge1 the statement that the current is everywhere the same must in effect be true 7#afbg472 for how1 otherwise1 could the results formerly described occur8 ,when currents of air constituted the mode of discharge between the portions of paper moistened with iodide of potassium or sulphate of soda 7#dfe4 #dfi471 decomposition occurred2 and ,i have since ascertained that1 whether a current of positive air issued from a spot1 or one of negative air passed towards it1 the effect of the evolution of iodine or of acid was the same1 whilst the reversed currents produced alkali4 ,so also in the magnetic experiments 7#cjg47 whether the discharge was effected by the introduction of a wire1 or the occurrence of a spark1 or the passage of convective currents either one way or the other 7depending on the electrified state of the particles71 the result was the same1 being in all cases dependent upon the perfect current4 #afcd4 ,hence1 the section of a current compared with other sections of the same current must be a constant quantity1 if the actions exerted be of the same kind2 or if of different kinds1 then the forms under which the effects are produced are equivalent to each other1 and experimentally convertible at pleasure4 ,it is in sections1 therefore1 we must look for identity of electrical force1 even to the sections of sparks and carrying actions1 as well as those of wires and electrolytes4 #afce4 ,in illustration of the utility and importance of establishing that which may be the true principle1 ,i will refer to a few cases4 ,the doctrine of unipolarity1 as formerly stated1 and ,i think generally understood,a1 is evidently inconsistent with my view of a current 7#afbg472 and the later singular phenomena of poles and flames described by ,erman and others,b partake of the same inconsistency of character4 ,if a unipolar body could exist1 i4e4 one that could conduct the one electricity and not the other1 what very new characters we should have a right to expect in the currents of single electricities passing through them1 and how greatly ought they to differ1 not only from the common current which is supposed to have both electricities travelling in opposite directions in equal amount at the same time1 but also from each other6 ,the facts1 which are excellent1 have1 however1 gradually been more correctly explained by ,becquerel,c1 ,andrews,d1 and others2 and ,i understand that ,professor ,ohms,e has perfected the work1 in his close examination of all the phenomena2 and after showing that similar phenomena can take place with good conductors1 proves that with soap1 c4 many of the effects are the mere consequences of the bodies evolved by electrolytic action4 ,a ,erman1 ,annales de ,chimie1 #ahjg4 lxi4 p4 #aae4 ,davy's ,elements1 p4 #afh4 ,biot1 ,ency4 ,brit4 ,supp1 iv4 p4 #ddd4 ,becquerel1 ,trait1 i4 p4 #afg4 ,de la ,rive1 ,bib4 ,univ4 #ahcg4 vii4 #cib4 ,b ,erman1 ,annales de ,chimie1 #ahbd4 xxv4 #bgh4 ,becquerel1 ,ibid4 xxxvi4 p4 #cbi ,c ,becquerel1 ,annales de ,chimie1 #ahca4 xlvi4 p4 #bhc4 ,d ,andrews1 ,philosophical ,magazine1 #ahcf4 ix4 #ahb4 ,e ,schweigger's ,jahrbuch de ,chimie1 c4 #ahcj4 ,heft #h4 ,not understanding ,german1 it is with extreme regret ,i confess ,i have not access1 and cannot do justice1 to the many most valuable papers in experimental electricity published in that language4 ,i take this opportunity also of stating another circumstance which occasions me great trouble1 and1 as ,i find by experience1 may make1 me seemingly regardless of the labours of others3--it is a gradual loss of memory for some years past2 and now1 often when ,i read a memoir1 ,i remember that ,i have seen it before1 and would have rejoiced if at the right time ,i could have recollected and referred to it in the progress of my own papers4--,m4,f4 #afcf4 ,i conclude1 therefore1 that the facts upon which the doctrine of unipolarity was founded are not adverse to that unity and indivisibility of character which ,i have stated the current to possess1 any more than the phenomena of the pile itself 7which might well bear comparison with those of unipolar bodies17 are opposed to it4 ,probably the effects which have been called effects of unipolarity1 and the peculiar differences of the positive and negative surface when discharging into air1 gases1 or other dielectrics 7#adhj4 #aebe47 which have been already referred to1 may have considerable relation to each other,a4 ,a ,see also ,hare in ,silliman's ,journal1 #ahcc4 xxiv4 #bdf4 99 99 99 99 99 #afcg4 ,m4 de la ,rive has recently described a peculiar and remarkable effect of heat on a current when passing between electrodes and a fluid,a4 ,it is1 that if platina electrodes dip into acidulated water1 no change is produced in the passing current by making the positive electrode hotter or colder2 whereas making the negative electrode hotter increased the deflexion of a galvanometer affected by the current1 from #ab to #cj and even #de1 whilst making it colder diminished the current in the same high proportions4 ,a ,bibliothque ,universelle1 #ahcg1 vii4 #chh4 #afch4 ,that one electrode should have this striking relation to heat whilst the other remained absolutely without1 seem to me as incompatible with what ,i conceived to be the character of a current as unipolarity 7#afbg4 #afce471 and it was therefore with some anxiety that ,i repeated the experiment4 ,the electrodes which ,i used were platina2 the electrolyte1 water containing about one sixth of sulphuric acid by weight3 the voltaic battery consisted of two pairs of amalgamated zinc and platina plates in dilute sulphuric acid1 and the galvanometer in the circuit was one with two needles1 and gave when the arrangement was complete a deflexion of #aj or #ab4 #afci4 ,under these circumstances heating either electrode increased the current2 heating both produced still more effect4 ,when both were heated1 if either were cooled1 the effect on the current fell in proportion4 ,the proportion of effect due to heating this or that electrode varied1 but on the whole heating the negative seemed to favour the passage of the current somewhat more than heating the positive4 ,whether the application of heat were by a flame applied underneath1 or one directed by a blowpipe from above1 or by a hot iron or coal1 the effect was the same4 #afdj4 ,having thus removed the difficulty out of the way of my views regarding a current1 ,i did not pursue this curious experiment further4 ,it is probable1 that the difference between my results and those of ,m4 de la ,rive may depend upon the relative values of the currents used2 for ,i employed only a weak one resulting from two pairs of plates two inches long and half an inch wide1 whilst ,m4 de la ,rive used four pairs of plates of sixteen square inches in surface4 99 99 99 99 99 #afda4 ,electric discharges in the atmosphere in the form of balls of fire have occasionally been described4 ,such phenomena appear to me to be incompatible with all that we know of electricity and its modes of discharge4 ,as time is an element in the effect 7#adah4 #adcf47 it is possible perhaps that an electric discharge might really pass as a ball from place to place2 but as every thing shows that its velocity must be almost infinite1 and the time of its duration exceedingly small1 it is impossible that the eye should perceive it as anything else than a line of light4 ,that phenomena of balls of fire may appear in the atmosphere1 ,i do not mean to deny2 but that they have anything to do with the discharge of ordinary electricity1 or are at all related to lightning or atmospheric electricity1 is much more than doubtful4 99 99 99 99 99 #afdb4 ,all these considerations1 and many others1 help to confirm the conclusion1 drawn over and over again1 that the current is an indivisible thing2 an axis of power1 in every part of which both electric forces are present in equal amount,a 7#eag4 #afbg474 ,with conduction and electrolyzation1 and even discharge by spark1 such a view will harmonize without hurting any of our preconceived notions2 but as relates to convection1 a more startling result appears1 which must therefore be considered4 ,a ,i am glad to refer here to the results obtained by ,mr4 ,christie with magneto-electricity1 ,philosophical ,transactions1 #ahcc1 p4 #aac note4 ,as regards the current in a wire1 they confirm everything that ,i am contending for4 #afdc4 ,if two balls ,a and ,b be electrified in opposite states and held within each other's influence1 the moment they move towards each other1 a current1 or those effects which are understood by the word current1 will be produced4 ,whether ,a move towards ,b1 or ,b move in the opposite direction towards ,a1 a current1 and in both cases having the same direction1 will result4 ,if ,a and ,b move from each other1 then a current in the opposite direction1 or equivalent effects1 will be produced4 #afdd4 ,or1 as charge exists only by induction 7#aagh4 #abii471 and a body when electrified is necessarily in relation to other bodies in the opposite state2 so1 if a ball be electrified positively in the middle of a room and be then moved in any direction1 effects will be produced1 as current in the same direction 7to use the conventional mode of expression7 had existed3 or1 if the ball be negatively electrified1 and then moved1 effects as if a current in a direction contrary to that of the motion had been formed1 will be produced4 #afde4 ,i am saying of a single particle or of two what ,i have before said1 in effect1 of many 7#afcc474 ,if the former account of currents be true1 then that just stated must be a necessary result4 ,and1 though the statement may seem startling at first1 it is to be considered that1 according to my theory of induction1 the charged conductor or particle is related to the distant conductor in the opposite state1 or that which terminates the extent of the induction1 by all the intermediate particles 7#aafe1 #abie471 these becoming polarized exactly as the particles of a solid electrolyte do when interposed between the two electrodes4 ,hence the conclusion regarding the unity and identity of the current in the case of convection1 jointly with the former cases1 is not so strange as it might at first appear4 99 99 99 99 99 #afdf4 ,there is a very remarkable phenomenon or effect of the electrolytic discharge1 first pointed out1 ,i believe1 by ,mr4 ,porrett1 of the accumulation of fluid under decomposing action in the current on one side of an interposed diaphragm,a4 ,it is a mechanical result2 and as the liquid passes from the positive towards the negative electrode in all the known cases1 it seems to establish a relation to the polar condition of the dielectric in which the current exists 7#aafd4 #aebe474 ,it has not as yet been sufficiently investigated by experiment2 for ,de la ,rive says,b1 it requires that the water should be a bad conductor1 as1 for instance1 distilled water1 the effect not happening with strong solutions2 whereas1 ,dutrochet says,c the contrary is the case1 and that1 the effect is not directly due to the electric current4 ,a ,annals of ,philosophy1 #ahaf4 viii4 p4 #ge4 ,b ,annales de ,chimie1 #ahce4 xxviii4 p4 #aif4 ,c ,annales de ,chimie1 #ahcb1 xlix4 p4 #dbc4 #afdg4 ,becquerel1 in his ,trait de l',electricit1 has brought together the considerations which arise for and against the opinion1 that the effect generally is an electric effect,a4 ,though ,i have no decisive fact to quote at present1 ,i cannot refrain from venturing an opinion1 that the effect is analogous both to combination and convection 7#afbc471 being a case of carrying due to the relation of the diaphragm and the fluid in contact with it1 through which the electric discharge is jointly effected2 and further1 that the peculiar relation of positive and negative small and large surfaces already referred to 7#adhb4 #aejc4 #aebe471 may be the direct cause of the fluid and the diaphragm travelling in contrary but determinate directions4 ,a very valuable experiment has been made by ,m4 ,becquerel with particles of clay,b1 which will probably bear importantly on this point4 ,a ,vol4 iv4 p4 #aib1 #aig4 ,b ,trait de l',electricit1 i4 p4 #bhe4 99 99 99 99 99 #afdh4 ,as long as the terms current and electro-dynamic are used to express those relations of the electric forces in which progression of either fluids or effects are supposed to occur 7#bhc471 so long will the idea of velocity be associated with them2 and this will1 perhaps1 be more especially the case if the hypothesis of a fluid or fluids be adopted4 #afdi4 ,hence has arisen the desire of estimating this velocity either directly or by some effect dependent on it2 and amongst the endeavours to do this correctly1 may be mentioned especially those of ,dr4 ,watson,a in #agdh1 and of ,professor ,wheatstone,b in #ahcd2 the electricity in the early trials being supposed to travel from end to end of the arrangement1 but in the later investigations a distinction occasionally appearing to be made between the transmission of the effect and of the supposed fluid by the motion of whose particles that effect is produced4 ,a ,philosophical ,transactions1 #agdh4 ,b ,ibid4 #ahcd1 p4 #ehc4 #afej4 ,electrolytic action has a remarkable bearing upon this question of the velocity of the current1 especially as connected with the theory of an electric fluid or fluids4 ,in it there is an evident transfer of power with the transfer of each particle of the anion or cathion present1 to the next particles of the cathion or anion2 and as the amount of power is definite1 we have in this way a means of localizing as it were the force1 identifying it by the particle and dealing it out in successive portions1 which leads1 ,i think1 to very striking results4 #afea4 ,suppose1 for instance1 that water is undergoing decomposition by the powers of a voltaic battery4 ,each particle of hydrogen as it moves one way1 or of oxygen as it moves in the other direction1 will transfer a certain amount of electrical force associated with it in the form of chemical affinity 7#hbb4 #heb4 #iah47 onwards through a distance1 which is equal to that through which the particle itself has moved4 ,this transfer will be accompanied by a corresponding movement in the electrical forces throughout every part of the circuit formed 7#afbg4 #afcd471 and its effects may be estimated1 as1 for instance1 by the heating of a wire 7#hec47 at any particular section of the current however distant4 ,if the water be a cube of an inch in the side1 the electrodes touching1 each by a surface of one square inch1 and being an inch apart1 then1 by the time that a tenth of it1 or #be4be grs41 is decomposed1 the particles of oxygen and hydrogen throughout the mass may be considered as having moved relatively to each other in opposite directions1 to the amount of the tenth of an inch2 i4e4 that two particles at first in combination will after the motion be the tenth of an inch apart4 ,other motions which occur in the fluid will not at all interfere with this result2 for they have no power of accelerating or retarding the electric discharge1 and possess in fact no relation to it4 #afeb4 ,the quantity of electricity in #be4be grains of water is1 according to an estimate of the force which ,i formerly made 7#hfa471 equal to above #bd millions of charges of a large ,leyden battery2 or it would have kept any length of a platina wire #a_/ajd of an inch in diameter red-hot for an hour and a half 7#hec474 ,this result1 though given only as an approximation1 ,i have seen no reason as yet to alter1 and it is confirmed generally by the experiments and results of ,m4 ,pouillet,a4 ,according to ,mr4 ,wheatstone's experiments1 the influence or effects of the current would appear at a distance of #egf1jjj miles in a second,b4 ,we have1 therefore1 in this view of the matter1 on the one hand1 an enormous quantity of power equal to a most destructive thunder-storm appearing instantly at the distance of #egf1jjj miles from its source1 and on the other1 a quiet effect1 in producing which the power had taken an hour and a half to travel through the tenth of an inch3 yet these are the equivalents to each other1 being effects observed at the sections of one and the same current 7#afcd474 ,a ,becquerel1 ,trait de l',electricit1 v4 p4 #bgh4 ,b ,philosophical ,transactions1 #ahcd1 p4 #ehi4 99 99 99 99 99 #afec4 ,it is time that ,i should call attention to the lateral or transverse forces of the current4 ,the great things which have been achieved by ,oersted1 ,arago1 ,ampre1 ,davy1 ,de la ,rive1 and others1 and the high degree of simplification which has been introduced into their arrangement by the theory of ,ampre1 have not only done their full service in advancing most rapidly this branch of knowledge1 but have secured to it such attention that there is no necessity for urging on its pursuit4 ,i refer of course to magnetic action and its relations2 but though this is the only recognised lateral action of the current1 there is great reason for believing that others exist and would by their discovery reward a close search for them 7#iea474 #afed4 ,the magnetic or transverse action of the current seems to be in a most extraordinary degree independent of those variations or modes of action which it presents directly in its course2 it consequently is of the more value to us1 as it gives us a higher relation of the power than any that might have varied with each mode of discharge4 ,this discharge1 whether it be by conduction through a wire with infinite velocity 7#afeb471 or by electrolyzation with its corresponding and exceeding slow motion 7#afea471 or by spark1 and probably even by convection1 produces a transverse magnetic action always the same in kind and direction4 #afee4 ,it has been shown by several experimenters1 that whilst the discharge is of the same kind the amount of lateral or magnetic force is very constant 7#baf4 #cff4 #cfg4 #cfh4 #cgf474 ,but when we wish to compare discharge of different kinds1 for the important purpose of ascertaining whether the same amount of current will in its different forms produce the same amount of transverse action1 we find the data very imperfect4 ,davy noticed1 that when the electric current was passing through an aqueous solution it affected a magnetic needle,a1 and ,dr4 ,ritchie says1 that the current in the electrolyte is as magnetic as that in a metallic wire,b1 and has caused water to revolve round a magnet as a wire carrying the current would revolve4 ,a ,philosophical ,transactions1 #ahba1 p4 #dbf4 ,b ,ibid4 #ahcb1 p4 #bid4 #afef4 ,disruptive discharge produces its magnetic effects3 a strong spark1 passed transversely to a steel needle1 will magnetise it as well as if the electricity of the spark were conducted by a metallic wire occupying the line of discharge2 and ,sir ,h4 ,davy has shown that the discharge of a voltaic battery in vacuo is affected and has motion given to it by approximated magnets,a4 ,a ,philosophical ,transactions1 #ahba1 p4 #dbg4 #afeg4 ,thus the three very different modes of discharge1 namely1 conduction1 electrolyzation1 and disruptive discharge1 agree in producing the important transverse phenomenon of magnetism4 ,whether convection or carrying discharge will produce the same phenomenon has not been determined1 and the few experiments ,i have as yet had time to make do not enable me to answer in the affirmative4 99 99 99 99 99 #afeh4 ,having arrived at this point in the consideration of the current and in the endeavour to apply its phenomena as tests of the truth or fallacy of the theory of induction which ,i have ventured to set forth1 ,i am now very much tempted to indulge in a few speculations respecting its lateral action and its possible connexion with the transverse condition of the lines of ordinary induction 7#aafe1 #acjd47;,a4 ,i have long sought and still seek for an effect or condition which shall be to statical electricity what magnetic force is to current electricity 7#adaa472 for as the lines of discharge are associated with a certain transverse effect1 so it appeared to me impossible but that the lines of tension or of inductive action1 which of necessity precede that discharge1 should also have their correspondent transverse condition or effect 7#iea474 ,a ,refer for further investigations to #agji4--agcf4--;,dec4 #ahch4 #afei4 ,according to the beautiful theory of ,ampre1 the transverse force of a current may be represented by its attraction for a similar current and its repulsion of a contrary current4 ,may not then the equivalent transverse force of static electricity be represented by that lateral tension or repulsion which the lines of inductive action appear to possess 7#acjd478 ,then again1 when current or discharge occurs between two bodies1 previously under inductrical relations to each other1 the lines of inductive force will weaken and fade away1 and1 as their lateral repulsive tension diminishes1 will contract and ultimately disappear in the line of discharge4 ,may not this be an effect identical with the attractions of similar currents8 i4e4 may not the passage of static electricity into current electricity1 and that of the lateral tension of the lines of inductive force into the lateral attraction of lines of similar discharge1 have the same relation and dependences1 and run parallel to each other8 #affj4 ,the phenomena of induction amongst currents which ,i had the good fortune to discover some years ago 7#f4 c4 #ajdh47 may perchance here form a connecting link in the series of effects4 ,when a current is first formed1 it tends to produce a current in the contrary direction in all the matter around it2 and if that matter have conducting properties and be fitly circumstanced1 such a current is produced4 ,on the contrary1 when the original current is stopped1 one in the same direction tends to form all around it1 and1 in conducting matter properly arranged1 will be excited4 #affa4 ,now though we perceive the effects only in that portion of matter which1 being in the neighbourhood1 has conducting properties1 yet hypothetically it is probable1 that the nonconducting matter has also its relations to1 and is affected by1 the disturbing cause1 though we have not yet discovered them4 ,again and again the relation of conductors and non-conductors has been shown to be one not of opposition in kind1 but only of degree 7#accd1 #afjc472 and1 therefore1 for this1 as well as for other reasons1 it is probable1 that what will affect a conductor will affect an insulator also2 producing perhaps what may deserve the term of the electrotonic state 7#fj4 #bdb4 #aaad474 #affb4 ,it is the feeling of the necessity of some lateral connexion between the lines of electric force 7#aaad472 of some link in the chain of effects as yet unrecognised1 that urges me to the expression of these speculations4 ,the same feeling has led me to make many experiments on the introduction of insulating dielectrics having different inductive capacities 7#abgj4 #abgg47 between magnetic poles and wires carrying currents1 so as to pass across the lines of magnetic force4 ,i have employed such bodies both at rest and in motion1 without1 as yet1 being able to detect any influence produced by them2 but ,i do by no means consider the experiments as sufficiently delicate1 and intend1 very shortly1 to render them more decisive,a4 ,a ,see onwards #agaa4--agbf4--;,dec4 #ahch4 #affc4 ,i think the hypothetical question may at present be put thus3 can such considerations as those already generally expressed 7#afeh47 account for the transverse effects of electrical currents8 are two such currents in relation to each other merely by the inductive condition of the particles of matter between them1 or are they in relation by some higher quality and condition 7#afed471 which1 acting at a distance and not by the intermediate particles1 has1 like the force of gravity1 no relation to them8 #affd4 ,if the latter be the case1 then1 when electricity is acting upon and in matter1 its direct and its transverse action are essentially different in their nature2 for the former1 if ,i am correct1 will depend upon the contiguous particles1 and the latter will not4 ,as ,i have said before1 this may be so1 and ,i incline to that view at present2 but ,i am desirous of suggesting considerations why it may not1 that the question may be thoroughly sifted4 #affe4 ,the transverse power has a character of polarity impressed upon it4 ,in the simplest forms it appears as attraction or repulsion1 according as the currents are in the same or different directions3 in the current and the magnet it takes up the condition of tangential forces2 and in magnets and their particles produces poles4 ,since the experiments have been made which have persuaded me that the polar forces of electricity1 as in induction and electrolytic action 7#abih4 #acdc471 show effects at a distance only by means of the polarized contiguous and intervening particles1 ,i have been led to expect that all polar forces act in the same general manner2 and the other kinds of phenomena which one can bring to bear upon the subject seem fitted to strengthen that expectation4 ,thus in crystallizations the effect is transmitted from particle to particle2 and in this manner1 in acetic acid or freezing water a crystal a few inches or even a couple of feet in length will form in less than a second1 but progressively and by a transmission of power from particle to particle4 ,and1 as far as ,i remember1 no case of polar action1 or partaking of polar action1 except the one under discussion1 can be found which does not act by contiguous particles,a4 ,it is apparently of the nature of polar forces that such should be the case1 for the one force either finds or developed the contrary force near to it1 and has1 therefore1 no occasion to seek for it at a distance4 ,a ,i mean by contiguous particles those which are next to each other1 not that there is no space between them4 ,see 7#afaf474 #afff4 ,but leaving these hypothetical notions respecting the nature of the lateral action out of sight1 and returning to the direct effects1 ,i think that the phenomena examined and reasoning employed in this and the two preceding papers tend to confirm the view first taken 7#adfd471 namely1 that ordinary inductive action and the effects dependent upon it are due to an action of the contiguous particles of the dielectric interposed between the charged surfaces or parts which constitute1 as it were1 the terminations of the effect4 ,the great point of distinction and power 7if it have any7 in the theory is1 the making the dielectric of essential and specific importance1 instead of leaving it as it were a mere accidental circumstance or the simple representative of space1 having no more influence over the phenomena than the space occupied by it4 ,i have still certain other results and views respecting the nature of the electrical forces and excitation1 which are connected with the present theory2 and1 unless upon further consideration they sink in my estimation1 ,i shall very shortly put them into form as another series of these electrical researches4 ,royal ,institution4 ,february #adth1 #ahch4 ,,fourteenth ,,series4 #bj4 ,nature of the electric force or forces4 #ba4 ,relation of the electric and magnetic forces4 #bb4 ,note on electrical excitation4 ,received ,june #ba1 #ahch4--,read ,june #ba1 #ahch4 #bj4 ,nature of the electric force or forces4 #affg4 ,the theory of induction set forth and illustrated in the three preceding series of experimental researches does not assume anything new as to the nature of the electric force or forces1 but only as to their distribution4 ,the effects may depend upon the association of one electric fluid with the particles of matter1 as in the theory of ,franklin1 ,epinus1 ,cavendish1 and ,mossotti2 or they may depend upon the association of two electric fluids1 as in the theory of ,dufay and ,poisson2 or they may not depend upon anything which can properly be called the electric fluid1 but on vibrations or other affections of the matter in which they appear4 ,the theory is unaffected by such differences in the mode of viewing the nature of the forces2 and though it professes to perform the important office of stating how the powers are arranged 7at least in inductive phenomena71 it does not1 as far as ,i can yet perceive1 supply a single experiment which can be considered as a distinguishing test of the truth of any one of these various views1 #affh4 ,but1 to ascertain how the forces are arranged1 to trace them in their various relations to the particles of matter1 to determine their general laws1 and also the specific differences which occur under these laws1 is as important as1 if not more so than1 to know whether the forces reside in a fluid or not2 and with the hope of assisting in this research1 ,i shall offer some further developments1 theoretical and experimental1 of the conditions under which ,i suppose the particles of matter are placed when exhibiting inductive phenomena4 #affi4 ,the theory assumes that all the particles1 whether of insulating or conducting matter1 are as wholes conductors4 #afgj4 ,that not being polar in their normal state1 they can become so by the influence of neighbouring charged particles1 the polar state being developed at the instant1 exactly as in an insulated conducting mass consisting of many particles4 #afga4 ,that the particles when polarized are in a forced state1 and tend to return to their normal or natural condition4 #afgb4 ,that being as wholes conductors1 they can readily be charged1 either bodily or polarly4 #afgc4 ,that particles which being contiguous,a are also in the line of inductive action can communicate or transfer their polar forces one to another more or less readily4 ,a ,see note to #aafd4--;,dec4 #ahch4 #afgd4 ,that those doing so less readily require the polar forces to be raised to a higher degree before this transference or communication takes place4 #afge4 ,that the ready communication of forces between contiguous particles constitutes conduction1 and the difficult communication insulation2 conductors and insulators being bodies whose particles naturally possess the property of communicating their respective forces easily or with difficulty2 having these differences just as they have differences of any other natural property4 #afgf4 ,that ordinary induction is the effect resulting from the action of matter charged with excited or free electricity upon insulating matter1 tending to produce in it an equal amount of the contrary state4 #afgg4 ,that it can do this only by polarizing the particles contiguous to it1 which perform the same office to the next1 and these again to those beyond2 and that thus the action is propagated from the excited body to the next conducting mass1 and there renders the contrary force evident in consequence of the effect of communication which supervenes in the conducting mass upon the polarization of the particles of that body 7#afge474 #afgh4 ,that therefore induction can only take place through or across insulators2 that induction is insulation1 it being the necessary consequence of the state of the particles and the mode in which the influence of electrical forces is transferred or transmitted through or across such insulating media4 #afgi4 ,the particles of an insulating dielectric whilst under induction may be compared to a series of small magnetic needles1 or more correctly still to a series of small insulated conductors4 ,if the space round a charged globe were filled with a mixture of an insulating dielectric1 as oil of turpentine or air1 and small globular conductors1 as shot1 the latter being at a little distance from each other so as to be insulated1 then these would in their condition and action exactly resemble what ,i consider to be the condition and action of the particles of the insulating dielectric itself 7#accg474 ,if the globe were charged1 these little conductors would all be polar2 if the globe were discharged1 they would all return to their normal state1 to be polarized again upon the recharging of the globe4 ,the state developed by induction through such particles on a mass of conducting mutter at a distance would be of the contrary kind1 and exactly equal in amount to the force in the inductric globe4 ,there would be a lateral diffusion of force 7#abbd4 #abig471 because each polarized sphere would be in an active or tense relation to all those contiguous to it1 just as one magnet can affect two or more magnetic needles near it1 and these again a still greater number beyond them4 ,hence would result the production of curved lines of inductive force if the inducteous body in such a mixed dielectric were an uninsulated metallic ball 7#abai4 c47 or other properly shaped mass4 ,such curved lines are the consequences of the two electric forces arranged as ,i have assumed them to be3 and1 that the inductive force can be directed in such curved lines is the strongest proof of the presence of the two powers and the polar condition of the dielectric particles4 #afhj4 ,i think it is evident1 that in the case stated1 action at a distance can only result through an action of the contiguous conducting particles4 ,there is no reason why the inductive body should polarize or affect distant conductors and leave those near it1 namely the particles of the dielectric1 unaffected3 and everything in the form of fact and experiment with conducting masses or particles of a sensible size contradicts such a supposition4 #afha4 ,a striking character of the electric power is that it is limited and exclusive1 and that the two forces being always present are exactly equal in amount4 ,the forces are related in one of two ways1 either as in the natural normal condition of an uncharged insulated conductor2 or as in the charged state1 the latter being a case of induction4 #afhb4 ,cases of induction are easily arranged so that the two forces being limited in their direction shall present no phenomena or indications external to the apparatus employed1 ,thus1 if a ,leyden jar1 having its external coating a little higher than the internal1 be charged and then its charging ball and rod removed1 such jar will present no electrical appearances so long as its outside is uninsulated4 ,the two forces which may be said to be in the coatings1 or in the particles of the dielectric contiguous to them1 are entirely engaged to each other by induction through the glass2 and a carrier ball 7#aaha47 applied either to the inside or outside of the jar will show no signs of electricity4 ,but if the jar be insulated1 and the charging ball and rod1 in an uncharged state and suspended by an insulating thread of white silk1 be restored to their place1 then the part projecting above the jar will give electrical indications and charge the carrier1 and at the same time the outside coating of the jar will be found in the opposite state and inductric towards external surrounding objects4 #afhc4 ,these are simple consequences of the theory4 ,whilst the charge of the inner coating could induce only through the glass towards the outer coating1 and the latter contained no more of the contrary force than was equivalent to it1 no induction external to the jar could be perceived2 but when the inner coating was extended by the rod and ball so that it could induce through the air towards external objects1 then the tension of the polarized glass molecules would1 by their tendency to return to the normal state1 fall a little1 and a portion of the charge passing to the surface of this new part of the inner conductor1 would produce inductive action through the air towards distant objects1 whilst at the same time a part of the force in the outer coating previously directed inwards would now be at liberty1 and indeed be constrained to induct outwards through the air1 producing in that outer coating what is sometimes called1 though ,i think very improperly1 free charge4 ,if a small ,leyden jar be converted into that form of apparatus usually known by the name of the electric well1 it will illustrate this action very completely4 #afhd4 ,the terms free charge and dissimulated electricity convey therefore erroneous notions if they are meant to imply any difference as to the mode or kind of action4 ,the charge upon an insulated conductor in the middle of a room is in the same relation to the walls of that room as the charge upon the inner coating of a ,leyden jar is to the outer coating of the same jar4 ,the one is not more free or more dissimulated than the other2 and when sometimes we make electricity appear where it was not evident before1 as upon the outside of a charged jar1 when1 after insulating it1 we touch the inner coating1 it is only because we divert more or less of the inductive force from one direction into another2 for not the slightest change is in such circumstances impressed upon the character or action of the force4 99 99 99 99 99 #afhe4 ,having given this general theoretical view1 ,i will now notice particular points relating to the nature of the assumed electric polarity of the insulating dielectric particles4 #afhf4 ,the polar state may be considered in common induction as a forced state1 the particles tending to return to their normal condition4 ,it may probably be raised to a very high degree by approximation of the inductric and inducteous bodies or by other circumstances2 and the phenomena of electrolyzation 7#hfa4 #afeb4 #agif47 seem to imply that the quantity of power which can thus be accumulated on a single particle is enormous4 ,hereafter we may be able to compare corpuscular forces1 as those of gravity1 cohesion1 electricity1 and chemical affinity1 and in some way or other from their effects deduce their relative equivalents2 at present we are not able to do so1 but there seems no reason to doubt that their electrical1 which are at the same time their chemical forces 7#hia4 #iah471 will be by far the most energetic4 #afhg4 ,i do not consider the powers when developed by the polarization as limited to two distinct points or spots on the surface of each particle to be considered as the poles of an axis1 but as resident on large portions of that surface1 as they are upon the surface of a conductor of sensible size when it is thrown into a polar state4 ,but it is very probable1 notwithstanding1 that the particles of different bodies may present specific differences in this respect1 the powers not being equally diffused though equal in quantity2 other circumstances also1 as form and quality1 giving to each a peculiar polar relation4 ,it is perhaps to the existence of some such differences as these that we may attribute the specific actions of the different dielectrics in relation to discharge7#acid4 #aejh474 ,thus with respect to oxygen and nitrogen singular contrasts were presented when spark and brush discharge were made to take place in these gases1 as may be seen by reference to the ,table in paragraph #aeah of the ,thirteenth ,series2 for with nitrogen1 when the small1 negative or the large positive ball was rendered inductric1 the effects corresponded with those which in oxygen were produced when the small positive or the large negative ball was rendered inductric4 #afhh4 ,in such solid bodies as glass1 lac1 sulphur1 c41 the particles appear to be able to become polarized in all directions1 for a mass when experimented upon so as to ascertain its inductive capacity in three or more directions 7#afij471 gives no indication of a difference4 ,now as the particles are fixed in the mass1 and as the direction of the induction through them must change with its change relative to the mass1 the constant effect indicates that they can be polarized electrically in any direction4 ,this accords with the view already taken of each particle as a whole being a conductor 7#affi471 and1 as an experimental fact1 helps to confirm that view4 #afhi4 ,but though particles may thus be polarized in any direction under the influence of powers which are probably of extreme energy 7#afhf471 it does not follow that each particle may not tend to polarize to a greater degree1 or with more facility1 in one direction than another2 or that different kinds may not have specific differences in this respect1 as they have differences of conducting and other powers 7#abif4 #acbf4 #acie474 ,i sought with great anxiety for a relation of this nature2 and selecting crystalline bodies as those in which all the particles are symmetrically placed1 and therefore best fitted to indicate any result which might depend upon variation of the direction of the forces to the direction of the particles in which they were developed1 experimented very carefully with them4 ,i was the more strongly stimulated to this inquiry by the beautiful electrical condition of the crystalline bodies tourmaline and boracite1 and hoped also to discover a relation between electric polarity and that of crystallization1 or even of cohesion itself 7#acaf474 ,my experiments have not established any connexion of the kind sought for4 ,but as ,i think it of equal importance to show either that there is or is not such a relation1 ,i shall briefly describe the results4 #afij4 ,the form of experiment was as follows4 ,a brass ball #j4gc of an inch in diameter1 fixed at the end of a horizontal brass rod1 and that at the end of a brass cylinder1 was by means of the latter connected with a large ,leyden battery 7#bia47 by perfect metallic communications1 the object being to keep that ball1 by its connexion with the charged battery in an electrified state1 very nearly uniform1 for half an hour at a time4 ,this was the inductric ball4 ,the inducteous ball was the carrier of the torsion electrometer 7#abbi4 #acad472 and the dielectric between them was a cube cut from a crystal1 so that two of its faces should be perpendicular to the optical axis1 whilst the other four were parallel to it4 ,a small projecting piece of shell-lac was fixed on the inductric ball at that part opposite to the attachment of the brass rod1 for the purpose of preventing actual contact between the ball and the crystal cube4 ,a coat of shell-lac was also attached to that side of the carrier ball which was to be towards the cube1 being also that side which was furthest from the repelled ball in the electrometer when placed in its position in that instrument4 ,the cube was covered with a thin coat of shell-lac dissolved in alcohol1 to prevent the deposition of damp upon its surface from the air4 ,it was supported upon a small table of shell-lac fixed on the top of a stem of the same substance1 the latter being of sufficient strength to sustain the cube1 and yet flexible enough from its length to act as a spring1 and allow the cube to bear1 when in its place1 against the shell-lac on the inductric ball4 ,illustration3 #afia4 ,thus it was easy to bring the inducteous ball always to the same distance from the inductric bull1 and to uninsulate and insulate it again in its place2 and then1 after measuring the force in the electrometer 7#aaha471 to return it to its place opposite to the inductric ball for a second observation4 ,or it was easy by revolving the stand which supported the cube to bring four of its faces in succession towards the inductric ball1 and so observe the force when the lines of inductive action 7#acjd47 coincided with1 or were transverse to1 the direction of the optical axis of the crystal4 ,generally from twenty to twenty-eight observations were made in succession upon the four vertical faces of a cube1 and then an average expression of the inductive force was obtained1 and compared with similar averages obtained at other times1 every precaution being taken to secure accurate results4 #afib4 ,the first cube used was of rock crystal2 it was #j4g of an inch in the side4 ,it presented a remarkable and constant difference1 the average of not less than #aig observations1 giving #ajj for the specific inductive capacity in the direction coinciding with the optical axis of the cube1 whilst #ic4ei and #ic4ca were the expressions for the two transverse directions4 #afic4 ,but with a second cube of rock crystal corresponding results were not obtained4 ,it was #j4gg of an inch in the side4 ,the average of many experiments gave #ajj for the specific inductive capacity coinciding with the direction of the optical axis1 and #ih4f and #ii4ib for the two other directions4 #afid4 ,lord ,ashley1 whom ,i have found ever ready to advance the cause of science1 obtained for me the loan of three globes of rock crystal belonging to ,her ,grace the ,duchess of ,sutherland for the purposes of this investigation4 ,two had such fissures as to render them unfit for the experiments 7#aaic4 #afih474 ,the third1 which was very superior1 gave me no indications of any difference in the inductive force for different directions4 #afie4 ,i then used cubes of ,iceland spar4 ,one #j4e of an inch in diameter gave #ajj for the axial direction1 and #ih4ff and #ie4gd for the two cross directions4 ,the other1 #j4h of an inch in the side1 gave #ajj for the axial direction1 whilst #aja4gc and #aja4hf were the numbers for the cross direction4 #afif4 ,besides these differences there were others1 which ,i do not think it needful to state1 since the main point is not confirmed4 ,for though the experiments with the first cube raised great expectation1 they have not been generalized by those which followed4 ,i have no doubt of the results as to that cube1 but they cannot as yet be referred to crystallization4 ,there are in the cube some faintly coloured layers parallel to the optical axis1 and the matter which colours them may have an influence2 but then the layers are also nearly parallel to a cross direction1 and if at all influential should show some effect in that direction also1 which they did not4 #afig4 ,in some of the experiments one half or one part of a cube showed a superiority to another part1 and this ,i could not trace to any charge the different parts had received4 ,it was found that the varnishing of the cubes prevented any communication of charge to them1 except 7in a few experiments7 a small degree of the negative state1 or that which was contrary to the state of the inductric ball 7#aefd4 #aeff474 #afih4 ,i think it right to say that1 as far as ,i could perceive1 the insulating character of the cubes used was perfect1 or at least so nearly perfect1 as to bear a comparison with shell-lac1 glass1 c4 7#abee74 ,as to the cause of the differences1 other than regular crystalline structure1 there may be several4 ,thus minute fissures in the crystal insensible to the eye may be so disposed as to produce a sensible electrical difference 7#aaic474 ,or the crystallization may be irregular2 or the substance may not be quite pure2 and if we consider how minute a quantity of matter will alter greatly the conducting power of water1 it will seem not unlikely that a little extraneous matter diffused through the whole or part of a cube1 may produce effects sufficient to account for all the irregularities of action that have been observed4 #afii4 ,an important inquiry regarding the electrical polarity of the particles of an insulating dielectric1 is1 whether it be the molecules of the particular substance acted on1 or the component or ultimate particles1 which thus act the part of insulated conducting polarizing portions 7#affi474 #agjj4 ,the conclusion ,i have arrived at is1 that it is the molecules of the substance which polarize as wholes 7#acdg472 and that however complicated the composition of a body may be1 all those particles or atoms which are held together by chemical affinity to form one molecule of the resulting body act as one conducting mass or particle when inductive phenomena and polarization are produced in the substance of which it is a part4 #agja4 ,this conclusion is founded on several considerations4 ,thus if we observe the insulating and conducting power of elements when they are used as dielectrics1 we find some1 as sulphur1 phosphorus1 chlorine1 iodine1 c41 whose particles insulate1 and therefore polarize in a high degree2 whereas others1 as the metals1 give scarcely any indication of possessing a sensible proportion of this power 7#acbh471 their particles freely conducting one to another4 ,yet when these enter into combination they form substances having no direct relation apparently1 in this respect1 to their elements2 for water1 sulphuric acid1 and such compounds formed of insulating elements1 conduct by comparison freely2 whilst oxide of lead1 flint glass1 borate of lead1 and other metallic compounds containing very high proportions of conducting matter1 insulate excellently well4 ,taking oxide of lead therefore as the illustration1 ,i conceive that it is not the particles of oxygen and lead which polarize separately under the act of induction1 but the molecules of oxide of lead which exhibit this effect1 all the elements of one particle of the resulting body1 being held together as parts of one conducting individual by the bonds of chemical affinity2 which is but another term for electrical force 7#iah474 #agjb4 ,in bodies which are electrolytes we have still further reason for believing in such a state of things4 ,thus when water1 chloride of tin1 iodide of lead1 c4 in the solid state are between the electrodes of the voltaic battery1 their particles polarize as those of any other insulating dielectric do 7#aafd472 but when the liquid state is conferred on these substances1 the polarized particles divide1 the two halves1 each in a highly charged state1 travelling onwards until they meet other particles in an opposite and equally charged state1 with which they combine1 to the neutralization of their chemical1 i4e4 their electrical forces1 and the reproduction of compound particles1 which can again polarize as wholes1 and again divide to repeat the same series of actions 7#acdg474 #agjc4 ,but though electrolytic particles polarize as wholes1 it would appear very evident that in them it is not a matter of entire indifference how the particle polarizes 7#afhi471 since1 when free to move 7#chj1 c47 the polarities are ultimately distributed in reference to the elements2 and sums of force equivalent to the polarities1 and very definite in kind and amount1 separate1 as it were1 from each other1 and travel onwards with the elementary particles4 ,and though ,i do not pretend to know what an atom is1 or how it is associated or endowed with electrical force1 or how this force is arranged in the cases of combination and decomposition1 yet the strong belief ,i have in the electrical polarity of particles when under inductive action1 and the hearing of such an opinion on the general effects of induction1 whether ordinary or electrolytic1 will be my excuse1 ,i trust1 for a few hypothetical considerations4 #agjd ,in electrolyzation it appears that the polarized particles would 7because of the gradual change which has been induced upon the chemical1 i4e4 the electrical forces of their elements 7#iah477 rather divide than discharge to each other without division 7#acdh472 for if their division1 i4e4 their decomposition and recombination1 be prevented by giving them the solid state1 then they will insulate electricity perhaps a hundredfold more intense than that necessary for their electrolyzation 7#dai1 c474 ,hence the tension necessary for direct conduction in such bodies appears to be much higher than that for decomposition 7#dai4 #aafd4 #acdd474 #agje4 ,the remarkable stoppage of electrolytic conduction by solidification 7#chj4 #aceh471 is quite consistent with these views of the dependence of that process on the polarity which is common to all insulating matter when under induction1 though attended by such peculiar electro-chemical results in the case of electrolytes4 ,thus it may be expected that the first effect of induction is so to polarize and arrange the particles of water that the positive or hydrogen pole of each shall be from the positive electrode and towards the negative electrode1 whilst the negative or oxygen pole of each shall be in the contrary direction2 and thus when the oxygen and hydrogen of a particle of water have separated1 passing to and combining with other hydrogen and oxygen particles1 unless these new particles of water could turn round they could not take up that position necessary for their successful electrolytic polarization4 ,now solidification1 by fixing the water particles and preventing them from assuming that essential preliminary position1 prevents also their electrolysis 7#dac472 and so the transfer of forces in that manner being prevented 7#acdg4 #agjc471 the substance acts as an ordinary insulating dielectric 7for it is evident by former experiments 7#dai4 #agjd47 that the insulating tension is higher than the electrolytic tension71 induction through it rises to a higher degree1 and the polar condition of the molecules as wholes1 though greatly exalted1 is still securely maintained4 #agjf4 ,when decomposition happens in a fluid electrolyte1 ,i do not suppose that all the molecules in the same sectional plane 7#afcd47 part with and transfer their electrified particles or elements at once4 ,probably the discharge force for that plane is summed up on one or a few particles1 which decomposing1 travelling and recombining1 restore the balance of forces1 much as in the case of spark disruptive discharge 7#adjf472 for as those molecules resulting from particles which have just transferred power must by their position 7#agje47 be less favourably circumstanced than others1 so there must be some which are most favourably disposed1 and these1 by giving way first1 will for the time lower the tension and produce discharge4 #agjg4 ,in former investigations of the action of electricity 7#hba1 c47 it was shown1 from many satisfactory cases1 that the quantity of electric power transferred onwards was in proportion to and was definite for a given quantity of matter moving as anion or cathion onwards in the electrolytic line of action2 and there was strong reason to believe that each of the particles of matter then dealt with1 had associated with it a definite amount of electrical force1 constituting its force of chemical affinity1 the chemical equivalents and the electro-chemical equivalents being the same 7#hcf474 ,it was also found with few1 and ,i may now perhaps say with no exceptions 7#acda471 that only those compounds containing elements in single proportions could exhibit the characters and phenomena of electrolytes 7#fig472 oxides1 chlorides1 and other bodies containing more than one proportion of the electro-negative element refusing to decompose under the influence of the electric current4 #agjh4 ,probable reasons for these conditions and limitations arise out of the molecular theory of induction4 ,thus when a liquid dielectric1 as chloride of tin1 consists of molecules1 each composed of a single particle of each of the elements1 then as these can convey equivalent opposite forces by their separation in opposite directions1 both decomposition and transfer can result4 ,but when the molecules1 as in the bichloride of tin1 consist of one particle or atom of one element1 and two of the other1 then the simplicity with which the particles may be supposed to be arranged and to act1 is destroyed4 ,and1 though it may be conceived that when the molecules of bichloride of tin are polarized as wholes by the induction across them1 the positive polar force might accumulate on the one particle of tin whilst the negative polar force accumulated on the two particles of chlorine associated with it1 and that these might respectively travel right and left to unite with other two of chlorine and one of tin1 in analogy with what happens in cases of compounds consisting of single proportions1 yet this is not altogether so evident or probable4 ,for when a particle of tin combines with two of chlorine1 it is difficult to conceive that there should not be some relation of the three in the resulting molecule analogous to fixed position1 the one particle of metal being perhaps symmetrically placed in relation to the two of chlorine3 and1 it is not difficult to conceive of such particles that they could not assume that position dependent both on their polarity and the relation of their elements1 which appears to be the first step in the process of electrolyzation 7#acde4 #agje474 #ba4 ,relation of the electric and magnetic forces4 #agji4 ,i have already ventured a few speculations respecting the probable relation of magnetism1 as the transverse force of the current1 to the divergent or transverse force of the lines of inductive action belonging to static electricity 7#afeh1 c474 #agaj4 ,in the further consideration of this subject it appeared to me to be of the utmost importance to ascertain1 if possible1 whether this lateral action which we call magnetism1 or sometimes the induction of electrical currents 7#bf4 #ajdh1 c471 is extended to a distance by the action of the intermediate particles in analogy with the induction of static electricity1 or the various effects1 such as conduction1 discharge1 c41 which are dependent on that induction2 or1 whether its influence at a distance is altogether independent of such intermediate particles 7#affb474 #agaa4 ,i arranged two magneto-electric helices with iron cores end to end1 but with an interval of an inch and three quarters between them1 in which interval was placed the end or pole of a bar magnet4 ,it is evident1 that on moving the magnetic pole from one core towards the other1 a current would tend to form in both helices1 in the one because of the lowering1 and in the other because of the strengthening of the magnetism induced in the respective soft iron cores4 ,the helices were connected together1 and also with a galvanometer1 so that these two currents should coincide in direction1 and tend by their joint force to deflect the needle of the instrument4 ,the whole arrangement was so effective and delicate1 that moving the magnetic pole about the eighth of an inch to and fro two or three times1 in periods equal to those required for the vibrations of the galvanometer needle1 was sufficient to cause considerable vibration in the latter2 thus showing readily the consequence of strengthening the influence of the magnet on the one core and helix1 and diminishing it on the other4 #agab4 ,then without disturbing the distances of the magnet and cores1 plates of substances were interposed4 ,thus calling the two cores ,a and ,b1 a plate of shell-lac was introduced between the magnetic pole and ,a for the time occupied by the needle in swinging one way2 then it was withdrawn for the time occupied in the return swing2 introduced again for another equal portion of time2 withdrawn for another portion1 and so on eight or nine times2 but not the least effect was observed on the needle4 ,in other cases the plate was alternated1 i4e4 it was introduced between the magnet and ,a for one period of time1 withdrawn and introduced between the magnet and ,b for the second period1 withdrawn and restored to its first place for the third period1 and so on1 but with no effect on the needle4 #agac4 ,in these experiments shell-lac in plates #j4i of an inch in thickness1 sulphur in a plate #j4i of an inch in thickness1 and copper in a plate #j4g of an inch in thickness were used without any effect4 ,and ,i conclude that bodies1 contrasted by the extremes of conducting and insulating power1 and opposed to each other as strongly as metals1 air1 and sulphur1 show no difference with respect to magnetic forces when placed in their lines of action1 at least under the circumstances described4 #agad4 ,with a plate of iron1 or even a small piece of that metal1 as the head of a nail1 a very different effect was produced1 for then the galvanometer immediately showed its sensibility1 and the perfection of the general arrangement4 #agae4 ,i arranged matters so that a plate of copper #j4b of an inch in thickness1 and ten inches in diameter1 should have the part near the edge interposed between the magnet and the core1 in which situation it was first rotated rapidly1 and then held quiescent alternately1 for periods according with that required for the swinging of the needle2 but not the least effect upon the galvanometer was produced4 #agaf4 ,a plate of shell-lac #j4f of an inch in thickness was applied in the same manner1 but whether rotating or not it produced no effect4 #agag4 ,occasionally the plane of rotation was directly across the magnetic curve3 at other times it was made as oblique as possible2 the direction of the rotation being also changed in different experiments1 but not the least effect was produced4 #agah4 ,i now removed the helices with their soft iron cores1 and replaced them by two flat helices wound upon card board1 each containing forty-two feet of silked copper wire1 and having no associated iron4 ,otherwise the arrangement was as before1 and exceedingly sensible2 for a very slight motion of the magnet between the helices produced an abundant vibration of the galvanometer needle4 #agai4 ,the introduction of plates of shell-lac1 sulphur1 or copper into the intervals between the magnet and these helices 7#agac471 produced not the least effect1 whether the former were quiescent or in rapid revolution 7#agae474 ,so here no evidence of the influence of the intermediate particles could be obtained 7#agaj474 #agbj4 ,the magnet was then removed and replaced by a flat helix1 corresponding to the two former1 the three being parallel to each other4 ,the middle helix was so arranged that a voltaic current could be sent through it at pleasure4 ,the former galvanometer was removed1 and one with a double coil employed1 one of the lateral helices being connected with one coil1 and the other helix with the other coil1 in such manner that when a voltaic current was sent through the middle helix its inductive action 7#bf47 on the lateral helices should cause currents in them1 having contrary directions in the coils of the galvanometer4 ,by a little adjustment of the distances these induced currents were rendered exactly equal1 and the galvanometer needle remained stationary notwithstanding their frequent production in the instrument4 ,i will call the middle coil ,c1 and the external coils ,a and ,b4 #agba4 ,a plate of copper #j4g of an inch thick and six inches square1 was placed between coils ,c and ,b1 their respective distances remaining unchanged2 and then a voltaic current from twenty pairs of #d inch plates was sent through the coil ,c1 and intermitted1 in periods fitted to produce an effect on the galvanometer 7#agab474 if any difference had been produced in the effect of ,c on ,a and ,b4 ,but notwithstanding the presence of air in one interval and copper in the other1 the inductive effect was exactly alike on the two coils1 and as if air had occupied both intervals4 ,so that notwithstanding the facility with which any induced currents might form in the thick copper plate1 the coil outside of it was just as much affected by the central helix ,c as if no such conductor as the copper had been there 7#fe474 #agbb4 ,then1 for the copper plate was substituted one of sulphur #j4i of an inch thick2 still the results were exactly the same1 i4e4 there was no action at the galvanometer4 #agbc4 ,thus it appears that when a voltaic current in one wire is exerting its inductive action to produce a contrary or a similar current in a neighbouring wire1 according as the primary current is commencing or ceasing1 it makes not the least difference whether the intervening space is occupied by such insulating bodies as air1 sulphur and shell-lac1 or such conducting bodies as copper1 and the other non-magnetic metals4 #agbd4 ,a correspondent effect was obtained with the like forces when resident in a magnet thus4 ,a single flat helix 7#agah47 was connected with a galvanometer1 and a magnetic pole placed near to it2 then by moving the magnet to and from the helix1 or the helix to and from the magnet1 currents were produced indicated by the galvanometer4 #agbe4 ,the thick copper plate 7#agba47 was afterwards interposed between the magnetic pole and the helix2 nevertheless on moving these to and fro1 effects1 exactly the same in direction and amount1 were obtained as if the copper had not been there4 ,so also on introducing a plate of sulphur into the interval1 not the least influence on the currents produced by motion of the magnet or coils could be obtained4 #agbf4 ,these results1 with many others which ,i have not thought it needful to describe1 would lead to the conclusion that 7judging by the amount of effect produced at a distance by forces transverse to the electric current1 i4e4 magnetic forces17 the intervening matter1 and therefore the intervening particles1 have nothing to do with the phenomena2 or in other words1 that though the inductive force of static electricity is transmitted to a distance by the action of the intermediate particles 7#aafd4 #afff471 the transverse inductive force of currents1 which can also act at a distance1 is not transmitted by the intermediate particles in a similar way4 #agbg4 ,it is however very evident that such a conclusion cannot be considered as proved4 ,thus when the metal copper is between the pole and the helix 7#agae4 #agai4 #agbe47 or between the two helices 7#agba47 we know that its particles are affected1 and can by proper arrangements make their peculiar state for the time very evident by the production of either electrical or magnetical effects4 ,it seems impossible to consider this effect on the particles of the intervening matter as independent of that produced by the inductric coil or magnet ,c1 on the inducteous coil or core ,a 7#agae4 #agba472 for since the inducteous body is equally affected by the inductric body whether these intervening and affected particles of copper are present or not 7#agbc4 #agbe471 such a supposition would imply that the particles so affected had no reaction back on the original inductric forces4 ,the more reasonable conclusion1 as it appears to me1 is1 to consider these affected particles as efficient in continuing the action onwards from the inductric to the inducteous body1 and by this very communication producing the effect of no loss of induced power at the latter4 #agbh4 ,but then it may be asked what is the relation of the particles of insulating bodies1 such as air1 sulphur1 or lac1 when they intervene in the line of magnetic action8 ,the answer to this is at present merely conjectural4 ,i have long thought there must be a particular condition of such bodies corresponding to the state which causes currents in metals and other conductors 7#bf4 #ec4 #aia4 #bja4 #bac472 and considering that the bodies are insulators one would expect that state to be one of tension4 ,i have by rotating non-conducting bodies near magnetic poles and poles near them1 and also by causing powerful electric currents to be suddenly formed and to cease around and about insulators in various directions1 endeavoured to make some such state sensible1 but have not succeeded4 ,nevertheless1 as any such state must be of exceedingly low intensity1 because of the feeble intensity of the currents which are used to induce it1 it may well be that the state may exist1 and may be discoverable by some more expert experimentalist1 though ,i have not been able to make it sensible4 #agbi4 ,it appears to me possible1 therefore1 and even probable1 that magnetic action may be communicated to a distance by the action of the intervening particles1 in a manner having a relation to the way in which the inductive forces of static electricity are transferred to a distance 7#afgg472 the intervening particles assuming for the time more or less of a peculiar condition1 which 7though with a very imperfect idea7 ,i have several times expressed by the term electro-tonic state 7#fj4 #bdb4 #aaad4 #affa474 ,i hope it will not be understood that ,i hold the settled opinion that such is the case4 ,i would rather in fact have proved the contrary1 namely1 that magnetic forces are quite independent of the matter intervening between the inductric and the inductions bodies2 but ,i cannot get over the difficulty presented by such substances as copper1 silver1 lead1 gold1 carbon1 and even aqueous solutions 7#bja4 #bac471 which though they are known to assume a peculiar state whilst intervening between the bodies acting and acted upon 7#agbg471 no more interfere with the final result than those which have as yet had no peculiarity of condition discovered in them4 #agcj4 ,a remark important to the whole of this investigation ought to be made here4 ,although ,i think the galvanometer used as ,i have described it 7#agaa4 #agbj47 is quite sufficient to prove that the final amount of action on each of the two coils or the two cores ,a and ,b 7#agac4 #agai47 is equal1 yet there is an effect which may be consequent on the difference of action of two interposed bodies which it would not show4 ,as time enters as an element into these actions,a 7#abe471 it is very possible that the induced actions on the helices or cores ,a1 ,b1 though they rise to the same degree when air and copper1 or air and lac are contrasted as intervening substances1 do not do so in the same time2 and yet1 because of the length of time occupied by a vibration of the needle1 this difference may not be visible1 both effects rising to their maximum in periods so short as to make no sensible portion of that required for a vibration of the needle1 and so exert no visible influence upon it4 ,a ,see ,annnles de ,chimie1 #ahcc1 tom4 li4 pp4 #dbb1 #dbh4 99 99 99 99 99 #agca4 ,if the lateral or transverse force of electrical currents1 or what appears to be the same thing1 magnetic power1 could be proved to be influential at a distance independently of the intervening contiguous particles1 then1 as it appears to me1 a real distinction of a high and important kind1 would be established between the natures of these two forces 7#afed4 #affd474 ,i do not mean that the powers are independent of each other and might be rendered separately active1 on the contrary they are probably essentially associated 7#afed471 but it by no means follows that they are of the same nature4 ,in common statical induction1 in conduction1 and in electrolyzation1 the forces at the opposite extremities of the particles which coincide with the lines of action and have commonly been distinguished by the term electric1 are polar1 and in the cases of contiguous particles act only to insensible distances2 whilst those which are transverse to the direction of these lines1 and are called magnetic1 are circumferential1 act at a distance1 and if not through the mediation of the intervening particles1 have their relations to ordinary matter entirely unlike those of the electrical forces with which they are associated4 #agcb4 ,to decide this question of the identity or distinction of the two kinds of power1 and establish their true relation1 would be exceedingly important4 ,the question seems fully within the reach of experiment1 and offers a high reward to him who will attempt its settlement4 #agcc4 ,i have already expressed a hope of finding an effect or condition which shall be to statical electricity what magnetic force is to current electricity 7#afeh474 ,if ,i could have proved to my own satisfaction that magnetic forces extended their influence to a distance by the conjoined action of the intervening particles in a manner analogous to that of electrical forces1 then ,i should have thought that the natural tension of the lines of inductive action 7#afei471 or that state so often hinted at as the electro-tonic state 7#affa4 #affb471 was this related condition of statical electricity4 #agcd4 ,it may be said that the state of no lateral action is to static or inductive force the equivalent of magnetism to current force2 but that can only be upon the view that electric and magnetic action are in their nature essentially different 7#affd474 ,if they are the same power1 the whole difference in the results being the consequence of the difference of direction1 then the normal or undeveloped state of electric force will correspond with the state of no lateral action of the magnetic state of the force2 the electric current will correspond with the lateral effects commonly called magnetism2 but the state of static induction which is between the normal condition and the current will still require a corresponding lateral condition in the magnetic series1 presenting its own peculiar phenomena2 for it can hardly be supposed that the normal electric1 and the inductive or polarized electric1 condition1 can both have the same lateral relation4 ,if magnetism be a separate and a higher relation of the powers developed1 then perhaps the argument which presses for this third condition of that force would not be so strong4 #agce4 ,i cannot conclude these general remarks upon the relation of the electric and magnetic forces without expressing my surprise at the results obtained with the copper plate 7#agbd4 #agbe474 ,the experiments with the flat helices represent one of the simplest cases of the induction of electrical currents 7#agbj472 the effect1 as is well known1 consisting in the production of a momentary current in a wire at the instant when a current in the contrary direction begins to pass through a neighbouring parallel wire1 and the production of an equally brief current in the reverse direction when the determining current is stopped 7#bf474 ,such being the case1 it seems very extraordinary that this induced current which takes place in the helix ,a when there is only air between ,a and ,c 7#agbj474 should be equally strong when that air is replaced by an enormous mass of that excellently conducting metal copper 7#agba474 ,it might have been supposed that this mass would have allowed of the formation and discharge of almost any quantity of currents in it1 which the helix ,c was competent to induce1 and so in some degree have diminished if not altogether prevented the effect in ,a3 instead of which1 though we can hardly doubt that an infinity of currents are formed at the moment in the copper plate1 still not the smallest diminution or alteration of the effect in ,a appears 7#fe474 ,almost the only way of reconciling this effect with generally received notions is1 as it appears to me1 to admit that magnetic action is communicated by the action of the intervening particles 7#agbi4 #agcc474 #agcf4 ,this condition of things1 which is very remarkable1 accords perfectly with the effects observed in solid helices where wires are coiled over wires to the amount of five or six or more layers in succession1 no diminution of effect on the outer ones being occasioned by those within4 #bb4 ,note on electrical excitation4 #agcg4 ,that the different modes in which electrical excitement takes place will some day or other be reduced under one common law can hardly be doubted1 though for the present we are bound to admit distinctions4 ,it will be a great point gained when these distinctions are1 not removed1 but understood4 #agch4 ,the strict relation of the electrical and chemical powers renders the chemical mode of excitement the most instructive of all1 and the case of two isolated combining particles is probably the simplest that we possess4 ,here however the action is local1 and we still want such a test of electricity as shall apply to it1 to cases of current electricity1 and also to those of static induction4 ,whenever by virtue of the previously combined condition of some of the acting particles 7#ibc47 we are enabled1 as in the voltaic pile1 to expand or convert the local action into a current1 then chemical action can be traced through its variations to the production of all the phenomena of tension and the static state1 these being in every respect the same as if the electric forces producing them had been developed by friction4 #agci4 ,it was ,berzelius1 ,i believe1 who first spoke of the aptness of certain particles to assume opposite states when in presence of each other 7#iei474 ,hypothetically we may suppose these states to increase in intensity by increased approximation1 or by heat1 c4 until at a certain point combination occurs1 accompanied by such an arrangement of the forces of the two particles between themselves as is equivalent to a discharge1 producing at the same time a particle which is throughout a conductor 7#agjj474 #agdj4 ,this aptness to assume an excited electrical state 7which is probably polar in those forming non-conducting matter7 appears to be a primary fact1 and to partake of the nature of induction 7#aafb471 for the particles do not seem capable of retaining their particular state independently of each other 7#aagg47 or of matter in the opposite state4 ,what appears to be definite about the particles of matter is their assumption of a particular state1 as the positive or negative1 in relation to each other1 and not of either one or other indifferently2 and also the acquirement of force up to a certain amount4 #agda4 ,it is easily conceivable that the same force which causes local action between two free particles shall produce current force if one of the particles is previously in combination1 forming part of an electrolyte 7#ibc4 #agch474 ,thus a particle of zinc1 and one of oxygen1 when in presence of each other1 exert their inductive forces 7#agdj471 and these at last rise up to the point of combination4 ,if the oxygen be previously in union with hydrogen1 it is held so combined by an analogous exertion and arrangement of the forces2 and as the forces of the oxygen and hydrogen are for the time of combination mutually engaged and related1 so when the superior relation of the forces between the oxygen and zinc come into play1 the induction of the former or oxygen towards the metal cannot be brought on and increased without a corresponding deficiency in its induction towards the hydrogen with which it is in combination 7for the amount of force in a particle is considered as definite71 and the latter therefore has its force turned towards the oxygen of the next particle of water2 thus the effect may be considered as extended to sensible distances1 and thrown into the condition of static induction1 which being discharged and then removed by the action of other particles produces currents4 #agdb4 ,in the common voltaic battery1 the current is occasioned by the tendency of the zinc to take the oxygen of the water from the hydrogen1 the effective action being at the place where the oxygen leaves the previously existing electrolyte4 ,but ,schoenbein has arranged a battery in which the effective action is at the other extremity of this essential part of the arrangement1 namely1 where oxygen goes to the electrolyte,a4 ,the first may be considered as a case where the current is put into motion by the abstraction of oxygen from hydrogen1 the latter by that of hydrogen from oxygen4 ,the direction of the electric current is in both cases the same1 when referred to the direction in which the elementary particles of the electrolyte are moving 7#ibc4 #ifb471 and both are equally in accordance with the hypothetical view of the inductive action of the particles just described 7#agdj474 ,a ,philosophical ,magazine1 #ahch1 xii4 #bbe1 #cae4 also ,de la ,rive's results with peroxide of manganese4 ,annales de ,chimie1 #ahcf1 lxi4 p4 #dj4--;,dec4 #ahch4 #agdc4 ,in such a view of voltaic excitement1 the action of the particles may be divided into two parts1 that which occurs whilst the force in a particle of oxygen is rising towards a particle of zinc acting on it1 and falling towards the particle of hydrogen with which it is associated 7this being the progressive period of the inductive action71 and that which occurs when the change of association takes place1 and the particle of oxygen leaves the hydrogen and combines with the zinc4 ,the former appears to be that which produces the current1 or if there be no current1 produces the state of tension at the termination of the battery2 whilst the latter1 by terminating for the time the influence of the particles which have been active1 allows of others coming into play1 and so the effect of current is continued4 #agdd4 ,it seems highly probable1 that excitement by friction may very frequently be of the same character4 ,wollaston endeavoured to refer such excitement to chemical action,a2 but if by chemical action ultimate union of the acting particles is intended1 then there are plenty of cases which are opposed to such a view4 ,davy mentions some such1 and for my own part ,i feel no difficulty in admitting other means of electrical excitement than chemical action1 especially if by chemical action is meant a final combination of the particles4 ,a ,philosophical ,transactions1 #ahja1 p4 #dbg4 #agde4 ,davy refers experimentally to the opposite states which two particles having opposite chemical relations can assume when they are brought into the close vicinity of each other1 but not allowed to combine,a4 ,this1 ,i think1 is the first part of the action already described 7#agdc472 but in my opinion it cannot give rise to a continuous current unless combination take place1 so as to allow other particles to act successively in the same manner1 and not even then unless one set of the particles be present as an element of an electrolyte 7#ibc4 #ifc472 i4e4 mere quiescent contact alone without chemical action does not in such cases produce a current4 ,a ,philosophical ,transactions1 #ahjg1 p4 #ca4 #agdf4 ,still it seems very possible that such a relation may produce a high charge1 and thus give rise to excitement by friction4 ,when two bodies are rubbed together to produce electricity in the usual way1 one at least must be an insulator4 ,during the act of rubbing1 the particles of opposite kinds must be brought more or less closely together1 the few which are most favourably circumstanced being in such close contact as to be short only of that which is consequent upon chemical combination4 ,at such moments they may acquire by their mutual induction 7#agdj47 and partial discharge to each other1 very exalted opposite states1 and when1 the moment after1 they are by the progress of the rub removed from each other's vicinity1 they will retain this state if both bodies be insulators1 and exhibit them upon their complete separation4 #agdg4 ,all the circumstances attending friction seem to me to favour such a view4 ,the irregularities of form and pressure will cause that the particles of the two rubbing surfaces will be at very variable distances1 only a few at once being in that very close relation which is probably necessary for the development of the forces2 further1 those which are nearest at one time will be further removed at another1 and others will become the nearest1 and so by continuing the friction many will in succession be excited4 ,finally1 the lateral direction of the separation in rubbing seems to me the best fitted to bring many pairs of particles1 first of all into that close vicinity necessary for their assuming the opposite states by relation to each other1 and then to remove them from each other's influence whilst they retain that state4 #agdh4 ,it would be easy1 on the same view1 to explain hypothetically1 how1 if one of the rubbing bodies be a conductor1 as the amalgam of an electrical machine1 the state of the other when it comes from under the friction is 7as a mass7 exalted2 but it would be folly to go far into such speculation before that already advanced has been confirmed or corrected by fit experimental evidence4 ,i do not wish it to be supposed that ,i think all excitement by friction is of this kind2 on the contrary1 certain experiments lead me to believe1 that in many cases1 and perhaps in all1 effects of a thermo-electric nature conduce to the ultimate effect2 and there are very probably other causes of electric disturbance influential at the same time1 which we have not as yet distinguished4 ,royal ,institution4 ,june1 #ahch4 ,,index4 99 99 99 99 99 ,n4,b4 ,a dash rule represents the italics immediately preceding it4 ,the references are sometimes to the individual paragraph1 and sometimes to that in conjunction with those which follow4 99 99 99 99 99 ,absolute charge of matter1 #aafi4 ---- quantity of electricity in matter1 #heb1 #hfa1 #hgc4 ,acetate of potassa1 its electrolysis1 #gdi4 ,acetates1 their electrolysis1 #ggd4 ,acetic acid1 its electrolysis1 #ggc4 ,acid1 nitric1 formed in air by a spark1 #cbd4 ----1 or alkali1 alike in exciting the pile1 #icb4 ----1 transference of1 #ebe4 ---- for battery1 its nature and strength1 #aabh1 #aacg4 ---- ----1 nitric1 the best1 #aach4 ---- ----1 effect of different strengths1 #aaci4 ---- in voltaic pile1 does not evolve the electricity1 #ibe1 #icc4 ---- ----1 its use1 #ibe4 ,acids and bases1 their relation in the voltaic pile1 #ibg1 #icc4 ,active battery1 general remarks on1 #ajcd1 #aacf4 ,adhesion of fluids to metals1 #ajch4 ,advantages of a new voltaic battery1 #aacb4 ,affinities1 chemical1 opposed voltaically1 #hia1 #ijd1 #iaj4 ----1 their relation in the active pile1 #idi4 ,air1 its attraction by surfaces1 #fbb4 ----1 charge of1 #aagc4 ----1 ----1 by brush1 #adcd1 #adda4 ----1 ----1 by glow1 #aecg1 #aedc4 ----1 convective currents in1 #aegb1 #aegf1 #aeha4 ----1 dark discharge in1 #aedh4 ----1 disruptive discharge in1 #acei1 #adjf1 #adbe1 #aebf4 ----1 induction in1 #abjh1 #abae1 #abhd1 #acfb4 ----1 its insulating and conducting power1 #daa1 #accb1 #accf1 #acfb4 ----1 its rarefaction facilitates discharge1 #acge4 ----1 electrified1 #addc4 ----1 electro-chemical decompositions in1 #ded1 #afbc4 ----1 hot1 discharges voltaic battery1 #bga1 #bgd4 ----1 poles of1 #dee1 #dfa1 #eei4 ----1 positive and negative brush in1 #adfg1 #adgb1 #adgf4 ----1 ---- glow in1 #aebf1 #aecj4 ----1 ---- spark in1 #adhe4 ----1 rarefied1 brush in1 #adea1 #adef4 ----1 retention of electricity on conductors by1 #acgg1 #acih4 ----1 specific inductive capacity of1 #abhd4 ----1 ----1 not varied by temperature or pressure1 #abhg1 #abhh4 ,alkali has strong exciting power in voltaic pile1 #hhd1 #ica1 #ida4 ----1 transference of1 #ebe4 ,amalgamated zinc1 its condition1 #ajjj4 ----1 how prepared1 #hfc4 ----1 its valuable use1 #hfc1 #iii4 ---- battery1 #ajja4 ,ammonia1 nature of its electrolysis1 #gdh4 ----1 solution of1 a bad conductor1 #eed1 #gdh4 ,ampre's inductive results1 #gh1 #bee1 #cgi note4 ,anions defined1 #ffe1 #hbd4 ----1 table of1 #hdg4 ---- related through the entire circuit1 #ifc4 ----1 their action in the voltaic pile1 #ibd4 ----1 their direction of transfer1 #ifb1 ,anode defined1 #ffc4 ,antimony1 its relation to magneto-electric induction1 #aci4 ----1 chloride of1 not an electrolyte1 #fij1 #gif4 ----1 oxide of1 how affected by the electric current1 #hja4 ---- supposed new protoxide1 #fic4 ---- ----1 sulphuret1 #fid4 ,animal electricity1 its general characters considered1 #cea4 ---- is identical with other electricities1 #ced1 #cfj4 ----1 its chemical force1 #cee4 ----1 enormous amount1 #cei4 ----1 evolution of heat1 #cec1 ----1 magnetic force1 #cea4 ----1 physiological effects1 #ceg4 ----1 spark1 #ceh4 ----1 tension1 #ceb4 ,apparatus1 inductive1 #aahg4 ,see ,inductive apparatus4 ,arago's magnetic phenomena1 their nature1 #ha1 #abj4 ----1 reason why no effect if no motion1 #abf1 ----1 direction of motion accounted for1 #aba4 ----1 due to induced electric currents1 #aai1 #bdh4 ----1 like electro-magnetic rotations in principle1 #aba4 ----1 not due to direct induction of magnetism1 #abh1 #ach1 #bae1 #bdc1 #bdh4 ----1 obtained with electro-magnets1 #abi4 ----1 produced by conductors only1 #acj1 #bae4 ----1 time an element in1 #abd4 ----1 ,babbage and ,hershel's results explained1 #abg4 ,arago's experiment1 ,sturgeon's form of1 #bai4 ,associated voltaic circles1 #ihi4 ,atmospheric balls of fire1 #afaa4 ----1 electricity1 its chemical action1 #ccf4 ,atomic number judged of from electrochemical equivalent1 #hea4 ,atoms of matter1 #hfi1 #agjc4 ----1 their electric power1 #hef1 #hfj4 ,attraction of particles1 its influence in ,dbereiner's phenomena1 #fai4 ,attractions1 electric1 their force1 #ajbb note4 ----1 chemic1 produce current force1 #heb1 #iah1 #idg1 #iif1 #agda4 ----1 ---- local force1 #heb1 #iba1 #idg1 #iei1 #agci4 ----1 hygrometric1 #fba4 ,aurora borealis referred to magneto-electric induction1 #aib4 ,axis of power1 the electric current on1 #eag1 #afbg1 #afdb4 ,balls of fire1 atmospheric1 #afaa4 ,barlow's revolving globe1 magnetic effects explained1 #acg1 #afj4 ,barry1 decomposed bodies by atmospheric electricity1 #cch4 ,bases and acids1 their relation in the pile1 #ibg4 ,battery1 ,leyden1 that generally used1 #bia4 ,battery1 voltaic1 its nature1 #hef1 #ihi4 ----1 origin of its power1 #hgh1 #ihi4 ----1 ---- not in contact1 #hhg1 #iae1 ----1 ---- chemical1 #hgi1 #iaf1 #iai1 #agda4 ----1 ----1 oxidation of the zinc1 #iai1 #idd4 ----1 its circulating force1 #heh1 #aabj4 ----1 its local force1 #aabj4 ----1 quantity of electricity circulating1 #iij4 ----1 intensity of electricity circulating1 #iij1 #iic4 ----1 intensity of its current1 #iji1 #iid4 ----1 ---- increased1 #ije1 #ihi4 ----1 its diminution in power1 #ajce4 ----1 ---- from adhesion of fluid1 #ajjc1 #aacf4 ----1 ---- ---- peculiar state of metal1 #ajdj4 ----1 ---- ---- exhaustion of charge1 #ajdb4 ----1 ---- ---- irregularity of plates1 #ajde1 #aadf4 ----1 use of metallic contact in1 #hic1 #hif4 ----1 electrolytes essential to it1 #iba4 ----1 ----1 why1 #heh1 #ibc4 ----1 state of metal and electrolyte before contact1 #iaf4 ----1 conspiring action of associated affinities1 #ihi4 ----1 purity of its zinc1 #aadd4 ----1 use of amalgamated zinc in1 #iii4 ----1 plates1 their number1 #aaea4 ----1 ---- size1 #aaed4 ----1 ---- vicinity1 #aadh4 ----1 ---- immersion1 #aaej4 ----1 ---- relative age1 #aadf4 ----1 ---- foulness1 #aade4 ----1 excited by acid1 #hhj1 #ibf1 #aacg4 ----1 ---- alkali1 #ica1 #icd1 #ida4 ----1 ---- sulphuretted solutions1 #idc4 ----1 the acid1 its use1 #ibe1 ----1 acid for1 #aabh1 #aacg4 ----1 nitric acid best for1 #aacg4 ----1 construction of1 #ihi1 #ajja1 #aaba4 ----1 with numerous alternations1 #ihi4 ----1 ,hare's1 #aabc4 ----1 general remarks on1 #ajca4 #aacf4 ----1 simultaneous decompositions with1 #aaef4 ----1 practical results with1 #aacf4 ----1 improved1 #ajja1 #ajjf1 #aabj4 ----1 ----1 its construction1 #aabd4 ----1 ----1 power1 #aabe1 #aabh4 ----1 ----1 advantages1 #aacb4 ----1 ----1 disadvantages1 #aacb4 ,batteries1 voltaic1 compared1 #aabf4 ,becquerel1 his important secondary results1 #gde1 #ghd4 ,berzelius1 his view of combustion1 #hgj1 #iei4 ,biot's theory of electro-chemical decomposition1 #dhf4 ,bismuth1 its relation to magneto-electric induction1 #aci4 ,bodies classed in relation to the electric current1 #hbc4 ---- classed in relation to magnetism1 #bee4 ,bodies electrolyzable1 #hbd4 ,bonijol decomposed substances by atmospheric electricity1 #ccf4 ,boracic acid a bad conductor1 #djh4 ,brush1 electric1 #adbe4 ----1 produced1 #adbe4 ----1 not affected by nature of conductors1 #aded1 #adgc4 ----1 is affected by the dielectrics1 #adee1 #adfc1 #adge4 ----1 not dependent on current of air1 #addj4 ----1 proves molecular action of dielectric1 #addi1 #adej4 ----1 its analysis1 #adbg1 #adcc4 ----1 nature1 #adcd1 #adda1 #addg4 ----1 form1 #adbh1 #addi1 #adea4 ----1 ramifications1 #adci4 ---- ----1 their coalescence1 #adec4 ----1 sound1 #adbf1 #adca4 ----1 requisite intensity for1 #addf4 ---- has sensible duration1 #adcg4 ---- is intermitting1 #adbg1 #adca1 #adea4 ----1 light of1 #addd1 #adde1 #adea4 ----1 ----1 in different gases1 #addf1 #aded4 ----1 dark8 #addd1 #aeeb4 ----1 passes into spark1 #addh4 ----1 spark and glow relation of1 #aecc1 #aeci1 #aedb4 ----1 in gases1 #aded1 #adfc1 #adgf4 ----1 oxygen1 #adeg1 #adgf4 ----1 nitrogen1 #adeh1 #adgf4 ----1 hydrogen1 #adei1 #adgf4 ----1 coal-gas1 #adfj1 #adgf4 ----1 carbonic acid gas1 #adfa1 #adgf4 ----1 muriatic acid gas1 #adfb1 #adgf4 ----1 rare air1 #adea1 #adee1 #adgd4 ----1 oil of turpentine1 #adeb4 ----1 positive1 #adee1 #adfg1 #adhd4 ----1 negative1 #adfh1 #adgb1 #adhd4 ----1 ----1 of rapid recurrence1 #adfh1 #adia4 ----1 positive and negative in different gases1 #adee1 #adge1 #aejf4 ,capacity1 specific inductive1 #abeb4 ----4 ,see ,specific inductive capacity4 ,carbonic acid gas facilitates formation of spark1 #adfc4 ----1 brush in1 #adfa1 #adgf4 ----1 glow in1 #aecd4 ----1 spark in1 #adbb1 #adfc4 ----1 positive and negative brush in1 #adgf4 ----1 ---- discharge in1 #aedf4 ----1 non-interference of1 #fde1 #feb4 ,carbonic oxide gas1 interference of1 #fde1 #feb4 ,carrying discharge1 #aefb4 ----4 ,see ,discharge convective4 ,cathode described1 #ffc1 #hbd4 ,cations1 or cathions1 described1 #ffe1 #hbd4 ----1 table of1 #hag4 ----1 direction of their transfer1 #ifb4 ,cations1 are in relation through the entire circuit1 #ifc4 ,characters of electricity1 table of1 #cfj4 ---- the electric current1 constant1 #afah1 #afbg4 ---- voltaic electricity1 #bfh4 ---- ordinary electricity1 #bhd4 ---- magneto-electricity1 #cdc4 ---- thermo-electricity1 #cdi4 ---- animal electricity1 #cea4 ,charge1 free1 #afhd4 ---- is always induction1 #aaga1 #aagg1 #acjj1 #afhb4 ---- on surface of conductors3 why1 #acja4 ----4 influence of form on1 #acjb4 ----1 ---- distance on1 #acjc4 ----1 loss of1 by convection1 #aefi4 ----1 removed from good insulators1 #abjc4 ---- of matter1 absolute1 #aafi4 ---- of air1 #aagc4 ---- ---- by brush1 #adcd1 #adda4 ---- ---- by glow1 #aebf1 #aecg1 #aedc4 ---- of particles in air1 #aefd4 ---- of oil of turpentine1 #aagb4 ---- of inductive apparatus divided1 #abjh4 ----1 residual1 of a ,leyden jar1 #abdi4 ----1 chemical1 for battery1 good1 #aacg4 -----1 ----1 weak and exhausted1 #ajdb1 #aadc4 ,chemical action1 the1 exciting the pile is oxidation1 #iba4 ---- superinduced by metals1 #efd4 ---- ---- platina1 #efd1 #fag1 #fcj4 ---- tested by iodide of potassium1 #cae4 ,chemical actions1 distant1 opposed to each other1 #hia1 #iaj1 #ajjg4 ,chemical affinity influenced by mechanical forces1 #fef4 ---- transferable through metals1 #iah4 ---- statical or local1 #heb1 #iba1 #iag1 #iei4 ---- current1 #heb1 #iah1 #idg1 #iif4 ,chemical decomposition by voltaic electricity1 #bgh1 #dej1 #ffa4 ---- common electricity1 #cji1 #dec4 ---- magneto-electricity1 #cdf4 ---- thermo-electricity1 #cdi4 ---- animal electricity1 #cee4 ----4 ,see ,decomposition electro-chemical4 ,chemical and electrical forces identical1 #hgg1 #iah1 #idg1 #ifj1 #ife1 #ajca4 ,chloride of antimony not an electrolyte1 #fij4 ---- lead1 its electrolysis1 #gid1 #hae4 ---- ----1 electrolytic intensity for1 #igh4 ---- silver1 its electrolysis1 #eda1 #hac1 #ijb4 ---- ----1 electrolytic intensity for1 #igi4 ---- tin1 its electrolysis1 #ghi1 #hai4 ,chlorides in solution1 their electrolysis1 #gff4 ---- fusion1 their electrolysis1 #ghi1 #hac4 ,circle of anions and cathions1 #ifc4 ,circles1 simple voltaic1 #hge4 ----1 associated voltaic1 #ihi4 ,circuit1 voltaic1 relation of bodies in1 #ifb4 ,classification of bodies in relation to magnetism1 #bee4 ---- the electric current1 #hbc1 #hag4 ,cleanliness of metals and other solids1 #fcc4 ,clean platina1 its characters1 #fcc1 #gag4 ----1 its power of effecting combination1 #eij1 #fje1 #fag1 #fcb4 ----1 ----4 ,see ,plates of platina4 ,coal gas1 brush in1 #adfj4 ----1 dark discharge in1 #aeef4 ----1 positive and negative brush in1 #adgf4 ----1 positive and negative discharge in1 #aeae4 ----1 spark in1 #adbb4 ,colladon on magnetic force of common electricity1 #bhi4 ,collectors1 magneto-electric1 #hf4 ,combination effected by metals1 #efd1 #fjh4 ---- solids1 #efd1 #fah4 ---- poles of platina1 #eff4 ---- platina1 #efd1 #efh1 #ega1 #eij1 #fcj4 ---- ----1 as plates1 #efi4 ---- ----1 as sponge1 #fji1 #fcf4 ---- ----1 cause of1 #eij1 #faf1 #fbe1 #fef4 ---- ----1 how1 #fcj4 ---- ----1 interferences with1 #fch1 #feb1 #fee4 ---- ---- retarded by olefiant gas1 #fdj4 ---- ---- ---- carbonic oxide1 #fde1 #feb4 ---- ---- ---- sulphuret of carbon1 #fej4 ---- ---- ---- ether1 #fea4 ---- ---- ---- other substances1 #fdi1 #fec1 #fed4 ,comparison of voltaic batteries1 #aabf1 #aadf4 ,conditions1 general1 of voltaic decomposition1 #ffi4 ----1 new1 of electro-chemical decomposition1 #dec4 ,conducting power measured by a magnet1 #baf4 ---- of solid electrolytes1 #dai4 ---- of water1 constant1 #ihd4 ,conduction1 #dah1 #acbj4 ----1 its nature1 #acbj1 #acbf1 #afaa4 ----1 of two kinds1 #ihg4 ----1 preceded by induction1 #acbi1 #accb1 #acch4 ---- and insulation1 cases of the same kind1 #acbj1 #acbf1 #accf1 #acch1 #aefa4 ----1 its relation to the intensity of the current conducted1 #dai4 ---- common to all bodies1 #ddd1 #ddi4 ---- by a vacuum1 #afac4 ---- by lac1 #abcd1 #acbd4 ---- by sulphur1 #abda1 #acbh4 ---- by glass1 #abci1 #acbd4 ---- by spermaceti1 #abdj1 #acbc4 ---- by gases1 #accf4 ----1 slow1 #abcc1 #abde1 #acbh4 ---- affected by temperature1 #dde1 #acci4 ---- by metals diminished by heat1 #dcb1 #dde4 ---- increased by heat1 #dcb1 #dda1 #dde4 ---- of electricity and heat1 relation of1 #daf4 ----1 simple1 can occur in electrolytes1 #ifg1 #ihc4 ----1 ---- with very feeble currents1 #igj4 ---- by electrolytes without decomposition1 #ifh1 #ajag1 #ajcb4 ---- and decomposition associated in electrolytes1 #dac1 #fgf1 #hed4 ---- facilitated in electrolytes1 #acee4 ---- by water bad1 #aaei4 ---- ---- improved by dissolved bodies1 #ihd1 #acee4 ----1 electrolytic1 stopped1 #chj1 #aceh1 #agje4 ---- of currents stopped by ice1 #cha4 ---- conferred by liquefaction1 #cid1 #daj4 ---- taken away by solidification1 #cid1 #agje4 ---- ---- why1 #iaj1 #agje4 ----1 new law of1 #chj1 #cid1 #daj4 ----1 ----1 supposed exception to1 #fia1 #acdj4 ----1 general results as to1 #ddc4 ,conductive discharge1 #acbj4 ,conductors1 electrolytic1 #dgd4 ----1 magneto-electric1 #hf4 ----1 their nature does not affect the electric brush1 #aded4 ----1 size of1 affects discharge1 #acgb4 ----1 form of1 affects discharge1 #acgd1 #adbe4 ----1 distribution of electricity on1 #acfh4 ----1 ----1 affected by form1 #acgd4 ----1 ----1 ---- distance1 #acfd1 #acga4 ----1 ----1 ---- air pressure1 #acge4 ----1 ----1 irregular with equal pressure1 #acgh4 ,constancy of electric current1 #afah4 ,constitution of electrolytes as to proportions1 #fgi1 #fig1 #hcj1 #agjh4 ---- liquidity1 #cid1 #hbc4 ,contact of metals not necessary for electrolyzation1 #hgi4 ----1 its use in the voltaic battery1 #hic4 ---- not necessary for spark1 #iae1 #ief4 ,contiguous particles1 their relation to induction1 #aafe1 #afgi4 ---- active in electrolysis1 #acdi1 #agjc4 ,convection1 #aefb1 #afdb4 ---- or convective discharge4 ,see ,discharge convective4 ,copper1 iron1 and sulphur circle1 #idc4 ,coruscations of lightning1 #adfd4 ,coulomb's electrometer1 #aahj4 ----1 precautions in its use1 #aahb1 #aahf1 #abjf4 ,crystals1 induction through1 #afhi4 ,cube1 large1 electrified1 #aagc4 ,cubes of crystals1 induction through1 #afib1 #afie4 ,current chemical affinity1 #heb1 #iah1 #idg1 #iif4 ,current1 voltaic1 without metallic contact1 #hgi1 #hhg4 ,current1 electric1 #afag4 ----1 defined1 #bhb1 #eaa4 ----1 nature of1 #eaa1 #ffg1 #afag1 #afbg4 ----1 variously produced1 #afah4 ----1 produced by chemical action1 #hgi1 #iaf1 #agda4 ----1 ---- animals1 #cea4 ----1 ---- friction1 #cja1 #cjg1 #caa4 ----1 ---- heat1 #cdi1 ----1 ---- discharge of static electricity1 #bif1 #cjg1 #cfc4 ----1 ---- induction by other currents1 #f1 #ajhi4 ----1 ---- ---- magnets1 #cj1 #hh1 #cdd4 ----1 evolved in the moving earth1 #aha4 ----1 in the earth1 #ahg4 ----1 natural standard of direction1 #ffc4 ----1 none of one electricity1 #afbg1 #afcb1 #afce4 ----1 two forces everywhere in it1 #afbg1 #afcb1 #afce1 #afdb4 ----1 one1 and indivisible1 #afbg4 ----1 an axis of power1 #eag1 #afdb4 ----1 constant in its characters1 #afah1 #afbg4 ----1 inexhaustibility of1 #afca4 ----1 its velocity in conduction1 #afdh4 ----1 ---- electrolyzation1 #afea4 ----1 regulated by a fine wire1 #hec1 note4 ----1 affected by heat1 #afcg4 ----1 stopped by solidification1 #cha4 ----1 its section1 #dih1 #ejd1 #afcd4 ----1 ---- presents a constant force1 #afcd4 ----1 produces chemical phenomena1 #afba4 ----1 ---- heat1 #afbe4 ----1 its heating power uniform1 #afcj4 ----1 produces magnetism1 #afec4 ----1 ,porrett's effects produced by1 #afdf4 ----1 induction of1 #a1 #f1 #bcb1 #bda1 #aaja1 #ajdh4 ----1 ----1 on itself1 #ajdh4 ----1 ----4 ,see ,induction of electric current4 ----1 its inductive force lateral1 #aajh4 ----1 induced in different metals1 #aic1 #bac1 #bja1 #baa4 ----1 its transverse effects1 #afec4 ----1 ---- constant1 #afee4 ----1 its transverse forces1 #afeh4 ----1 ---- are in relation to contiguous particles1 #affd4 ----1 ---- their polarity of character1 #affe4 ---- and magnet1 their relation remembered1 #ch1 note4 ,currents in air by convection1 #aegb1 #aeha4 ----1 metals by convection1 #afjc4 ----1 oil of turpentine by convection1 #aeie1 #aeih4 ,curved lines1 induction in1 #abae4 ,curves1 magnetic1 their relation to dynamic induction1 #bag1 #bcb4 ,daniell on the size of the voltaic metals1 #aebe4 ,dark discharge1#addd1 #aedd4 ----4 ,see ,discharge1 dark4 ,dates of some facts and publications1 #aci1 note after4 ,davy's theory of electro-chemical decomposition1 #dhb1 #ejj4 ---- electro-chemical views1 #ife4 ---- mercurial cones1 convective phenomena1 #afjc4 ,decomposing force alike in every section of the current1 #eja1 #eje4 ----1 variation of1 on each particle1 #ejc4 ,decomposition and conduction associated in electrolytes1 #dac1 #hed4 ----1 primary and secondary results of1 #gdb1 #ggg4 ---- by common electricity1 #cji1 #ded4 ---- ----1 precautions1 #cbb4 ,decomposition1 electro-chemical1 #dej1 #ffi4 ----1 nomenclature of1 #ffa4 ----1 new terms relating to1 #ffb4 ----1 its distinguishing character1 #cji4 ----1 by common electricity1 #cji1 #ded4 ----1 by a single pair of plates1 #hfb1 #hig1 #ijd1 #ica4 ----1 by the electric current1 #afba4 ----1 without metallic contact1 #hhj1 #hhb4 ----1 its cause1 #hia1 #ijd1 #iaj4 ----1 not due to direct attraction or repulsion of poles1 #dic1 #dig1 #ecf1 #edb1 #edfj4 ----1 dependent on previous induction1 #acde4 ----1 ---- the electric current1 #dic1 #eaj1 #ebd1 #hed4 ----1 ---- intensity of current1 #ije4 ----1 ---- chemical affinity of particles1 #eai1 #ebe1 #eai4 ----1 resistance to1 #hia1 #iaj1 #ajjg4 ----1 intensity requisite for1 #iff1 #aced4 ----1 stopped by solidification1 #chj1 #aceh1 #agje4 ----1 retarded by interpositions1 #ajjg4 ----1 assisted by dissolved bodies1 #acee4 ----1 division of the electrolyte1 #acdg1 #afbc1 #agja4 ----1 transference1 #eai1 #ebe1 #ech1 #eej1 #acdg1 #agjf4 ----1 why elements appear at the poles1 #ece4 ----1 uncombined bodies do not travel1 #edd1 #edf4 ----1 circular series of effects1 #efb1 #ifb4 ----1 simultaneous1 #aaef1 ----1 definite1 #cbi1 #cgb1 #cgg1 #ejd1 #gjd1 #gad1 #gbb1 #gbf1 #gcb1 #gfd1 #ghc1 #hjg1 #hba1 #ifj4 ----1 ---- independent of variations of electrodes1 #gad1 #gbb1 #hjg1 #hcb4 ----1 necessary intensity of current1 #iaa1 #iff1 #acde1 #aced4 ----1 influence of water in1 #dgb4 ----1 in air1 #dea1 #dfa1 #dfi4 ----1 some general conditions of1 #ffi4 ----1 new conditions of1 #dec4 ----1 primary results1 #gdb4 ----1 secondary results1 #gjb1 #gdb1 #gdh1 #ggg4 ----1 of acetates1 #ggd4 ----1 acetic acid1 #ggc4 ----1 ammonia1 #gdh4 ----1 chloride of antimony1 #fij1 #gif4 ----1 ---- lead1 #gid1 #hae4 ----1 ---- silver1 #eda1 #hac1 #igi4 ----1 chlorides in solution1 #gff4 ----1 ---- fusion1 #ghi1 #iac4 ----1 fused electrolytes1 #ghi4 ----1 hydriodic acid and iodides1 #gfg1 #ghg4 ----1 hydrocyanic acid and cyanides1 #gga4 ----1 hydrofluoric acid and fluorides1 #ggj4 ----1 iodide of lead1 #hjb1 #hah4 ----1 ---- potassium1 #hje4 ----1 muriatic acid1 #geh1 #ghj4 ----1 nitre1 #gec4 ----1 nitric acid1 #geb4 ----1 oxide antimony1 #hja4 ----1 ---- lead1 #gig4 ----1 protochloride of tin1 #ghi1 #hai4 ----1 protiodide of tin1 #hjd4 ----1 sugar1 gum1 c41 #ggf4 ----1 of sulphate of magnesia1 #die4 ----1 sulphuric acid1 #geg4 ----1 sulphurous acid1 #gee4 ----1 tartaric acid1 #gge4 ----1 water1 #gjd1 #ghe1 #hjg4 ----1 theory of1 #dgg1 #acde4 ----1 ----1 by ,a4 de la ,rive1 #dhi1 #ejg1 #ead1 #edc4 ----1 ----1 ,biot1 #dhf4 ----1 ----1 ,davy1 #dhb1 #ejj4 ----1 ----1 ,grotthuss1 #dha1 #dii1 #eae4 ----1 ----1 ,hachette1 #dia1 #eac1 ----1 ----1 ,riffault and ,chompr1 #dhe1 #ejg1 #eab4 ----1 author's theory1 #eah1 #ebd1 #acde1 #afbc1 #agjc1 #agff4 ,definite decomposing action of electricity1 #cbi1 #cgb1 #cgg1 #ejd1 #gjd1 #ghc1 #hba4 ----1 magnetic action of electricity1 #baf1 #cfb1 #cfg1 #cgg4 ----1 electro-chemical action1 #hbb1 #hfi1 #ifj4 ----1 ----1 general principles of1 #hbb1 #hfb4 ----1 ----1 in chloride of lead1 #hae4 ----1 ----1 ---- silver1 #hac4 ----1 ----1 in hydriodic acid1 #gfg1 #ghg4 ----1 ----1 iodide of lead1 #hjb1 #hah4 ----1 ----1 muriatic acid1 #geh1 #ghf1 ----1 ----1 protochloride of tin1 #hai4 ----1 ----1 water1 #gcb1 #ghe1 #hjg4 ,degree in measuring electricity1 proposal for1 #gcf4 ,de la ,rive on heat at the electrodes1 #afcg4 ----1 his theory of electro-chemical decomposition1 #dhi1 #ejg1 #ead1 #edc4 ,dielectrics1 what1 #aafh4 ----1 their importance in electrical actions1 #afff4 ----1 their relation to static induction1 #abif4 ----1 their condition under induction1 #acfi1 #afgi4 ----1 their nature affects the brush1 #adee4 ----1 their specific electric actions1 #abif1 #acih1 #adbc1 #aded1 #aejc1 #aefj4 ,difference of positive and negative discharge1 #adfe1 #adhj1 #adhe4 ,differential inductometer1 #acjg4 ,direction of ions in the circuit1 #ifb4 ----1 the electric current1 #efc4 ----1 the magneto-electric current1 #aad1 #aaf4 ----1 the induced volta-electric current1 #ai1 #bf1 #ajia4 ,disruptive discharge1 #acei1 #adje4 ,see ,discharge1 disruptive4 ,discharge1 electric1 as balls of fire1 #afda4 ----1 of ,leyden jar1 #acjj4 ----1 of voltaic battery by hot air1 #bga1 #bgd4 ----1 ---- points1 #bgb4 ----1 velocity of1 in metal1 varied1 #accc4 ----1 varieties of1 #acai4 ----1 brush1 #adbe4 ,see ,brush4 ----1 carrying1 #aefb4 ,see ,discharge1 convective4 ----1 conductive1 #acbj4 ,see ,conduction4 ----1 dark1 #addd1 #aedd4 ----1 disruptive1 #acei1 #adje4 ----1 electrolytic1 #acdc1 #afbb1 #agjd4 ----1 glow1 #aebf4 ,see ,glow4 ----1 positive and negative1 #adfe4 ----1 spark1 #adjf4 ,see ,spark1 electric4 ,discharge1 connective1 #addb1 #aefb1 #afja1 #afbc1 #afcc1 #afdb4 ----1 in insulating media1 #aefb1 #aegb4 ----1 in good conductors1 #afjc4 ----1 with fluid terminations in air1 #aeha1 #aehi4 ----1 ---- liquids1 #aeig4 ----1 from a ball1 #aegf1 #aeij4 ----1 influence of points in1 #aegc4 ----1 affected by mechanical causes1 #aegi4 ----1 ---- flame1 #aehj4 ----1 with glow1 #aegf4 ----1 charge of a particle in air1 #aefd4 ----1 ---- oil of turpentine1 #aegj4 ----1 charge of air by1 #addb1 #aeib4 ----1 currents produced in air1 #aegb1 #aeha1 #aeia4 ----1 ---- oil of turpentine1 #aeie1 #aeih4 ----1 direction of the currents1 #aeii1 #afde4 ----1 ,porrett's effects1 #afdf1 ----1 positive and negative1 #aeic1 #afjj1 #afdc4 ----1 related to electrolytic discharge1 #afbb1 #afcc4 ,discharge1 dark1 #addd1 #aedd1 #aefj4 ----1 with negative glow1 #aedd4 ----1 between positive and negative glow1 #aedg4 ----1 in air1 #aedh4 ----1 muriatic acid gas1 #aeed4 ----1 coal gas1 #aeef4 ----1 hydrogen1 #aeeh4 ----1 nitrogen1 #aeei4 ,discharge1 disruptive1 #adje4 ----1 preceded by induction1 #acfb4 ----1 determined by one particle1 #acgj1 #adji4 ----1 necessary intensity1 #adji1 #aeec4 ----1 determining intensity constant1 #adaj4 ----1 related to particular dielectric1 #aejc4 ----1 facilitates like action1 #adag1 #adce1 #adec1 #aeec4 ----1 its time1 #adah1 #adcf1 #adih1 #afda4 ----1 varied by form of conductors1 #acjb1 #acgb1 #acgd4 ----1 ---- change in the dielectric1 #acie1 #adbb1aded4 ----1 ---- rarefaction of air1 #acfe1 #acge1 #adea4 ----1 ---- temperature1 #acfg1 #achj4 ----1 ---- distance of conductors1 #acjc1 #acfd1 #acga4 ----1 ---- size of conductors1 #acgb4 ----1 in liquids and solids1 #adjc4 ----1 in different gases1 #acha1 #achh1 #adba4 ----1 ---- not alike1 #acie4 ----1 ---- specific differences1 #acii1 #adbb1 #afhg4 ----1 positive and negative1 #acic1 #acii1 #adfe1 #aebd4 ----1 ----1 distinctions1 #adfg1 #adge1 #adhb4 ----1 ----1 differences1 #adhe1 #aeja4 ----1 ----1 relative facility1 #adif1 #aebj4 ----1 ----1 dependent on the dielectric1 #aejc4 ----1 ----1 in different gases1 #aejf1 #aeaj1 #aeah1 #afhg4 ----1 ----1 of voltaic current1 #aebd4 ----1 brush1 #adbe4 ----1 collateral1 #adab4 ----1 dark1 #addd1 #aedd1 #aefj4 ----1 glow1 #aebf4 ----1 spark1 #adjf4 ----1 theory of1 #acjh1 #adjf1 #adcd4 ,discharge1 electrolytic1 #aafd1 #acdc1 #afba1 #agjc1 #agjf4 ----1 previous induction1 #acde1 #acea4 ----1 necessary intensity1 #iab1 #iff1 #acdf1 #aced4 ----1 division of the electrolyte1 #acdg1 #agjd4 ----1 stopped by solidifying the electrolyte1 #chj1 #aceh1 #agje4 ----1 facilitated by added bodies1 #acee4 ----1 in curved lines1 #eba1 #abaf1 #acea4 ----1 proves action of contiguous particles1 #acdi4 ----1 positive and negative1 #aebe4 ----1 velocity of electric current in1 #afej4 ----1 related to convective discharge1 #afbb4 ----1 theory of1 #acdd1 #afbb1 #agjd4 ,discharging train generally used1 #bib4 ,disruptive discharge1 #adje4 ,see ,discharge1 disruptive4 ,dissimulated electricity1 #afhd4 ,distance1 its influence in induction1 #acjc1 #acfd1acga4 ---- over disruptive discharge1 #acfd1 #acga4 ,distant chemical actions1 connected and opposed1 #hia1 #iji4 ,distinction of magnetic and magneto-electric action1 #ach1 #bae1 #bdc1 #bec4 ,division of a charge by inductive apparatus1 #abjh4 ,dbereiner on combination effected by platina1 #fji1 #faj4 ,dulong and ,thenard on combination by platina and solids1 #fji1 #faa4 ,dust1 charge of its particles1 #aefg4 ,earth1 natural magneto-electric induction in1 #aha1 #aij1 #aib4 ,elasticity of gases1 #fbf4 ---- gaseous particles1 #feh4 ,electric brush1 #adbe4 ,see ,brush1 electric4 ---- condition of particles of matter1 #hfb1 #affi4 ---- conduction1 #acbj4 ,see ,conduction4 ---- current defined1 #bhc1 #eaa4 ---- ----1 nature of1 #eaa1 #afag1 #afbg4 ---- ----4 ,see ,current1 electric4 ---- ----1 induction of1 #f1 #bcb1 #bda1 #ajdh1 #aaja4 ,see ,induction of electric current4 ---- ----1 ----1 on itself1 #ajdh4 ---- discharge1 #acai4 ,see ,discharge4 ---- force1 nature of1 #affg4 ,see ,forces4 ---- induction1 #aafb4 ,see ,induction4 ---- inductive capacity1 #abeb4 ,see ,specific inductive capacity4 ---- polarity1 #afhe4 ,see ,polarity1 electric4 ---- spark1 #adjf4 ,see ,spark1 electric4 ---- and magnetic forces1 their relation1 #aah1 #adaa1 #afec1 #afeh1 #agji1 #agca4 ,electrics1 charge of1 #aaga1 #abdg4 ,electrical excitation1 #agcg4 ,see ,excitation4 ---- machine generally used1 #bij4 ---- battery generally used1 #bia4 ---- and chemical forces identical1 #hgg1 #iag1 #idg1 #ifj1 #ife1 #ajca4 ,electricities1 their identity1 however excited1 #bfe1 #cfj4 ----1 one or two1 #eaf1 #affg4 ----1 two1 #aafc4 ----1 ----1 their independent existence1 #aafh4 ----1 ----1 their inseparability1 #aafh1 #aagg1 #abdd4 ----1 ----1 never separated in the current1 #afbh4 ,electricity1 quantity of1 in matter1 #heb1 #hfa4 ----1 its distribution on conductors1 #acfh4 ----1 ---- influenced by form1 #acjb1 #acgd4 ----1 ---- ---- distance1 #acjc1 #acfd1 #acga4 ----1 ---- ---- air's pressure1 #acge4 ----1 relation of a vacuum to1 #afac4 ----1 dissimulated1 #afhd4 ----1 common and voltaic1 measured1 #cfa1 #hfj4 ----1 its definite decomposing action1 #cbi1 #cgg1 #ghc1 #afba4 ----1 ---- heating action1 #afbe4 ----1 ---- magnetic action1 #baf1 #cff4 ----1 animal1 its characters1 #cea4 ----1 magneto-1 its characters1 #cdc4 ----1 ordinary1 its characters1 #bhd4 ----1 thermo-1 its characters1 #cdi4 ----1 voltaic1 its characters1 #bfh4 ,electricity from magnetism1 #bg1 #cf1 #eg1 #hc1 #ace1 #adj4 ----1 on magnetisation of soft iron by currents1 #bg1 #cd1 #eg1 #aac4 ---- ---- magnets1 #cf1 #dd4 ----1 employing permanent magnets1 #ci1 #hd1 #aab4 ----1 ---- terrestrial magnetic force1 #adj1 #aej1 #afa4 ----1 ---- moving conductors1 #ee1 #hc1 #acb1 #aci1 #adi1 #afa1 #aga4 ----1 ---- ---- essential condition1 #bag4 ---- by revolving plate1 #hc1 #adi1 #bdj4 ---- ---- a constant source of electricity1 #hi1 #ij1 #aed4 ---- ----1 law of evolution1 #aad4 ---- ----1 direction of the current evolved1 #ia1 #ii1 #aaj1 #aaf1 #aag4 ---- ----1 course of the currents in the plate1 #abc1 #aej4 ---- by a revolving globe1 #acg1 #afj4 ---- by plates1 #id1 #aja4 ---- by a wire1 #di1 #ee1 #aji1 #aab1 #acg4 ----1 conductors and magnet may move together1 #bah4 ----1 current produced in a single wire1 #di1 #ee1 #agj4 ----1 ---- a ready source of electricity1 #df1 note4 ----1 ---- momentary1 #bh1 #cj1 #dg4 ----1 ---- permanent1 #hi1 #aed4 ----1 ---- deflects galvanometer1 #cj1 #ci1 #df4 ----1 ---- makes magnets1 #cd4 ----1 ----1 shock of1 #ef4 ----1 ----1 spark of1 #cb4 ----1 ---- traverses fluids1 #bc1 #cc4 ----1 ----1 its direction1 #cj1 #ch1 #da1 #eb1 #ec1 #ed1 #gh1 #ia1 #ii1 #aad1 #adb1 #aff1 #bbj1 #bbb4 ----1 effect of approximation and recession1 #ah1 #ci1 #ej4 ----1 the essential condition1 #bag4 ----1 general expression of the effects1 #bef4 ----1 from magnets alone1 #bbj4 ,electricity of the voltaic pile1 #hge4 ---- its source1 #hge4 ---- ---- not metallic contact1 #hhg1 #iae4 ---- ---- is in chemical action1 #hgi1 #iaf1 #iai1 #agch1 #agda4 ,electro-chemical decomposition1 #dej1 #ffa4 ----1 nomenclature1 #ffa4 ----1 general conditions of1 #ffi4 ----1 new conditions of1 #dec1 ----1 influence of water in1 #dgb4 ----1 primary and secondary results1 #gdb4 ----1 definite1 #gcb1 #ghc4 ----1 theory of1 #dgg4 ----4 ,see also ,decomposition1 electrochemical4 ,electro-chemical equivalents1 #hbd1 #hcc1 #hce1 #hee4 ----1 table of1 #hdg4 ----1 how ascertained1 #hcg4 ---- always consistent1 #hce4 ---- same as chemical equivalents1 #hcf1 #hci4 ---- able to determine atomic number1 #hea4 ,electro-chemical excitation1 #hgh1 #iai1 #agch4 ,electrode defined1 #ffb4 ,electrodes affected by heat1 #afcg4 ----1 varied in size1 #gad1 #gbb4 ----1 ---- nature1 #hjg4 ----4 ,see ,poles4 ,electrolysis1 resistance to1 #ajjg4 ,electrolyte defined1 #ffd4 ---- exciting1 solution of acid1 #hha1 #ibe4 ---- ---- alkali1 #ica1 #ida4 ---- exciting1 water1 #idd1 #ide4 ---- ---- sulphuretted solution1 #idc4 ,electrolytes1 their necessary constitution1 #ffi1 #hbc1 #hbi1 #heh1 #iba1 #acdg1 #agjh4 ---- consist of single proportionals of elements1 #fgi1 #fig1 #hcj1 #agjg4 ---- essential to voltaic pile1 #iba4 ---- ----1 why1 #heh1 #ibc4 ---- conduct and decompose simultaneously1 #dac4 ---- can conduct feeble currents without decomposition1 #ifg4 ----1 as ordinary conductors1 #igj1 #ihc1 #acdd4 ----1 solid1 their insulating and conducting power1 #dai4 ----1 real conductive power not affected by dissolved matters1 #acef4 ----1 needful conducting power1 #aaeh4 ---- are good conductors when fluid1 #cid1 #hbc4 ,electrolytes non-conductors when solid #cha1 #cid4 ----1 why1 #iaj1 #agje4 ----1 the exception1 #ajcb4 ,electrolytes1 their particles polarize as wholes1 #agjj4 ----1 polarized light sent across1 #iea4 ----1 relation of their moving elements to the passing current1 #ibc1 #agjd4 ----1 their resistance to decomposition1 #hia1 #ajjg1 #agje4 ----1 and metal1 their states in the voltaic pile1 #idf4 ----1 salts considered as1 #fih4 ----1 acids not of this class1 #fha4 ,electrolytic action of the current1 #dgh1 #eah1 #afbj4 ---- conductors1 #dgd4 ---- discharge1 #acdc4 ,see ,discharge1 electrolytic4 ---- induction1 #aafd1 #acdc4 ---- intensity1 #iaa1 #iff1 #ihc4 ---- ---- varies for different bodies1 #iab1 #ihf1 #aced4 ---- ---- of chloride of lead1 #igh4 ---- ---- chloride of silver1 #igi4 ---- ---- sulphate of soda1 #ige4 ---- ---- water1 #ifh1 #iha4 ---- ---- its natural relation1 #ihg4 ,electrolyzation1 #dej1 #ffa1 #aafd1 #acdg1 #agjd4 ,see ,decomposition electro-chemical4 ---- defined1 #ffd4 ---- facilitated1 #cid1 #dag1 #edi1 #acee4 ---- in a single circuit1 #hfc1 #hgi4 ----1 intensity needful for1 #iai1 #iff1 ---- of chloride of silver1 #eda1 #igi4 ---- sulphate of magnesia1 #die4 ---- and conduction associated1 #dac1 #fgf4 ,electro-magnet1 inductive effects in1 #ajfj4 ,electro-magnetic induction definite1 #baf1 #cff4 ,electrometer1 ,coulomb's1 described1 #aahj4 ----1 how used1 #aahc4 ,electro-tonic state1 #fj1 #bca1 #bdb1 #aaad1 #affa1 #agbi4 ---- considered common to all metals1 #ff4 ---- ---- conductors1 #gf4 ---- is a state of tension1 #ga4 ---- is dependent on particles1 #gc4 ,elementary bodies probably ions1 #hdi4 ,elements evolved by force of the current1 #dic1 #ebj1 #ebd4 ---- at the poles1 why1 #ece4 ---- determined to either pole1 #eeb1 #fha1 #geg4 ----1 transference of1 #ded1 #ech4 ----1 if not combined1 do not travel1 #edd1 #edf4 ,equivalents1 electro-chemical1 #hbd1 #hcc1 #hee4 ----1 chemical and electro-chemical1 the same1 #hcf1 #hci4 ,ether1 interference of1 #fea4 ,evolution of electricity1 #aafb1 #agcg4 ---- of one electric force impossible1 #aage4 ---- of elements at the poles1 why1 #ece4 ,excitation1 electrical1 #agcg4 ---- by chemical action1 #hgh1 #iaf1 #agci4 ---- by friction1 #agdd4 ,exclusive induction1 #afha4 ,flame favours convectivc discharge1 #aehj4 ,flowing water1 electric currents in1 #aij4 ,fluid terminations for convection1 #aeha4 ,fluids1 their adhesion to metals1 #ajch4 ,fluoride of lead1 hot1 conducts well1 #acdj4 ,force1 chemical1 local1 #idg1 #iei1 #agci4 ----1 circulating1 #iag1 #idg1 #iif1 #aabj4 ,force1 electric1 nature of1 #aafc1 #affg4 ----1 inductive1 of currents1 its nature1 #fj1 #aaac1 #agce4 ,forces1 electric1 two1 #aafc4 ----1 inseparable1 #aafc1 #aagg1 #abdd1 #afbg4 ---- and chemical1 are the same1 #hgg1 #iaf4 ---- and magnetic1 relation of1 #adaa1 #afec1 #afeh1 #agji4 ---- ----1 are they essentially different8 #affc1 #agca4 ,forces1 exciting1 of voltaic apparatus1 #hhg1 #iaf4 ----1 exalted1 #ije1 #iid1 #aach1 #aadh4 ,forces1 polar1 #affe4 ---- of the current1 direct1 #afbj4 ---- ----1 lateral or transverse1 #afec1 #agji4 ,form1 its influence on induction1 #acjb1 #acgd4 ---- discharge1 #acgb1 #acgd4 ,fox1 his terrestrial electric currents1 #ahg4 ,friction electricity1 its characters1 #bhd4 ----1 excitement by1 #agdd4 ,fusion1 conduction consequent upon1 #cid1 #djb4 ,fusinieri1 on combination effected by platina1 #fac4 ,galvanometer1 affected by common electricity1 #bhi1 #cff4 ----1 a correct measure of electricity1 #cfg1 note4 ,gases1 their elasticity1 #fbf1 #feg4 ----1 conducting power1 #accf4 ----1 insulating power1 #acha1 #aejg4 ----1 ---- not alike1 #acie1 #aejh4 ----1 specific inductive capacity1 #abhc1 #abij4 ----1 ---- alike in all1 #abib4 ----1 specific influence on brush and spark1 #adfc1 #afhg4 ----1 discharge1 disruptive1 through1 #acha4 ----1 brush in1 #aded4 ----1 spark in1 #adba4 ----1 positive and negative brushes in1 #adge4 ----1 ----1 their differences1 #adgf4 ----1 positive and negative discharge in1 #acic1 #aejf1 #afhg4 ----1 solubility of1 in cases of electrolyzation1 #gag1 #gbh4 ----1 from water1 spontaneous recombination of1 #eff4 ----1 mixtures of1 affected by platina plates1 #ega4 ----1 mixed1 relation of their particles1 #fbe4 ,general principles of definite electrolytic action1 #hbb4 ---- remarks on voltaic batteries1 #ajca1 #aacf4 ---- results as to conduction1 #ddc4 ---- ---- induction1 #abie4 ,glass1 its conducting power1 #abci4 ----1 its specific inductive capacity1 #abga4 ----1 its attraction for air1 #fbb4 ----1 ---- water1 #abea4 ,globe1 revolving of ,barlow1 effects explained1 #acg1 #afj4 ----1 is magnetic1 #afd4 ,glow1 #adje1 #aebe4 ----1 produced1 #aebg4 ----1 positive1 #aebg4 ----1 negative1 #aecj4 ----1 favoured by rarefaction of air1 #aebi4 ----1 is a continuous charge of air1 #aebf1 #aecg1 #aedc4 ----1 occurs in all gases1 #aecd4 ----1 accompanied by a wind1 #aece4 ----1 its nature1 #aedc1 ----1 discharge1 #aebf4 ----1 brush and spark relation of1 #aecc1 #aech1 #aeci1 #aedb4 ,grotthuss' theory of electro-chemical decomposition1 #dha1 #dii1 #eae4 ,growth of a brush1 #adcg4 ---- spark1 #aeec4 ,hachette's view of electro-chemical decomposition1 #dia4 ,hare's voltaic trough1 #aabc1 #aacb4 ,harris on induction in air1 #acfc4 ,heat affects the two electrodes1 #afcg4 ---- increases the conducting power of some bodies1 #dcb1 #dch1 #acdj4 ----1 its conduction related to that of electricity1 #daf4 ----1 as a result of the electric current1 #hec1 note1 #afbe1 #afcj4 ---- evolved by animal electricity1 #cec4 ---- ---- common electricity1 #bhg4 ---- ---- magneto-electricity1 #cdd4 ---- ---- thermo-electricity1 #cdi4 ---- ---- voltaic electricity1 #bgf4 ,helix1 inductive effects in1 #ajfa1 #ajid4 ,hydriodic acid1 its electrolyses1 #gfg1 #ghg4 ,hydrocyanic acid1 its electrolyses1 #gga1 #ghh4 ,hydrofluoric acid1 not electrolysable1 #ggj4 ,hydrogen1 brush in1 #adei4 ----1 positive and negative brush in1 #adgf4 ----1 ---- discharge in1 #aead4 ,hydrogen and oxygen combined by platina plates1 #egj1 #fje4 ---- spongy platina1 #fji4 ,ice1 its conducting power1 #dai4 ---- a non-conductor of voltaic currents1 #cha4 ,iceland crystal1 induction across1 #afie4 ,identity1 of electricities1 #bfe1 #cfj4 ---- of chemical and electrical forces1 #hgg1 #iag1 #idg1 #ifa1 #ajca4 ,ignition of wire by electric current1 #hec1 note1 #afcj4 ,improved voltaic battery1 #ajjf1 #aabj4 ,increase of cells in voltaic battery1 effect of1 #iij4 ,inducteous surfaces1 #adhc4 ,induction apparatus1 #aahg4 ----1 fixing the stem1 #aaij1 #aaic1 #abjj4 ----1 precautions1 #aaid1 #aaii1 #abac1 #abcb1 #abej4 ----1 removal of charge1 #abjc4 ----1 retention of charge1 #abje1 #abjg4 ----1 a charge divided1 #abjh4 ----1 peculiar effects with1 #abcc4 ,induction1 static1 #aafa4 ----1 an action of contiguous particles1 #aafe1 #abca1 #abec1 #abie1 #adej1 #affh1 #afgi4 ----1 consists in a polarity of particles1 #abih1 #afgj1 #afgi4 ----1 continues only in insulators1 #abih1 #acbd1 #acch4 ----1 intensity of1 sustained1 #acfb4 ----1 influenced by the form of conductors1 #acjb4 ----1 ---- distance of conductors1 #acjc4 ----1 ---- relation of the bounding surfaces1 #adhc4 ----1 charge1 a case of1 #aaga1 #aagg1 #acjj4 ----1 exclusive action1 #afha4 ----1 towards space1 #afad4 ----1 across a vacuum1 #afad4 ---- through air1 #abag1 #abhd4 ---- ---- different gases1 #acha1 #acie4 ---- ---- crystals1 #afhi1 ---- ---- lac1 #abbh1 #abee1 #acjh4 ---- ---- metals1 #acbi1 #accb4 ---- ---- all bodies1 #acca1 #accd4 ----1 its relation to other electrical actions1 #aafe1 #aagh4 ----1 ---- insulation1 #acbd1 #acfjb1 #acfh1 #afgh4 ----1 ---- conduction1 #acbj4 ----1 ---- discharge1 #acai1 #acbc1 #acfb4 ----1 ---- electrolyzation1 #aafd1 #acdc4 ----1 ---- intensity1 #aagh1 #acfb4 ----1 ---- excitation1 #aagh1 #agdj4 ----1 its relation to charge1 #aagg1 #abii4 ---- an essential general electric function1 #aagh1 #abii4 ----1 general results as to1 #abie4 ----1 theory of1 #aafe1 #abca1 #abie1 #affg1 #affi4 ---- in curved lines1 #aaff1 #abae1 #afgi4 ---- ----1 through air1 #abah1 #addi4 ---- ----1 ---- other gases1 #abbf4 ---- ----1 ---- lac1 #abbh4 ---- ----1 ---- sulphur1 #abbh4 ---- ----1 ---- oil of turpentine1 #abbg4 induction1 specific1 #aafg1 #abeb1 #acjg4 ----1 the problem stated1 #abeb4 ----1 ---- solved1 #acjg4 ----1 of air1 #abhd4 ----1 ----1 invariable1 #abhg1 #abhh4 ----1 of gases1 #abhc1 #abij4 ----1 ---- alike in all1 #abib4 ----1 of shell-lac1 #abef1 #abfi4 ----1 glass1 #abga4 ----1 sulphur1 #abge4 ----1 spermaceti1 #abgi4 ----1 certain fluid insulators1 #abhj4 ,induction of electric currents1 #f1 #cd1 #bcb1 #bda1 #ajdh1 #ajhi1 #aaja1 #affj1 #agah4 ----1 on aiming the principal current1 #aj1 #bch1 #aaja4 ----1 on stopping the principal current1 #aj1 #ag1 #bch1 #ajhg1 #aajj4 ---- by approximation1 #ah1 #bcf4 ---- by increasing distance1 #ai1 #bcg4 ---- effective through conductors1 #agai1 #agba1 #agce4 ---- ---- insulators1 #agai1 #agbb1 #agce4 ---- in different metals1 #aic1 #bjb1 #baa1 #bac4 ---- in the moving earth1 #aha4 ---- in flowing water1 #aij4 ---- in revolving plates1 #he1 #bdj4 ----1 the induced current1 its direction1 #bf1 #bcb4 ----1 ---- duration1 #ai1 #dg1 #hi4 ----1 ----1 traverses fluids1 #bj1 #bc4 ----1 ----1 its intensity in different conductors1 #ahc1 #aic1 #bja1 #baa1 #bac4 ----1 ----1 not obtained by ,leyden discharge1 #bd4 ----1 ,ampre's results1 #gh1 #bee1 #cgi1 note4 ,induction of a current on itself1 #ajdh1 #aaji4 ----1 apparatus used1 #ajeb4 ----1 in a long wire1 #ajfd1 #ajfh1 #ajib1 #aaah4 ----1 ---- doubled wire1 #ajif4 ----1 ---- helix1 #ajec1 #ajfa4 ---- in doubled helices1 #ajif4 ---- in an electro-magnet1 #ajef1 #ajfj4 ----1 wire and helix compared1 #ajfe4 ----1 short wire1 effects with1 #ajfg4 ----1 action momentary1 #ajgj1 #ajia1 #aajj4 ----1 causes no permanent change in the current1 #ajga4 ----1 not due to momentum1 #ajgg4 ----1 induced current separated1 #ajgh1 #ajhi4 ----1 effect at breaking contact1 #ajfj1 #ajha1 #ajhd1 #ajhg4 ----1 ---- making contact1 #aaja1 #aajf4 ----1 effects produced1 shock1 #ajfj1 #ajfd1 #ajgi4 ----1 ---- spark1 #ajfj1 #ajfd1 #ajhj4 ----1 ---- chemical decomposition1 #ajhd4 ----1 ---- ignition of wire1 #ajha1 #aajd4 ----1 cause is in the conductor1 #ajei1 #ajgj4 ----1 general principles of the action1 #ajic1 #aajg4 ----1 direction of the forces lateral1 #aajh4 induction1 magnetic1 #bee1 #afeh1 #agaj4 ----1 by intermediate particles1 #affc1 #agaj1 #agbi1 #agce4 ----1 through quiescent bodies1 #agab1 #agai1 #agbj1 #agce4 ----1 ---- moving bodies1 #agae1 #agaf1 #agai4 ---- and magneto-electric1 distinguished1 #ach1 #bae1 #bdc1 #bec4 ,induction1 magneto-electric1 #bg1 #eh1 #ha1 #adj1 #aic1 #agji4 ,see ,arago's magnetic phenomena4 ----1 magnelectric1 #eh4 ----1 electrolytic1 #aafd1 #acde1 #agjb1 #agdj4 ----1 volta-electric1 #bf4 ,inductive capacity1 specific1 #aafg1 #abeb4 ,inductive force of currents lateral1 #bf1 #aajh4 ----1 its nature1 #aaac1 #affj1 #affc1 #agji4 ,inductive force1 lines of1 #abca1 #abig1 #acjd4 ----1 often curved1 #abai1 #abbd1 #abcj4 ----1 exhibited by the brush1 #addi4 ----1 their lateral relation1 #abca1 #abig1 #acjd4 ----1 their relation to magnetism1 #adaa1 #afeh1 #agji4 ,inductometer1 differential1 #acjg1 #acag4 ,inductric surfaces1 #adhc4 ,inexhaustible nature of the electric current1 #afca4 ,inseparability of the two electric forces1 #aafc1 #aagg1 #abdd1 #afbh4 ,insulating power of different gases1 #achh1 #acie1 #aejg4 ,insulation1 #acbj1 #acei1 #acfa4 ----1 its nature1 #acba4 ---- is sustained induction1 #acbd4 ----1 degree of induction sustained1 #acfb4 ---- dependent on the dielectrics1 #acfh4 ---- ---- distance in air1 #acjc1 #acfd1 #acga4 ---- ---- density of air1 #acfe1 #acge4 ---- ---- induction1 #acfh4 ---- ---- form of conductors1 #acjb1 #acgd4 ----1 as affected by temperature of air1 #acfg1 #achj4 ---- in different gases1 #acha1 #achh4 ---- ---- differs1 #acie4 ---- in liquids and solids1 #adjc4 ---- in metals1 #acbh1 #acca1 #accb4 ---- and conduction not essentially different1 #acbj1 #acbf1 #accf1 #acch1 #aefa4 ----1 its relation to induction1 #acbd1 #acfb1 #acfh1 #afgh4 ,insulators1 liquid1 good1 #aagb4 ----1 solid1 good1 #abed4 ----1 the best conduct1 #abcc1 #abda1 #abde1 #abdg1 #abed4 ---- tested as to conduction1 #abee4 ---- and conductors1 relation of1 #acbh1 #accd1 #acch4 ,intensity1 its influence in conduction1 #dai4 ----1 inductive1 how represented1 #acgj4 ----1 relative1 of magneto-electric currents1 #ahc1 #aic1 #baa1 #bac4 ---- of disruptive discharge constant1 #adaj4 ----1 electrolytic1 #iab1 #iff1 #ihc1 #aced4 ---- necessary for electrolyzation1 #iaa1 #iff4 ---- of the current of single circles1 #ijd4 ---- ---- increased1 #ijf4 ---- of electricity in the voltaic battery1 #iij1 #iic4 ---- of voltaic current increased1 #ijf1 #iij4 ,interference with combining power of platina1 #fch1 #fee4 ---- by olefiant gas1 #fdj4 ---- carbonic oxide1 #fde4 ---- sulphuret of carbon1 #fej4 ---- ether1 #fea4 ,interpositions1 their retarding effects1 #ajah4 ,iodides in solution1 their electrolysis1 #gfi4 ---- fusion1 their electrolysis1 #hjb1 #hac4 ,iodide of lead1 electrolysed1 #hjb1 #hah4 ---- of potassium1 test of chemical action1 #caf4 ,ions1 what1 #ffe1 #hbd1 #hcc1 #hcd1 #hdi4 ---- not transferable alone1 #edb1 #edg1 #hbf4 ----1 table of1 #hdg4 ,iron1 both magnetic and magneto-electric at once1 #ach1 #bed4 ----1 copper and sulphur circles1 #idc4 ,jenkin1 his shock by one pair of plates1 #ajdi4 ,kemp1 his amalgam of zinc1 #iii4 ,knight1 ,dr4 ,gowin1 his magnet1 #dd4 ,lac1 charge removed from1 #abjc4 ----1 induction through1 #abee4 ----1 specific inductive capacity of1 #abef1 #abfi4 ----1 effects of its conducting power1 #abcd4 ----1 its relation to conduction and insulation1 #acbd4 ,lateral direction of inductive forces of currents1 #bf1 #aajh4 ---- forces of the current1 #afec1 #agji4 ,law of conduction1 new1 #chj1 #cid1 #daj4 ---- magneto-electric induction1 #aad4 ---- volta-electric induction1 #bf4 ,lead1 chloride of1 electrolysed1 #gid1 #hae4 ----1 fluoride of1 conducts well when heated1 #acdj4 ----1 iodide of1 electrolysed1 #hjb1 #hah4 ----1 oxide of1 electrolysed1 #gig4 ,leyden jar1 condition of its charge1 #afhb4 ----1 its charge1 nature of1 #acjj4 ----1 its discharge1 #acjj4 ----1 its residual charge1 #abdi4 ,light1 polarized1 passed across electrolytes1 #iea4 ----1 electric1 #adje1 #adde1 #aefj1 note4 ----1 ----1 spark1 #adjf1 #aeec4 ----1 ----1 brush1 #adbe1 #addd1 #adde4 ----1 ----1 glow1 #aebf4 ,lightning1 #adbj1 #adjd1 #afda4 ,lines of inductive force1 #abca1 #acjd1 ---- often curved1 #abai1 #abbd1 #abcj4 ----1 as shown by the brush1 #addi4 ----1 their lateral relation1 #abca1 #abig1 #acjd4 ----1 their relation to magnetism1 #adaa1 #afeh1 #agji4 ,liquefaction1 conduction consequent upon1 #chj1 #cid1 #daj4 ,liquid bodies which are non-conductors1 #dje4 ,local chemical affinity1 #idg1 #iei1 #ifa1 #agci4 ,machine1 electric1 evolution of electricity by1 #agdh4 ------1 magneto-electric1 #ace1 #aed1 #aeh1 #aaah4 ,magnelectric induction1 #eh4 ----1 collectors or conductors1 #hf4 ,magnesia1 sulphate1 decomposed against water1 #did1 #ecc4 ----1 transference of1 #die4 ,magnet1 a measure of conducting power1 #baf4 ---- and current1 their relation remembered1 #ch1 note4 ---- ---- plate revolved together1 #bah4 ---- ---- cylinder revolved together1 #bai4 ---- revolved alone1 #bbj1 #bbc4 ---- and moving conductors1 their general relation1 #bef4 ---- made by induced current1 #ac1 #ad4 ----1 electricity from1 #cf1 #bbj1 #bbc4 ,magnetic bodies1 but few1 #bee4 ----1 curves1 their inductive relation1 #bag1 #bcb4 ---- effects of voltaic electricity1 #bgg4 ---- ---- common electricity1 #bhh1 #cfg4 ---- ---- magneto-electricity1 #bg1 #hc1 #cde4 ---- ---- thermo-electricity1 #cdi4 ---- ---- animal electricity1 #ced4 ---- and electric forces1 their relation1 #aah1 #adaa1 #afec1 #afeh1 #agji1 #agca4 ---- forces active through intermediate particles1 #affc1 #agaj1 #agbi1 #agce4 ---- forces of the current1 #afec4 ---- ---- very constant1 #afed4 ---- deflection by common electricity1 #bhi1 #bif4 ---- phenomena of ,arago explained1 #ha4 ---- induction4 ,see ,induction1 magnetic4 ---- induction through quiescent bodies1 #agab1 #agai1 #agbj1 #agce4 ---- ---- moving bodies1 #agae1 #agai4 ---- and magneto-electric action distinguished1 #ach1 #bae1 #bdc1 #bec4 ,magnetism1 electricity evolved by1 #bg4 ----1 its relation to the lines of inductive force1 #adaa1 #afeh1 #agji4 ---- bodies classed in relation to1 #bee4 ,magneto-electric currents1 their intensity1 #ahc1 #aic1 #baa1 #bac4 ----1 their direction1 #aad1 #aaj4 ---- traverse fluids1 #cc4 ---- momentary1 #cj4 ---- permanent1 #hi4 ---- in all conductors1 #aic1 #bac4 ,magneto-electric induction1 #bg1 #eh4 ----1 terrestrial1 #aaj1 #aha4 ----1 law of1 #aad4 ----4 ,see ,arago's magnetic phenomena4 ,magneto-electric machines1 #ace1 #aed1 #aeh4 ----1 inductive effects in their wires1 #aaah1 ,magneto-electricity1 its general characters considered1 #cdc1 c4 ---- identical with other electricities1 #cfj4 ----1 its tension1 #cdc4 ----1 evolution of heat1 #cdd4 ----1 magnetic force1 #cde4 ----1 chemical force1 #cdf4 ----1 spark1 #cdh4 ----1 physiological effects1 #cdg4 ----4 ,see ,induction1 magnetic4 ,matter1 atoms of1 #hfi1 #agjc4 ----1 new condition of1 #fj1 #bca1 #bdb1 #aaad1 #affa1 #agbi4 ----1 quantity of electricity in1 #heb1 #hfa1 #hgc1 #afeb4 ----1 absolute charge of1 #aafi4 ,measures of electricity1 galvanometer1 #cfg1 note4 ----1 voltameter1 #gjd1 #gcf1 #gci4 ----1 metal precipitated1 #gdj1 #hdb4 ,measure of specific inductive capacity1 #acjg1 #afjj4 ,measurement of common and voltaic electricities1 #cfa1 #hfj1 #afeb4 ---- electricity1 degree1 #gcf1 #gch4 ---- ---- by voltameter1 #gjd1 #gcf1 #gci4 ---- ---- by galvanometer1 #cfg1 note4 ---- ---- by metal precipitated1 #gdj1 #hdb4 ,mechanical forces affect chemical affinity1 #fef4 ,mercurial terminations for convection1 #aeha4 ,mercury1 periodide of1 an exception to the law of conduction8 #fia1 #acda4 ----1 perchloride of1 #fib1 #acda4 ,metallic contact not necessary for electrolyzation1 #hgi4 ---- not essential to the voltaic current1 #hgi1 #hhg1 #iae4 ---- its use in the pile1 #hic1 #hif4 ,metallic poles1 #eeg4 ,metal and electrolyte1 their state1 #idf4 ,metals1 adhesion of fluids to1 #ajch4 ----1 their power of inducing combination #efd1 #fjh4 ----1 ---- interfered with1 #fch4 ----1 static induction in1 #acbi1 #accb4 ----1 different1 currents induced in1 #aic1 #baa4 ----1 generally secondary results of electrolysis1 #gdf4 ---- transfer chemical force1 #iah4 ----1 transference of1 #eci1 #ede4 ---- insulate in a certain degree1 #acbh4 ----1 convective currents in1 #afjc4 ----1 but few magnetic1 #bee4 ,model of relation of magnetism and electricity1 #aaf4 ,molecular inductive action1 #aafd1 #affi4 ,motion essential to magneto-electric induction1 #ci1 #bag1 #bef4 ---- across magnetic curves1 #bag4 ---- of conductor and magnet1 relative1 #aad4 ---- ---- not necessary1 #bah4 ,moving magnet is electric1 #bbj4 ,muriatic acid gas1 its high insulating power1 #acie4 ----1 brush in1 #adfb4 ----1 dark discharge in1 #aeed4 ----1 glow in1 #aecd4 ----1 positive and negative brush in1 #adgf4 ----1 spark in1 #adbb1 #adfc4 ----1 ----1 has no dark interval1 #adfc1 #aeee4 ,muriatic acid decomposed by common electricity1 #cad4 ----1 its electrolysis 7primary71 #geh1 #ghf4 ,nascent state1 its relation to combination1 #feh1 #gag4 ,natural standard of direction for current1 #ffc4 ---- relation of electrolytic intensity1 #ihg4 ,nature of the electric current1 #afag4 ---- force or forces1 #affg4 ,negative current1 none1 #afbg1 #afcb4 ---- discharge1 #adfe1 #adhd4 ---- ----1 as ,spark1 #adfg1 #adhb4 ---- ----1 as brush1 #adff1 #aejb4 ---- spark or brush1 #adhd1 #aejb4 ,negative and positive discharge1 #adfe1 #adhb1 #aebe ---- in different gases1 #acic4 ,new electrical condition of matter1 #fj1 #bca1 #bdb1 #aaad1 #affa1 #agbi4 ---- law of conduction1 #chj1 #cid1 #daj4 ,nitric acid formed by spark in air1 #cbd4 ---- favours excitation of current1 #ijf1 #aach ---- ---- transmission of current1 #ajbj4 ---- is best for excitation of battery1 #aacg4 ----1 nature of its electrolysis1 #geb4 ,nitrogen determined to either pole1 #eed1 #gdh1 #geb4 ---- a secondary result of electrolysis1 #gdf1 #gdh4 ----1 brush in1 #adeh4 ----1 dark discharge in1 #aeei4 ----1 glow in1 #aecd4 ----1 spark in1 #adbb1 #adfc4 ----1 positive and negative brush in1 #adgf4 ----1 ---- discharge in1 #aeab4 ----1 its influence on lightning1 #adfd4 ,nomenclature1 #ffb1 #adhc4 ,nonconduction by solid electrolytes1 #cha1 #aceh1 #agje4 ,note on electrical excitation1 #agcg4 ,nuclei1 their action1 #fbc1 #feg4 ,olefiant gas1 interference of1 #faj1 #feb4 ,ordinary electricity1 its tension1 #bhe4 ---- evolution of heat1 #bhg4 ---- magnetic force1 #bhh1 #cfb4 ---- chemical force1 #cji1 #ded4 ---- ----1 precautions1 #cbb4 ---- spark1 #ccc4 ---- physiological effect1 #ccb4 ---- general characters considered1 #bhd4 ----1 identity with other electricities1 #cfj4 ,origin of the force of the voltaic pile1 #hgh1 #iaj1 #iai4 ,oxidation the origin of the electric current in the voltaic pile1 #iai1 #icj4 ,oxide of lead electrolysed1 #gig4 ,oxygen1 brush in1 #adeg4 ----1 positive and negative brush in1 #adgf1 ----1 ---- discharge in1 #aeac4 ----1 solubility of1 in cases of electrolyzation1 #gag1 #gbh4 ----1 spark in1 #adbb4 ---- and hydrogen combined by platina plates1 #egj1 #fje1 #fcj4 ---- ---- spongy platina1 #fji1 #fcf4 ---- ---- other metals1 #fjh4 ,particles1 their nascent state1 #feh4 ---- in air1 how charged1 #aefd4 ----1 neighbouring1 their relation to each other1 #fai1 #fbd1 #feg4 ----1 contiguous1 active in induction1 #aafe1 #afgg4 ---- of a dielectric1 their inductive condition1 #acfi1 #adaj1 #affi4 ----1 polarity of1 when under induction1 #abih1 #afgf4 ----1 how polarised1 #affi1 #afgi4 ----1 ----1 in any direction1 #afhi4 ----1 ----1 as wholes or elements1 #afii4 ----1 ----1 in electrolytes1 #agjb4 ----1 crystalline1 #afhi4 ----1 contiguous1 active in electrolysis1 #acdi1 #agjb4 ----1 their action in electrolyzation1 #ebj1 #acdc1 #agjc4 ----1 ---- local chemical action1 #ifa1 #agci4 ----1 ---- relation to electric action1 #gc4 ----1 ---- electric action1 #affi1 #afgi1 #agdj4 ,path of the electric spark1 #aajg4 ,phosphoric acid not an electrolyte1 #fhb4 ,physiological effects of voltaic-electricity1 #bgi4 ---- common electricity1 #ccb4 ---- magneto-electricity1 #ef1 #cdg4 ---- thermo-electricity1 #cdi4 ---- animal electricity1 #ceg4 ,pile1 voltaic1 electricity of1 #hge4 ----4 ,see ,battery1 voltaic4 ,plates of platina effect combination1 #efh1 #ega1 #eij1 #fcj4 ---- prepared by electricity1 #egj1 #ehe1 #ehh4 ---- ---- friction1 #eia4 ---- ---- heat1 #eie4 ---- ---- chemical cleansing1 #eii1 #fje1 ----1 clean1 their general properties1 #fcc1 #gag4 ----1 their power preserved1 #egf4 ----1 ---- in water1 #ehj4 ----1 their power diminished by action1 #eha4 ----1 ---- exposure to air1 #fcf4 ----1 their power affected by washing in water1 #ehb4 ----1 ---- heat1 #ehd1 #eig4 ----1 ---- presence of certain gases1 #fch1 #fee4 ----1 their power1 cause of1 #eij1 #faf1 #fcj4 ----1 theory of their action1 ,dbereiner's1 #faj4 ----1 ----1 ,dulong and ,thenard's1 #faa4 ----1 ----1 ,fusinieri's1 #fac4 ----1 ----1 author's1 #fai1 #fbf1 #fcj1 #fef4 ,plates of voltaic battery foul1 #aade4 ----1 new and old1 #aaaf4 ----1 vicinity of1 #aadh4 ----1 immersion of1 #ajjc1 #aaej4 ----1 number of1 #ihi1 #aaea4 ----1 large or small1 #aaed4 ,platina1 clean1 its characters1 #fcc1 #gag4 ---- attracts matter from the air1 #fcd4 ----1 spongy1 its state1 #fcg4 ----1 clean1 its power of effecting combination1 #efd1 #eij1 #fje1 #fag1 #fcj4 ----1 ---- interfered with1 #fch4 ----1 its action retarded by olefiant gas1 #fdj1 #feb4 ----1 ----1 carbonic oxide1 #fde1 #feb4 ----4 ,see ,combination1 ,plates of platina1 and ,interference4 ---- poles1 recombination effected by1 #efg1 #ehh4 ,plumbago poles for chlorides1 #gid4 ,poisson's theory of electric induction1 #acje4 ,points1 favour convective discharge1 #aegc4 ----1 fluid for convection1 #aeha4 ,polar forces1 their character1 #affe4 ---- decomposition by common electricity1 #cab1 #cba1 #dfi4 ,polarity1 meaning intended1 #acjd1 #afhe4 ---- of particles under induction1 #abih1 #afgf4 ----1 electric1 #ajgj1 #ajhe4 ----1 ----1 its direction1 #afhh1 #agjc1 ----1 ----1 its variation1 #afhg4 ----1 ----1 its degree1 #afhf4 ----1 ----1 in crystals1 #afhi4 ----1 ----1 in molecules or atoms1 #afii4 ----1 ----1 in electrolytes1 #agjb4 ,polarized light across electrolytes1 #iea4 ,poles1 electric1 their nature1 #dfa1 #dih1 #eef1 #ffb4 ----1 appearance of evolved bodies at1 accounted for1 #ece4 ---- one element to either8 #eeb1 #fha1 #geg4 ----1 of air1 #dee1 #dfa1 #eei4 ----1 of water1 #dia1 #eeh4 ----1 of metal1 #eeg4 ----1 of platina1 recombination effected by1 #efg1 #ehh4 ----1 of plumbago1 #gid4 ,poles1 magnetic1 distinguished1 #dd1 note4 ,porrett's peculiar effects1 #afdf4 ,positive current none1 #afbg1 #afcb4 ---- discharge1 #adfe1 #adhj4 ---- ----1 as spark1 #adfg1 #adhb4 ---- ----1 as brush1 #adfg1 #adgf4 ---- spark or brush1 #adhd1 #aejb4 ---- and negative1 convective discharge1 #afjj4 ---- ---- disruptive discharge1 #adfe1 #adhb1 #adhe1 #aebe4 ---- ---- ---- in different gases1 #acic4 ---- ---- voltaic discharge1 #aebd4 ---- ---- electrolytic discharge1 #aebe4 ,potassa acetate1 nature of its electrolysis1 #gdi4 ,potassium1 iodide of1 electrolysed1 #hje4 ,power of voltaic batteries estimated1 #aabf4 ,powers1 their state of tension in the pile1 #idi4 ,practical results with the voltaic battery1 #aacf4 ,pressure of air retains electricity1 explained1 #acgg1 #acih4 ,primary electrolytical results1 #gdb4 ,principles1 general1 of definite electrolytic action1 #hbb4 ,proportionals in electrolytes1 single1 #fgi1 #fig4 ,quantity of electricity in matter1 #heb1 #hfa1 #hgc1 #afeb4 ---- voltaic battery1 #iij4 ,rarefaction of air facilitates discharge1 why1 #acge4 ,recombination1 spontaneous1 of gases from water1 #eff4 ,relation1 by measure1 of electricities1 #cfa4 ---- of magnets and moving conductors1 #bef4 ---- of magnetic induction to intervening bodies1 #affb1 #agbh4 ---- of a current and magnet1 to remember1 #ch1 note4 ---- of electric and magnetic forces1 #aah1 #adaa1 #afec1 #afeh1agji1 #agca4 ---- of conductors and insulators1 #acba1 #acbf1 #accd1 #acch4 ---- of conduction and induction1 #acbj1 #accg4 ---- of induction and disruptive discharge1 #acfb4 ---- ---- electrolyzation1 #aafd1 #acdc4 ---- ---- excitation1 #aagh1 #agdj4 ---- ---- charge1 #aaga1 #aagg1 #acjj4 ---- of insulation and induction1 #acbd1 #acfb1 #acfh1 #afgh4 ----1 lateral1 of lines of inductive force1 #abca1 #abig1 #acjd4 ---- of a vacuum to electricity1 #afac4 ---- of spark1 brush1 and glow1 #aecc1 #aeci1 #aedb4 ---- of gases to positive and negative discharge1 #aeaj4 ---- of neighbouring particles to each other1 #fai1 #fbd4 ---- of elements in decomposing electrolytes1 #ibc1 #agjb4 ---- ---- exciting electrolytes1 #iba4 ---- of acids and bases voltaically1 #ibg1 #icc4 ,remarks on the active battery1 #ajcd1 #aacf4 ,residual charge of a ,leyden jar1 #abdi4 ,resistance to electrolysis1 #hia1 #ijd1 #iaa1 #ajjg4 ---- of an electrolyte to decomposition1 #ajjg4 ,results of electrolysis1 primary or secondary1 #gdb1 #ggg4 ----1 practical1 with the voltaic battery1 #aacf4 ----1 general1 as to induction1 #abie1 #affi4 ,retention of electricity by pressure of the atmosphere explained1 #acgg1 #acih4 ,revolving plate4 ,see ,arago's phenomena4 ---- globe1 ,barlow's1 effect explained1 #acg1 #afj1 #afi4 ---- ----1 magnetic1 #afd4 ---- ----1 direction of currents in1 #afa1 #aff4 ,riffault's and ,chompr's theory of electro-chemical decomposition1 #dhe1 #ejg1 #eab4 ,rock crystal1 induction across1 #afib4 ,room1 insulated and electrified1 #aagc4 ,rotation of the earth a cause of magneto-electric induction1 #aha4 ,salts considered as electrolytes1 #fih4 ,scale of electrolytic intensities1 #iab4 ,secondary electrolytical results1 #gjb1 #gdb1 #gdh1 #ggg4 ---- become measures of the electric current1 #hdc4 ,sections of the current1 #dih1 #afcd4 ----1 decomposing force alike in all1 #eja1 #afba4 ,sections of lines of inductive action1 #acfi4 ----1 amount of force constant1 #acfi4 ,shock1 strong1 with one voltaic pair1 #ajdi4 ,silver1 chloride of1 its electrolyzation1 #eda1 #hac1 #ijb4 ----1 electrolytic intensity for1 #igi4 ,silver1 sulphuret of1 hot1 conducts well1 #dcc4 ,simple voltaic circles1 #hge4 ----1 decomposition effected by1 #hig1 #ijd1 #ica4 ,single and many pairs of plates1 relation of1 #iij4 ,single voltaic circuits1 #hge4 ---- without metallic contact1 #hgi4 ---- with metallic contact1 #hic4 ---- their force exalted1 #ijf4 ---- give strong shocks1 #ajdi4 ---- ---- a bright spark1 #ajej4 ,solid electrolytes are non-conductors1 #cid1 #djb1 #aceh4 ----1 why1 #iaj1 #agje4 ,solids1 their power of inducing combination1 #efd1 #fah4 ---- interfered with1 #fch4 ,solubility of gases in cases of electrolyzation1 #gag1 #gbh4 ,source of electricity in the voltaic pile1 #hge4 ---- is chemical action1 #hgi1 #iaf1 #iai1 #agda4 ,spark1 #acfj1 #adjf4 ,spark1 electric1 its conditions1 #acfj1 #adjf1 #aeec4 ---- path1 #adjg4 ---- light1 #aeec4 ---- insensible duration or time1 #adch4 ---- accompanying dark parts1 #aedg1 #afcb4 ---- determination1 #acgj4 #adji4 ,spark is affected by the dielectrics1 #acie1 #adba4 ---- size of conductor1 #acgb4 ---- form of conductor1 #acjb1 #acgd4 ---- rarefaction of air1 #acge4 ,spark1 atmospheric or lightning1 #adfd1 #afda4 ----1 negative1 #acic1 #adfg1 #adhb1 #adhd1 #aejb4 ----1 positive1 #acic1 #addh1 #adfg1 #adhb1 #adhd1 #aejb4 ----1 ragged1 #adbj1 #addh4 ----1 when not straight1 why1 #aefh4 ----1 variation in its length1 #acha4 ----1 tendency to its repetition1 #acib4 ----1 facilitates discharge1 #adag1 #aeec4 ----1 passes into brush1 #addh4 ----1 preceded by induction1 #acfb4 ----1 forms nitric acid in air1 #cbd4 ----1 in gases1 #achc1 #adba4 ----1 in air1 #adbb4 ----1 in nitrogen1 #adbb1 #adfc4 ----1 in oxygen1 #adbb4 ----1 in hydrogen1 #adbb4 ----1 in carbonic acid1 #adbb1 #adfc4 ----1 in muriatic acid gas1 #adbb1 #adfc4 ----1 in coal-gas1 #adbb4 ----1 in liquids1 #adbd4 ----1 precautions1 #ieh1 #ajgd4 ----1 voltaic1 without metallic contact1 #iae1 #ief4 ---- from single voltaic pair1 #ajej4 ---- from common and voltaic electricity assimilated1 #ccd4 ----1 first magneto-electric1 #cb4 ---- of voltaic electricity1 #bhj4 ---- of common electricity1 #ccc4 ---- of magneto-electricity1 #cdh4 ---- of thermo-electricity1 #cdi4 ---- of animal electricity1 #ceh4 ----1 brush and glow related1 #aecc1 #aeci1 #aedb4 ,sparks1 their expected coalition1 #adab4 ,specific induction4 ,see ,induction1 specific1 #abeb4 ,specific inductive capacity1 #abeb4 ----1 apparatus for1 #aahg4 ---- of lac1 #abef1 #abgj1 #acjh4 ---- of sulphur1 #abge1 #acaj4 ---- of air1 #abhd4 ---- of gases1 #abhc1 #abij4 ---- of glass1 #abga4 ,spermaceti1 its conducting power1 #abdj1 #acbc4 ----1 its relation to conduction and insulation1 #acbb4 ,standard of direction in the current1 #ffc4 ,state1 electrotonic1 #fj1 #bca1 #bdb1 #aaad1 #affa1 #agbi4 ,static induction4 ,see ,induction1 static4 ,sturgeon1 his form of ,arago's experiment1 #bdi4 ----1 use of amalgamated zinc by1 #hfc1 #iii4 ,sulphate of soda1 decomposed by common electricity1 #cag4 ----1 electrolytic intensity for1 #ige4 ,sulphur determined to either pole1 #eeb1 #fha1 #geg4 ----1 its conducting power1 #abda1 #abde4 ----1 its specific inductive capacity1 #abge4 ----1 copper and iron1 circle1 #idc4 ,sulphuret of carbon1 interference of1 #fej4 ---- silver1 hot1 conducts well1 #dcc4 ,sulphuretted solution excites the pile1 #idc4 ,sulphuric acid1 conduction by1 #dji1 #fha4 ----1 magneto-electric induction on1 #bjj1 #bac4 ---- in voltaic pile1 its use1 #ibe4 ---- not an electrolyte1 #fha4 ----1 its transference1 #ebe4 ----1 its decomposition1 #fha1 #geg4 ,sulphurous acid1 its decomposition1 #gee4 ,summary of conditions of conduction1 #ddc4 ---- molecular inductive theory1 #affi4 ,table of discharge in gases1 #achh4 ---- electric effects1 #cfj4 ---- electro-chemical equivalents1 #hdg4 ---- electrolytes affected by fusion1 #djb4 ---- insulation in gases1 #achh4 ---- ions1 anions1 and cathions1 #hdg4 ,tartaric acid1 nature of its electrolysis1 #gge4 ,tension1 inductive1 how represented1 #acgj4 ---- of voltaic electricity1 #bfh4 ---- of common electricity1 #bhe4 ---- of thermo-electricity1 #cdi4 ---- of magneto-electricity1 #cdc4 ---- of animal electricity1 #ceb4 ---- of zinc and electrolyte in the voltaic pile1 #idi4 ,terrestrial electric currents1 #ahg4 ,terrestrial magneto-electric induction1 #adj4 ---- cause of aurora borealis1 #aib4 ----1 electric currents produced by1 #ada1 #aej4 ----1 ----1 in helices alone1 #adh4 ----1 ----1 ---- with iron1 #ada1 #adf4 ----1 ----1 ---- with a magnet1 #adg4 ----1 ---- a single wire1 #agj4 ----1 ---- a revolving plate1 #adi4 ----1 ---- a revolving ball1 #afj4 ----1 ---- the earth1 #agc4 ,test between magnetic and magneto-electric action1 #bae1 #bdc4 ,theory of combination of gases by clean platina1 #fai1 #fbf1 #fcj1 #fef4 ---- electro-chemical decomposition1 #dgg1 #ffa1 #afbc1 #agjd4 ---- the voltaic apparatus1 #hge1 #agda4 ---- static induction1 #aafe1 #abca1 #abie1 #afff1 #affg4 ---- disruptive discharge1 #acfh1 #adjf1 #adcd4 ---- ,arago's phenomena1 #abj4 ,thermo-electricity1 its general characters1 #cdi4 ---- identical with other electricities1 #cfj4 ----1 its evolution of heat1 #cdi4 ----1 magnetic1 force1 #cdi4 ----1 physiological effects1 #cdi4 ----1 spark1 #cdi4 ,time1 #ei1 #fh1 #abd1 #abdh1 #acbh1 #acdf1 #adah1 #adca1 #adcf1 #adci1 #afab1 #afda1 #agcj4 ,tin1 iodide of1 electrolysed1 #hjd4 ----1 protochloride1 electrolysis of1 definite1 #ghi1 #hai4 ,torpedo1 nature of its electric discharge1 #cei4 ----1 its enormous amount of electric force1 #cei4 ,transfer of elements and the current1 their relation1 #ibc1 #ifb4 ,transference is simultaneous in opposite directions1 #edb1 #hbh4 ----1 uncombined bodies do not travel1 #edd1 #edf1 #hbf4 ---- of elements1 #ded1 #ejg1 #eci1 #eej1 #hbf4 ---- ---- across great intervals1 #dee1 #dfh4 ---- ----1 its nature1 #eai1 #ebe1 #ech1 #edi4 ---- of chemical force1 #iah4 ,transverse forces of the current1 #afec1 #agji4 ,travelling of charged particles1 #aefc4 ,trough1 voltaic4 ,see ,battery1 voltaic4 ,turpentine1 oil of1 a good fluid insulator1 #aagb4 ----1 its insulating power destroyed1 #aega4 ---- charged1 #aagb4 ----1 brush in1 #adeb1 ----1 electric motions in1 #aehh1 #aeie1 ----1 convective currents in1 #aeie1 #aeih4 ,unipolarity1 #afce4 ,vacuum1 its relation to electricity1 #afac4 ,vaporization1 #feg4 ,velocity of conduction in metals varied1 #accc4 ---- the electric discharge1 #afda1 #afdi4 ---- conductive and electrolytic discharge1 difference of1 #afej4 ,vicinity of plates in voltaic battery1 #aadh4 ,volta-electric induction1 #bf4 ,volta-electrometer1 #gjd1 #gcf4 ----1 fluid decomposed in it1 water1 #gjf1 #gbh1 #gcb4 ----1 forms of1 #gjg1 #gcd4 ---- tested for variation of electrodes1 #gad1 #gbb4 ---- ---- fluid within1 #gbg4 ---- ---- intensity1 #gbc4 ----1 strength of acid used in1 #gbh1gcc4 ----1 its indications by oxygen and hydrogen1 #gcf4 ----1 ---- hydrogen1 #gcd4 ----1 ---- oxygen1 #gce4 ----1 how used1 #gcg4 ,voltameter1 #gjd4 ,voltaic battery1 its nature1 #hge1 #ihi4 ----1 remarks on1 #ajcd1 #aacf4 ----1 improved1 #ajja1 #aaai4 ----1 practical results with1 #aacf4 ----4 ,see ,battery1 voltaic4 ,voltaic circles1 simple1 #hge4 ----1 decomposition by1 #hig4 ,voltaic circles associated1 or battery1 #ihi4 ,voltaic circuit1 relation of bodies in1 #ifb4 ----1 defined1 #bhb1 #eaa4 ----1 origin of1 #iaf1 #agda4 ----1 its direction1 #ffc1 #ibe1 ----1 intensity increased1 #ije1 #iij4 ----1 produced by oxidation of zinc1 #iai1 #icj4 ---- not due to combination of oxide and acid1 #ibe1 #icc4 ----1 its relation to the combining oxygen1 #iba1 #ifb4 ----1 ---- combining sulphur1 #idc4 ----1 ---- the transferred elements1 #ibc1 #ifb4 ----1 relation of bodies in1 #ifb4 ,voltaic current1 #afag4 ,see ,current1 electric4 ,voltaic discharge1 positive and negative1 #aebd4 ,voltaic decomposition1 #dej1 #fjj4 ,see ,decomposition1 electro-chemical4 ,voltaic electricity1 identical with electricity1 otherwise evolved1 #bfh1 #cfj4 ----1 discharged by points1 #bgb4 ----1 ---- hot air1 #bga1 #bgd4 ----1 its tension1 #bfh1 #bge4 ----1 evolution of heat by1 #bgf4 ----1 its magnetic force1 #bgg4 ----1 its chemical force1 #bgh4 ----1 its spark1 #bhj4 ----1 its physiological effects1 #bgi4 ----1 its general characters considered1 #bfh4 ,voltaic pile distinguished1 #hef1 note4 ----1 electricity of1 #hge4 ----1 depends on chemical action1 #hgb4 ----1 relation of acid and bases in the1 #ibg4 ----4 ,see ,battery1 voltaic4 ,voltaic spark without contact1 #iae1 #ief4 ----1 precautions1 #ieh1 #ajgd4 ,voltaic trough1 #ihi4 ,see ,battery1 voltaic4 ,water1 flowing1 electric currents in1 #aij4 ----1 retardation of current by1 #aaei4 ----1 its direct conducting power1 #ajag1 #aaei1 #acee4 ----1 ---- constant1 #ihd4 ----1 electro-chemical decomposition against1 #did1 #ecb4 ----1 poles of1 #did1 #ecc1 #eeh4 ----1 its influence in electro-chemical decomposition1 #dgb4 ---- is the great electrolyte1 #ibd4 ----1 the exciting electrolyte when pure1 #idd4 ----1 ---- acidulated1 #hhj1 #ibf1 #aacg4 ----1 ---- alkalized1 #ica1 #icd1 #ida4 ----1 electrolytic intensity for1 #ifh1 #iha1 #ajag4 ---- electrolyzed in a single circuit1 #hfb4 ----1 its electrolysis definite1 #gcb1 #ghe1 #hjg4 ----1 decomposition of by fine wires1 #cbg4 ----1 quantity of electricity in its elements1 #hec1 #hfa4 ----1 determined to either pole1 #eec4 ,wheatstone's analysis of the electric brush1 #adbg4 ---- measurement of conductive velocity in metals1 #acbh4 ,wire1 ignition of1 by the electric current1 #hec1 note1 #afca4 ---- is uniform throughout1 #afcj4 ,wire a regulator of the electric current1 #hec1 note4 ----1 velocity of conduction in1 varied1 #accc4 ----1 single1 a current induced in1 #agj4 ----1 long1 inductive effects in1 #ajfd1 #aaah4 ,wollaston on decomposition by common electricity1 #cji4 ---- decomposition of water by points1 #cbg4 ,zinc1 amalgamated1 its condition1 #hfc1 #ajjj4 ----1 used in pile1 #iii4 ,zinc1 how amalgamated1 #hfc4 ----1 of troughs1 its purity1 #aadd4 ----1 its relation to the electrolyte1 #idi4 ----1 its oxidation is the source of power in the pile1 #iai4 ---- plates of troughs1 foul1 #aade4 ---- ----1 new and old1 #aadf4 ----1 waste of1 in voltaic batteries1 #iig4 ,,the ,,end4 ,,printed ,,by ,,richard ,,and ,,john ,e4 ,,taylor4 ,,red ,,lion ,,court1 ,,fleet ,,street4 ,,works ,,published ,,by ,,richard ,,and ,,john ,e4 ,,taylor1 ,,printers ,,and ,,publishers ,,to ,,the ,,university ,,of ,,london1 ,,red ,,lion ,,court1 ,,fleet ,,street4 ,daubeny on ,active and ,extinct ,volcanos1 ,earthquakes1 and ,thermal ,springs2 with ,remarks on their ,causes1 ,products1 and influence on the condition of the ,globe4 ,by ,professor ,,charles ,,daubeny1 ,m4,d41 ,f4,r4,s4 ,second ,edition1 greatly enlarged4 #bas4 cloth1 with #ab ,maps and ,plates4 ,the ,london1 ,edinburgh and ,dublin ,philosophical ,magazine and ,journal of ,science1 being a continuation of ,tilloch's ',philosophical ,magazine1' ,nicholson's ',journal1' and ,thomson's ',annals of ,philosophy1' conducted by ,,sir ,,david ,,brewster1 ,k4,r4 ,,ll4,d4 ,f4,r4,s4 ,l4,e4 c4 ,,richard ,,taylor1 ,f4,s4,a4 ,l4,s4 ,g4,s4 ,astr4 ,s4 c4 ,,richard ,,phillips1 ,f4,r4,s4 ,l4,e4 ,f4,g4,s4 c4 ,,sir ,,robert ,,kane1 ,m4,d4 ,m4,r4,i4,a4 ,in ,monthly ,numbers1 price #bs4 #f;d4 each4 ,the ,second ,series1 in eleven volumes1 with a general ,index2 and the ,third or present ,series1 in thirty-one volumes 7with a general ,index to the first twelve71 may be had2 also a complete set at a reduced price1 from #agih to ,june #ahdh1 in one hundred and eleven volumes4 ,annals and ,magazine of ,natural ,history2 including ,zoology1 ,botany1 and ,geology2 being a continuation of the ',annals' combined with ,messrs4 ,london and ,charlesworth's ',magazine of ,natural ,history1' conducted by ,,sir ,w4 ,,jardine1 ,,bart41 ,f4,l4,s4 ,p4,j4 ,,selby1 ,,esq41 ,f4,l4,s4 ,dr4 ,,johnston4 ,,charles ,c4 ,,babington1 ,esq1 ,m4,a41 ,f4,l4,s4 ,dr4 ,,balfour1 ,prof4 ,bot4 ,edinb41 and ,,richard ,,taylor1 ,f4,l4,s4 ,new ,series4--,in 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,,the ,,advancement ,,of ,,science2 containing the ,mean ,right ,ascensions and ,north ,,polar ,,distances of ,,eight ,,thousand ,,three ,,hundred ,,and ,,seventy-,,seven ,,fixed ,,stars1 reduced to ,january #a1 #ahej3 together with their ,annual ,precessions1 ,secular ,variations1 and ,proper ,motions1 as well as the ,logarithmic ,constants for computing ,precession1 ,aberration and ,nutation3 with a ,preface explanatory of their ,construction and ,application4 ,by the late ,,francis ,,baily1 ,esq41 ,d4,c4,l4 ,oxford and ,dublin2 ,president of the ,royal ,astr4 ,soc4 c4 c4 c4--,price ,three ,guineas4 ,a ,catalogue of #dg1cij ,stars1 for the beginning of the year #ahjj1 from the observations of ,lalande1 in the ,,histoire ,,celeste ,,fran,,aise4 ,reduced at the expense of the ,british ,association for the ,advancement of ,science1 under the immediate superintendence of the late ,,francis ,,baily1 ,esq4 ,printed at the expense of ,her ,majesty's ,government4--,price #a #as4 ,a ,catalogue of #igff ,stars in the ,southern ,hemisphere1 for the beginning of the year #agej1 from the ,observations of the ,,abbe ,,de ,,lacaille1 made at the ,cape of ,good ,hope in the years #agea and #ageb4 ,reduced at the expense of the ,british ,association for the ,advancement of ,science1 under the immediate superintendence of the late ,professor ,,henderson1 ,director of the ,royal ,observatory1 ,edinburgh4 ,and printed at the expense of ,her ,majesty's ,government1 under the direction of the late ,,francis ,,baily1 ,esq4 ,with a ,preface by ,sir ,j4,f4,w4 ,,herschel1 ,bart41 ,h4,k41 ,president of the ,royal ,astronomical ,society4--,price #es4 ,hygrometrical ,tables1 to be used with1 and ,description of the ,,dry- and ,,wet-,,bulb ,,thermometers4 ,by ,,james ,,glaisher1 ,esq41 of the ,royal ,observatory1 ,greenwich4 ,royal #hvo1 #bs4 #f;d4 ,griffith's ,practical ,manual on ,urine1 c41 containing a ,description of the ,,general1 ,,chemical and ,,microscopical ,,characters of 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