,illustration3 ,to face the ,title4 ,,experiments ,,and ,,observations ,,on ,,different ,,kinds ,,of ,,air4 ,price #es4 unbound4 ,quamobrem1 si qua est erga ,creatorem humilitas1 si qua operum ejus reverentia et magnificatio1 si qua charitas in homines1 si erga necessitates et rumnas humanas relevandas studium1 si quis amor veritatis in naturalibus1 et odium tenebrarum1 et intellectus purificandi desiderium2 orandi sunt homines iterum atque iterum1 ut1 missis philosophiis istis volaticis et preposteris1 qu theses hypothesibus anterposuerunt1 et experientiam captivam duxerunt1 atque de operibus dei triumpharunt1 summisse1 et cum veneratione quadam1 ad volumen creaturarum evolvendum accedant2 atque in eo moram faciant1 meditentur1 et ab opinionibus abluti et mundi1 caste et integre versentur4----,in interpretatione ejus eruenda nulli oper parcant1 sed strenue procedant1 persistant1 immoriantur4 ,,lord ,,bacon ,,in ,,instauratione ,,magna4 ,,experiments ,,and ,,observations ,,on ,,different ,,kinds ,,of ,,air4 ,by ,,joseph ,,priestley1 ,,ll4,d4 ,f4,r4,s4 ,the ,,second ,,edition ,corrected4 ,fert animus ,causas tantarum expromere rerum2 ,immensumque aperitur opus4 ,,lucan ,,london3 ,printed for ,j4 ,,johnson1 ,no4 #gb1 in ,st4 ,paul's ,church-,yard4 ,,mdcclxxv4 ,,to ,,the ,,right ,,honourable ,,the ,,earl ,,of ,,shelburne1 ,,this ,,treatise ,,is ,,with ,,the ,,greatest ,,gratitude ,,and ,,respect1 ,,inscribed1 ,,by ,,his ,,lordship's ,,most ,,obliged1 ,,and ,,obedient ,,humble ,,servant1 ,j4 ,,priestley4 ,transcriber's ,note3 ,footnotes have been moved to the end of the chapter4 ,the errata listed at the end of the book have been corrected in the text4 ,in the text1 there are places where the apothecary symbols for ounce and dram are used4 ,these are changed to oz4 and dr4 in the text file4 ,,the ,,preface4 ,one reason for the present publication has been the favourable reception of those of my ,observations on different kinds of air1 which were published in the ,philosophical ,transactions for the year #aggb1 and the demand for them by persons who did not chuse1 for the sake of those papers only1 to purchase the whole volume in which they were contained4 ,another motive was the additions to my observations on this subject1 in consequence of which my papers grew too large for such a publication as the ,philosophical ,transactions4 ,contrary1 therefore1 to my intention1 expressed ,philosophical ,transactions1 vol4 #fd4 p4 #ij1 but with the approbation of the ,president1 and of my friends in the society1 ,i have determined to send them no more papers for the present on this subject1 but to make a separate and immediate publication of all that ,i have done with respect to it4 ,besides1 considering the attention which1 ,i am informed1 is now given to this subject by philosophers in all parts of ,europe1 and the rapid progress that has already been made1 and may be expected to be made in this branch of knowledge1 all unnecessary delays in the publication of experiments relating to it are peculiarly unjustifiable4 ,when1 for the sake of a little more reputation1 men can keep brooding over a new fact1 in the discovery of which they might1 possibly1 have very little real merit1 till they think they can astonish the world with a system as complete as it is new1 and give mankind a prodigious idea of their judgment and penetration2 they are justly punished for their ingratitude to the fountain of all knowledge1 and for their want of a genuine love of science and of mankind1 in finding their boasted discoveries anticipated1 and the field of honest fame pre-occupied1 by men1 who1 from a natural ardour of mind1 engage in philosophical pursuits1 and with an ingenuous simplicity immediately communicate to others whatever occurs to them in their inquiries4 ,as to myself1 ,i find it absolutely impossible to produce a work on this subject that shall be any thing like complete4 ,my first publication ,i acknowledged to be very imperfect1 and the present1 ,i am as ready to acknowledge1 is still more so4 ,but1 paradoxical as it may seem1 this will ever be the case in the progress of natural science1 so long as the works of ,god are1 like himself1 infinite and inexhaustible4 ,in completing one discovery we never fail to get an imperfect knowledge of others1 of which we could have no idea before2 so that we cannot solve one doubt without creating several new ones4 ,travelling on this ground resembles ,pope's description of travelling among the ,alps1 with this difference1 that here there is not only succession1 but an increase of new objects and new difficulties4 ,so pleas'd at first the tow'ring ,alps we try1 ,mount o'er the vales1 and seem to tread the sky4 ,th' eternal snows appear already past1 ,and the first clouds and mountains seem the last1 ,but those attain'd1 we tremble to survey ,the growing labours of the lengthen'd way4 ,th' increasing prospect tires our wand'ring eyes1 ,hills peep o'er hills1 and ,alps on ,alps arise4 ,,essay ,,on ,,criticism4 ,newton1 as he had very little knowledge of air1 so he had few doubts concerning it4 ,had ,dr4 ,hales1 after his various and valuable investigations1 given a list of all his desiderata1 ,i am confident that he would not have thought of one in ten that had occurred to me at the time of my last publication2 and my doubts1 queries1 and hints for new experiments are very considerably increased1 after a series of investigations1 which have thrown great light upon many things of which ,i was not able to give any explanation before4 ,i would observe farther1 that a person who means to serve the cause of science effectually1 must hazard his own reputation so far as to risk even mistakes in things of less moment4 ,among a multiplicity of new objects1 and new relations1 some will necessarily pass without sufficient attention2 but if a man be not mistaken in the principal objects of his pursuits1 he has no occasion to distress himself about lesser things4 ,in the progress of his inquiries he will generally be able to rectify his own mistakes2 or if little and envious souls should take a malignant pleasure in detecting them for him1 and endeavouring to expose him1 he is not worthy of the name of a philosopher1 if he has not strength of mind sufficient to enable him not to be disturbed at it4 ,he who does not foolishly affect to be above the failings of humanity1 will not be mortified when it is proved that he is but a man4 ,in this work1 as well as in all my other philosophical writings1 ,i have made it a rule not to conceal the real views with which ,i have made experiments2 because though1 by following a contrary maxim1 ,i might have acquired a character of greater sagacity1 ,i think that two very good ends are answered by the method that ,i have adopted4 ,for it both tends to make a narrative of a course of experiments more interesting1 and likewise encourages other adventurers in experimental philosophy2 shewing them that1 by pursuing even false lights1 real and important truths may be discovered1 and that in seeking one thing we often find another4 ,in some respects1 indeed1 this method makes the narrative longer1 but it is by making it less tedious2 and in other respects ,i have written much more concisely than is usual with those who publish accounts of their experiments4 ,in this treatise the reader will often find the result of long processes expressed in a few lines1 and of many such in a single paragraph2 each of which1 if ,i had1 with the usual parade1 described it at large 7explaining first the preparation1 then reciting the experiment itself1 with the result of it1 and lastly making suitable reflections7 would have made as many sections or chapters1 and have swelled my book to a pompous and respectable size4 ,but ,i have the pleasure to think that those philosophers who have but little time to spare for reading1 which is always the case with those who do much themselves1 will thank me for not keeping them too long from their own pursuits2 and that they will find rather more in the volume1 than the appearance of it promises4 ,i do not think it at all degrading to the business of experimental philosophy1 to compare it1 as ,i often do1 to the diversion of hunting1 where it sometimes happens that those who have beat the ground the most1 and are consequently the best acquainted with it1 weary themselves without starting any game2 when it may fall in the way of a mere passenger2 so that there is but little room for boasting in the most successful termination of the chace4 ,the best founded praise is that which is due to the man1 who1 from a supreme veneration for the ,god of nature1 takes pleasure in contemplating his works1 and from a love of his fellow-creatures1 as the offspring of the same all-wise and benevolent parent1 with a grateful sense and perfect enjoyment of the means of happiness of which he is already possessed1 seeks1 with earnestness1 but without murmuring or impatience1 that greater command of the powers of nature1 which can only be obtained by a more extensive and more accurate knowledge of them2 and which alone can enable us to avail ourselves of the numerous advantages with which we are surrounded1 and contribute to make our common situation more secure and happy4 ,besides1 the man who believes that there is a governor as well as a maker of the world 7and there is certainly equal reason to believe both7 will acknowledge his providence and favour at least as much in a successful pursuit of knowledge1 as of wealth2 which is a sentiment that entirely cuts off all boasting with respect to ourselves1 and all envy and jealousy with respect to others2 and disposes us mutually to rejoice in every new light that we receive1 through whose hands soever it be conveyed to us4 ,i shall pass for an enthusiast with some1 but ,i am perfectly easy under the imputation1 because ,i am happy in those views which subject me to it2 but considering the amazing improvements in natural knowledge which have been made within the last century1 and the many ages1 abounding with men who had no other object but study1 in which1 however1 nothing of this kind was done1 there appears to me to be a very particular providence in the concurrence of those circumstances which have produced so great a change2 and ,i cannot help flattering myself that this will be instrumental in bringing about other changes in the state of the world1 of much more consequence to the improvement and happiness of it4 ,this rapid progress of knowledge1 which1 like the progress of a wave of the sea1 of sound1 or of light from the sun1 extends itself not this way or that way only1 but in all directions1 will1 ,i doubt not1 be the means1 under ,god1 of extirpating all error and prejudice1 and of putting an end to all undue and usurped authority in the business of religion1 as well as of science2 and all the efforts of the interested friends of corrupt establishments of all kinds will be ineffectual for their support in this enlightened age3 though1 by retarding their downfal1 they may make the final ruin of them more complete and glorious4 ,it was ill policy in ,leo the ,xth to patronize polite literature4 ,he was cherishing an enemy in disguise4 ,and the ,english hierarchy 7if there be any thing unsound in its constitution7 has equal reason to tremble even at an air-pump1 or an electrical machine4 ,there certainly never was any period in which natural knowledge made such a progress as it has done of late years1 and especially in this country2 and they who affect to speak with supercilious contempt of the publications of the present age in general1 or of the ,royal ,society in particular1 are only those who are themselves engaged in the most trifling of all literary pursuits1 who are unacquainted with all real science1 and are ignorant of the progress and present state of it4#a ,it is true that the rich and the great in this country give less attention to these subjects than1 ,i believe1 they were ever known to do1 since the time of ,lord ,bacon1 and much less than men of rank and fortune in other countries give to them4 ,but with us this loss is made up by men of leisure1 spirit1 and ingenuity1 in the middle ranks of life1 which is a circumstance that promises better for the continuance of this progress in useful knowledge than any noble or royal patronage4 ,with us1 politics chiefly engage the attention of those who stand foremost in the community1 which1 indeed1 arises from the freedom and peculiar excellence of our constitution1 without which even the spirit of men of letters in general1 and of philosophers in particular1 who never directly interfere in matters of government1 would languish4 ,it is rather to be regretted1 however1 that1 in such a number of nobility and gentry1 so very few should have any taste for scientifical pursuits1 because1 for many valuable purposes of science1 wealth gives a decisive advantage4 ,if extensive and lasting fame be at all an object1 literary1 and especially scientifical pursuits1 are preferable to political ones in a variety of respects4 ,the former are as much more favourable for the display of the human faculties than the latter1 as the system of nature is superior to any political system upon earth4 ,if extensive usefulness be the object1 science has the same advantage over politics4 ,the greatest success in the latter seldom extends farther than one particular country1 and one particular age2 whereas a successful pursuit of science makes a man the benefactor of all mankind1 and of every age4 ,how trifling is the fame of any statesman that this country has ever produced to that of ,lord ,bacon1 of ,newton1 or of ,boyle2 and how much greater are our obligations to such men as these1 than to any other in the whole ,biographia ,britannica2 and every country1 in which science has flourished1 can furnish instances for similar observations4 ,here my reader will thank me1 and the writer will1 ,i hope1 forgive me1 if ,i quote a passage from the postscript of a letter which ,i happen to have just received from that excellent1 and in my opinion1 not too enthusiastical philosopher1 father ,beccaria of ,turin4 ,mi spiace che il mondo politico ch' pur tanto passeggero1 rubbi il grande ,franklin al mondo della natura1 che non sa ne cambiare1 ne mancare4 ,in ,english4 ,i am sorry that the political world1 which is so very transitory1 should take the great ,franklin from the world of nature1 which can never change1 or fail4 ,i own it is with peculiar pleasure that ,i quote this passage1 respecting this truly great man1 at a time when some of the infatuated politicians of this country are vainly thinking to build their wretched and destructive projects1 on the ruins of his established reputation2 a reputation as extensive as the spread of science itself1 and of which it is saying very little indeed1 to pronounce that it will last and flourish when the names of all his enemies shall be forgotten4 ,i think it proper1 upon this occasion1 to inform my friends1 and the public1 that ,i have1 for the present1 suspended my design of writing the history and present state of all the branches of experimental philosophy4 ,this has arisen not from any dislike of the undertaking1 but1 in truth1 because ,i see no prospect of being reasonably indemnified for so much labour and expence1 notwithstanding the specimens ,i have already given of that work 7in the history of electricity1 and of the discoveries relating to vision1 light1 and colours7 have met with a much more favourable reception from the best judges both at home and abroad1 than ,i expected4 ,immortality1 if ,i should have any view to it1 is not the proper price of such works as these4 ,i propose1 however1 having given so much attention to the subject of air1 to write1 at my leisure1 the history and present state of discoveries relating to it2 in which case ,i shall1 as a part of it1 reprint this work1 with such improvements as shall have occurred to me at that time2 and ,i give this notice of it1 that no person who intends to purchase it may have reason 7being thus apprised of my intention7 to complain of buying the same thing twice4 ,if any person chuse it1 he may save his five or six shillings for the present1 and wait five or six years longer 7if ,i should live so long7 for the opportunity of buying the same thing1 probably much enlarged1 and at the same time a complete account of all that has been done by others relating to this subject4 ,though for the plain1 and ,i hope satisfactory reason above mentioned1 ,i shall probably write no other histories of this kind1 ,i shall1 as opportunity serves1 endeavour to provide materials for such histories1 by continuing my experiments1 keeping my eyes open to such new appearances as may present themselves1 investigating them as far as ,i shall be able1 and never failing to communicate to the public1 by some channel or other1 the result of my observations4 ,in the publication of this work ,i have thought that it would be agreeable to my readers to preserve1 in some measure1 the order of history1 and therefore ,i have not thrown together all that ,i have observed with respect to each kind of air1 but have divided the work into two parts2 the former containing what was published before1 in the ,philosophical ,transactions1 with such observations and corrections as subsequent experience has suggested to me2 and ,i have reserved for the latter part of the work an account of the experiments which ,i have made since that publication1 and after a pretty long interruption in my philosophical pursuits1 in the course of the last summer4 ,besides ,i am sensible that in the latter part of this work a different arrangement of the subjects will be more convenient1 for their mutual illustration4 ,some persons object to the term air1 as applied to acid1 alkaline1 and even nitrous air2 but it is certainly very convenient to have a common term by which to denote things which have so many common properties1 and those so very striking2 all of them agreeing with the air in which we breathe1 and with fixed air1 in elasticity1 and transparency1 and in being alike affected by heat or cold2 so that to the eye they appear to have no difference at all4 ,with much more reason1 as it appears to me1 might a person object to the common term metal1 as applied to things so very different from one another as gold1 quicksilver1 and lead4 ,besides1 acid and alkaline air do not differ from common air 7in any respect that can countenance an objection to their having a common appellation7 except in such properties as are common to it with fixed air1 though in a different degree2 viz4 that of being imbibed by water4 ,but1 indeed1 all kinds of air1 common air itself not excepted1 are capable of being imbibed by water in some degree4 ,some may think the terms acid and alkaline vapour more proper than acid and alkaline air4 ,but the term vapour having always been applied to elastic matters capable of being condensed in the temperature of the atmosphere1 especially the vapour of water1 it seems harsh to apply it to any elastic substance1 which at the same time that it is as transparent as the air we breathe1 is no more affected by cold than it is4 ,as my former papers were immediately translated into several foreign languages1 ,i may presume that this treatise1 having a better title to it1 will be translated also2 and1 upon this presumption1 ,i cannot help expressing a wish1 that it may be done by persons who have a competent knowledge of subject1 as well as of the ,english language4 ,the mistakes made by some foreigners1 have induced me to give this caution4 ,london1 ,feb4 #aggd4 ,,advertisement4 ,the weights mentioned in the course of this treatise are ,troy1 and what is called an ounce measure of air1 is the space occupied by an ounce weight of water1 which is equal to #dhj grains1 and is1 therefore1 almost two cubic inches of water2 for one cubic inch weighs #bed grains4 ,,footnotes3 #a ,see ,sir ,john ,pringle's ,discourse on the different kinds of air1 p4 #bi1 which1 if it became me to do it1 ,i would recommend to the reader1 as containing a just and elegant account of the several discoveries that have been successively made1 relating to the subject of this treatise4 ,,the ,,contents4 ,,the ,,introduction4 ,section ,i4 ,a general view of ,,preceding ,,discoveries relating to ,,air ,page #a ,sect4 ,,ii4 ,an ,account of the ,,apparatus with which the following ,experiments were made #f ,,part ,i4 ,experiments and ,observations made in1 and before the ,year #aggb4 #bc ,sect4 ,i4 ,of ,,fixed ,,air #be ,sect4 ,,ii4 ,of ,,air in which a ,,candle1 or ,,brimstone1 has burned out #dc ,sect4 ,,iii4 ,of ,,inflammable ,,air #ee ,sect4 ,,iv4 ,of ,,air infected with ,,animal ,,respiration1 or ,,putrefaction #gj ,sect4 ,v4 ,of ,,air in which a mixture of ,,brimstone and ,,filings of ,,iron has stood #aje ,sect4 ,,vi4 ,of ,,nitrous ,,air #ajh ,sect4 ,,vii4 ,of ,,air infected with the ,,fumes of ,,burning ,,charcoal #abi ,sect4 ,,viii4 ,of the effect of the ,,calcination of ,,metals1 and of the ,,effluvia of ,,paint made with ,,white-,,lead and ,,oil1 on ,,air #acc ,sect4 ,,ix4 ,of ,,marine ,,acid ,,air #adc ,sect4 ,x4 ,miscellaneous ,observations #aed ,,part ,,ii4 ,experiments and ,observations made in the ,year #aggc1 and the ,beginning of #aggd4 ,sect4 ,i4 ,observations on ,,alkaline ,,air #afc ,sect4 ,,ii4 ,of ,,common ,,air diminished1 and made noxious by various processes #agg ,sect4 ,,iii4 ,of ,,nitrous ,,air #bjc ,sect4 ,,iv4 ,of ,,marine ,,acid ,,air #bbi ,sect4 ,v4 ,of ,,inflammable ,,air #bdb ,sect4 ,,vi4 ,of ,,fixed ,,air #bdh ,sect4 ,,vii4 ,,miscellaneous ,,experiments #beb ,sect4 ,,viii4 ,,queries1 ,,speculations1 and ,,hints #beh ,,the ,,appendix4 ,number ,i4 ,,experiments made by ,mr4 ,hey to prove that there is no ,,oil of ,,vitriol in water impregnated with ,,fixed ,,air #bhh ,number ,,ii4 ,a ,letter from ,mr4 ,,hey to ,dr4 ,,priestley1 concerning the effects of fixed ,air applied by way of ,clyster #bib ,number ,,iii4 ,observations on the ,,medicinal ,,uses of ,,fixed ,,air4 ,by ,,thomas ,,percival1 ,m4 ,d4 ,fellow of the ,,royal ,,society1 and of the ,,society of ,,antiquaries in ,,london #cjj ,number ,,iv4 ,extract of a ,letter from ,,william ,,falconer1 ,m4 ,d4 of ,,bath #cad ,number ,v4 ,extract of a ,letter from ,mr4 ,,william ,,bewley1 of ,,great ,,massingham1 ,,norfolk #cag ,num4 ,,vi4 ,a ,letter from ,dr4 ,,franklin #cba ,number ,,vii4 ,extract of ,letter from ,mr4 ,,henry of ,,manchester #cbc ,,the ,,introduction4 ,,section ,i4 ,a general view of ,,preceding ,,discoveries relating to air4 ,for the better understanding of the experiments and observations on different kinds of air contained in this treatise1 it will be useful to those who are not acquainted with the history of this branch of natural philosophy1 to be informed of those facts which had been discovered by others1 before ,i turned my thoughts to the subject2 which suggested1 and by the help of which ,i was enabled to pursue1 my inquiries4 ,let it be observed1 however1 that ,i do not profess to recite in this place all that had been discovered concerning air1 but only those discoveries the knowledge of which is necessary1 in order to understand what ,i have done myself2 so that any person who is only acquainted with the general principles of natural philosophy1 may be able to read this treatise1 and1 with proper attention1 to understand every part of it4 ,that the air which constitutes the atmosphere in which we live has weight1 and that it is elastic1 or consists of a compressible and dilatable fluid1 were some of the earliest discoveries that were made after the dawning of philosophy in this western part of the world4 ,that elastic fluids1 differing essentially from the air of the atmosphere1 but agreeing with it in the properties of weight1 elasticity1 and transparency1 might be generated from solid substances1 was discovered by ,mr4 ,boyle1 though two remarkable kinds of factitious air1 at least the effects of them1 had been known long before to all miners4 ,one of these is heavier than common air4 ,it lies at the bottom of pits1 extinguishes candles1 and kills animals that breathe it1 on which account it had obtained the name of the choke damp4 ,the other is lighter than common air1 taking its place near the roofs of subterraneous places1 and because it is liable to take fire1 and explode1 like gunpowder1 it had been called the fire damp4 ,the word damp signifies vapour or exhalation in the ,german and ,saxon language4 ,though the former of these kinds of air had been known to be noxious1 the latter ,i believe had not been discovered to be so1 having always been found in its natural state1 so much diluted with common air1 as to be breathed with safety4 ,air of the former kind1 besides having been discovered in various caverns1 particularly the grotta del ,cane in ,italy1 had also been observed on the surface of fermenting liquors1 and had been called gas 7which is the same with geist1 or spirit7 by ,van ,helmont1 and other ,german chymists2 but afterwards it obtained the name of fixed air1 especially after it had been discovered by ,dr4 ,black of ,edinburgh to exist1 in a fixed state1 in alkaline salts1 chalk1 and other calcareous substances4 ,this excellent philosopher discovered that it is the presence of the fixed air in these substances that renders them mild1 and that when they are deprived of it1 by the force of fire1 or any other process1 they are in that state which had been called caustic1 from their corroding or burning animal and vegetable substances4 ,fixed air had been discovered by ,dr4 ,macbride of ,dublin1 after an observation of ,sir ,john ,pringle's1 which led to it1 to be in a considerable degree antiseptic2 and since it is extracted in great plenty from fermenting vegetables1 he had recommended the use of wort 7that is an infusion of malt in water7 as what would probably give relief in the sea-scurvy1 which is said to be a putrid disease4 ,dr4 ,brownrigg had also discovered that the same species of air is contained in great quantities in the water of the ,pyrmont spring at ,spa in ,germany1 and in other mineral waters1 which have what is called an acidulous taste1 and that their peculiar flavour1 briskness1 and medicinal virtues1 are derived from this ingredient4 ,dr4 ,hales1 without seeming to imagine that there was any material difference between these kinds of air and common air1 observed that certain substances and operations generate air1 and others absorb it2 imagining that the diminution of air was simply a taking away from the common mass1 without any alteration in the properties of what remained4 ,his experiments1 however1 are so numerous1 and various1 that they are justly esteemed to be the solid foundation of all our knowledge of this subject4 ,mr4 ,cavendish had exactly ascertained the specific gravities of fixed and inflammable air1 shewing the former of them to be #a-a_/b heavier than common air1 and the latter ten times lighter4 ,he also shewed that water would imbibe more than its own bulk of fixed air4 ,lastly1 ,mr4 ,lane discovered that water thus impregnated with fixed air will dissolve a considerable quantity of iron1 and thereby become a strong chalybeate4 ,these1 ,i would observe1 are by no means all the discoveries concerning air that have been made by the gentlemen whose names ,i have mentioned1 and still less are they all that have been made by others2 but they comprise all the previous knowledge of this subject that is necessary to the understanding of this treatise2 except a few particulars1 which will be mentioned in the course of the work1 and which it is1 therefore1 unnecessary to recite in this place4 ,,section ,,ii4 ,an account of the ,,apparatus with which the following experiments were made4 ,rather than describe at large the manner in which every particular experiment that ,i shall have occasion to recite was made1 which would both be very tedious1 and require an unnecessary multiplicity of drawings1 ,i think it more adviseable to give1 at one view1 an account of all my apparatus and instruments1 or at least of every thing that can require a description1 and of all the different operations and processes in which ,i employ them4 ,it will be seen that my apparatus for experiments on air is1 in fact1 nothing more than the apparatus of ,dr4 ,hales1 ,dr4 ,brownrigg1 and ,mr4 ,cavendish1 diversified1 and made a little more simple4 ,yet notwithstanding the simplicity of this apparatus1 and the ease with which all the operations are conducted1 ,i would not have any person1 who is altogether without experience1 to imagine that he shall be able to select any of the following experiments1 and immediately perform it1 without difficulty or blundering4 ,it is known to all persons who are conversant in experimental philosophy1 that there are many little attentions and precautions necessary to be observed in the conducting of experiments1 which cannot well be described in words1 but which it is needless to describe1 since practice will necessarily suggest them2 though1 like all other arts in which the hands and fingers are made use of1 it is only much practice that can enable a person to go through complex experiments1 of this or any other kind1 with ease and readiness4 ,for experiments in which air will bear to be confined by water1 ,i first used an oblong trough made of earthen ware1 as a fig4 #a4 about eight inches deep1 at one end of which ,i put thin flat stones1 b4 b4 about an inch1 or half an inch1 under the water1 using more or fewer of them according to the quantity of water in the trough4 ,but ,i have since found it more convenient to use a larger wooden trough1 of the same general shape1 eleven inches deep1 two feet long1 and #a-a_/b wide1 with a shelf about an inch lower than the top1 instead of the flat stones above-mentioned4 ,this trough being larger than the former1 ,i have no occasion to make provision for the water being higher or lower1 the bulk of a jar or two not making so great a difference as did before4 ,the several kinds of air ,i usually keep in cylindrical jars1 as c1 c1 fig4 #a1 about ten inches long1 and #b-a_/b wide1 being such as ,i have generally used for electrical batteries1 but ,i have likewise vessels of very different forms and sizes1 adapted to particular experiments4 ,when ,i want to remove vessels of air from the large trough1 ,i place them in pots or dishes1 of various sizes1 to hold more or less water1 according to the time that ,i have occasion to keep the air1 as fig4 #b4 ,these ,i plunge in water1 and slide the jars into them2 after which they may be taken out together1 and be set wherever it shall be most convenient4 ,for the purpose of merely removing a jar of air from one place to another1 where it is not to stand longer than a few days1 ,i make use of common tea-dishes1 which will hold water enough for that time1 unless the air be in a state of diminution1 by means of any process that is going on in it4 ,if ,i want to try whether an animal will live in any kind of air1 ,i first put the air into a small vessel1 just large enough to give it room to stretch itself2 and as ,i generally make use of mice for this purpose1 ,i have found it very convenient to use the hollow part of a tall beer-glass1 d fig4 #a1 which contains between two and three ounce measures of air4 ,in this vessel a mouse will live twenty minutes1 or half an hour4 ,for the purpose of these experiments it is most convenient to catch the mice in small wire traps1 out of which it is easy to take them1 and holding them by the back of the neck1 to pass them through the water into the vessel which contains the air4 ,if ,i expect that the mouse will live a considerable time1 ,i take care to put into the vessel something on which it may conveniently sit1 out of the reach of the water4 ,if the air be good1 the mouse will soon be perfectly at its ease1 having suffered nothing by its passing through the water4 ,if the air be supposed to be noxious1 it will be proper 7if the operator be desirous of preserving the mice for farther use7 to keep hold of their tails1 that they may be withdrawn as soon as they begin to shew signs of uneasiness2 but if the air be thoroughly noxious1 and the mouse happens to get a full inspiration1 it will be impossible to do this before it be absolutely irrecoverable4 ,in order to keep the mice1 ,i put them into receivers open at the top and bottom1 standing upon plates of tin perforated with many holes1 and covered with other plates of the same kind1 held down by sufficient weights1 as fig4 #c4 ,these receivers stand upon a frame of wood1 that the fresh air may have an opportunity of getting to the bottoms of them1 and circulating through them4 ,in the inside ,i put a quantity of paper or tow1 which must be changed1 and the vessel washed and dried1 every two or three days4 ,this is most conveniently done by having another receiver1 ready cleaned and prepared1 into which the mice may be transferred till the other shall be cleaned4 ,mice must be kept in a pretty exact temperature1 for either much heat or much cold kills them presently4 ,the place in which ,i have generally kept them is a shelf over the kitchen fire-place where1 as it is usual in ,yorkshire1 the fire never goes out2 so that the heat varies very little1 and ,i find it to be1 at a medium1 about #gj degrees of ,fahrenheit's thermometer4 ,when they had been made to pass through the water1 as they necessarily must be in order to a change of air1 they require1 and will bear a very considerable degree of heat1 to warm and dry them4 ,i found1 to my great surprize1 in the course of these experiments1 that mice will live intirely without water2 for though ,i have kept them for three or four months1 and have offered them water several times1 they would never taste it2 and yet they continued in perfect health and vigour4 ,two or three of them will live very peaceably together in the same vessel2 though ,i had one instance of a mouse tearing another almost in pieces1 and when there was plenty of provisions for both of them4 ,in the same manner in which a mouse is put into a vessel of any kind of air1 a plant1 or any thing else1 may be put into it1 viz4 by passing it through the water2 and if the plant be of a kind that will grow in water only1 there will be no occasion to set it in a pot of earth1 which will otherwise be necessary4 ,there may appear1 at first sight1 some difficulty in opening the mouth of a phial1 containing any substance1 solid or liquid1 to which water must not be admitted1 in a jar of any kind of air1 which is an operation that ,i have sometimes had recourse to2 but this ,i easily effect by means of a cork cut tapering1 and a strong1 wire thrust through it1 as in fig4 #d1 for in this form it will sufficiently fit the mouth of any phial1 and by holding the phial in one hand1 and the wire in the other1 and plunging both my hands into the trough of water1 ,i can easily convey the phial through the water into the jar2 which must either be held by an assistant1 or be fastened by strings1 with its mouth projecting over the shelf4 ,when the phial is thus conveyed into the jar1 the cork may easily be removed1 and may also be put into it again at pleasure1 and conveyed the same way out again4 ,when any thing1 as a gallipot1 c4 is to be supported at a considerable height within a jar1 it is convenient to have such wire stands as are represented fig4 #e4 ,they answer better than any other1 because they take up but little room1 and may be easily bended to any shape or height4 ,if ,i have occasion to pour air from a vessel with a wide mouth into another with a very narrow one1 ,i am obliged to make use of a funnel1 fig4 #f1 but by this means the operation is exceedingly easy2 first filling the vessel into which the air is to be conveyed with water1 and holding the mouth of it1 together with the funnel1 both under water with one hand1 while the other is employed in pouring the air2 which1 ascending through the funnel up into the vessel1 makes the water descend1 and takes its place4 ,these funnels are best made of glass1 because the air being visible through them1 the quantity of it may be more easily estimated by the eye4 ,it will be convenient to have several of these funnels of different sizes4 ,in order to expel air from solid substances by means of heat1 ,i sometimes put them into a gun-barrel1 fig4 #g1 and filling it up with dry sand1 that has been well burned1 so that no air can come from it1 ,i lute to the open end the stem of a tobacco pipe1 or a small glass tube4 ,then having put the closed end of the barrel1 which contains the materials1 into the fire1 the generated air1 issuing through the tube1 may be received in a vessel of quicksilver1 with its mouth immersed in a bason of the same1 suspended all together in wires1 in the manner described in the figure3 or any other fluid substance may be used instead of quicksilver4 ,but the most accurate method of procuring air from several substances1 by means of heat1 is to put them1 if they will bear it1 into phials full of quicksilver1 with the mouths immersed in the same1 and then throw the focus of a burning mirror upon them4 ,for this purpose the phials should be made with their bottoms round1 and very thin1 that they may not be liable to break with a pretty sudden application of heat4 ,if ,i want to expel air from any liquid1 ,i nearly fill a phial with it1 and having a cork perforated1 ,i put through it1 and secure with cement1 a glass tube1 bended in the manner represented at e fig4 #a4 ,i then put the phial into a kettle of water1 which ,i set upon the fire and make to boil4 ,the air expelled by the heat1 from the liquor contained in the phial1 issues through the tube1 and is received in the bason of quicksilver1 fig4 #g4 ,instead of this suspended bason1 ,i sometimes content myself with tying a flaccid bladder to the end of the tube1 in both these processes1 that it may receive the newly generated air4 ,in experiments on those kinds of air which are readily imbibed by water1 ,i always make use of quicksilver1 in the manner represented fig4 #h1 in which a is the bason of quicksilver1 b a glass vessel containing quicksilver1 with its mouth immersed in it1 c a phial containing the ingredients from which the air is to be produced2 and d is a small recipient1 or glass vessel designed to receive and intercept any liquor that may be discharged along with the air1 which is to be transmitted free from any moisture into the vessel b4 ,if there be no apprehension of moisture1 ,i make use of the glass tube only1 without any recipient1 in the manner represented e fig4 #a4 ,in order to invert the vessel b1 ,i first fill it with quicksilver1 and then carefully cover the mouth of it with a piece of soft leather2 after which it may be turned upside down without any danger of admitting the air1 and the leather may be withdrawn when it is plunged in the quicksilver4 ,in order to generate air by the solution of metals1 or any process of a similar nature1 ,i put the materials into a phial1 prepared in the manner represented at e fig4 #a1 and put the end of the glass tube under the mouth of any vessel into which ,i want to convey the air4 ,if heat be necessary ,i can easily apply to it a candle1 or a red hot poker while it hangs in this position4 ,when ,i have occasion to transfer air from a jar standing in the trough of water to a vessel standing in quicksilver1 or in any other situation whatever1 ,i make use of the contrivance represented fig4 #i1 which consists of a bladder1 furnished at one end with a small glass tube bended1 and at the other with a cork1 perforated so as just to admit the small end of a funnel4 ,when the common air is carefully pressed out of this bladder1 and the funnel is thrust tightly into the cork1 it may be filled with any kind of air as easily as a glass jar2 and then a string being tied above the cork in which the funnel is inserted1 and the orifice in the other cork closed1 by pressing the bladder against it1 it may be carried to any place1 and if the tube be carefully wiped1 the air may be conveyed quite free from moisture through a body of quicksilver1 or any thing else4 ,a little practice will make this very useful manoeuvre perfectly easy and accurate4 ,in order to impregnate fluids with any kind of air1 as water with fixed air1 ,i fill a phial with the fluid larger or less as ,i have occasion 7as a fig4 #aj27 and then inverting it1 place it with its mouth downwards1 in a bowl b1 containing a quantity of the same fluid2 and having filled the bladder1 fig4 #i1 with the air1 ,i throw as much of it as ,i think proper into the phial1 in the manner described above4 ,to accelerate the impregnation1 ,i lay my hand on the top of the phial1 and shake it as much as ,i think proper4 ,if1 without having any air previously generated1 ,i would convey it into the fluid immediately as it arises from the proper materials1 ,i keep the same bladder in connection with a phial c fig4 #aj1 containing the same materials 7as chalk1 salt of tartar1 or pearl ashes in diluted oil of vitriol1 for the generation of fixed air7 and taking care1 lest1 in the act of effervescence1 any of the materials in the phial c should get into the vessel a1 to place this phial on a stand lower than that on which the bason was placed1 ,i press out the newly generated air1 and make it ascend directly into the fluid4 ,for this purpose1 and that ,i may more conveniently shake the phial c1 which is necessary in some processes1 especially with chalk and oil of vitriol1 ,i sometimes make use of a flexible leathern tube d1 and sometimes only a glass tube4 ,for if the bladder be of a sufficient length1 it will give room for the agitation of the phial2 or if not1 it is easy to connect two bladders together by means of a perforated cork1 to which they may both be fastened4 ,when ,i want to try whether any kind of air will admit a candle to burn in it1 ,i make use of a cylindrical glass vessel1 fig4 #aa4 and a bit of wax candle a fig4 #ab1 fastened to the end of a wire b1 and turned up1 in such a manner as to be let down into the vessel with the flame upwards4 ,the vessel should be kept carefully covered till the moment that the candle is admitted4 ,in this manner ,i have frequently extinguished a candle more than twenty times successively1 in a vessel of this kind1 though it is impossible to dip the candle into it without giving the external air an opportunity of mixing with the air in the inside more or less4 ,the candle c1 at the other end of the wire is very convenient for holding under a jar standing in water1 in order to burn as long as the inclosed air can supply it2 for the moment that it is extinguished1 it may be drawn through the water before any smoke can have mixed with the air4 ,in order to draw air out of a vessel which has its mouth immersed in water1 and thereby to raise the water to whatever height may be necessary1 it is very convenient to make use of a glass syphon1 fig4 #ac1 putting one of the legs up into the vessel1 and drawing the air out at the other end by the mouth4 ,if the air be of a noxious quality1 it may be necessary to have a syringe fastened to the syphon1 the manner of which needs no explanation4 ,i have not thought it safe to depend upon a valve at the top of the vessel1 which ,dr4 ,hales sometimes made use of4 ,if1 however1 a very small hole be made at the top of a glass vessel1 it may be filled to any height by holding it under water1 while the air is issuing out at the hole1 which may then be closed with wax or cement4 ,if the generated air will neither be absorbed by water1 nor diminish common air1 it may be convenient to put part of the materials into a cup1 supported by a stand1 and the other part into a small glass vessel1 placed on the edge of it1 as at f1 fig4 #a4 ,then having1 by means of a syphon1 drawn the air to at convenient height1 the small glass vessel may be easily pushed into the cup1 by a wire introduced through the water2 or it may be contrived1 in a variety of ways1 only to discharge the contents of the small vessel into the larger4 ,the distance between the boundary of air and water1 before and after the operation1 will shew the quantity of the generated air4 ,the effect of processes that diminish air may also be tried by the same apparatus4 ,when ,i want to admit a particular kind of air to any thing that will not bear wetting1 and yet cannot be conveniently put into a phial1 and especially if it be in the form of a powder1 and must be placed upon a stand 7as in those experiments in which the focus of a burning mirror is to be thrown upon it7 ,i first exhaust a receiver1 in which it is previously placed2 and having a glass tube1 bended for the purpose1 as in fig4 #ad1 ,i screw it to the stem of a transfer of the air pump on which the receiver had been exhausted1 and introducing it through the water into a jar of that kind of air with which ,i would fill the receiver1 ,i only turn the cock1 and ,i gain my purpose4 ,in this method1 however1 unless the pump be very good1 and several contrivances1 too minute to be particularly described1 be made use of a good deal of common air will get into the receiver4 ,when ,i want to measure the goodness of any kind of air1 ,i put two measures of it into a jar standing in water2 and when ,i have marked upon the glass the exact place of the boundary of air and water1 ,i put to it one measure of nitrous air2 and after waiting a proper time1 note the quantity of its diminution4 ,if ,i be comparing two kinds of air that are nearly alike1 after mixing them in a large jar1 ,i transfer the mixture into a long glass tube1 by which ,i can lengthen my scale to what degree ,i please4 ,if the quantity of the air1 the goodness of which ,i want to ascertain1 be exceedingly small1 so as to be contained in a part of a glass tube1 out of which water will not run spontaneously1 as a fig4 #ae2 ,i first measure with a pair of compasses the length of the column of air in the tube1 the remaining part being filled with water1 and lay it down upon a scale2 and then1 thrusting a wire of a proper thickness1 b1 into the tube1 ,i contrive1 by means of a thin plate of iron1 bent to a sharp angle c1 to draw it out again1 when the whole of this little apparatus has been introduced through the water into a jar of nitrous air2 and the wire being drawn out1 the air from the jar must supply its place4 ,i then measure the length of this column of nitrous air which ,i have got into the tube1 and lay it also down upon the scale1 so as to know the exact length of both the columns4 ,after this1 holding the tube under water1 with a small wire ,i force the two separate columns of air into contact1 and when they have been a sufficient time together1 ,i measure the length of the whole1 and compare it with the length of both the columns taken before4 ,a little experience will teach the operator how far to thrust the wire into the tube1 in order to admit as much air as he wants and no more4 ,in order to take the electric spark in a quantity of any kind of air1 which must be very small1 to produce a sensible effect upon it1 in a short time1 by means of a common machine1 ,i put a piece of wire into the end of a small tube1 and fasten it with hot cement1 as in fig4 #af2 and having got the air ,i want into the tube by means of the apparatus fig4 #ae1 ,i place it inverted in a bason containing either quicksilver1 or any other fluid substance by which ,i chuse to have the air confined4 ,i then1 by the help of the air pump1 drive out as much of the air as ,i think convenient1 admitting the quicksilver1 c4 to it1 as at a1 and putting a brass ball on the end of the wire1 ,i take the sparks or shocks upon it1 and thereby transmit them through the air to the liquor in the tube4 ,to take the electric sparks in any kind of fluid1 as oil1 c4 ,i use the same apparatus described above1 and having poured into the tube as much of the fluid as ,i conjecture ,i can make the electric spark pass through1 ,i fill the rest with quicksilver2 and placing it inverted in a bason of quicksilver1 ,i take the sparks as before4 ,if air be generated very fast by this process1 ,i use a tube that is narrow at the top1 and grows wider below1 as fig4 #ag1 that the quicksilver may not recede too soon beyond the striking distance4 ,sometimes ,i have used a different apparatus for this purpose1 represented fig4 #ah4 ,taking a pretty wide glass tube1 hermetically sealed at the upper-end1 and open below1 at about an inch1 or at what distance ,i think convenient from the top1 ,i get two holes made in it1 opposite to each other4 ,through these ,i put two wires1 and fastening them with warm cement1 ,i fix them at what distance ,i please from each other4 ,between these wires ,i take the sparks1 and the bubbles of air rise1 as they are formed1 to the top of the tube4 ,,part ,i4 ,experiments and ,observations made in1 and before the year #aggb4 ,in writing upon the subject of different kinds of air1 ,i find myself at a loss for proper terms1 by which to distinguish them1 those which have hitherto obtained being by no means sufficiently characteristic1 or distinct4 ,the only terms in common use are1 fixed air1 mephitic1 and inflammable4 ,the last1 indeed1 sufficiently characterizes and distinguishes that kind of air which takes fire1 and explodes on the approach of flame2 but it might have been termed fixed with as much propriety as that to which ,dr4 ,black and others have given that denomination1 since it is originally part of some solid substance1 and exists in an unelastic state4 ,all these newly discovered kinds of air may also be called factitious2 and if1 with others1 we use the term fixable1 it is still obvious to remark1 that it is applicable to them all2 since they are all capable of being imbibed by some substance or other1 and consequently of being fixed in them1 after they have been in an elastic state4 ,the term mephitic is equally applicable to what is called fixed air1 to that which is inflammable1 and to many other kinds2 since they are equally noxious1 when breathed by animals4 ,rather1 however1 than either introduce new terms1 or change the signification of old ones1 ,i shall use the term fixed air1 in the sense in which it is now commonly used1 and distinguish the other kinds by their properties1 or some other periphrasis4 ,i shall be under a necessity1 however1 of giving names to those kinds of air1 to which no names had been given by others1 as nitrous1 acid1 and alkaline4 ,,section ,i4 ,of ,,fixed ,,air4 ,it was in consequence of living for some time in the neighbourhood of a public brewery1 that ,i was induced to make experiments on fixed air1 of which there is always a large body1 ready formed1 upon the surface of the fermenting liquor1 generally about nine inches1 or a foot in depth1 within which any kind of substance may be very conveniently placed2 and though1 in these circumstances1 the fixed air must be continually mixing with the common air1 and is therefore far from being perfectly pure1 yet there is a constant fresh supply from the fermenting liquor1 and it is pure enough for many purposes4 ,a person1 who is quite a stranger to the properties of this kind of air1 would be agreeably amused with extinguishing lighted candles1 or chips of wood in it1 as it lies upon the surface of the fermenting liquor2 for the smoke readily unites with this kind of air1 probably by means of the water which it contains2 so that very little or none of the smoke will escape into the open air1 which is incumbent upon it4 ,it is remarkable1 that the upper surface of this smoke1 floating in the fixed air1 is smooth1 and well defined2 whereas the lower surface is exceedingly ragged1 several parts hanging down to a considerable distance within the body of the fixed air1 and sometimes in the form of balls1 connected to the upper stratum by slender threads1 as if they were suspended4 ,the smoke is also apt to form itself into broad flakes1 parallel to the surface of the liquor1 and at different distances from it1 exactly like clouds4 ,these appearances will sometimes continue above an hour1 with very little variation4 ,when this fixed air is very strong1 the smoke of a small quantity of gunpowder fired in it will be wholly retained by it1 no part escaping into the common air4 ,making an agitation in this air1 the surface of it1 7which still continues to be exactly defined7 is thrown into the form of waves1 which it is very amusing to look upon2 and if1 by this agitation1 any of the fixed air be thrown over the side of the vessel1 the smoke1 which is mixed with it1 will fall to the ground1 as if it was so much water1 the fixed air being heavier than common air4 ,the red part of burning wood was extinguished in this air1 but ,i could not perceive that a red-hot poker was sooner cooled in it4 ,fixed air does not instantly mix with common air4 ,indeed if it did1 it could not be caught upon the surface of the fermenting liquor4 ,a candle put under a large receiver1 and immediately plunged very deep below the surface of the fixed air1 will burn some time4 ,but vessels with the smallest orifices1 hanging with their mouths downwards in the fixed air1 will in time have the common air1 which they contain1 perfectly mixed with it4 ,when the fermenting liquor is contained in vessels close covered up1 the fixed air1 on removing the cover1 readily affects the common air which is contiguous to it2 so that1 candles held at a considerable distance above the surface will instantly go out4 ,i have been told by the workmen1 that this will sometimes be the case1 when the candles are held two feet above the mouth of the vessel4 ,fixed air unites with the smoke of rosin1 sulphur1 and other electrical substances1 as well as with the vapour of water2 and yet1 by holding the wire of a charged phial among these fumes1 ,i could not make any electrical atmosphere1 which surprized me a good deal1 as there was a large body of this smoke1 and it was so confined1 that it could not escape me4 ,i also held some oil of vitriol in a glass vessel within the fixed air1 and by plunging a piece of red-hot glass into it1 raised a copious and thick fume4 ,this floated upon the surface of the fixed air like other fumes1 and continued as long4 ,considering the near affinity between water and fixed air1 ,i concluded that if a quantity of water was placed near the yeast of the fermenting liquor1 it could not fail to imbibe that air1 and thereby acquire the principal properties of ,pyrmont1 and some other medicinal mineral waters4 ,accordingly1 ,i found1 that when the surface of the water was considerable1 it always acquired the pleasant acidulous taste that ,pyrmont water has4 ,the readiest way of impregnating water with this virtue1 in these circumstances1 is to take two vessels1 and to keep pouring the water from one into the other1 when they are both of them held as near the yeast as possible2 for by this means a great quantity of surface is exposed to the air1 and the surface is also continually changing4 ,in this manner1 ,i have sometimes1 in the space of two or three minutes1 made a glass of exceedingly pleasant sparkling water1 which could hardly be distinguished from very good ,pyrmont1 or rather ,seltzer water4 ,but the most effectual way of impregnating water with fixed air is to put the vessels which contain the water into glass jars1 filled with the purest fixed air made by the solution of chalk in diluted oil of vitriol1 standing in quicksilver4 ,in this manner ,i have1 in about two days1 made a quantity of water to imbibe more than an equal bulk of fixed air1 so that1 according to ,dr4 ,brownrigg's experiments1 it must have been much stronger than the best imported ,pyrmont2 for though he made his experiments at the spring-head1 he never found that it contained quite so much as half its bulk of this air4 ,if a sufficient quantity of quicksilver cannot be procured1 oil may be used with sufficient advantage1 for this purpose1 as it imbibes the fixed air very slowly4 ,fixed air may be kept in vessels standing in water for a long time1 if they be separated by a partition of oil1 about half an inch thick4 ,pyrmont water made in these circumstances1 is little or nothing inferior to that which has stood in quicksilver4 ,the readiest method of preparing this water for use is to agitate it strongly with a large surface exposed to the fixed air4 ,by this means more than an equal bulk of air may be communicated to a large quantity of water in the space of a few minutes4 ,but since agitation promotes the dissipation of fixed air from water1 it cannot be made to imbibe so great a quantity in this method as in the former1 where more time is taken4 ,easy directions for impregnating water with fixed air ,i have published in a small pamphlet1 designed originally for the use of seamen in long voyages1 on the presumption that it might be of use for preventing or curing the sea scurvy1 equally with wort1 which was recommended by ,dr4 ,macbride for this purpose1 on no other account than its property of generating fixed air1 by its fermentation in the stomach4 ,water thus impregnated with fixed air readily dissolves iron1 as ,mr4 ,lane has discovered2 so that if a quantity of iron filings be put to it1 it presently becomes a strong chalybeate1 and of the mildest and most agreeable kind4 ,i have recommended the use of chalk and oil of vitriol as the cheapest1 and1 upon the whole1 the best materials for this purpose4 ,but some persons prefer pearl ashes1 pounded marble1 or other calcareous or alkaline substances2 and perhaps with reason4 ,my own experience has not been sufficient to enable me to decide in this case4 ,whereas some persons had suspected that a quantity of the oil of vitriol was rendered volatile by this process1 ,i examined it1 by all the chemical methods that are in use2 but could not find that water thus impregnated contained the least perceivable quantity of that acid4 ,mr4 ,hey1 indeed1 who assisted me in this examination1 found that distilled water1 impregnated with fixed air1 did not mix so readily with soap as the distilled water itself2 but this was also the case when the fixed air had passed through a long glass tube filled with alkaline salts1 which1 it may be supposed1 would have imbibed any of the oil of vitriol that might have been contained in that air#b4 ,fixed air itself may be said to be of the nature of an acid1 though of a weak and peculiar sort4----,mr4 ,bergman of ,upsal1 who honoured me with a letter upon the subject1 calls it the arial acid1 and1 among other experiments to prove it to be an acid1 he says that it changes the blue juice of tournesole into red4 ,this ,mr4 ,hey found to be true1 and he moreover discovered that when water tinged blue with the juice of tournesole1 and then red with fixed air1 has been exposed to the open air1 it recovers its blue colour again4 ,the heat of boiling water will expel all the fixed air1 if a phial containing the impregnated water be held in it2 but it will often require above half an hour to do it completely4 ,dr4 ,percival1 who is particularly attentive to every improvement in the medical art1 and who has thought so well of this impregnation as to prescribe it in several cases1 informs me that it seems to be much stronger1 and sparkles more1 like the true ,pyrmont water1 after it has been kept some time4 ,this circumstance1 however1 shews that1 in time1 the fixed air is more easily disengaged from the water2 and though1 in this state1 it may affect the taste more sensibly1 it cannot be of so much use in the stomach and bowels1 as when the air is more firmly retained by the water4 ,by the process described in my pamphlet1 fixed air may be readily incorporated with wine1 beer1 and almost any other liquor whatever2 and when beer1 wine1 or cyder1 is become flat or dead 7which is the consequence of the escape of the fixed air they contained7 they may be revived by this means2 but the delicate and agreeable flavour1 or acidulous taste1 communicated by fixed air1 and which is very manifest in water1 can hardly be perceived in wine1 or any liquors which have much taste of their own4 ,i should think that there can be no doubt1 but that water thus impregnated with fixed air must have all the medicinal virtues of genuine ,pyrmont or ,seltzer water2 since these depend upon the fixed air they contain4 ,if the genuine ,pyrmont water derives any advantage from its being a natural chalybeate1 this may also be obtained by providing a common chalybeate water1 and using it in these processes1 instead of common water4 ,having succeeded so well with this artificial ,pyrmont water1 ,i imagined that it might be possible to give ice the same virtue1 especially as cold is known to promote the absorption of fixed air by water2 but in this ,i found myself quite mistaken4 ,i put several pieces of ice into a quantity of fixed air1 confined by quicksilver1 but no part of the air was absorbed in two days and two nights2 but upon bringing it into a place where the ice melted1 the air was absorbed as usual4 ,i then took a quantity of strong artificial ,pyrmont water1 and putting it into a thin glass phial1 ,i set it in a pot that was filled with snow and salt4 ,this mixture instantly freezing the water that was contiguous to the sides of the glass1 the air was discharged plentifully1 so that ,i catched a considerable quantity1 in a bladder tied to the mouth of the phial4 ,i also took two quantities of the same ,pyrmont water1 and placed one of them where it might freeze1 keeping the other in a cold place1 but where it would not freeze4 ,this retained its acidulous taste1 though the phial which contained it was not corked2 whereas the other being brought into the same place1 where the ice melted very slowly1 had at the same time the taste of common water only4 ,that quantity of water which had been frozen by the mixture of snow and salt1 was almost as much like snow as ice1 such a quantity of air-bubbles were contained in it1 by which it was prodigiously increased in bulk4 ,the pressure of the atmosphere assists very considerably in keeping fixed air confined in water2 for in an exhausted receiver1 ,pyrmont water will absolutely boil1 by the copious discharge of its air4 ,this is also the reason why beer and ale froth so much in vacuo4 ,i do not doubt1 therefore1 but that1 by the help of a condensing engine1 water might be much more highly impregnated with the virtues of the ,pyrmont spring2 and it would not be difficult to contrive a method of doing it4 ,the manner in which ,i made several experiments to ascertain the absorption of fixed air by different fluid substances1 was to put the liquid into a dish1 and holding it within the body of the fixed air at the brewery1 to set a glass vessel into it1 with its mouth inverted4 ,this glass being necessarily filled with the fixed air1 the liquor would rise into it when they were both taken into the common air1 if the fixed air was absorbed at all4 ,making use of ether in this manner1 there was a constant bubbling from under the glass1 occasioned by this fluid easily rising in vapour1 so that ,i could not1 in this method1 determine whether it imbibed the air or not4 ,i concluded however1 that they did incorporate1 from a very disagreeable circumstance1 which made me desist from making any more experiments of the kind4 ,for all the beer1 over which this experiment was made1 contracted a peculiar taste2 the fixed air impregnated with the ether being1 ,i suppose1 again absorbed by the beer4 ,i have also observed1 that water which remained a long time within this air has sometimes acquired a very disagreeable taste4 ,at one time it was like tar-water4 ,how this was acquired1 ,i was very desirous of making some experiments to ascertain1 but ,i was discouraged by the fear of injuring the fermenting liquor4 ,it could not come from the fixed air only4 ,insects and animals which breathe very little are stifled in fixed air1 but are not soon quite killed in it4 ,butterflies and flies of other kinds will generally become torpid1 and seemingly dead1 after being held a few minutes over the fermenting liquor2 but they revive again after being brought into the fresh air4 ,but there are very great varieties with respect to the time in which different kinds of flies will either become torpid in the fixed air1 or die in it4 ,a large strong frog was much swelled1 and seemed to be nearly dead1 after being held about six minutes over the fermenting liquor2 but it recovered upon being brought into the common air4 ,a snail treated in the same manner died presently4 ,fixed air is presently fatal to vegetable life4 ,at least sprigs of mint growing in water1 and placed over the fermenting liquor1 will often become quite dead in one day1 or even in a less space of time2 nor do they recover when they are afterwards brought into the common air4 ,i am told1 however1 that some other plants are much more hardy in this respect4 ,a red rose1 fresh gathered1 lost its redness1 and became of a purple colour1 after being held over the fermenting liquor about twenty-four hours2 but the tips of each leaf were much more affected than the rest of it4 ,another red rose turned perfectly white in this situation2 but various other flowers of different colours were very little affected4 ,these experiments were not repeated1 as ,i wish they might be done1 in pure fixed air1 extracted from chalk by means of oil of vitriol4 ,for every purpose1 in which it was necessary that the fixed air should be as unmixed as possible1 ,i generally made it by pouring oil of vitriol upon chalk and water1 catching it in a bladder fastened to the neck of the phial in which they were contained1 taking care to press out all the common air1 and also the first1 and sometimes the second1 produce of fixed air2 and also1 by agitation1 making it as quickly as ,i possibly could4 ,at other times1 ,i made it pass from the phial in which it was generated through a glass tube1 without the intervention of any bladder1 which1 as ,i found by experience1 will not long make a sufficient separation between several kinds of air and common air4 ,i had once thought that the readiest method of procuring fixed air1 and in sufficient purity1 would be by the simple process of burning chalk1 or pounded lime-stone in a gun-barrel1 making it pass through the stem of a tobacco-pipe1 or a glass tube carefully luted to the orifice of it4 ,in this manner ,i found that air is produced in great plenty2 but1 upon examining it1 ,i found1 to my very great surprise1 that little more than one half of it was fixed air1 capable of being absorbed by water2 and that the rest was inflammable1 sometimes very weakly1 but sometimes pretty highly so4 ,whence this inflammability proceeds1 ,i am not able to determine1 the lime or chalk not being supposed to contain any other than fixed air4 ,i conjecture1 however1 that it must proceed from the iron1 and the separation of it from the calx may be promoted by that small quantity of oil of vitriol1 which ,i am informed is contained in chalk1 if not in lime-stone also4 ,but it is an objection to this hypothesis1 that the inflammable air produced in this manner burns blue1 and not at all like that which is produced from iron1 or any other metal1 by means of an acid4 ,it also has not the smell of that kind of inflammable air which is produced from mineral substances4 ,besides1 oil of vitriol without water1 will not dissolve iron2 nor can inflammable air be got from it1 unless the acid be considerably diluted2 and when ,i mixed brimstone with the chalk1 neither the quality nor the quantity of the air was changed by it4 ,indeed no air1 or permanently elastic vapour1 can be got from brimstone1 or any oil4 ,perhaps this inflammable principle may come from some remains of the animals1 from which it is thought that all calcareous matter proceeds4 ,in the method in which ,i generally made the fixed air 7and indeed always1 unless the contrary be particularly mentioned1 viz4 by diluted oil of vitriol and chalk7 ,i found by experiment that it was as pure as ,mr4 ,cavendish made it4 ,for after it had patted through a large body of water in small bubbles1 still #a_/ej or #a_/fj part only was not absorbed by water4 ,in order to try this as expeditiously as possible1 ,i kept pouring the air from one glass vessel into another1 immersed in a quantity of cold water1 in which manner ,i found by experience1 that almost any quantity may be reduced as far as possible in a very short time4 ,but the most expeditious method of making water imbibe any kind of air1 is to confine it in a jar2 and agitate it strongly1 in the manner described in my pamphlet on the impregnation of water with fixed air1 and represented fig4 #aj4 ,at the same time that ,i was trying the purity of my fixed air1 ,i had the curiosity to endeavour to ascertain whether that part of it which is not miscible in water1 be equally diffused through the whole mass2 and1 for this purpose1 ,i divided a quantity of about a gallon into three parts1 the first consisting of that which was uppermost1 and the last of that which was the lowest1 contiguous to the water2 but all these parts were reduced in about an equal proportion1 by passing through the water1 so that the whole mass had been of an uniform composition4 ,this ,i have also found to be the case with several kinds of air1 which will1 not properly incorporate4 ,a mouse will live very well1 though a candle will not burn in the residuum of the purest fixed air that ,i can make2 and ,i once made a very large quantity for the sole purpose of this experiment4 ,this1 therefore1 seems to be one instance of the generation of genuine common air1 though vitiated in some degree4 ,it is also another proof of the residuum of fixed air being1 in part at least1 common air1 that it becomes turbid1 and is diminished by the mixture of nitrous air1 as will be explained hereafter4 ,that fixed air only wants some addition to make it permanent1 and immiscible with water if not in all respects1 common air1 ,i have been led to conclude1 from several attempts which ,i once made to mix it with air in which a quantity of iron filings and brimstone1 made into a paste with water1 had stood2 for1 in several mixtures of this kind1 ,i imagined that not much more than half of the fixed air could be imbibed by water2 but1 not being able to repeat the experiment1 ,i conclude that ,i either deceived myself in it1 or that ,i overlooked some circumstance on which the success of it depended4 ,these experiments1 however1 whether they were fallacious or otherwise1 induced me to try whether any alteration would be made in the constitution of fixed air1 by this mixture of iron filings and brimstone4 ,i therefore put a mixture of this kind into a quantity of as pure fixed air as ,i could make1 and confined the whole in quicksilver1 lest the water should absorb it before the effects of the mixture could take place4 ,the consequence was1 that the fixed air was diminished1 and the quicksilver rose in the vessel1 till about the fifth part was occupied by it2 and1 as near as ,i could judge1 the process went on1 in all respects1 as if the air in the inside had been common air4 ,what is most remarkable1 in the result of this experiment1 is1 that the fixed air1 into which this mixture had been put1 and which had been in part diminished by it1 was in part also rendered insoluble in water by this means4 ,i made this experiment four times1 with the greatest care1 and observed1 that in two of them about one sixth1 and in the other two about one fourteenth1 of the original quantity1 was such as could not be absorbed by water1 but continued permanently elastic4 ,lest ,i should have made any mistake with respect to the purity of the fixed air1 the last time that ,i made the experiment1 ,i set part of the fixed air1 which ,i made use of1 in a separate vessel1 and found it to be exceedingly pure1 so as to be almost wholly absorbed by water2 whereas the other part1 to which ,i had put the mixture1 was far from being so4 ,in one of these cases1 in which fixed air was made immiscible with water1 it appeared to be not very noxious to animals2 but in another case1 a mouse died in it pretty soon4 ,this difference probably arose from my having inadvertently agitated the air in water rather more in one case than in the other4 ,as the iron is reduced to a calx by this process1 ,i once concluded1 that it is phlogiston that fixed air wants1 to make it common air2 and1 for any thing ,i yet know this may be the case1 though ,i am ignorant of the method of combining them2 and when ,i calcined a quantity of lead in fixed air1 in the manner which will be described hereafter1 it did not seem to have been less soluble in water than it was before4 ,,footnotes3 #b ,an account of ,mr4 ,hey's experiments will be found in the ,appendix to these papers4 ,,section ,,ii4 ,of ,,air in which a ,,candle1 or ,,brimstone1 has burned out4 ,it is well known that flame cannot subsist long without change of air1 so that the common air is necessary to it1 except in the case of substances1 into the composition of which nitre enters1 for these will burn in vacuo1 in fixed air1 and even under water1 as is evident in some rockets1 which are made for this purpose4 ,the quantity of air which even a small flame requires to keep it burning is prodigious4 ,it is generally said1 that an ordinary candle consumes1 as it is called1 about a gallon in a minute4 ,considering this amazing consumption of air1 by fires of all kinds1 volcanos1 c4 it becomes a great object of philosophical inquiry1 to ascertain what change is made in the constitution of the air by flame1 and to discover what provision there is in nature for remedying the injury which the atmosphere receives by this means4 ,some of the following experiments will1 perhaps1 be thought to throw light upon the subject4 ,the diminution of the quantity of air in which a candle1 or brimstone1 has burned out1 is various2 ,but ,i imagine that1 at a medium1 it may be about one fifteenth1 or one sixteenth of the whole2 which is one third as much as by animal or vegetable substances putrefying in it1 by the calcination of metals1 or by any of the other causes of the complete diminution of air1 which will be mentioned hereafter4 ,i have sometimes thought1 that flame disposes the common air to deposit the fixed air it contains2 for if any lime-water be exposed to it1 it immediately becomes turbid4 ,this is the case1 when wax candles1 tallow candles1 chips of wood1 spirit of wine1 ether1 and every other substance which ,i have yet tried1 except brimstone1 is burned in a close glass vessel1 standing in lime-water4 ,this precipitation of fixed air 7if this be the case7 may be owing to something emitted from the burning bodies1 which has a stronger affinity with the other constituent parts of the atmosphere#c4 ,if brimstone be burned in the same circumstances1 the lime-water continues transparent1 but still there may have been the same precipitation of the fixed part of the air2 but that1 uniting with the lime and the vitriolic acid1 it forms a selenetic salt1 which is soluble in water4 ,having evaporated a quantity of water thus impregnated1 by burning brimstone a great number of times over it1 a whitish powder remained1 which had an acid taste2 but repeating the experiment with a quicker evaporation1 the powder had no acidity1 but was very much like chalk4 ,the burning of brimstone but once over a quantity of lime-water1 will affect it in such a manner1 that breathing into it will not make it turbid1 which otherwise it always presently does4 ,dr4 ,hales supposed1 that by burning brimstone repeatedly in the same quantity of air1 the diminution would continue without end4 ,but this ,i have frequently tried1 and not found to be the case4 ,indeed1 when the ignition has been imperfect in the first instance1 a second firing of the same substance will increase the effect of the first1 c4 but this progress soon ceases4 ,in many cases of the diminution of air1 the effect is not immediately apparent1 even when it stands in water2 for sometimes the bulk of air will not be much reduced1 till it has passed several times through a quantity of water1 which has thereby a better opportunity of absorbing that part of the air1 which had not been perfectly detatched from the rest4 ,i have sometimes found a very great reduction of a mass of air1 in consequence of passing but once through cold water4 ,if the air has stood in quicksilver1 the diminution is generally inconsiderable1 till it has undergone this operation1 there not being any substance exposed to the air that could absorb any part of it4 ,i could not find any considerable alteration in the specific gravity of the air1 in which candles1 or brimstone1 had burned out4 ,i am satisfied1 however1 that it is not heavier than common air1 which must have been manifest1 if so great a diminution of the quantity had been owing1 as ,dr4 ,hales and others supposed1 to the elasticity of the whole mass being impaired4 ,after making several trials for this purpose1 ,i concluded that air1 thus diminished in bulk1 is rather lighter than common air1 which favours the supposition of the fixed1 or heavier part of the common air1 having been precipitated4 ,an animal will live nearly1 if not quite as long1 in air in which candles have burned out1 as in common air4 ,this fact surprized me very greatly1 having imagined that what is called the consumption of air by flame1 or respiration1 to have been of the same nature1 and in the same degree2 but ,i have since found1 that this fact has been observed by many persons1 and even so early as by ,mr4 ,boyle4 ,i have also observed1 that air1 in which brimstone has burned1 is not in the least injurious to animals1 after the fumes1 which at first make it very cloudy1 have intirely subsided4 ,i must1 in this place1 admonish my reader not to confound the simple burning of brimstone1 or of matches 7i4 e4 bits of wood dipped in it7 and the burning of brimstone with a burning mirror1 or any foreign heat4 ,the effect of the former is nothing more than that of any other flame1 or ignited vapour1 which will not burn1 unless the air with which it is surrounded be in a very pure state1 and which is therefore extinguished when the air begins to be much vitiated4 ,lighted brimstone1 therefore reduces the air to the same state as lighted wood4 ,but the focus of a burning mirror thrown for a sufficient time either upon brimstone1 or wood1 after it has ceased to burn of its own accord1 and has become charcoal1 will have a much greater effect3 of the same kind1 diminishing the air to its utmost extent1 and making it thoroughly noxious4 ,in fact1 as will be seen hereafter1 more phlogiston is expelled from these substances in the latter case than in the former4 ,i never1 indeed1 actually carried this experiment so far with brimstone2 but from the diminution of air that ,i did produce by this means1 ,i concluded that1 by continuing the process some time longer1 it would have been effected4 ,having read1 in the ,memoirs of the ,philosophical ,society at ,turin1 vol4 ,i4 p4 #da4 that air in which candles had burned out was perfectly restored1 so that other candles would burn in it again as well as ever1 after having been exposed to a considerable degree of cold1 and likewise after having been compressed in bladders1 7for the cold had been supposed to have produced this effect by nothing but condensation7 ,i repeated those experiments1 and did1 indeed1 find1 that when ,i compressed the air in bladders1 as the ,count de ,saluce1 who made the observation1 had done1 the experiment succeeded3 but having had sufficient reason to distrust bladders1 ,i compressed the air in a glass vessel standing in water2 and then ,i found1 that this process is altogether ineffectual for the purpose4 ,i kept the air compressed much more1 and much longer1 than the ,count had done1 but without producing any alteration in it4 ,i also find1 that a greater degree of cold than that which he applied1 and of longer continuance1 did by no means restore this kind of air3 for when ,i had exposed the phials which contained it a whole night1 in which the frost was very intense2 and also when ,i kept it surrounded with a mixture of snow and salt1 ,i found it1 in all respects1 the same as before4 ,it is also advanced1 in the same ,memoir1 p4 #da4 that heat only1 as the reverse of cold1 renders air unfit for candles burning in it4 ,but ,i repeated the experiment of the ,count for that purpose1 without finding any such effect from it4 ,i also remember that1 many years ago1 ,i filled an exhausted receiver with air1 which had passed through a glass tube made red-hot1 and found that a candle would burn in it perfectly well4 ,also1 rarefaction by the air-pump does not injure air in the least degree4 ,though this experiment failed1 ,i have been so happy1 as by accident to have hit upon a method of restoring air1 which has been injured by the burning of candles1 and to have discovered at least one of the restoratives which nature employs for this purpose4 ,it is vegetation4 ,this restoration of vitiated air1 ,i conjecture1 is effected by plants imbibing the phlogistic matter with which it is overloaded by the burning of inflammable bodies4 ,but whether there be any foundation for this conjecture or not1 the fact is1 ,i think1 indisputable4 ,i shall introduce the account of my experiments on this subject1 by reciting some of the observations which ,i made on the growing of plants in confined air1 which led to this discovery4 ,one might have imagined that1 since common air is necessary to vegetable1 as well as to animal life1 both plants and animals had affected it in the same manner2 and ,i own ,i had that expectation1 when ,i first put a sprig of mint into a glass jar1 standing inverted in a vessel of water3 but when it had continued growing there for some months1 ,i found that the air would neither extinguish a candle1 nor was it at all inconvenient to a mouse1 which ,i put into it4 ,the plant was not affected any otherwise than was the necessary consequence of its confined situation2 for plants growing in several other kinds of air1 were all affected in the very same manner4 ,every succession of leaves was more diminished in size than the preceding1 till1 at length1 they came to be no bigger than the heads of pretty small pins4 ,the root decayed1 and the stalk also1 beginning from the root2 and yet the plant continued to grow upwards1 drawing its nourishment through a black and rotten stem4 ,in the third or fourth set of leaves1 long and white hairy filaments grew from the insertion of each leaf and sometimes from the body of the stem1 shooting out as far as the vessel in which it grew would permit1 which1 in my experiments1 was about two inches4 ,in this manner a sprig of mint lived1 the old plant decaying1 and new ones shooting up in its place1 but less and less continually1 all the summer season4 ,in repeating this experiment1 care must be taken to draw away all the dead leaves from about the plant1 lest they should putrefy1 and affect the air4 ,i have found that a fresh cabbage leaf1 put under a glass vessel filled with common air1 for the space of one night only1 has so affected the air1 that a candle would not burn in it the next morning1 and yet the leaf had not acquired any smell of putrefaction4 ,finding that candles would burn very well in air in which plants had grown a long time1 and having had some reason to think1 that there was something attending vegetation1 which restored air that had been injured by respiration1 ,i thought it was possible that the same process might also restore the air that had been injured by the burning of candles4 ,accordingly1 on the #agth of ,august #agga1 ,i put a sprig of mint into a quantity of air1 in which a wax candle had burned out1 and found that1 on the #bgth of the same month1 another candle burned perfectly well in it4 ,this experiment ,i repeated1 without the least variation in the event1 not less than eight or ten times in the remainder of the summer4 ,several times ,i divided the quantity of air in which the candle had burned out1 into two parts1 and putting the plant into one of them1 left the other in the same exposure1 contained1 also1 in a glass vessel immersed in water1 but without any plant2 and never failed to find1 that a candle would burn in the former1 but not in the latter4 ,i generally found that five or six days were sufficient to restore this air1 when the plant was in its vigour2 whereas ,i have kept this kind of air in glass vessels1 immersed in water many months1 without being able to perceive that the least alteration had been made in it4 ,i have also tried a great variety of experiments upon it1 as by condensing1 rarefying1 exposing to the light and heat1 c4 and throwing into it the effluvia of many different substances1 but without any effect4 ,experiments made in the year #aggb1 abundantly confirmed my conclusion concerning the restoration of air1 in which candles had burned out by plants growing in it4 ,the first of these experiments was made in the month of ,may2 and they were frequently repeated in that and the two following months1 without a single failure4 ,for this purpose ,i used the flames of different substances1 though ,i generally used wax or tallow candles4 ,on the #bdth of ,june the experiment succeeded perfectly well with air in which spirit of wine had burned out1 and on the #bgth of the same month it succeeded equally well with air in which brimstone matches had burned out1 an effect of which ,i had despaired the preceding year4 ,this restoration of air1 ,i found1 depended upon the vegetating state of the plant2 for though ,i kept a great number of the fresh leaves of mint in a small quantity of air in which candles had burned out1 and changed them frequently1 for a long space of time1 ,i could perceive no melioration in the state of the air4 ,this remarkable effect does not depend upon any thing peculiar to mint1 which was the plant that ,i always made use of till ,july #aggb2 for on the #afth of that month1 ,i found a quantity of this kind of air to be perfectly restored by sprigs of balm1 which had grown in it from the #gth of the same month4 ,that this restoration of air was not owing to any aromatic effluvia of these two plants1 not only appeared by the essential oil of mint having no sensible effect of this kind2 but from the equally complete restoration of this vitiated air by the plant called groundsel1 which is usually ranked among the weeds1 and has an offensive smell4 ,this was the result of an experiment made the #afth of ,july1 when the plant had been growing in the burned air from the #hth of the same month4 ,besides1 the plant which ,i have found to be the most effectual of any that ,i have tried for this purpose is spinach1 which is of quick growth1 but will seldom thrive long in water4 ,one jar of burned air was perfectly restored by this plant in four days1 and another in two days4 ,this last was observed on the #bb;d of ,july4 ,in general1 this effect may be presumed to have taken place in much less time than ,i have mentioned2 because ,i never chose to make a trial of the air1 till ,i was pretty sure1 from preceding observations1 that the event which ,i had expected must have taken place1 if it would succeed at all2 lest1 returning back that part of the air on which ,i made the trial1 and which would thereby necessarily receive a small mixture of common air1 the experiment might not be judged to be quite fair2 though ,i myself might be sufficiently satisfied with respect to the allowance that was to be made for that small imperfection4 ,,footnotes3 #c ,the supposition1 mentioned in this and other passages of the first part of this publication1 viz4 that the diminution of common air1 by this and other processes is1 in part at least1 owing to the precipitation of the fixed air from it1 the reader will find confirmed by the experiments and observations in the second part4 ,,section ,,iii4 ,of ,,inflammable ,,air4 ,i have generally made inflammable air in the manner described by ,mr4 ,cavendish1 in the ,philosophical ,transactions1 from iron1 zinc1 or tin2 but chiefly from the two former metals1 on account of the process being the least troublesome3 but when ,i extracted it from vegetable or animal substances1 or from coals1 ,i put them into a gun-barrel1 to the orifice of which ,i luted a glass tube1 or the stem of a tobacco-pipe1 and to the end of this ,i tied a flaccid bladder in order to catch the generated air2 or ,i received the air in a vessel of quicksilver1 in the manner represented ,fig4 #g4 ,there is not1 ,i believe1 any vegetable or animal substance whatever1 nor any mineral substance1 that is inflammable1 but what will yield great plenty of inflammable air1 when they are treated in this manner1 and urged with a strong heat2 but1 in order to get the most air1 the heat must be applied as suddenly1 and as vehemently1 as possible4 ,for1 notwithstanding the same care be taken in luting1 and in every other respect1 six or even ten times more air may be got by a sudden heat than by a slow one1 though the heat that is last applied be as intense as that which was applied suddenly4 ,a bit of dry oak1 weighing about twelve grains1 will generally yield about a sheep's bladder full of inflammable air with a brisk heat1 when it will only give about two or three ounce measures1 if the same heat be applied to it very gradually4 ,to what this difference is owing1 ,i cannot tell4 ,perhaps the phlogiston being extricated more slowly may not be intirely expelled1 but form another kind of union with its base2 so that charcoal made with a heat slowly applied shall contain more phlogiston than that which is made with a sudden heat4 ,it may be worth while to examine the properties of the charcoal with this view4 ,inflammable air1 when it is made by a quick process1 has a very strong and offensive smell1 from whatever substance it be generated2 but this smell is of three different kinds1 according as the air is extracted from mineral1 vegetable1 or animal substances4 ,the last is exceedingly fetid2 and it makes no difference1 whether it be extracted from a bone1 or even an old and dry tooth1 from soft muscular flesh2 or any other part of the animal4 ,the burning of any substance occasions the same smell3 for the gross fume which arises from them1 before they flame1 is the inflammable air they contain1 which is expelled by heat1 and then readily ignited4 ,the smell of inflammable air is the very same1 as far as ,i am able to perceive1 from whatever substance of the same kingdom it be extracted4 ,thus it makes no difference whether it be got from iron1 zinc1 or tin1 from any kind of wood1 or1 as was observed before1 from any part of an animal4 ,if a quantity of inflammable air be contained in a glass vessel standing in water1 and have been generated very fast1 it will smell even through the water1 and this water will also soon become covered with a thin film1 assuming all the different colours4 ,if the inflammable air have been generated from iron1 this matter will appear to be a red okre1 or the earth of iron1 as ,i have found by collecting a considerable quantity of it2 and if it have been generated from zinc1 it is a whitish substance1 which ,i suppose to be the calx of the metal4 ,it likewise settles to the bottom of the vessel1 and when the water is stirred1 it has very much the appearance of wool4 ,when water is once impregnated in this manner1 it will continue to yield this scum for a considerable time after the air is removed from it4 ,this ,i have often observed with respect to iron4 ,inflammable air1 made by a violent effervescence1 ,i have observed to be much more inflammable than that which is made by a weak effervescence1 whether the water or the oil of vitriol prevailed in the mixture4 ,also the offensive smell was much stronger in the former case than in the latter4 ,the greater degree of inflammability appeared by the greater number of successive explosions1 when a candle was presented to the neck of a phial filled with it4#d ,it is possible1 however1 that this diminution of inflammability may1 in some measure1 arise from the air continuing so much longer in the bladder when it is made very slowly2 though ,i think the difference is too great for this cause to have produced the whole of it4 ,it may1 perhaps1 deserve to be tried by a different process1 without a bladder4 ,inflammable air is not thought to be miscible with water1 and when kept many months1 seems1 in general1 to be as inflammable as ever4 ,indeed1 when it is extracted from vegetable or animal substances1 a part of it will be imbibed by the water in which it stands2 but it may be presumed1 that in this case1 there was a mixture of fixed air extracted from the substance along with it4 ,i have indisputable evidence1 however1 that inflammable air1 standing long in water1 has actually lost all its inflammability1 and even come to extinguish flame much more than that air in which candles have burned out4 ,after this change it appears to be greatly diminished in quantity1 and it still continues to kill animals the moment they are put into it4 ,this very remarkable fact first occurred to my observation on the twenty-fifth of ,may #agga1 when ,i was examining a quantity of inflammable air1 which had been made from zinc1 near three years before4 ,upon this1 ,i immediately set by a common quart-bottle filled with inflammable air from iron1 and another equal quantity from zinc2 and examining them in the beginning of ,december following1 that from the iron was reduced near one half in quantity1 if ,i be not greatly mistaken2 for ,i found the bottle half full of water1 and ,i am pretty clear that it was full of air when it was set by4 ,that which had been produced from zinc was not altered1 and filled the bottle as at first4 ,another instance of this kind occurred to my observation on the #aith of ,june #aggb1 when a quantity of air1 half of which had been inflammable air from zinc1 and half air in which mice had died1 and which had been put together the #cjth of ,july #agga1 appeared not to be in the least inflammable1 but extinguished flame1 as much as any kind of air that ,i had ever tried4 ,i think that1 in all1 ,i have had four instances of inflammable air losing its inflammability1 while it stood in water4 ,though air tainted with putrefaction extinguishes flame1 ,i have not found that animals or vegetables putrefying in inflammable air render it less inflammable4 ,but one quantity of inflammable air1 which ,i had set by in ,may #agga1 along with the others above mentioned1 had had some putrid flesh in it2 and this air had lost its inflammability1 when it was examined at the same time with the other in the ,december following4 ,the bottle in which this air had been kept1 smelled exactly like very strong ,harrogate water4 ,i do not think that any person could have distinguished them4 ,i have made plants grow for several months in inflammable air made from zinc1 and also from oak2 but1 though the plants grew pretty well1 the air still continued inflammable4 ,the former1 indeed1 was not so highly inflammable as when it was fresh made1 but the latter was quite as much so2 and the diminution of inflammability in the former case1 ,i attribute to some other cause than the growth of the plant4 ,no kind of air1 on which ,i have yet made the experiment1 will conduct electricity2 but the colour of an electric spark is remarkably different in some different kinds of air1 which seems to shew that they are not equally good non-conductors4 ,in fixed air1 the electric spark is exceedingly white2 but in inflammable air it is of a purple1 or red colour4 ,now1 since the most vigorous sparks are always the whitest1 and1 in other cases1 when the spark is red1 there is reason to think that the electric matter passes with difficulty1 and with less rapidity3 it is possible that the inflammable air may contain particles which conduct electricity1 though very imperfectly2 and that the whiteness of the spark in the fixed air1 may be owing to its meeting with no conducting particles at all4 ,when an explosion was made in a quantity of inflammable air1 it was a little white in the center1 but the edges of it were still tinged with a beautiful purple4 ,the degree of whiteness in this case was probably owing to the electric matter rushing with more violence in an explosion than in a common spark4 ,inflammable air kills animals as suddenly as fixed air1 and1 as far as can be perceived1 in the same manner1 throwing them into convulsions1 and thereby occasioning present death4 ,i had imagined that1 by animals dying in a quantity of inflammable air1 it would in time become less noxious2 but this did not appear to be the case2 for ,i killed great number of mice in a small quantity of this air2 which ,i kept several months for this purpose1 without its being at all sensibly mended2 the last1 as well as the first mouse1 dying the moment it was put into it4 ,i once imagined that1 since fixed and inflammable air are the reverse of one another1 in several remarkable properties1 a mixture of them would make common air2 and while ,i made the mixtures in bladders1 ,i imagined that ,i had succeeded in my attempt2 but ,i have since found that thin bladders do not sufficiently prevent the air that is contained in them from mixing with the external air4 ,also corks will not sufficiently confine different kinds of air1 unless the phials in which they are confined be set with their mouths downwards1 and a little water lie in the necks of them1 which1 indeed1 is equivalent to the air standing in vessels immersed in water4 ,in this manner1 however1 ,i have kept different kinds of air for several years4 ,whatever methods ,i took to promote the mixture of fixed and inflammable air1 they were all ineffectual4 ,i think it my duty1 however1 to recite the issue of an experiment or two of this kind1 in which equal mixtures of these two kinds of air had stood near three years1 as they seem to shew that they had in part affected one another1 in that long space of time4 ,these mixtures ,i examined ,april #bg1 #agga4 ,one of them had stood in quicksilver1 and the other in a corked phial1 with a little water in it4 ,on opening the latter in water1 the water instantly rushed in1 and filled almost half of the phial1 and very little more was absorbed afterwards4 ,in this case the water in the phial had probably absorbed a considerable part of the fixed air1 so that the inflammable air was exceedingly rarefied2 and yet the whole quantity that must have been rendered non-elastic was ten times more than the bulk of the water1 and it has not been found that water can contain much more than its own bulk of fixed air4 ,but in other cases ,i have found the diminution of a quantity of air1 and especially of fixed air1 to be much greater than ,i could well account for by any kind of absorption4 ,the phial which had stood immersed in quicksilver had lost very little of its original quantity of air2 and being now opened in water1 and left there1 along with another phial1 which was just then filled1 as this had been three years before1 viz4 with air half inflammable and half fixed1 ,i observed that the quantity of both was diminished1 by the absorption of the water1 in the same proportion4 ,upon applying a candle to the mouths of the phials which had been kept three years1 that which had stood in quicksilver went off at one explosion1 exactly as it would have done if there had been a mixture of common air with the inflammable4 ,as a good deal depends upon the apertures of the vessels in which the inflammable air is mixed1 ,i mixed the two kinds of air in equal proportions in the same phial1 and after letting the phial stand some days in water1 that the fixed air might be absorbed1 ,i applied a candle to it1 but it made ten or twelve explosions 7stopping the phial after each of them7 before the inflammable matter was exhausted4 ,the air which had been confined in the corked phial exploded in the very same manner as an equal and fresh mixture of the two kinds of air in the same phial1 the experiment being made as soon as the fixed air was absorbed1 as before2 so that in this case1 the two kinds of air did not seem to have affected one another at all4 ,considering inflammable air as air united to1 or loaded with phlogiston1 ,i exposed to it several substances1 which are said to have a near affinity with phlogiston1 as oil of vitriol1 and spirit of nitre 7the former for above a month71 but without making any sensible alteration in it4 ,i observed1 however1 that inflammable air1 mixed with the fumes of smoking spirit of nitre1 goes off at one explosion1 exactly like a mixture of half common and half inflammable air4 ,this ,i tried several times1 by throwing the inflammable air into a phial full of spirit of nitre1 with its mouth immersed in a bason containing some of the same spirit1 and then applying the flame of a candle to the mouth of the phial1 the moment that it was uncovered1 after it had been taken out of the bason4 ,this remarkable effect ,i hastily concluded to have arisen from the inflammable air having been in part deprived of its inflammability1 by means of the stronger affinity1 which the spirit of nitre had with phlogiston1 and therefore ,i imagined that by letting them stand longer in contact1 and especially by agitating them strongly together1 ,i should deprive the air of all its inflammability2 but neither of these operations succeeded1 for still the air was only exploded at once1 as before4 ,and lastly1 when ,i passed a quantity of inflammable air1 which had been mixed with the fumes of spirit of nitre1 through a body of water1 and received it in another vessel1 it appeared not to have undergone any change at all1 for it went off in several successive explosions1 like the purest inflammable air4 ,the effect above-mentioned must1 therefore1 have been owing to the fumes of the spirit of nitre supplying the place of common air for the purpose of ignition1 which is analogous to other experiments with nitre4 ,having had the curiosity1 on the #beth of ,july #aggb1 to expose a great variety of different kinds of air to water out of which the air it contained had been boiled1 without any particular view2 the result was1 in several respects1 altogether unexpected1 and led to a variety of new observations on the properties and affinities of several kinds of air with respect to water4 ,among the rest three fourths of that which was inflammable was absorbed by the water in about two days1 and the remainder was inflammable1 but weakly so4 ,upon this1 ,i began to agitate a quantity of strong inflammable air in a glass jar1 standing in a pretty large trough of water1 the surface of which was exposed to the common air1 and ,i found that when ,i had continued the operation about ten minutes1 near one fourth of the quantity of air had disappeared2 and finding that the remainder made an effervescence with nitrous air1 ,i concluded that it must have become fit for respiration1 whereas this kind of air is1 at the first1 as noxious as any other kind whatever4 ,to ascertain this1 ,i put a mouse into a vessel containing #b-a_/b ounce measures of it1 and observed that it lived in it twenty minutes1 which is as long as a mouse will generally live in the same quantity of common air4 ,this mouse was even taken out alive1 and recovered very well4 ,still also the air in which it had breathed so long was inflammable1 though very weakly so4 ,i have even found it to be so when a mouse has actually died in it4 ,inflammable air thus diminished by agitation in water1 makes but one explosion on the approach of a candle1 exactly like a mixture of inflammable air with common air4 ,from this experiment ,i concluded that1 by continuing the same process1 ,i should deprive inflammable air of all its inflammability1 and this ,i found to be the case2 for1 after a longer agitation1 it admitted a candle to burn in it1 like common air1 only more faintly2 and indeed by the test of nitrous air it did not appear to be near so good as common air4 ,continuing the same process still farther1 the air which had been most strongly inflammable a little before1 came to extinguish a candle1 exactly like air in which a candle had burned out1 nor could they be distinguished by the test of nitrous air4 ,i found1 by repeated trials1 that it was difficult to catch the time in which inflammable air obtained from metals1 in coming to extinguish flame1 was in the state of common air1 so that the transition from the one to the other must be very short4 ,indeed ,i think that in many1 perhaps in most cases1 there may be no proper medium at all1 the phlogiston passing at once from that mode of union with its base which constitutes inflammable air1 to that which constitutes an air that extinguishes flame1 being so much overloaded as to admit of no more4 ,i readily1 however1 found this middle state in a quantity of inflammable air extracted from oak1 which air ,i had kept a year1 and in which a plant had grown1 though very poorly1 for some part of the time4 ,a quantity of this air1 after being agitated in water till it was diminished about one half1 admitted a candle to burn in it exceedingly well1 and was even hardly to be distinguished from common air by the test of nitrous air4 ,i took some pains to ascertain the quantity of diminution1 in fresh made and very highly-inflammable air from iron1 at which it ceased to be inflammable1 and1 upon the whole1 ,i concluded that it was so when it was diminished a little more than one half2 for a quantity which was diminished exactly one half had something inflammable in it1 but in the slightest degree imaginable4 ,it is not improbable1 however1 but there may be great differences in the result of this experiment4 ,finding that water would imbibe inflammable air1 ,i endeavoured to impregnate water with it1 by the same process by which ,i had made water imbibe fixed air2 but though ,i found that distilled water would imbibe about one fourteenth of its bulk of inflammable air1 ,i could not perceive that the taste of it was sensibly altered4 ,,footnotes3 #d ,to try this1 after every explosion1 which immediately follows the presenting of the flame1 the mouth of the phial should be closed 7,i generally do it with a finger of the hand in which ,i hold the phial7 for otherwise the inflammable air will continue burning1 though invisibly in the day time1 till the whole be consumed4 ,,section ,,iv4 ,of ,,air infected with ,,animal ,,respiration1 or ,,putrefaction4 ,that candles will burn only a certain time1 in a given quantity of air is a fact not better known1 than it is that animals can live only a certain time in it2 but the cause of the death of the animal is not better known than that of the extinction of flame in the same circumstances2 and when once any quantity of air has been rendered noxious by animals breathing in it as long as they could1 ,i do not know that any methods have been discovered of rendering it fit for breathing again4 ,it is evident1 however1 that there must be some provision in nature for this purpose1 as well as for that of rendering the air fit for sustaining flame2 for without it the whole mass of the atmosphere would1 in time1 become unfit for the purpose of animal life2 and yet there is no reason to think that it is1 at present1 at all less fit for respiration than it has ever been4 ,i flatter myself1 however1 that ,i have hit upon two of the methods employed by nature for this great purpose4 ,how many others there may be1 ,i cannot tell4 ,when animals die upon being put into air in which other animals have died1 after breathing in it as long as they could1 it is plain that the cause of their death is not the want of any pabulum vit1 which has been supposed to be contained in the air1 but on account of the air being impregnated with something stimulating to their lungs2 for they almost always die in convulsions1 and are sometimes affected so suddenly1 that they are irrecoverable after a single inspiration1 though they be withdrawn immediately1 and every method has been taken to bring them to life again4 ,they are affected in the same manner1 when they are killed in any other kind of noxious air that ,i have tried1 viz4 fixed air1 inflammable air1 air filled with the fumes of brimstone1 infected with putrid matter1 in which a mixture of iron filings and brimstone has stood1 or in which charcoal has been burned1 or metals calcined1 or in nitrous air1 c4 ,as it is known that convulsions weaken1 and exhaust the vital powers1 much more than the most vigorous voluntary action of the muscles1 perhaps these universal convulsions may exhaust the whole of what we may call the vis vit at once1 at least that the lungs may be rendered absolutely incapable of action1 till the animal be suffocated1 or be irrecoverable for want of respiration4 ,if a mouse 7which is an animal that ,i have commonly made use of for the purpose of these experiments7 can stand the first shock of this stimulus1 or has been habituated to it by degrees1 it will live a considerable time in air in which other mice will die instantaneously4 ,i have frequently found that when a number of mice have been confined in a given quantity of air1 less than half the time that they have actually lived in it1 a fresh mouse being introduced to them has been instantly thrown into convulsions1 and died4 ,it is evident1 therefore1 that if the experiment of the ,black ,hole were to be repeated1 a man would stand the better chance of surviving it1 who should enter at the first1 than at the last hour4 ,i have also observed1 that young mice will always live much longer than old ones1 or than those which are full grown1 when they are confined in the same quantity of air4 ,i have sometimes known a young mouse to live six hours in the same circumstances in which an old mouse has not lived one4 ,on these accounts1 experiments with mice1 and1 for the same reason1 no doubt1 with other animals also1 have a considerable degree of uncertainty attending them2 and therefore1 it is necessary to repeat them frequently1 before the result can be absolutely depended upon4 ,but every person of feeling will rejoice with me in the discovery of nitrous air1 to be mentioned hereafter1 which supersedes many experiments with the respiration of animals1 being a much more accurate test of the purity of air4 ,the discovery of the provision in nature for restoring air1 which has been injured by the respiration of animals1 having long appeared to me to be one of the most important problems in natural philosophy1 ,i have tried a great variety of schemes in order to effect it4 ,in these my guide has generally been to consider the influences to which the atmosphere is1 in fact1 exposed2 and1 as some of my unsuccessful trials may be of use to those who are disposed to take pains in the farther investigation of this subject1 ,i shall mention the principal of them4 ,the noxious effluvium with which air is loaded by animal respiration1 is not absorbed by standing1 without agitation2 in fresh or salt water4 ,i have kept it many months in fresh water1 when1 instead of being meliorated1 it has seemed to become even more deadly1 so as to require more time to restore it1 by the methods which will be explained hereafter1 than air which has been lately made noxious4 ,i have even spent several hours in pouring this air from one glass vessel into another1 in water1 sometimes as cold1 and sometimes as warm1 as my hands could bear it1 and have sometimes also wiped the vessels many times1 during the course of the experiment1 in order to take off that part of the noxious matter1 which might adhere to the glass vessels1 and which evidently gave them an offensive smell2 but all these methods were generally without any sensible effect4 ,the motion1 also1 which the air received in these circumstances1 it is very evident1 was of no use for this purpose4 ,i had not then thought of the simple1 but most effectual method of agitating air in water1 by putting it into a tall jar and shaking it with my hand4 ,this kind of air is not restored by being exposed to the light1 or by any other influence to which it is exposed1 when confined in a thin phial1 in the open air1 for some months4 ,among other experiments1 ,i tried a great variety of different effluvia1 which are continually exhaling into the air1 especially of those substances which are known to resist putrefaction2 but ,i could not by these means effect any melioration of the noxious quality of this kind of air4 ,having read1 in the memoirs of the ,imperial ,society1 of a plague not affecting a particular village1 in which there was a large sulphur-work1 ,i immediately fumigated a quantity of this kind of air2 or 7which will hereafter appear to be the very same thing7 air tainted with putrefaction1 with the fumes of burning brimstone1 but without any effect4 ,i once imagined1 that the nitrous acid in the air might be the general restorative which ,i was in quest of2 and the conjecture was favoured1 by finding that candles would burn in air extracted from saltpetre4 ,i therefore spent a good deal of time in attempting1 by a burning glass1 and other means1 to impregnate this noxious air1 with some effluvium of saltpetre1 and1 with the same view1 introduced into it the fumes of the smoaking spirit of nitre2 but both these methods were altogether ineffectual4 ,in order to try the effect of heat1 ,i put a quantity of air1 in which mice had died1 into a bladder1 tied to the end of the stem of a tobacco-pipe1 at the other end of which was another bladder1 out of which the air was carefully pressed4 ,i then put the middle part of the stem into a chafing-dish of hot coals1 strongly urged with a pair of bellows2 and1 pressing the bladders alternately1 ,i made the air pass several times through the heated part of the pipe4 ,i have also made this kind of air very hot1 standing in water before the fire4 ,but neither of these methods were of any use4 ,rarefaction and condensation by instruments were also tried1 but in vain4 ,thinking it possible that the earth might imbibe the noxious quality of the air1 and thence supply the roots of plants with such putrescent matter as is known to be nutritive to them1 ,i kept a quantity of air1 in which mice had died1 in a phial1 one half of which was filled with fine garden-mould2 but1 though it stood two months in these circumstances1 it was not the better for it4 ,i once imagined that1 since several kinds of air cannot be long separated from common air1 by being confined in bladders1 in bottles well corked2 or even closed with ground stopples1 the affinity between this noxious air and the common air might be so great1 that they would mix through a body of water interposed between them2 the water continually receiving from the one1 and giving to the other1 especially as water receives some kind of impregnation from1 ,i believe1 every kind of air to which it is contiguous2 but ,i have seen no reason to conclude1 that a mixture of any kind of air with the common air can be produced in this manner4 ,i have kept air in which mice have died1 air in which candles have burned out1 and inflammable air1 separated from the common air1 by the slightest partition of water that ,i could well make1 so that it might not evaporate in a day or two1 if ,i should happen not to attend to them2 but ,i found no change in them after a month or six weeks4 ,the inflammable air was still inflammable1 mice died instantly in the air in which other mice had died before1 and candles would not burn where they had burned out before4 ,since air tainted with animal or vegetable putrefaction is the same thing with air rendered noxious by animal respiration1 ,i shall now recite the observations which ,i have made upon this kind of air1 before ,i treat of the method of restoring them4 ,that these two kinds of air are1 in fact1 the same thing1 ,i conclude from their having several remarkable common properties1 and from their differing in nothing that ,i have been able to observe4 ,they equally extinguish flame1 they are equally noxious to animals1 they are equally1 and in the same way1 offensive to the smell1 and they are restored by the same means4 ,since air which has passed through the lungs is the same thing with air tainted with animal putrefaction1 it is probable that one use of the lungs is to carry off a putrid effluvium1 without which1 perhaps1 a living body might putrefy as soon as a dead one4 ,when a mouse putrefies in any given quantity of air1 the bulk of it is generally increased for a few days2 but in a few days more it begins to shrink up1 and in about eight or ten days1 if the weather be pretty warm1 it will be found to be diminished #a_/f1 or #a_/e of its bulk4 ,if it do not appear to be diminished after this time1 it only requires to be passed through water1 and the diminution will not fail to be sensible4 ,i have sometimes known almost the whole diminution to take place1 upon once or twice passing through the water4 ,the same is the case with air1 in which animals have breathed as long as they could4 ,also1 air in which candles have burned out may almost always be farther reduced by this means4 ,all these processes1 as ,i observed before1 seem to dispose the compound mass of air to part with some constituent part belonging to it 7which appears to be the fixed air that enters into its constitution7 and this being miscible with water1 must be brought into contact with it1 in order to mix with it to the most advantage1 especially when its union with the other constituent principles of the air is but partially broken4 ,i have put mice into vessels which had their mouths immersed in quicksilver1 and observed that the air was not much contracted after they were dead or cold2 but upon withdrawing the mice1 and admitting lime water to the air1 it immediately became turbid1 and was contracted in its dimensions as usual4 ,i tried the same thing with air tainted with putrefaction1 putting a dead mouse to a quantity of common air1 in a vessel which had its mouth immersed in quicksilver1 and after a week ,i took the mouse out1 drawing it through the quicksilver1 and observed that1 for some time1 there was an apparent increase of the air perhaps about #a_/bj4 ,after this1 it stood two days in the quicksilver1 without any sensible alteration2 and then admitting water to it1 it began to be absorbed1 and continued so1 till the original quantity was diminished about #a_/f4 ,if1 instead of common water1 ,i had made use of lime-water in this experiment1 ,i make no doubt but it would have become turbid4 ,if a quantity of lime-water in a phial be put under a glass vessel standing in water1 it will not become turbid1 and provided the access of the common air be prevented1 it will continue lime-water1 ,i do not know how long2 but if a mouse be left to putrefy in the vessel1 the water will deposit all its lime in a few days4 ,this is owing to the fixed air deposited by the common air1 and perhaps also from more fixed air discharged from the putrefying substances in some part of the process of putrefaction4 ,the air that is discharged from putrefying substances seems1 in some cases1 to be chiefly fixed air1 with the addition of some other effluvium1 which has the power of diminishing common air4 ,the resemblance between the true putrid effluvium and fixed air in the following experiment1 which is as decisive as ,i can possibly contrive it1 appeared to be very great2 indeed much greater than ,i had expected4 ,i put a dead mouse into a tall glass vessel1 and having filled the remainder with quicksilver1 and set it1 inverted1 in a pot of quicksilver1 ,i let it stand about two months1 in which time the putrid effluvium issuing from the mouse had filled the whole vessel1 and part of the dissolved blood1 which lodged upon the surface of the quicksilver1 began to be thrown out4 ,i then filled another glass vessel1 of the same size and shape1 with as pure fixed air as ,i could make1 and exposed them both1 at the same time1 to a quantity of lime-water4 ,in both cases the water grew turbid alike1 it rose equally fast in both the vessels1 and likewise equally high2 so that about the same quantity remained unabsorbed by the water4 ,one of these kinds of air1 however1 was exceedingly sweet and pleasant1 and the other insufferably offensive2 one of them also would have made an addition to any quantity of common air1 with which it had been mixed1 and the other would have diminished it4 ,this1 at least1 would have been the consequence1 if the mouse itself had putrefied in any quantity of common air4 ,it seems to depend1 in some measure1 upon the time1 and other circumstances1 in the dissolution of animal or vegetable substances1 whether they yield the proper putrid effluvium1 or fixed1 or inflammable air2 but the experiments which ,i have made upon this subject1 have not been numerous enough to enable me to decide with certainty concerning those circumstances4 ,putrid cabbage1 green or boiled1 infects the air in the very same manner as putrid animal substances4 ,air thus tainted is equally contracted in its dimensions1 it equally extinguishes flame1 and is equally noxious to animals2 but they affect the air very differently1 if the heat that is applied to them be considerable4 ,if beef or mutton1 raw or boiled1 be placed so near to the fire1 that the heat to which it is exposed shall equal1 or rather exceed1 that of the blood1 a considerable quantity of air will be generated in a day or two1 about #a_/gth of which ,i have generally found to be absorbed by water1 while all the rest was inflammable2 but air generated from vegetables1 in the same circumstances1 will be almost all fixed air1 and no part of it inflammable4 ,this ,i have repeated again and again1 the whole process being in quicksilver2 so that neither common air nor water1 had any access to the substance on which the experiment was made2 and the generation of air1 or effluvium of any kind1 except what might be absorbed by quicksilver1 or resorbed by the substance itself1 might be distinctly noted4 ,a vegetable substance1 after standing a day or two in these circumstances1 will yield nearly all the air that can be extracted from it1 in that degree of heat2 whereas an animal substance will continue to give more air1 or effluvium1 of some kind or other1 with very little alteration1 for many weeks4 ,it is remarkable1 however1 that though a piece of beef or mutton1 plunged in quicksilver1 and kept in this degree of heat1 yield air1 the bulk of which is inflammable1 and contracts no putrid smell 7at least1 in a day or two7 a mouse treated in the same manner1 yields the proper putrid effluvium1 as indeed the smell sufficiently indicates4 ,that the putrid effluvium will mix with water seems to be evident from the following experiment4 ,if a mouse be put into a jar full of water1 standing with its mouth inverted in another vessel of water1 a considerable quantity of elastic matter 7and which may1 therefore1 be called air7 will soon be generated1 unless the weather be so cold as to check all putrefaction4 ,after a short time1 the water contracts an extremely fetid and offensive smell1 which seems to indicate that the putrid effluvium pervades the water1 and affects the neighbouring air2 and since1 after this1 there is often no increase of the air1 that seems to be the very substance which is carried off through the water1 as fast as it is generated2 and the offensive smell is a sufficient proof that it is not fixed air4 ,for this has a very agreeable flavour1 whether it be produced by fermentation1 or extracted from chalk by oil of vitriol2 affecting not only the mouth1 but even the nostrils2 with a pungency which is peculiarly pleasing to a certain degree1 as any person may easily satisfy himself1 who will chuse to make the experiment4 ,if the water in which the mouse was immersed1 and which is saturated with the putrid air1 be changed1 the greater part of the putrid air1 will1 in a day or two1 be absorbed1 though the mouse continues to yield the putrid effluvium as before2 for as soon as this fresh water becomes saturated with it1 it begins to be offensive to the smell1 and the quantity of the putrid air upon its surface increases as before4 ,i kept a mouse producing putrid air in this manner for the space of several months4 ,six ounce measures of air not readily absorbed by water1 appeared to have been generated from one mouse1 which had been putrefying eleven days in confined air1 before it was put into a jar which was quite filled with water1 for the purpose of this observation4 ,air thus generated from putrid mice standing in water1 without any mixture of common air1 extinguishes flame1 and is noxious to animals1 but not more so than common air only tainted with putrefaction4 ,it is exceedingly difficult and tedious to collect a quantity of this putrid air1 not miscible in water1 so very great a proportion of what is collected being absorbed by the water in which it is kept2 but what that proportion is1 ,i have not endeavoured to ascertain4 ,it is probably the same proportion that that part of fixed air1 which is not readily absorbed by water1 bears to the rest2 and therefore this air1 which ,i at first distinguished by the name of the putrid effluvium1 is probably the same with fixed air1 mixed with the phlogistic matter1 which1 in this and other processes1 diminishes common air4 ,though a quantity of common air be diminished by any substance putrefying in it1 ,i have not yet found the same effect to be produced by a mixture of putrid air with common air2 but1 in the manner in which ,i have hitherto made the experiment1 ,i was obliged to let the putrid air pass through a body of water1 which might instantly absorb the phlogistic matter that diminished the common air4 ,insects of various kinds live perfectly well in air tainted with animal or vegetable putrefaction1 when a single inspiration of it would have instantly killed any other animal4 ,i have frequently tried the experiment with flies and butterflies4 ,the aphides also will thrive as well upon plants growing in this kind of air1 as in the open air4 ,i have even been frequently obliged to take plants out of the putrid air in which they were growing1 on purpose to brush away the swarms of these insects which infected them2 and yet so effectually did some of them conceal themselves1 and so fast did they multiply1 in these circumstances1 that ,i could seldom keep the plants quite clear of them4 ,when air has been freshly and strongly tainted with putrefaction1 so as to smell through the water1 sprigs of mint have presently died1 upon being put into it1 their leaves turning black2 but if they do not die presently1 they thrive in a most surprizing manner4 ,in no other circumstances have ,i ever seen vegetation so vigorous as in this kind of air1 which is immediately fatal to animal life4 ,though these plants have been crouded in jars filled with this air1 every leaf has been full of life2 fresh shoots have branched out in various directions1 and have grown much faster than other similar plants1 growing in the same exposure in common air4 ,this observation led me to conclude1 that plants1 instead of affecting the air in the same manner with animal respiration1 reverse the effects of breathing1 and tend to keep the atmosphere sweet and wholesome1 when it is become noxious1 in consequence of animals either living and breathing1 or dying and putrefying in it4 ,in order to ascertain this1 ,i took a quantity of air1 made thoroughly noxious1 by mice breathing and dying in it1 and divided it into two parts2 one of which ,i put into a phial immersed in water2 and to the other 7which was contained in a glass jar1 standing in water7 ,i put a sprig of mint4 ,this was about the beginning of ,august #agga1 and after eight or nine days1 ,i found that a mouse lived perfectly well in that part of the air1 in which the sprig of mint had grown1 but died the moment it was put into the other part of the same original quantity of air2 and which ,i had kept in the very same exposure1 but without any plant growing in it4 ,this experiment ,i have several times repeated2 sometimes using air in which animals had breathed and died1 and at other times using air1 tainted with vegetable or animal putrefaction2 and generally with the same success4 ,once1 ,i let a mouse live and die in a quantity of air which had been noxious1 but which had been restored by this process1 and it lived nearly as long as ,i conjectured it might have done in an equal quantity of fresh air2 but this is so exceedingly various1 that it is not easy to form any judgment from it2 and in this case the symptom of difficult respiration seemed to begin earlier than it would have done in common air4 ,since the plants that ,i made use of manifestly grow and thrive in putrid air2 since putrid matter is well known to afford proper nourishment for the roots of plants2 and since it is likewise certain that they receive nourishment by their leaves as well as by their roots1 it seems to be exceedingly probable1 that the putrid effluvium is in some measure extracted from the air1 by means of the leaves of plants1 and therefore that they render the remainder more fit for respiration4 ,towards the end of the year some experiments of this kind did not answer so well as they had done before1 and ,i had instances of the relapsing of this restored air to its former noxious state4 ,i therefore suspended my judgment concerning the efficacy of plants to restore this kind of noxious air1 till ,i should have an opportunity of repeating my experiments1 and giving more attention to them4 ,accordingly ,i resumed the experiments in the summer of the year #aggb1 when ,i presently had the most indisputable proof of the restoration of putrid air by vegetation2 and as the fact is of some importance1 and the subsequent variation in the state of this kind of air is a little remarkable1 ,i think it necessary to relate some of the facts pretty circumstantially4 ,the air1 on which ,i made the first experiments1 was rendered exceedingly noxious by mice dying in it on the #bjth of ,june4 ,into a jar nearly filled with one part of this air1 ,i put a sprig of mint1 while ,i kept another part of it in a phial1 in the same exposure2 and on the #bgth of the same month1 and not before1 ,i made a trial of them1 by introducing a mouse into a glass vessel1 containing #b-a_/b ounce measures filled with each kind of air2 and ,i noted the following facts4 ,when the vessel was filled with the air in which the mint had grown1 a very large mouse lived five minutes in it1 before it began to shew any sign of uneasiness4 ,i then took it out1 and found it to be as strong and vigorous as when it was first put in2 whereas in that air which had been kept in the phial only1 without a plant growing in it1 a younger mouse continued not longer than two or three seconds1 and was taken out quite dead4 ,it never breathed after1 and was immediately motionless4 ,after half an hour1 in which time the larger mouse 7which ,i had kept alive1 that the experiment might be made on both the kinds of air with the very same animal7 would have been sufficiently recruited1 supposing it to have received any injury by the former experiment1 was put into the same vessel of air2 but though it was withdrawn again1 after being in it hardly one second1 it was recovered with difficulty1 not being able to stir from the place for near a minute4 ,after two days1 ,i put the same mouse into an equal quantity of common air1 and observed that it continued seven minutes without any sign of uneasiness2 and being very uneasy after three minutes longer1 ,i took it out4 ,upon the whole1 ,i concluded that the restored air wanted about one fourth of being as wholesome as common air4 ,the same thing also appeared when ,i applied the test of nitrous air4 ,in the seven days1 in which the mint was growing in this jar of noxious air1 three old shoots had extended themselves about three inches1 and several new ones had made their appearance in the same time4 ,dr4 ,franklin and ,sir ,john ,pringle happened to be with me1 when the plant had been three or four days in this state1 and took notice of its vigorous vegetation1 and remarkably healthy appearance in that confinement4 ,on the #cjth of the same month1 a mouse lived fourteen minutes1 breathing naturally all the time1 and without appearing to be much uneasy1 till the last two minutes1 in the vessel containing two ounce measures and a half of air which had been rendered noxious1 by mice breathing in it almost a year before1 and which1 ,i had found to be most highly noxious on the #aith of this month1 a plant having grown in it1 but not exceedingly well1 these eleven days2 on which account ,i had deferred making the trial so long4 ,the restored air was affected by a mixture of nitrous air1 almost as much as common air4 ,as this putrid air was thus easily restored to a considerable degree of fitness for respiration1 by plants growing in it1 ,i was in hopes that by the same means it might in time be so much more perfectly restored1 that a candle would burn in it2 and for this purpose ,i kept plants growing in the jars which contained this air till the middle of ,august following1 but did not take sufficient care to pull out all the old and rotten leaves4 ,the plants1 however1 had grown1 and looked so well upon the whole1 that ,i had no doubt but that the air must constantly have been in a mending state2 when ,i was exceedingly surprized to find1 on the #bdth of that month1 that though the air in one of the jars had not grown worse1 it was no better2 and that the air in the other jar was so much worse than it had been1 that a mouse would have died in it in a few seconds4 ,it also made no effervescence with nitrous air1 as it had done before4 ,suspecting that the same plant might be capable of restoring putrid air to a certain degree only1 or that plants might have a contrary tendency in some stages of their growth1 ,i withdrew the old plant1 and put a fresh one in its place2 and found that1 after seven days1 the air was restored to its former wholesome state4 ,this fact ,i consider as a very remarkable one1 and well deserving of a farther investigation1 as it may throw more light upon the principles of vegetation4 ,it is not1 however1 a single fact2 for ,i had several instances of the same kind in the preceding year2 but it seemed so very extraordinary1 that air should grow worse by the continuance of the same treatment by which it had grown better1 that1 whenever ,i observed it1 ,i concluded that ,i had not taken sufficient care to satisfy myself of its previous restoration4 ,that plants are capable of perfectly restoring air injured by respiration1 may1 ,i think1 be inferred with certainty from the perfect restoration1 by this means1 of air which had passed through my lungs1 so that a candle would burn in it again1 though it had extinguished flame before1 and apart of the same original quantity of air still continued to do so4 ,of this one instance occurred in the year #agga1 a sprig of mint having grown in a jar of this kind of air1 from the #beth of ,july to the #agth of ,august following2 and another trial ,i made1 with the same success1 the #gth of ,july #aggb1 the plant having grown in it from the #bith of ,june preceding4 ,in this case also ,i found that the effect was not owing to any virtue in the leaves of mint2 for ,i kept them constantly changed in a quantity of this kind of air1 for a considerable time1 without making any sensible alteration in it4 ,these proofs of a partial restoration of air by plants in a state of vegetation1 though in a confined and unnatural situation1 cannot but render it highly probable1 that the injury which is continually done to the atmosphere by the respiration of such a number of animals1 and the putrefaction of such masses of both vegetable and animal matter1 is1 in part at least1 repaired by the vegetable creation4 ,and1 notwithstanding the prodigious mass of air that is corrupted daily by the above-mentioned causes2 yet1 if we consider the immense profusion of vegetables upon the face of the earth1 growing in places1 suited to their nature1 and consequently at full liberty to exert all their powers1 both inhaling and exhaling1 it can hardly be thought1 but that it may be a sufficient counterbalance to it1 and that the remedy is adequate to the evil4 ,dr4 ,franklin1 who1 as ,i have already observed1 saw some of my plants in a very flourishing state1 in highly noxious air1 was pleased to express very great satisfaction with the result of the experiments4 ,in his answer to the letter in which ,i informed him of it1 he says1 ,that the vegetable creation should restore the air which is spoiled by the animal part of it1 looks like a rational system1 and seems to be of a piece with the rest4 ,thus fire purifies water all the world over4 ,it purifies it by distillation1 when it raises it in vapours1 and lets it fall in rain2 and farther still by filtration1 when1 keeping it fluid1 it suffers that rain to percolate the earth4 ,we knew before that putrid animal substances were converted into sweet vegetables1 when mixed with the earth1 and applied as manure2 and now1 it seems1 that the same putrid substances1 mixed with the air1 have a similar effect4 ,the strong thriving state of your mint in putrid air seems to shew that the air is mended by taking something from it1 and not by adding to it4 ,he adds1 ,i hope this will give some check to the rage of destroying trees that grow near houses1 which has accompanied our late improvements in gardening1 from an opinion of their being unwholesome4 ,i am certain1 from long observation1 that there is nothing unhealthy in the air of woods2 for we ,americans have every where our country habitations in the midst of woods1 and no people on earth enjoy better health1 or are more prolific4 ,having rendered inflammable air perfectly innoxious by continued agitation in a trough of water1 deprived of its air1 ,i concluded that other kinds of noxious air might be restored by the same means2 and ,i presently found that this was the case with putrid air1 even of more than a year's standing4 ,i shall observe once for all1 that this process has never failed to restore any kind of noxious air on which ,i have tried it1 viz4 air injured by respiration or putrefaction1 air infected with the fumes of burning charcoal1 and of calcined metals1 air in which a mixture of iron filings and brimstone1 that in which paint made of white lead and oil has stood1 or air which has been diminished by a mixture of nitrous air4 ,of the remarkable effect which this process has on nitrous air itself1 an account will be given in its proper place4 ,if this process be made in water deprived of air1 either by the air-pump1 by boiling1 or by distillation1 or if fresh rain-water be used1 the air will always be diminished by the agitation2 and this is certainly the fairest method of making the experiment4 ,if the water be fresh pump-water1 there will always be an increase of the air by agitation1 the air contained in the water being set loose1 and joining that which is in the jar4 ,in this case1 also1 the air has never failed to be restored2 but then it might be suspected that the melioration was produced by the addition of some more wholesome ingredient4 ,as these agitations were made in jars with wide mouths1 and in a trough which had a large surface exposed to the common air1 ,i take it for granted that the noxious effluvia1 whatever they be1 were first imbibed by the water1 and thereby transmitted to the common atmosphere4 ,in some cases this was sufficiently indicated by the disagreeable smell which attended the operation4 ,after ,i had made these experiments1 ,i was informed that an ingenious physician and philosopher had kept a fowl alive twenty-four hours1 in a quantity of air in which another fowl of the same size had not been able to live longer than an hour1 by contriving to make the air1 which it breathed1 pass through no very large quantity of acidulated water1 the surface of which was not exposed to the common air2 and that even when the water was not acidulated1 the fowl lived much longer than it could have done1 if the air which it breathed had not been drawn through the water4 ,as ,i should not have concluded that this experiment would have succeeded so well1 from any observations that ,i had made upon the subject1 ,i took a quantity of air in which mice had died1 and agitated it very strongly1 first in about five times its own quantity of distilled water1 in the manner in which ,i had impregnated water with fixed air2 but though the operation was continued a long time1 it made no sensible change in the properties of the air4 ,i also repeated the operation with pump-water1 but with as little effect4 ,in this case1 however1 though the air was agitated in a phial1 which had a narrow neck1 the surface of the water in the bason was considerably large1 and exposed to the common atmosphere1 which must have tended a little to favour the experiment4 ,in order to judge more precisely of the effect of these different methods of agitating air1 ,i transferred the very noxious air1 which ,i had hot been able to amend in the least degree by the former method1 into an open jar1 standing in a trough of water2 and when ,i had agitated it till it was diminished about one third1 ,i found it to be better than air in which candles had burned out1 as appeared by the test of the nitrous air2 and a mouse lived in #b-a_/b ounce measures of it a quarter of an hour1 and was not sensibly affected the first ten or twelve minutes4 ,in order to determine whether the addition of any acid to the water1 would make it more capable of restoring putrid air1 ,i agitated a quantity of it in a phial containing very strong vinegar2 and after that in aqua fortis1 only half diluted with water2 but by neither of these processes was the air at all mended1 though the agitation was repeated1 at intervals1 during a whole day1 and it was moreover allowed to stand in that situation all night4 ,since1 however1 water in these experiments must have imbibed and retained a certain portion of the noxious effluvia1 before they could be transmitted to the external air1 ,i do not think it improbable but that the agitation of the sea and large lakes may be of some use for the purification of the atmosphere1 and the putrid matter contained in water may be imbibed by aquatic plants1 or be deposited in some other manner4 ,having found1 by several experiments above-mentioned that the proper putrid effluvium is something quite distinct from fixed air1 and finding1 by the experiments of ,dr4 ,macbride1 that fixed air corrects putrefaction2 it occured to me1 that fixed air1 and air tainted with putrefaction1 though equally1 noxious when separate1 might make a wholesome mixture1 the one1 correcting the other2 and ,i was confirmed in this opinion by1 ,i believe1 not less than fifty or sixty instances1 in which air1 that had been made in the highest degree noxious1 by respiration or putrefaction1 was so far sweetened1 by a mixture of about four times as much fixed air1 that afterwards mice lived in it exceedingly well1 and in some cases almost as long as in common air4 ,i found it1 indeed1 to be more difficult to restore old putrid air by this means2 but ,i hardly ever failed to do it1 when the two kinds of air had stood a long time together2 by which ,i mean about a fortnight or three weeks4 ,the reason why ,i do not absolutely conclude that the restoration of air in these cases was the effect of fixed air1 is that1 when ,i made a trial of the mixture1 ,i sometimes agitated the two kinds of air pretty strongly together1 in a trough of water1 or at least passed it several times through water1 from one jar to another1 that the superfluous fixed air might be absorbed1 not suspecting at that time that the agitation could have any other effect4 ,but having since found that very violent1 and especially long-continued agitation in water1 without any mixture of fixed air1 never failed to render any kind of noxious air in some measure fit for respiration 7and in one particular instance the mere transferring of the air from one vessel to another through the water1 though for a much longer time than ,i ever used for the mixtures of air1 was of considerable use for the same purpose7 ,i began to entertain some doubt of the efficacy of fixed air in this case4 ,in some cases also the mixture of fixed air had by no means so much effect on the putrid air as1 from the generality of my observations1 ,i should have expected4 ,i was always aware1 indeed1 that it might be said1 that1 the residuum of fixed air not being very noxious1 such an addition must contribute to mend the putrid air2 but1 in order to obviate this objection1 ,i once mixed the residuum of as much fixed air as ,i had found1 by a variety of trials1 to be sufficient to restore a given quantity of putrid air1 with an equal quantity of that air1 without making any sensible melioration of it4 ,upon the whole1 ,i am inclined to think that this process could hardly have succeeded so well as it did with me1 and in so great a number of trials1 unless fixed air have some tendency to correct air tainted with respiration or putrefaction2 and it is perfectly agreeable to the analogy of ,dr4 ,macbride's discoveries1 and may naturally be expected from them1 that it should have such an effect4 ,by a mixture of fixed air ,i have made wholesome the residuum of air generated by putrefaction only1 from mice plunged in water4 ,this1 one would imagine1 priori1 to be the most noxious of all kinds of air4 ,for if common air only tainted with putrefaction be so deadly1 much more might one expect that air to be so1 which was generated from putrefaction only2 but it seems to be nothing more than common air 7or at least that kind of fixed air which is not absorbed by water7 tainted with putrefaction1 and therefore requires no other process to sweeten it4 ,in this case1 however1 we seem to have an instance of the generation of genuine common air1 though mixed with something that is foreign to it4 ,perhaps the residuum of fixed air may be another instance of the same nature1 and also the residuum of inflammable air1 and of nitrous air1 especially nitrous air loaded with phlogiston1 after long agitation in water4 ,fixed air is equally diffused through the whole mass of any quantity of putrid air with which it is mixed3 for dividing the mixture into two equal parts1 they were reduced in the same proportion by passing through water4 ,but this is also the case with some of the kinds of air which will not incorporate1 as inflammable air1 and air in which brimstone has burned4 ,if fixed air tend to correct air which has been injured by animal respiration or putrefaction1 lime kilns1 which discharge great quantities of fixed air1 may be wholesome in the neighbourhood of populous cities1 the atmosphere of which must abound with putrid effluvia4 ,i should think also that physicians might avail themselves of the application of fixed air in many putrid disorders1 especially as it may be so easily administered by way of clyster1 where it would often find its way to much of the putrid matter4 ,nothing is to be apprehended from the distention of the bowels by this kind of air1 since it is so readily absorbed by any fluid or moist substance4 ,since fixed air is not noxious per se1 but1 like fire1 only in excess1 ,i do not think it at all hazardous to attempt to breathe it4 ,it is however easily conveyed into the stomach1 in natural or artificial ,pyrmont water1 in briskly-fermenting liquors1 or a vegetable diet4 ,it is even possible1 that a considerable quantity of fixed air might be imbibed by the absorbing vessels of the skin1 if the whole body1 except the head1 should be suspended over a vessel of strongly-fermenting liquor2 and in some putrid disorders this treatment might be very salutary4 ,if the body was exposed quite naked1 there would be very little danger from the cold in this situation1 and the air having freer access to the skin might produce a greater effect4 ,being no physician1 ,i run no risk by throwing out these random1 and perhaps whimsical proposals4#e ,having communicated my observations on fixed air1 and especially my scheme of applying it by way of clyster in putrid disorders1 to ,mr4 ,hey1 an ingenious surgeon in ,leeds a case presently occurred1 in which he had an opportunity of giving it a trial2 and mentioning it to ,dr4 ,hird and ,dr4 ,crowther1 two physicians who attended the patient1 they approved the scheme1 and it was put in execution2 both by applying the fixed air by way of clyster1 and at the same time making the patient drink plentifully of liquors strongly impregnated with it4 ,the event was such1 that ,i requested ,mr4 ,hey to draw up a particular account of the case1 describing the whole of the treatment1 that the public might be satisfied that this new application of fixed air is perfectly safe1 and also1 have an opportunity of judging how far it had the effect which ,i expected from it2 and as the application is new1 and not unpromising1 ,i shall subjoin his letter to me on the subject1 by way of ,appendix to these papers4 ,when ,i began my inquires into the properties of different kinds of air1 ,i engaged my friend ,dr4 ,percival to attend to the medicinal uses of them1 being sensible that his knowledge of philosophy as well as of medicine would give him a singular advantage for this purpose4 ,the result of his observations ,i shall also insert in the ,appendix4 ,,footnotes3 #e ,some time after these papers were first printed1 ,i was pleased to find the same proposal in ,dr4 ,alexander's ,experimental ,essays4 ,,section ,v4 ,of ,,air in which a mixture of ,,brimstone and ,,filings of ,,iron has stood4 ,reading in ,dr4 ,hales's account of his experiments1 that there was a great diminution of the quantity of air in which a mixture of powdered brimstone and filings of iron1 made into a paste with water1 had stood1 ,i repeated the experiment1 and found the diminution greater than ,i had expected4 ,this diminution of air is made as effectually1 and as expeditiously1 in quicksilver as in water2 and it may be measured with the greatest accuracy1 because there is neither any previous expansion or increase of the quantity of air1 and because it is some time before this process begins to have any sensible effect4 ,this diminution of air is various2 but ,i have generally found it to be between one fifth and one fourth of the whole4 ,air thus diminished is not heavier1 but rather lighter than common air2 and though lime-water does not become turbid when it is exposed to this air1 it is probably owing to the formation of a selenitic salt1 as was the case with the simple burning of brimstone above-mentioned4 ,that something proceeding from the brimstone strongly affects the water which is confined in the same place with this mixture1 is manifest from the very strong smell that it has of the volatile spirit of vitriol4 ,i conclude that the diminution of air by this1 process is of the same kind with the diminution of it in the other cases1 because when this mixture is put into air which has been previously diminished1 either by the burning of candles1 by respiration1 or putrefaction1 though it never fails to diminish it something more1 it is1 however1 no farther than this process alone would have done it4 ,if a fresh mixture be introduced into a quantity of air which had been reduced by a former mixture1 it has little or no farther effect4 ,i once observed1 that when a mixture of this kind was taken out of a quantity of air in which a candle had before burned out1 and in which it had stood for several days1 it was quite cold and black1 as it always becomes in a confined place2 but it presently grew very hot1 smoaked copously1 and smelled very offensively2 and when it was cold1 it was brown1 like the rust of iron4 ,i once put a mixture of this kind to a quantity of inflammable air1 made from iron1 by which means it was diminished #a_/i or #a_/aj in its bulk2 but1 as far as ,i could judge1 it was still as inflammable as ever4 ,another quantity of inflammable air was also reduced in the same proportion1 by a mouse putrefying in it2 but its inflammability was not seemingly lessened4 ,air diminished by this mixture of iron filings and brimstone1 is exceedingly noxious to animals1 and ,i have not perceived that it grows any better by keeping in water4 ,the smell of it is very pungent and offensive4 ,the quantity of this mixture which ,i made use of in the preceding experiments1 was from two to four ounce measures2 but ,i did not perceive1 but that the diminution of the quantity of air 7which was generally about twenty ounce measures7 was as great with the smallest1 as with the largest quantity4 ,how small a quantity is necessary to diminish a given quantity of air to a maximum1 ,i have made no experiments to ascertain4 ,as soon as this mixture of iron filings with1 brimstone and water1 begins to ferment1 it also turns black1 and begins to swell1 and it continues to do so1 till it occupies twice as much space as it did at first4 ,the force with which it expands is great2 but how great it is ,i have not endeavoured to determine4 ,when this mixture is immersed in water1 it generates no air1 though it becomes black1 and swells4 ,,section ,,vi4 ,of ,,nitrous ,,air4 ,ever since ,i first read ,dr4 ,hales's most excellent ,statical ,essays1 ,i was particularly struck with that experiment of his1 of which an account is given1 ,,vol4 ,i1 p4 #bbd4 and ,,vol4 ,,ii1 p4 #bhj4 in which common air1 and air generated from the ,walton pyrites1 by spirit of nitre1 made a turbid red mixture1 and in which part of the common air was absorbed2 but ,i never expected to have the satisfaction of seeing this remarkable appearance1 supposing it to be peculiar to that particular mineral4 ,happening to mention this subject to the ,hon4 ,mr4 ,cavendish1 when ,i was in ,london1 in the spring of the year #aggb1 he said that he did not imagine but that other kinds of pyrites1 or the metals might answer as well1 and that probably the red appearance of the mixture depended upon the spirit of nitre only4 ,this encouraged me to attend to the subject2 and having no pyrites1 ,i began with the solution of the different metals in spirit of nitre1 and catching the air which was generated in the solution1 ,i presently found what ,i wanted1 and a good deal more4 ,beginning with the solution of brass1 on the #dth of ,june #aggb1 ,i first found this remarkable species of air1 only one effect of which1 was casually observed by ,dr4 ,hales2 and he gave so little attention to it1 and it has been so much unnoticed since his time1 that1 as far as ,i know1 no name has been given to it4 ,i therefore found myself1 contrary to my first resolution1 under an absolute necessity of giving a name to this kind of air myself4 ,when ,i first began to speak and write of it to my friends1 ,i happened to distinguish it by the name of nitrous air1 because ,i had procured it by means of spirit of nitre only2 and though ,i cannot say that ,i altogether like the term1 neither myself nor any of my friends1 to whom ,i have applied for the purpose1 have been able to hit upon a better2 so that ,i am obliged1 after all1 to content myself with it4 ,i have found that this kind of air is readily procured from iron1 copper1 brass1 tin1 silver1 quicksilver1 bismuth1 and nickel1 by the nitrous acid only1 and from gold and the regulus of antimony by aqua regia4 ,the circumstances attending the solution of each of these metals are various1 but hardly worth mentioning1 in treating of the properties of the air which they yield2 which1 from what metal soever it is extracted1 has1 as far as ,i have been able to observe1 the very same properties4 ,one of the most conspicuous properties of this kind of air is the great diminution of any quantity of common air with which it is mixed1 attended with a turbid red1 or deep orange colour1 and a considerable heat4 ,the smell of it1 also1 is very strong1 and remarkable1 but very much resembling that of smoking spirit of nitre4 ,the diminution of a mixture of this and common air is not an equal diminution of both the kinds1 which is all that ,dr4 ,hales could observe1 but of about one fifth of the common air1 and as much of the nitrous air as is necessary to produce that effect2 which1 as ,i have found by many trials1 is about one half as much as the original quantity of common air4 ,for if one measure of nitrous air be put to two measures of common air1 in a few minutes 7by which time the effervescence will be over1 and the mixture will have recovered its transparency7 there will want about one ninth of the original two measures2 and if both the kinds of air be very pure1 the diminution will still go on slowly1 till in a day or two1 the whole will be reduced to one fifth less than the original quantity of common air4 ,this farther diminution1 by long standing1 ,i had not observed at the time of the first publication of these papers4 ,i hardly know any experiment that is more adapted to amaze and surprize than this is1 which exhibits a quantity of air1 which1 as it were1 devours a quantity of another kind of air half as large as itself1 and yet is so far from gaining any addition to its bulk1 that it is considerably diminished by it4 ,if1 after this full saturation of common air with nitrous air1 more nitrous air be put to it1 it makes an addition equal to its own bulk1 without producing the least redness1 or any other visible effect4 ,if the smallest quantity of common air be put to any larger quantity of nitrous air1 though the two together will not occupy so much space as they did separately1 yet the quantity will still be larger than that of the nitrous air only4 ,one ounce measure of common air being put to near twenty ounce measures of nitrous air1 made an addition to it of about half an ounce measure4 ,this being a much greater proportion than the diminution of common air1 in the former experiment1 proves that part of the diminution in the former case is in the nitrous air4 ,besides1 it will presently appear1 that nitrous air is subject to a most remarkable diminution2 and as common air1 in a variety of other cases1 suffers a diminution from one fifth to one fourth1 ,i conclude1 that in this case also it does not exceed that proportion1 and therefore that the remainder of the diminution respects the nitrous air4 ,in order to judge whether the water contributed to the diminution of this mixture of nitrous and common air1 ,i made the whole process several times in quicksilver1 using one third of nitrous1 and two thirds of common air1 as before4 ,in this case the redness continued a very long time1 and the diminution was not so great as when the mixtures had been made in water1 there remaining one seventh more than the original quantity of common air4 ,this mixture stood all night upon the quicksilver2 and the next morning ,i observed that it was no farther diminished upon the admission of water to it1 nor by pouring it several times through the water1 and letting it stand in water two days4 ,another mixture1 which had stood about six hours on the quicksilver1 was diminished a little more upon the admission of water1 but was never less than the original quantity of common air4 ,in another case however1 in which the mixture had stood but a very short time in quicksilver1 the farther diminution1 which took place upon the admission of water1 was much more considerable2 so that the diminution1 upon the whole1 was very nearly as great as if the process had been intirely in water4 ,it is evident from these experiments1 that the diminution is in part owing to the absorption by the water2 but that when the mixture is kept a long time1 in a situation in which there is no water to absorb any part of it1 it acquires a constitution1 by which it is afterwards incapable of being absorbed by water1 or rather1 there is an addition to the quantity of air by nitrous air produced by the solution of the quicksilver4 ,it will be seen1 in the second part of this work1 that1 in the decomposition of nitrous air by its mixture with common air1 there is nothing at hand when the process is made in quicksilver1 with which the acid that entered into its composition can readily unite4 ,in order to determine whether the fixed part of common air was deposited in the diminution of it by nitrous air1 ,i inclosed a vessel full of lime-water in the jar in which the process was made1 but it occasioned no precipitation of the lime2 and when the vessel was taken out1 after it had been in that situation a whole day1 the lime was easily precipitated by breathing into it as usual4 ,but though the precipitation of the lime was not sensible in this method of making the experiment1 it is sufficiently so when the whole process is made in lime-water1 as will be seen in the second part of this work2 so that we have here another evidence of the deposition of fixed air from common air4 ,i have made no alteration1 however1 in the preceding paragraph1 because it may not be unuseful1 as a caution to future experimenters4 ,it is exceedingly remarkable that this effervescence and diminution1 occasioned by the mixture of nitrous air1 is peculiar to common air1 or air fit for respiration2 and1 as far as ,i can judge1 from a great number of observations1 is at least very nearly1 if not exactly1 in proportion to its fitness for this purpose2 so that by this means the goodness of air may be distinguished much more accurately than it can be done by putting mice1 or any other animals1 to breathe in it4 ,this was a most agreeable discovery to me1 as ,i hope it may be an useful one to the public2 especially as1 from this time1 ,i had no occasion for so large a stock of mice as ,i had been used to keep for the purpose of these experiments1 using them only in those which required to be very decisive2 and in these cases ,i have seldom failed to know beforehand in what manner they would be affected4 ,it is also remarkable that1 on whatever account air is unfit for respiration1 this same test is equally applicable4 ,thus there is not the least effervescence between nitrous and fixed air1 or inflammable air1 or any species of diminished air4 ,also the degree of diminution being from nothing at all to more than one third of the whole of any quantity of air1 we are1 by this means1 in possession of a prodigiously large scale1 by which we may distinguish very small degrees of difference in the goodness of air4 ,i have not attended much to this circumstance1 having used this test chiefly for greater differences2 but1 if ,i did not deceive myself1 ,i have perceived a real difference in the air of my study1 after a few persons have been with me in it1 and the air on the outside of the house4 ,also a phial of air having been sent me1 from the neighbourhood of ,york1 it appeared not to be so good as the air near ,leeds2 that is1 it was not diminished so much by an equal mixture of nitrous air1 every other circumstance being as nearly the same as ,i could contrive4 ,it may perhaps be possible1 but ,i have not yet attempted it1 to distinguish some of the different winds1 or the air of different times of the year1 c4 c4 by this test4 ,by means of this test ,i was able to determine what ,i was before in doubt about1 viz4 the kind as well as the degree of injury done to air by candles burning in it4 ,i could not tell with certainty1 by means of mice1 whether it was at all injured with respect to respiration2 and yet if nitrous air may be depended upon for furnishing an accurate test1 it must be rather more than one third worse than common air1 and have been diminished by the same general cause of the other diminutions of air4 ,for when1 after many trials1 ,i put one measure of thoroughly putrid and highly noxious air1 into the same vessel with two measures of good wholesome air1 and into another vessel an equal quantity1 viz4 three measures of air in which a candle had burned out2 and then put equal quantities of nitrous air to each of them1 the latter was diminished rather more than the former4 ,it agrees with this observation1 that burned air is farther diminished both by putrefaction1 and a mixture of iron filings and brimstone2 and ,i therefore take it for granted by every other cause of the diminution of air4 ,it is probable1 therefore1 that burned air is air so far loaded with phlogiston1 as to be able to extinguish a candle1 which it may do long before it is fully saturated4 ,inflammable air with a mixture of nitrous air burns with a green flame4 ,this makes a very pleasing experiment when it is properly conducted4 ,as1 for some time1 ,i chiefly made use of copper for the generation of nitrous air1 ,i first ascribed this circumstance to that property of this metal1 by which it burns with a green flame2 but ,i was presently satisfied that it must arise from the spirit of nitre1 for the effect is the very same from which ever of the metals the nitrous air is extracted1 all of which ,i tried for this purpose1 even silver and gold4 ,a mixture of oil of vitriol and spirit of nitre in equal proportions dissolved iron1 and the produce was nitrous air2 but a less degree of spirit of nitre in the mixture produced air that was inflammable1 and which burned with a green flame4 ,it also tinged common air a little red1 and diminished it1 though not much4 ,the diminution of common air by a mixture of nitrous air1 is not so extraordinary as the diminution which nitrous air itself is subject to from a mixture of iron filings and brimstone1 made into a paste with water4 ,this mixture1 as ,i have already observed1 diminishes common air between one fifth and one fourth1 but has no such effect upon any kind of air that has been diminished1 and rendered noxious by any other process2 but when it is put to a quantity of nitrous air1 it diminishes it so much1 that no more than one fourth of the original quantity will be left4 ,the effect of this process is generally perceived in five or six hours1 about which time the visible effervesence of the mixture begins2 and in a very short time it advances so rapidly1 that in about an hour almost the whole effect will have taken place4 ,if it be suffered to stand a day or two longer1 the air will still be diminished farther1 but only a very little farther1 in proportion to the first diminution4 ,the glass jar1 in which the air and this mixture have been confined1 has generally been so much heated in this process1 that ,i have not been able to touch it4 ,nitrous air thus diminished has not so strong a smell as nitrous air itself1 but smells just like common air in which the same mixture has stood2 and it is not capable of being diminished any farther1 by a fresh mixture of iron and brimstone4 ,common air saturated with nitrous air is also no farther diminished by this mixture of iron filings and brimstone1 though the mixture ferments with great heat1 and swells very much in it4 ,plants die very soon1 both in nitrous air1 and also in common air saturated with nitrous air1 but especially in the former4 ,neither nitrous air1 nor common air saturated with nitrous air1 differ in specific gravity from common air4 ,at least1 the difference is so small1 that ,i could not be sure there was any2 sometimes about three pints of it seeming to be about half a grain heavier1 and at other times as much lighter than common air4 ,having1 among other kinds of air1 exposed a quantity of nitrous air to water out of which the air had been well boiled1 in the experiment to which ,i have more than once referred 7as having been the occasion of several new and important observations7 ,i found that #ai_/bj of the whole was absorbed4 ,perceiving1 to my great surprize1 that so very great a proportion of this kind of air was miscible with water1 ,i immediately began to agitate a considerable quantity of it1 in a jar standing in a trough of the same kind of water2 and1 with about four times as much agitation as fixed air requires1 it was so far absorbed by the water1 that only about one fifth remained4 ,this remainder extinguished flame1 and was noxious to animals4 ,afterwards ,i diminished a pretty large quantity of nitrous air to one eighth of its original bulk1 and the remainder still retained much of its peculiar smell1 and diminished common air a little4 ,a mouse also died in it1 but not so suddenly as it would have done in pure nitrous air4 ,in this operation the peculiar smell of nitrous air is very manifest1 the water being first impregnated with the air1 and then transmitting it to the common atmosphere4 ,this experiment gave me the hint of impregnating water with nitrous air1 in the manner in which ,i had before done it with fixed air2 and ,i presently found that distilled water would imbibe about one tenth of its bulk of this kind of air1 and that it acquired a remarkably acid and astringent taste from it4 ,the smell of water thus impregnated is at first peculiarly pungent4 ,i did not chuse to swallow any of it1 though1 for any thing that ,i know1 it may be perfectly innocent1 and perhaps1 in some cases1 salutary4 ,this kind of air is retained very obstinately by water4 ,in an exhausted receiver a quantity of water thus saturated emitted a whitish fume1 such as sometimes issues from bubbles of this air when it is first generated1 and also some air-bubbles2 but though it was suffered to stand a long time in this situation1 it still retained its peculiar taste2 but when it had stood all night pretty near the fire1 the water was become quite vapid1 and had deposited a filmy kind of matter1 of which ,i had often collected a considerable quantity from the trough in which jars containing this air had stood4 ,this ,i suppose to be a precipitate of the metal1 by the solution of which the nitrous air was generated4 ,i have not given so much attention to it as to know1 with certainty1 in what circumstances this deposit is made1 any more than ,i do the matter deposited from inflammable air above-mentioned2 for ,i cannot get it1 at least in any considerable quantity1 when ,i please2 whereas ,i have often found abundance of it1 when ,i did not expect it at all4 ,the nitrous air with which ,i made the first impregnation of water was extracted from copper2 but when ,i made the impregnation with air from quicksilver1 the water had the very same taste1 though the matter deposited from it seemed to be of a different kind2 for it was whitish1 whereas the other had a yellowish tinge4 ,except the first quantity of this impregnated water1 ,i could never deprive any more that ,i made of its peculiar taste4 ,i have even let some of it stand more than a week1 in phials with their mouths open1 and sometimes very near the fire1 without producing any alteration in it#f4 ,whether any of the spirit of nitre contained in the nitrous air be mixed with the water in this operation1 ,i have not yet endeavoured to determine4 ,this1 however1 may probably be the case1 as the spirit of nitre is1 in a considerable degree1 volatile#g4 ,it will perhaps be thought1 that the most useful1 if not the most remarkable1 of all the properties of this extraordinary kind of air1 is its power of preserving animal substances from putrefaction1 and of restoring those that are already putrid1 which it possesses in a far greater degree than fixed air4 ,my first observation of this was altogether casual4 ,having found nitrous air to suffer so great a diminution as ,i have already mentioned by a mixture of iron filings and brimstone1 ,i was willing to try whether it would be equally diminished by other causes of the diminution of common air1 especially by putrefaction2 and for this purpose ,i put a dead mouse into a quantity of it1 and placed it near the fire1 where the tendency to putrefaction was very great4 ,in this case there was a considerable diminution1 viz4 from #e-a_/d to #c-a_/d2 but not so great as ,i had expected1 the antiseptic power of the nitrous air having checked the tendency to putrefaction2 for when1 after a week1 ,i took the mouse out1 ,i perceived1 to my very great surprize1 that it had no offensive smell4 ,upon this ,i took two other mice1 one of them just killed1 and the other soft and putrid1 and put them both into the same jar of nitrous air1 standing in the usual temperature of the weather1 in the months of ,july and ,august of #aggb2 and after twenty-five days1 having observed that there was little or no change in the quantity of the air1 ,i took the mice out2 and1 examining them1 found them both perfectly sweet1 even when cut through in several places4 ,that which had been put into the air when just dead was quite firm2 and the flesh of the other1 which had been putrid and soft1 was still soft1 but perfectly sweet4 ,in order to compare the antiseptic power of this kind of air with that of fixed air1 ,i examined a mouse which ,i had inclosed in a phial full of fixed air1 as pure as ,i could make it1 and which ,i had corked very close2 but upon opening this phial in water about a month after1 ,i perceived that a large quantity of putrid effluvium had been generated2 for it rushed with violence out of the phial2 and the smell that came from it1 the moment the cork was taken out1 was insufferably offensive4 ,indeed ,dr4 ,macbride says1 that he could only restore very thin pieces of putrid flesh by means of fixed air4 ,perhaps the antiseptic power of these kinds of air may be in proportion to their acidity4 ,if a little pains were taken with this subject1 this remarkable antiseptic power of nitrous air might possibly be applied to various uses1 perhaps to the preservation of the more delicate birds1 fishes1 fruits1 c4 mixing it in different proportions with common or fixed air4 ,of this property of nitrous air anatomists may perhaps avail themselves1 as animal substances may by this means be preserved in their natural soft state2 but how long it will answer for this purpose1 experience only can shew4 ,i calcined lead and tin in the manner hereafter described in a quantity of nitrous air1 but with very little sensible effect2 which rather surprized me2 as1 from the result of the experiment with the iron filings and brimstone1 ,i had expected a very great diminution of the nitrous air by this process2 the mixture of iron filings and brimstone1 and the calcination of metals1 having the same effect upon common air1 both of them diminishing it in nearly the same proportion4 ,but though ,i made the metals fume copiously in nitrous air1 there might be no real calcination1 the phlogiston not being separated1 and the proper calcination prevented by there being no fixed air1 which is necessary to the formation of the calx1 to unite with it4 ,nitrous air is procured from all the proper metals by spirit of nitre1 except lead1 and from all the semi-metals that ,i have tried1 except zinc4 ,for this purpose ,i have used bismuth and nickel1 with spirit of nitre only1 and regulus of antimony and platina1 with aqua regia4 ,i got little or no air from lead by spirit of nitre1 and have not yet made any experiments to ascertain the nature of this solution4 ,with zinc ,i have taken a little pains4 ,four penny-weights and seventeen grains of zinc dissolved in spirit of nitre1 to which as much water was added1 yielded about twelve ounce measures of air1 which had1 in some degree1 the properties of nitrous air1 making a slight effervescence with common air1 and diminishing it about as much as nitrous air1 which had been itself diminished one half by washing in water4 ,the smell of them both was also the same2 so that ,i concluded it to be the same thing1 that part of the nitrous air1 which is imbibed by water1 being retained in this solution4 ,in order to discover whether this was the case1 ,i made the solution boil in a sand-heat4 ,some air came from it in this state1 which seemed to be the same thing1 with nitrous air diminished about one sixth1 or one eighth1 by washing in water4 ,when the fluid part was evaporated1 there remained a brown fixed substance1 which was observed by ,mr4 ,hellot1 who describes it1 ,ac4 ,par4 #agce1 ,m4 p4 #ce4 ,a part of this ,i threw into a small red-hot crucible2 and covering it immediately with a receiver1 standing in water1 ,i observed that very dense red fumes rose from it1 and filled the receiver4 ,this redness continued about as long as that which is occasioned by a mixture of nitrous and common air2 the air was also considerably diminished within the receiver4 ,this substance1 therefore1 must certainly have contained within it the very same thing1 or principle1 on which the peculiar properties of nitrous air depend4 ,it is remarkable1 however1 that though the air within the receiver was diminished about one fifth by this process1 it was itself as much affected with a mixture of nitrous air1 as common air is1 and a candle burned in it very well4 ,this may perhaps be attributed to some effect of the spirit of nitre1 in the composition of that brown substance4 ,nitrous air1 ,i find1 will be considerably diminished in its bulk by standing a long time in water1 about as much as inflammable air is diminished in the same circumstances4 ,for this purpose ,i kept for some months a quart-bottle full of each of these kinds of air2 but as different quantities of inflammable air vary very much in this respect1 it is not improbable but that nitrous air may vary also4 ,from one trial that ,i made1 ,i conclude that nitrous air may be kept in a bladder much better than most other kinds of air4 ,the air to which ,i refer was kept about a fortnight in a bladder1 through which the peculiar smell of the nitrous air was very sensible for several days4 ,in a day or two the bladder became red1 and was much contracted in its dimensions4 ,the air within it had lost very little of its peculiar property of diminishing common air4 ,i did not endeavour to ascertain the exact quantity of nitrous air produced from given quantities1 of all the metals which yield it2 but the few observations which ,i did make for this purpose ,i shall recite in this place3 dwt4 gr4 #f #j of silver yielded #ag-a_/b ounce measures4 #e #ai of quicksilver #d-a_/b #a #b-a_/b of copper #ad-a_/b #b #j of brass #ba #j #bj of iron #af #a #e of bismuth #f #j #ab of nickel #d ,,footnotes3 #f ,i have since found1 that nitrous air has never failed to escape from the water1 which has been impregnated with it1 by long exposure to the open air4 #g ,this suspicion has been confirmed by the ingenious ,mr4 ,bewley1 of ,great ,massingham in ,norfolk1 who has discovered that the acid taste of this water is not the necessary consequence of its impregnation with nitrous air1 but is the effect of the acid vapour1 into which part of this air is resolved1 when it is decomposed by a mixture with common air4 ,this1 it will be seen1 exactly agrees with my own observation on the constitution of nitrous air1 in the second part of this work4 ,a more particular account of ,mr4 ,bewley's observation will be given in the ,appendix4 ,,section ,,vii4 ,of ,,air infected with the ,,fumes of ,,burning ,,charcoal4 ,air infected with the fumes of burning charcoal is well known to be noxious2 and the ,honourable ,mr4 ,cavendish favoured me with an account of some experiments of his1 in which a quantity of common air was reduced from #ahj to #afb ounce measures1 by passing through a red-hot iron tube filled with the dust of charcoal4 ,this diminution he ascribed to such a destruction of common air as ,dr4 ,hales imagined to be the consequence of burning4 ,mr4 ,cavendish also observed1 that there had been a generation of fixed air in this process1 but that it was absorbed by sope leys4 ,this experiment ,i also repeated1 with a small variation of circumstances1 and with nearly the same result4 ,afterwards1 ,i endeavoured to ascertain1 by what appears to me to be an easier and more certain method1 in what manner air is affected with the fumes of charcoal1 viz4 by suspending bits of charcoal within glass vessels1 filled to a certain height with water1 and standing inverted in another vessel of water1 while ,i threw the focus of a burning mirror1 or lens1 upon them4 ,in this manner ,i diminished a given quantity of air one fifth1 which is nearly in the same proportion with other diminutions of air4 ,if1 instead of pure water1 ,i used lime-water in this process1 it never failed to become turbid by the precipitation of the lime1 which could only be occasioned by fixed air1 either discharged from the charcoal1 or deposited by the common air4 ,at first ,i concluded that it came from the charcoal2 but considering that it is not probable that fixed air1 confined in any substance1 can bear so great a degree of heat as is necessary to make charcoal1 without being wholly expelled2 and that in other diminutions of common air1 by phlogiston only1 there appears to be a deposition of fixed air1 ,i have now no doubt but that1 in this case also1 it is supplied from the same source4 ,this opinion is the more probable1 from there being the same precipitation of lime1 in this process1 with whatever degree of heat the charcoal had been made4 ,if1 however1 the charcoal had not been made with a very considerable degree of heat1 there never failed to be a permanent addition of inflammable air produced2 which agrees with what ,i observed before1 that1 in converting dry wood into charcoal1 the greatest part is changed into inflammable air4 ,i have sometimes found1 that charcoal which was made with the most intense heat of a smith's fire1 which vitrified part of a common crucible in which the charcoal was confined1 and which had been continued above half an hour1 did not diminish the air in which the focus of a burning mirror was thrown upon it2 a quantity of inflammable air equal to the diminution of the common air being generated in the process3 whereas1 at other times1 ,i have not perceived that there was any generation of inflammable air1 but a simple diminution of common air1 when the charcoal had been made with a much less degree of heat4 ,this subject deserves to be farther investigated4 ,to make the preceding experiment with still more accuracy1 ,i repeated it in quicksilver2 when ,i perceived that there was a small increase of the quantity of air1 probably from a generation of inflammable air4 ,thus it stood without any alteration a whole night1 and part of the following day2 when lime-water1 being admitted to it1 it presently became turbid1 and1 after some time1 the whole quantity of air1 which was about four ounce measures1 was diminished one fifth1 as before4 ,in this case1 ,i carefully weighed the piece of charcoal1 which was exactly two grains1 and could not find that it was sensibly diminished in weight by the operation4 ,air thus diminished by the fumes of burning charcoal not only extinguishes flame1 but is in the highest degree noxious to animals2 it makes no effervescence with nitrous air1 and is incapable of being diminished any farther by the fumes of more charcoal1 by a mixture of iron filings and brimstone1 or by any other cause of the diminution of air that ,i am acquainted with4 ,this observation1 which respects all other kinds of diminished air1 proves that ,dr4 ,hales was mistaken in his notion of the absorption of air in those circumstances in which he observed it4 ,for he supposed that the remainder was1 in all cases1 of the same nature with that which had been absorbed1 and that the operation of the same cause would not have failed to produce a farther diminution2 whereas all my observations shew that air1 which has once been fully diminished by any cause whatever1 is not only incapable of any farther diminution1 either from the same or from any other cause1 but that it has likewise acquired new properties1 most remarkably different from those which it had before1 and that they are1 in a great measure1 the same in all the cases4 ,these circumstances give reason to suspect1 that the cause of diminution is1 in reality1 the same in all the cases4 ,what this cause is1 may1 perhaps1 appear in the next course of observations4 ,,section ,,viii4 ,of the effect of the ,,calcination of ,,metals1 and of the ,,effluvia of ,,paint made with ,,white-,,lead and ,,oil1 on ,,air4 ,having been led to suspect1 from the experiments which ,i had made with charcoal1 that the diminution of air in that case1 and perhaps in other cases also1 was1 in some way or other the consequence of its having more than its usual quantity of phlogiston1 it occurred to me1 that the calcination of metals1 which are generally supposed to consist of nothing but a metallic earth united to phlogiston1 would tend to ascertain the fact1 and be a kind of experimentum crucis in the case4 ,accordingly1 ,i suspended pieces of lead and tin in given quantities of air1 in the same manner as ,i had before treated the charcoal2 and throwing the focus of a burning mirror or lens upon them1 so as to make them fume copiously4 ,i presently perceived a diminution of the air4 ,in the first trial that ,i made1 ,i reduced four ounce measures of air to three1 which is the greatest diminution of common air that ,i had ever observed before1 and which ,i account for1 by supposing that1 in other cases1 there was not only a cause of diminution1 but causes of addition also1 either of fixed or inflammable air1 or some other permanently elastic matter1 but that the effect of the calcination of metals being simply the escape of phlogiston1 the cause of diminution was alone and uncontrouled4 ,the air1 which ,i had thus diminished by calcination of lead1 ,i transferred into another clean phial1 but found that the calcination of more lead in it 7or at least the attempt to make a farther calcination7 had no farther effect upon it4 ,this air also1 like that which had been infected with the fumes of charcoal1 was in the highest degree noxious1 made no effervescence with nitrous air1 was no farther diminished by the mixture of iron filings and brimstone1 and was not only rendered innoxious1 but also recovered1 in a great measure1 the other properties of common air1 by washing in water4 ,it might be suspected that the noxious quality of air in which lead was calcined1 might be owing to some fumes peculiar to that metal2 but ,i found no sensible difference between the properties of this air1 and that in which tin was calcined4 ,the water over which metals are calcined acquires a yellowish tinge1 and an exceedingly pungent smell and taste1 pretty much 7as near as ,i can recollect1 for ,i did not compare them together7 like that over which brimstone has been frequently burned4 ,also a thin and whitish pellicle covered both the surface of the water1 and likewise the sides of the phial in which the calcination was made2 insomuch that1 without frequently agitating the water1 it grew so opaque by this constantly accumulating incrustation1 that the sun-beams could not be transmitted through it in a quantity sufficient to produce the calcination4 ,i imagined1 however1 that1 even when this air was transferred into a clean phial1 the metals were not so easily melted or calcined as they were in fresh air2 for the air being once fully saturated with phlogiston1 may not so readily admit any more1 though it be only to transmit it to the water4 ,i also suspected that metals were not easily melted or calcined in inflammable1 fixed1 or nitrous air1 or any kind of diminished air4#h ,none of these kinds of air suffered any change by this operation2 nor was there any precipitation of lime1 when charcoal was heated in any of these kinds of air standing in lime-water4 ,this furnishes another1 and ,i think a pretty decisive proof1 that1 in the precipitation of lime by charcoal1 the fixed air does not come from the charcoal1 but from the common air4 ,otherwise it is hard to assign a reason1 why the same degree of heat 7or at least a much greater7 should not expel the fixed air from this substance1 though surrounded by these different kinds of air1 and why the fixed air might not be transmitted through them to the lime-water4 ,query4 ,may not water impregnated with phlogiston from calcined metals1 or by any other method1 be of some use in medicine8 ,the effect of this impregnation is exceedingly remarkable2 but the principle with which it is impregnated is volatile1 and intirely escapes in a day or two1 if the surface of the water be exposed to the common atmosphere4 ,it should seem that phlogiston is retained more obstinately by charcoal than it is by lead or tin2 for when any given quantity of air is fully saturated with phlogiston from charcoal1 no heat that ,i have yet applied has been able to produce any more effect upon it2 whereas1 in the same circumstances1 lead and tin may still be calcined1 at least be made to emit a copious fume1 in which some part of the phlogiston may be set loose4 ,the air indeed1 can take no more2 but the water receives it1 and the sides of the phial also receive an addition of incrustation4 ,this is a white powdery substance1 and well deserves to be examined4 ,i shall endeavour to do it at my leisure4 ,lime-water never became turbid by the calcination of metals over it1 the calx immediately seizing the precipitated fixed air1 in preference to the lime in the water2 but the colour1 smell1 and taste of the water was always changed and the surface of it became covered with a yellow pellicle1 as before4 ,when this process was made in quicksilver1 the air was diminished only one fifth2 and upon water being admitted to it1 no more was absorbed2 which is an effect similar to that of a mixture of nitrous and common air1 which was mentioned before4 ,the preceding experiments on the calcination of metals suggested to me a method of explaining the cause of the mischief which is known to arise from fresh paint1 made with white-lead 7which ,i suppose is an imperfect calx of lead7 and oil4 ,to verify my hypothesis1 ,i first put a small pot full of this kind of paint1 and afterwards 7which answered much better1 by exposing a greater surface of the paint7 ,i daubed several pieces of paper with it1 and put them under a receiver1 and observed1 that in about twenty-four hours1 the air was diminished between one fifth and one fourth1 for ,i did not measure it very exactly4 ,this air also was1 as ,i expected to find1 in the highest degree noxious2 it did not effervesce with nitrous air1 it was no farther diminished by a mixture of iron filings and brimstone1 and was made wholesome by agitation in water deprived of all air4 ,i think it appears pretty evident1 from the preceding experiments on the calcination of metals that air is1 some way or other1 diminished in consequence of being highly charged with phlogiston2 and that agitation in water restores it1 by imbibing a great part of the phlogistic matter4 ,that water has a considerable affinity with phlogiston1 is evident from the strong impregnation which it receives from it4 ,may not plants also restore air diminished by putrefaction by absorbing part of the phlogiston with which it is loaded8 ,the greater part of a dry plant1 as well as of a dry animal substance1 consists of inflammable air1 or something that is capable of being converted into inflammable air2 and it seems to be as probable that this phlogistic matter may have been imbibed by the roots and leaves of plants1 and afterwards incorporated into their substance1 as that it is altogether produced by the power of vegetation4 ,may not this phlogistic matter be even the most essential part of the food and support of both vegetable and animal bodies8 ,in the experiments with metals1 the diminution of air seems to be the consequence of nothing but a saturation with phlogiston2 and in all the other cases of the diminution of air1 ,i do not see but that it may be effected by the same means4 ,when a vegetable or animal substance is dissolved by putrefaction1 the escape of the phlogistic matter 7which1 together with all its other constituent parts1 is then let loose from it7 may be the circumstance that produces the diminution of the air in which it putrefies4 ,it is highly improbable that what remains after an animal body has been thoroughly dissolved by putrefaction1 should yield so great a quantity of inflammable air1 as the dried animal substance would have done4 ,of this ,i have not made an actual trial1 though ,i have often thought of doing it1 and still intend to do it2 but ,i think there can be no doubt of the result4 ,again1 iron1 by its fermentation with brimstone and water1 is evidently reduced to a calx1 so that phlogiston must have escaped from it4 ,phlogiston also must evidently be set loose by the ignition of charcoal1 and is not improbably the matter which flies off from paint1 composed of white-lead and oil4 ,lastly1 since spirit of nitre is known to have a very remarkable affinity with phlogiston1 it is far from being improbable that nitrous air may also produce the same effect by the same means4 ,to this hypothesis it may be objected1 that1 if diminished air be air saturated with phlogiston1 it ought to be inflammable4 ,but this by no means follows2 since its inflammability may depend upon some particular mode of combination1 or degree of affinity1 with which we are not acquainted4 ,besides1 inflammable air seems to consist of some other principle1 or to have some other constituent part1 besides phlogiston and common air1 as is probable from that remarkable deposit1 which1 as ,i have observed1 is made by inflammable air1 both from iron and zinc4 ,it is not improbable1 however1 but that a greater degree of heat may inflame that air which extinguishes a common candle1 if it could be conveniently applied4 ,air that is inflammable1 ,i observe1 extinguishes red-hot wood2 and indeed inflammable substances can only be those which1 in a certain degree of heat1 have a less affinity with the phlogiston they contain1 than the air1 or some other contiguous substance1 has with it2 so that the phlogiston only quits one substance1 with which it was before combined1 and enters another1 with which it may be combined in a very different manner4 ,this substance1 however1 whether it be air or any thing else1 being now fully saturated with phlogiston1 and not being able to take any more1 in the same circumstances1 must necessarily extinguish fire1 and put a stop to the ignition of all other bodies1 that is1 to the farther escape of phlogiston from them4 ,that plants restore noxious air1 by imbibing the phlogiston with which it is loaded1 is very agreeable to the conjectures of ,dr4 ,franklin1 made many years ago1 and expressed in the following extract from the last edition of his ,letters1 p4 #cdf4 ,i have been inclined to think that the fluid fire1 as well as the fluid air1 is attracted by plants in their growth1 and becomes consolidated with the other materials of which they are formed1 and makes a great part of their substance2 that1 when they come to be digested1 and to suffer in the vessels a kind of fermentation1 part of the fire1 as well as part of the air1 recovers its fluid active state again1 and diffuses itself in the body1 digesting and separating it2 that the fire so re-produced1 by digestion and separation1 continually leaving the body1 its place is supplied by fresh quantities1 arising from the continual separation2 that whatever quickens the motion of the fluids in an animal1 quickens the separation1 and re-produces more of the fire1 as exercise2 that all the fire emitted by wood1 and other combustibles1 when burning1 existed in them before in a solid state1 being only discovered when separating2 that some fossils1 as sulphur1 sea-coal1 c4 contain a great deal of solid fire2 and that1 in short1 what escapes and is dissipated in the burning of bodies1 besides water and earth1 is generally the air and fire1 that before made parts of the solid4 ,,footnotes3 #h ,i conclude from the experiments of ,m4 ,lavoisier1 which were made with a much better burning lens than ,i had an opportunity of making use of1 that there was no real calcination of the metals1 though they were made to fume in inflammable or nitrous air2 because he was not able to produce more than a slight degree of calcination in any given quantity of common air4 ,,section ,,ix4 ,of ,,marine ,,acid ,,air4 ,being very much struck with the result of an experiment of the ,hon4 ,mr4 ,cavendish1 related ,phil4 ,trans4 ,vol4 ,,lvi4 p4 #aeg1 by which1 though1 he says1 he was not able to get any inflammable air from copper1 by means of spirit of salt1 he got a much more remarkable kind of air1 viz4 one that lost its elasticity by coming into contact with water1 ,i was exceedingly desirous of making myself acquainted with it4 ,on this account1 ,i began with making the experiment in quicksilver1 which ,i never failed to do in any case in which ,i suspected that air might either be absorbed by water1 or be in any other manner affected by it2 and by this means ,i presently got a much more distinct idea of the nature and effects of this curious solution4 ,having put some copper filings into a small phial1 with a quantity of spirit of salt2 and making the air 7which was generated in great plenty1 on the application of heat7 ascend into a tall glass vessel full of quicksilver1 and standing in quicksilver1 the whole produce continued a considerable time without any change of dimensions4 ,i then introduced a small quantity of water to it2 when about three fourths of it 7the whole being about four ounce measures7 presently1 but gradually1 disappeared1 the quicksilver rising in the vessel4 ,i then introduced a considerable quantity of water2 but there was no farther diminution of the air1 and the remainder ,i found to be inflammable4 ,having frequently continued this process a long time after the admission of the water1 ,i was much amused with observing the large bubbles of the newly generated air1 which came through the quicksilver1 the sudden diminution of them when they came to the water1 and the very small bubbles which went through the water4 ,they made1 however1 a continual1 though slow1 increase of inflammable air4 ,fixed air1 being admitted to the whole produce of this air from copper1 had no sensible effect upon it4 ,upon the admission of water1 a great part of the mixture presently disappeared2 another part1 which ,i suppose to have been the fixed air1 was absorbed slowly2 and in this particular case the very small permanent residuum did not take fire2 but it is very possible that it might have done so1 if the quantity had been greater4 ,the solution of lead in the marine acid is attended with the very same phnomena as the solution of copper in the same acid2 about three fourths of the generated air disappearing on the admission of water2 and the remainder being inflammable4 ,the solutions of iron1 tin1 and zinc1 in the marine acid1 were all attended with the same phnomena as the solutions of copper and lead1 but in a less degree2 for in iron one eighth1 in tin one sixth1 and in zinc one tenth of the generated air disappeared on the admission of water4 ,the remainder of the air from iron1 in this case1 burned with a green1 or very light blue flame4 ,i had always thought it something extraordinary that a species of air should lose its elasticity by the mere contact of any thing1 and from the first suspected that it must have been imbibed by the water that was admitted to it2 but so very great a quantity of this air disappeared upon the admission of a very small quantity of water1 that at first ,i could not help concluding that appearances favoured the former hypothesis4 ,i found1 however1 that when ,i admitted a much smaller quantity of water1 confined in a narrow glass tube1 a part only of the air disappeared1 and that very slowly1 and that more of it vanished upon the admission of more water4 ,this observation put it beyond a doubt1 that this air was properly imbibed by the water1 which1 being once fully saturated with it1 was not capable of receiving any more4 ,the water thus impregnated tasted very acid1 even when it was much diluted with other water1 through which the tube containing it was drawn4 ,it even dissolved iron very fast1 and generated inflammable air4 ,this last observation1 together with another which immediately follows1 led me to the discovery of the true nature of this remarkable kind of air4 ,happening1 at one time1 to use a good deal of copper and a small quantity of spirit of salt1 in the generation of this kind of air1 ,i was surprized to find that air was produced long after1 ,i could not but think that the acid must have been saturated with the metal2 and ,i also found that the proportion of inflammable air to that which was absorbed by the water continually diminished1 till1 instead of being one fourth of the whole1 as ,i had first observed1 it was not so much as one twentieth4 ,upon this1 ,i concluded that this subtle air did not arise from the copper1 but from the spirit of salt2 and presently making the experiment with the acid only1 without any copper1 or metal of any kind1 this air was immediately produced in as great plenty as before2 so that this remarkable kind of air is1 in fact1 nothing more than the vapour1 or fumes of spirit of salt1 which appear to be of such a nature1 that they are not liable to be condensed by cold1 like the vapour of water1 and other fluids1 and therefore may be very properly called an acid air1 or more restrictively1 the marine acid air4 ,this elastic acid vapour1 or acid air1 extinguishes flame1 and is much heavier than common air2 but how much heavier1 will not be easy to ascertain4 ,a cylindrical glass vessel1 about three fourths of an inch in diameter1 and four inches deep1 being filled with it1 and turned upside down1 a lighted candle may be let down into it more than twenty times before it will burn at the bottom4 ,it is pleasing to observe the colour of the flame in this experiment2 for both before the candle goes out1 and also when it is first lighted again1 it burns with a beautiful green1 or rather light-blue flame1 such as is seen when common salt is thrown into the fire4 ,when this air is all expelled from any quantity of spirit of salt1 which is easily perceived by the subsequent vapour being condensed by cold1 the remainder is a very weak acid1 barely capable of dissolving iron4 ,being now in the possession of a new subject of experiments1 viz4 an elastic acid vapour1 in the form of a permanent air1 easily procured1 and effectually confined by glass and quicksilver1 with which it did not seem to have any affinity2 ,i immediately began to introduce a variety of substances to it2 in order to ascertain its peculiar properties and affinities1 and also the properties of those other bodies with respect to it4 ,beginning with water1 which1 from preceding observations1 ,i knew would imbibe it1 and become impregnated with it2 ,i found that #b-a_/b grains of rain-water absorbed three ounce measures of this air1 after which it was increased one third in its bulk1 and weighed twice as much as before2 so that this concentrated vapour seems to be twice as heavy as rain-water3 ,water impregnated with it makes the strongest spirit of salt that ,i have seen1 dissolving iron with the most rapidity4 ,consequently1 two thirds of the best spirit of salt is nothing more than mere phlegm or water4 ,iron filings1 being admitted to this air1 were dissolved by it pretty fast1 half of the air disappearing1 and the other half becoming inflammable air1 not absorbed by water4 ,putting chalk to it1 fixed air was produced4 ,i had not introduced many substances to this air1 before ,i discovered that it had an affinity with phlogiston1 so that it would deprive other substances of it1 and form with it such an union as constitutes inflammable air2 which seems to shew1 that inflammable air universally consists of the union of some acid vapour with phlogiston4 ,inflammable air was produced1 when to this acid air ,i put spirit of wine1 oil of olives1 oil of turpentine1 charcoal1 phosphorus1 bees-wax1 and even sulphur4 ,this last observation1 ,i own1 surprized me2 for1 the marine acid being reckoned the weakest of the three mineral acids1 ,i did not think that it had been capable of dislodging the oil of vitriol from this substance2 but ,i found that it had the very same effect both upon alum and nitre2 the vitriolic acid in the former case1 and the nitrous in the latter1 giving place to the stronger vapour of spirit of salt4 ,the rust of iron1 and the precipitate of nitrous air made from copper1 also imbibed this air very fast1 and the little that remained of it was inflammable air2 which proves1 that these calces contain phlogiston4 ,it seems also to be pretty evident1 from this experiment1 that the precipitate above mentioned is a real calx of the metal1 by the solution of which the nitrous air is generated4 ,as some remarkable circumstances attend the absorption of this acid air1 by the substances above-mentioned1 ,i shall briefly mention them4 ,spirit of wine absorbs this air as readily as water itself1 and is increased in bulk by that means4 ,also1 when it is saturated1 it dissolves iron with as much rapidity1 and still continues inflammable4 ,oil of olives absorbs this air very slowly1 and at the same time1 it turns almost black1 and becomes glutinous4 ,it is also less miscible with water1 and acquires a very disagreeable smell4 ,by continuing upon the surface of the water1 it became white1 and its offensive smell went off in a few days4 ,oil of turpentine absorbed this air very fast1 turning brown1 and almost black4 ,no inflammable air was formed1 till ,i raised more of the acid air than the oil was able to absorb1 and let it stand a considerable time2 and still the air was but weakly inflammable4 ,the same was the case with the oil of olives1 in the last mentioned experiment2 and it seems to be probable1 that1 the longer this acid air had continued in contact with the oil1 the more phlogiston it would have extracted from it4 ,it is not wholly improbable1 but that1 in the intermediate state1 before it becomes inflammable air1 it may be nearly of the nature of common air4 ,bees-wax absorbed this air very slowly4 ,about the bigness of a hazel-nut of the wax being put to three ounce measures of the acid air1 the air was diminished one half in two days1 and1 upon the admission of water1 half of the remainder also disappeared4 ,this air was strongly inflammable4 ,charcoal absorbed this air very fast4 ,about one fourth of it was rendered immiscible in water1 and was but weakly inflammable4 ,a small bit of phosphorus1 perhaps about half a grain1 smoked1 and gave light in the acid air1 just as it would have done in common air confined4 ,it was not sensibly wasted after continuing about twelve hours in that state1 and the bulk of the air was very little diminished4 ,water being admitted to it absorbed it as before1 except about one fifth of the whole4 ,it was but weakly inflammable4 ,putting several pieces of sulphur to this air1 it was absorbed but slowly4 ,in about twenty-four hours about one fifth of the quantity had disappeared2 and water being admitted to the remainder1 very little more was absorbed4 ,the remainder was inflammable1 and burned with a blue flame4 ,notwithstanding the affinity which this acid air appears to have with phlogiston1 it is not capable of depriving all bodies of it4 ,i found that dry wood1 crusts of bread1 and raw flesh1 very readily imbibed this air1 but did not part with any of their phlogiston to it4 ,all these substances turned very brown1 after they had been some time exposed to this air1 and tasted very strongly of the acid when they were taken out2 but the flesh1 when washed in water1 became very white1 and the fibres easily separated from one another1 even more than they would have done if it had been boiled or roasted#i4 ,when ,i put a piece of saltpetre to this air it was presently surrounded with a white fume1 which soon filled the whole vessel1 exactly like the fume which bursts from the bubbles of nitrous air1 when it is generated by a vigorous fermentation1 and such as is seen when nitrous air is mixed with this acid air4 ,in about a minute1 the whole quantity of air was absorbed1 except a very little1 which might be the common air that had lodged upon the surface of the spirit of salt within the phial4 ,a piece of alum exposed to this air turned yellow1 absorbed it as fast as the saltpetre had done1 and was reduced by it to the form of a powder4 ,common salt1 as might be expected1 had no effect whatever on this marine acid air4 ,i had also imagined1 that if air diminished by the processes above-mentioned was affected in this manner1 in consequence of its being saturated with phlogiston1 a mixture of this acid air might imbibe that phlogiston1 and render it wholesome again2 but ,i put about one fourth of this air to a quantity of air in which metals had been calcined1 without making any sensible alteration in it4 ,i do not1 however1 infer from this1 that air is not diminished by means of phlogiston1 since the common air1 like some other substances1 may hold the phlogiston too fast1 to be deprived of it by this acid air4 ,i shall conclude my account of these experiments with observing1 that the electric spark is visible in acid air1 exactly as it is in common air2 and though ,i kept making this spark a considerable time in a quantity of it1 ,i did not perceive that any sensible alteration was made in it4 ,a little inflammable air was produced1 but not more than might have come from the two iron nails which ,i made use of in taking the sparks4 ,,footnotes3 #i ,it will be seen1 in the second part of this work1 that1 in some of these processes1 ,i had afterwards more success4 ,,section ,x4 ,,miscellaneous ,,observations4 #a4 ,as many of the preceding observations relate to the vinous and putrefactive fermentations1 ,i had the curiosity to endeavour to ascertain in what manner the air would be affected by the acetous fermentation4 ,for this purpose ,i inclosed a phial full of small beer in a jar standing in water2 and observed that1 during the first two or three days1 there was an increase of the air in the jar1 but from that time it gradually decreased1 till at length there appeared to be a diminution of about one tenth of the whole quantity4 ,during this time the whole surface of it was gradually covered with a scum1 beautifully corrugated4 ,after this there was an increase of the air till there was more than the original quantity2 but this must have been fixed air1 not incorporated with the rest of the mass2 for1 withdrawing the beer1 which ,i found to be sour1 after it had stood #ah or #bj days under the jar1 and passing the air several times through cold water1 the original quantity was diminished about one ninth4 ,in the remainder a candle would not burn1 and a mouse would have died presently4 ,the smell of this air was exceedingly pungent1 but different from that of the putrid effluvium4 ,a mouse lived perfectly well in this air1 thus affected with the acetous fermentation2 after it had stood several days mixed with four times the quantity of fixed air4 #b4 ,all the kinds of factitious air on which ,i have yet made the experiment are highly noxious1 except that which is extracted from saltpetre1 or alum2 but in this even a candle burned just as in common air#aj4 ,in one quantity which ,i got from saltpetre a candle not only burned1 but the flame was increased1 and something was heard like a hissing1 similar to the decrepitation of nitre in an open fire4 ,this experiment was made when the air was fresh made1 and while it probably contained some particles of nitre1 which would have been deposited afterwards4 ,the air was extracted from these substances by heating them in a gun-barrel1 which was much corroded and soon spoiled by the experiment4 ,what effect this circumstance may have had upon the air ,i have not considered4 ,november #f1 #aggb1 ,i had the curiosity to examine the state of a quantity of this air which had been extracted from saltpetre above a year1 and which at first was perfectly wholesome2 when1 to my very great surprize1 ,i found that it was become1 in the highest degree1 noxious4 ,it made no effervescence with nitrous air1 and a mouse died the moment it was put into it4 ,i had not1 however1 washed it in rain-water quite ten minutes 7and perhaps less time would have been sufficient7 when ,i found1 upon trial1 that it was restored to its former perfectly wholesome state4 ,it effervesced with nitrous air as much as the best common air ever does2 and even a candle burned in it very well1 which ,i had never before observed of any kind of noxious air meliorated by agitation in water4 ,this series of facts1 relating to air extracted from nitre1 appear to me to be very extraordinary and important1 and1 in able hands1 may lead to considerable discoveries4 #c4 ,there are many substances which impregnate common air in a very remarkable manner1 but without making it noxious to animals4 ,among other things ,i tried volatile alkaline salts1 and camphor2 the latter of which ,i melted with a burning-glass1 in air inclosed in a phial4 ,the mouse1 which was put into this air1 sneezed and coughed very much1 especially after it was taken out2 but it presently recovered1 and did not appear to have been sensibly injured4 #d4 ,having made several experiments with a mixture of iron filings and brimstone1 kneaded to a paste with water1 ,i had the curiosity to try what would be the effect of substituting brass dust in the place of the iron filings4 ,the result was1 that when this mixture had stood about three weeks1 in a given quantity of air1 it had turned black1 but was not increased in bulk4 ,the air also was neither sensibly increased nor decreased1 but the nature of it was changed2 for it extinguished flame1 it would have killed a mouse presently1 and was not restored by fixed air1 which had been mixed with it several days4 #e4 ,i have frequently mentioned my having1 at one time1 exposed equal quantities of different kinds of air in jars standing in boiled water4 ,common air in this experiment was diminished four sevenths1 and the remainder extinguished flame4 ,this experiment demonstrates that water does not absorb air equally1 but that it decomposes it1 taking one part1 and leaving the rest4 ,to be quite sure of this fact1 ,i agitated a quantity of common air in boiled water1 and when ,i had reduced it from eleven ounce measures to seven1 ,i found that it extinguished a candle1 but a mouse lived in it very well4 ,at another time a candle barely went out when the air was diminished one third1 and at other times ,i have found this effect lake place at other very different degrees of diminution4 ,this difference ,i attribute to the differences in the state of the water with respect to the air contained in it2 for sometimes it had stood longer than at other times before ,i made use of it4 ,i also used distilled-water1 rain-water1 and water out of which the air had been pumped1 promiscuously with rain water4 ,i even doubt1 not but that1 in a certain state of the water1 there might be no sensible difference in the bulk of the agitated air1 and yet at the end of the process it would extinguish a candle1 air being supplied from the water in the place of that part of the common air which had been absorbed4 ,it is certainly a little extraordinary that the very same process should so far mend putrid air1 as to reduce it to the standard of air in which candles have burned out2 and yet that it should so far injure common and wholesome air as to reduce it to about the same standard3 but so the fact certainly is4 ,if air extinguish flame in consequence of its being previously saturated with phlogiston1 it must1 in this case1 have been transferred from the water to the air1 and it is by no means inconsistent with this hypothesis to suppose1 that1 if the air be over saturated with phlogiston1 the water will imbibe it1 till it be reduced to the same proportion that agitation in water would have communicated to it4 ,to a quantity of common air1 thus diminished by agitation in water1 till it extinguished a candle1 ,i put a plant1 but it did not so far restore it as that a candle would burn in it again2 which to me appeared not a little extraordinary1 as it did not seem to be in a worse state than air in which candles had burned out1 and which had never failed to be restored by the same means4 ,i had no better success with a quantity of permanent air which ,i had collected from my pump-water4 ,indeed these experiments were begun before ,i was acquainted with that property of nitrous air1 which makes it so accurate a measure of the goodness of other kinds of air2 and it might perhaps be rather too late in the year when ,i made the experiments4 ,having neglected these two jars of air1 the plants died and putrefied in both of them2 and then ,i found the air in them both to be highly noxious1 and to make no effervescence with nitrous air4 ,i found that a pint of my pump-water contained about one fourth of an ounce measure of air1 one half of which was afterwards absorbed by standing in fresh pump-water4 ,a candle would not burn in this air1 but a mouse lived in it very well4 ,upon the whole1 it seemed to be in about the same state as air in which a candle had burned out4 #f4 ,i once imagined that1 by mere stagnation1 air might become unfit for respiration1 or at least the burning of candles2 but if this be the case1 and the change be produced gradually1 it must require a long time for the purpose4 ,for on the #bb;d of ,september #aggb1 ,i examined a quantity of common air1 which had been kept in a phial1 without agitation1 from ,may #agga1 and found it to be in no respect worse than fresh air1 even by the test of the nitrous air4 #g4 ,the crystallization of nitre makes no sensible alteration in the air in which the process is made4 ,for this purpose ,i dissolved as much nitre as a quantity of hot water would contain1 and let it cool under a receiver1 standing in water4 #h4 ,november #f1 #aggb1 a quantity of inflammable air1 which1 by long keeping1 had come to extinguish flame1 ,i observed to smell very much like common air in which a mixture of iron filings and brimstone had stood4 ,it was not1 however1 quite so strong1 but it was equally noxious4 #i4 ,bismuth and nickel are dissolved in the marine acid with the application of a considerable degree of heat2 but little or no air is got from either of them2 but1 what ,i thought a little remarkable1 both of them smelled very much like ,harrowgate water1 or liver of sulphur4 ,this smell ,i have met with several times in the course of my experiments1 and in processes very different from one another4 ,,footnotes3 #aj ,experiments1 of which an account will be given in the second part of this work1 make it probable1 that though a candle burned even more than well in this air1 an animal would not have lived in it4 ,at the time of this first publication1 however1 ,i had no idea of this being possible in nature4 ,,part ,,ii4 ,experiments and ,observations made in the ,year #aggc1 and the ,beginning of #aggd4 ,,section ,i4 ,observations on ,,alkaline ,,air4 ,after ,i had made the discovery of the marine acid air1 which the vapour of spirit of salt may properly enough be called1 and had made those experiments upon it1 of which ,i have given an account in the former part of this work1 and others which ,i propose to recite in this part2 it occurred to me1 that1 by a process similar to that by which this acid air is expelled from the spirit of salt1 an alkaline air might be expelled from substances containing volatile alkali4 ,accordingly ,i procured some volatile spirit of sal ammoniac1 and having put it into a thin phial1 and heated it with the flame of a candle1 ,i presently found that a great quantity of vapour was discharged from it2 and being received in a vessel of quicksilver1 standing in a bason of quicksilver1 it continued in the form of a transparent and permanent air1 not at all condensed by cold2 so that ,i had the same opportunity of making experiments upon it1 as ,i had before on the acid air1 being in the same favourable circumstances4 ,with the same ease ,i also procured this air from spirit of hartshorn1 and sal volatile either in a fluid or solid form1 i4 e4 from those volatile alkaline salts which are produced by the distillation of sal ammoniac with fixed alkalis4 ,but in this case ,i soon found that the alkaline air ,i procured was not pure2 for the fixed air1 which entered into the composition of my materials1 was expelled along with it4 ,also1 uniting again with the alkaline air1 in the glass tube through which they were conveyed1 they stopped it up1 and were often the means of bursting my vessels4 ,while these experiments were new to me1 ,i imagined that ,i was able to procure this air with peculiar advantage and in the greatest abundance1 either from the salts in a dry state1 when they were just covered with water1 or in a perfectly fluid state2 for1 upon applying a candle to the phials in which they were contained1 there was a most astonishing production of air2 but having examined it1 ,i found it to be chiefly fixed air1 especially after the first or second produce from the same materials2 and removing my apparatus to a trough of water and using the water instead of quicksilver1 ,i found that it was not presently absorbed by it4 ,this1 however1 appears to be an easy and elegant method of procuring fixed air1 from a small quantity of materials1 though there must be a mixture of alkaline air along with it2 as it is by means of its combination with this principle only1 that it is possible1 that so much fixed air should be retained in any liquid4 ,water1 at least1 we know1 cannot be made to contain much more than its own bulk of fixed air4 ,after this disappointment1 ,i confined myself to the use of that volatile spirit of sal ammoniac which is procured by a distillation with slaked lime1 which contains no fixed air2 and which seems1 in a general state1 to contain about as much alkaline air1 as an equal quantity of spirit of salt contains of the acid air4 ,wanting1 however1 to procure this air in greater quantities1 and this method being rather expensive1 it occurred to me1 that alkaline air might1 probably1 be procured1 with the most ease and convenience1 from the original materials1 mixed in the same proportions that chemists had found by experience to answer the best for the production of the volatile spirit of sal ammoniac4 ,accordingly ,i mixed one fourth of pounded sal ammoniac1 with three fourths of slaked lime2 and filling a phial with the mixture1 ,i presently found it completely answered my purpose4 ,the heat of a candle expelled from this mixture a prodigious quantity of alkaline air2 and the same materials 7as much as filled an ounce phial7 would serve me a considerable time1 without changing2 especially when1 instead of a glass phial1 ,i made use of a small iron tube1 which ,i find much more convenient for the purpose4 ,as water soon begins to rise in this process1 it is necessary1 if the air is intended to be conveyed perfectly dry into the vessel of quicksilver1 to have a small vessel in which this water 7which is the common volatile spirit of sal ammoniac7 may be received4 ,this small vessel must be interposed between the vessel which contains the materials for the generation of the air1 and that in which it is to be received1 as d fig4 #h4 ,this alkaline air being perfectly analogous to the acid air1 ,i was naturally led to investigate the properties of it in the same manner1 and nearly in the same order4 ,from this analogy ,i concluded1 as ,i presently found to be the fact1 that this alkaline air would be readily imbibed by water1 and1 by its union with it1 would form a volatile spirit of sal ammoniac4 ,and as the water1 when admitted to the air in this manner1 confined by quicksilver1 has an opportunity of fully saturating itself with the alkaline vapour1 it is made prodigiously stronger than any volatile spirit of sal ammoniac that ,i have ever seen2 and ,i believe stronger than it can be made in the common way4 ,in order to ascertain what addition1 with respect to quantity and weight1 water would acquire by being saturated with alkaline air1 ,i put #a-a_/d grains of rain-water into a small glass tube1 closed at one end with cement1 and open at the other1 the column of water measuring #g_/aj of an inch2 and having introduced it through the quicksilver into a vessel containing alkaline air1 observed that it absorbed #g_/h of an ounce measure of the air1 and had then gained about half a grain in weight1 and was increased to #h-a_/b tenths of an inch in length4 ,i did not make a second experiment of this kind1 and therefore will not answer for the exactness of these proportions in future trials4 ,what ,i did sufficiently answered my purpose1 in a general view of the subject4 ,when ,i had1 at one time1 saturated a quantity of distilled water with alkaline air1 so that a good deal of the air remained unabsorbed on the surface of the water1 ,i observed that1 as ,i continued to throw up more air1 a considerable proportion of it was imbibed1 but not the whole2 and when ,i had let the apparatus stand a day1 much more of the air that lay on the surface was imbibed4 ,and after the water would imbibe no more of the old air1 it imbibed new4 ,this shews that water requires a considerable time to saturate itself with this kind of air1 and that part of it more readily unites with water than the rest4 ,the same is also1 probably1 the case with all the kinds of air with which water can be impregnated4 ,mr4 ,cavendish made this observation with respect to fixed air1 and ,i repeated the whole process above-mentioned with acid air1 and had precisely the same result4 ,the alkaline water which ,i procured in this experiment was1 beyond comparison1 stronger to the smell1 than any spirit of sal ammoniac that ,i had seen4 ,this experiment led me to attempt the making of spirit of sal ammoniac in a larger quantity1 by impregnating distilled water with this alkaline air4 ,for this purpose ,i filled a piece of a gun-barrel with the materials above-mentioned1 and luted to the open end of it a small glass tube1 one end of which was bent1 and put within the mouth of a glass vessel1 containing a quantity of distilled water upon quicksilver1 standing in a bason of quicksilver1 as in fig4 #g4 ,in these circumstances the heat of the fire1 applied gradually1 expelled the alkaline air1 which1 passing through the tube1 and the quicksilver1 came at last to the water1 which1 in time1 became fully saturated with it4 ,by this means ,i got a very strong alkaline liquor1 from which ,i could again expel the alkaline air which ,i had put into it1 whenever it happened to be more convenient to me to get it in that manner4 ,this process may easily be performed in a still larger way2 and by this means a liquor of the same nature with the volatile spirit of sal ammoniac1 might be made much stronger1 and much cheaper1 than it is now made4 ,having satisfied myself with respect to the relation that alkaline air bears to water1 ,i was impatient to find what would be the consequence of mixing this new air with the other kinds with which ,i was acquainted before1 and especially with acid air2 having a notion that these two airs1 being of opposite natures1 might compose a neutral air1 and perhaps the very same thing with common air4 ,but the moment that these two kinds of air came into contact1 a beautiful white cloud was formed1 and presently filled the whole vessel in which they were contained4 ,at the same time the quantity of air began to diminish1 and1 at length1 when the cloud was subsided1 there appeared to be formed a solid while salt1 which was found to be the common sal ammoniac1 or the marine acid united to the volatile alkali4 ,the first quantity that ,i produced immediately deliquesced1 upon being exposed to the common air2 but if it was exposed in a very dry and warm place1 it almost all evaporated1 in a white cloud4 ,i have1 however1 since1 from the same materials1 produced the salt above-mentioned in a state not subject to deliquesce or evaporate4 ,this difference1 ,i find1 is owing to the proportion of the two kinds of air in the compound4 ,it is only volatile when there is more than a due proportion of either of the constituent parts4 ,in these cases the smell of the salts is extremely pungent1 but very different from one another2 being manifestly acid1 or alkaline1 according to the prevalence of each of these airs respectively4 ,nitrous air admitted to alkaline air likewise occasioned a whitish cloud1 and part of the air was absorbed2 but it presently grew clear again2 leaving only a little dimness on the sides of the vessel4 ,this1 however1 might be a kind of salt1 formed by the union of the two kinds of air4 ,there was no other salt formed that ,i could perceive4 ,water being admitted to this mixture of nitrous and alkaline air presently absorbed the latter1 and left the former possessed of its peculiar properties4 ,fixed air admitted to alkaline air formed oblong and slender crystals1 which crossed one another1 and covered the sides of the vessel in the form of net-work4 ,these crystals must be the same thing with the volatile alkalis which chemists get in a solid form1 by the distillation of sal ammoniac with fixed alkaline salts4 ,inflammable air admitted to alkaline air exhibited no particular appearance4 ,water1 as in the former experiment1 absorbed the alkaline air1 and left the inflammable air as it was before4 ,it was remarkable1 however1 that the water which was admitted to them became whitish1 and that this white cloud settled1 in the form of a white powder1 to the bottom of the vessel4 ,alkaline air mixed with common air1 and standing together several days1 first in quicksilver1 and then in water 7which absorbed the alkaline air7 it did not appear that there was any change produced in the common air3 at least it was as much diminished by nitrous air as before4 ,the same was the case with a mixture of acid air and common air4 ,having mixed air that had been diminished by the fermentation of a mixture of iron filings and brimstone with alkaline air1 the water absorbed the latter1 but left the former1 with respect to the test of nitrous air 7and therefore1 as ,i conclude1 with respect to all its properties7 the same that it was before4 ,spirit of wine imbibes alkaline air as readily as water1 and seems to be as inflammable afterwards as before4 ,alkaline air contracts no union with olive oil4 ,they were in contact almost two days1 without any diminution of the air4 ,oil of turpentine1 and essential oil of mint1 absorbed a very small quantity of alkaline air1 but were not sensibly changed by it4 ,ether1 however1 imbibed alkaline air pretty freely2 but it was afterwards as inflammable as before1 and the colour was not changed4 ,it also evaporated as before1 but ,i did not attend to this last circumstance very accurately4 ,sulphur1 nitre1 common salt1 and flints1 were put to alkaline air without imbibing any part of it2 but charcoal1 spunge1 bits of linen cloth1 and other substances of that nature1 seemed to condense this air upon their surfaces2 for it began to diminish immediately upon their being put to it2 and when they were taken out the alkaline smell they had contracted was so pungent as to be almost intolerable1 especially that of the spunge4 ,perhaps it might be of use to recover persons from swooning4 ,a bit of spunge1 about as big as a hazel nut1 presently imbibed an ounce measure of alkaline air4 ,a piece of the inspissated juice of turnsole was made very dry and warm1 and yet it imbibed a great quantity of the air2 by which it contracted a most pungent smell1 but the colour of it was not changed4 ,alum undergoes a very remarkable change by the action of alkaline air4 ,the outward shape and size remain the same1 but the internal structure is quite changed1 becoming opaque1 beautifully white1 and1 to appearance1 in all respects1 like alum which had been roasted2 and so as not to be at all affected by a degree of heat that would have reduced it to that state by roasting4 ,this effect is produced slowly2 and if a piece of alum be taken out of alkaline air before the operation is over1 the inside will be transparent1 and the outside1 to an equal thickness1 will be a white crust4 ,i imagine that the alkaline vapour seizes upon the water that enters into the constitution of crude alum1 and which would have been expelled by heat4 ,roasted alum also imbibes alkaline air1 and1 like the raw alum that has been exposed to it1 acquires a taste that is peculiarly disagreeable4 ,phosphorus gave no light in alkaline air1 and made no lasting change in its dimensions4 ,it varied1 indeed1 a little1 being sometimes increased and sometimes diminished1 but after a day and a night1 it was in the same state as at the first4 ,water absorbed this air just as if nothing had been put to it4 ,having put some spirit of salt to alkaline air1 the air was presently absorbed1 and a little of the white salt above-mentioned was formed4 ,a little remained unabsorbed1 and transparent1 but upon the admission of common air to it1 it instantly became white4 ,oil of vitriol1 also formed a white salt with alkaline air1 and this did not rise in white fumes4 ,acid air1 as ,i have observed in my former papers1 extinguishes a candle4 ,alkaline air1 on the contrary1 ,i was surprized to find1 is slightly inflammable2 which1 however1 seems to confirm the opinion of chemists1 that the volatile alkali contains phlogiston4 ,i dipped a lighted candle into a tall cylindrical vessel1 filled with alkaline air1 when it went out three or four times successively2 but at each time the flame was considerably enlarged1 by the addition of another flame1 of a pale yellow colour2 and at the last time this light flame descended from the top of the vessel to the bottom4 ,at another time1 upon presenting a lighted candle to the mouth of the same vessel1 filled with the same kind of air1 the yellowish flame ascended two inches higher than the flame of the candle4 ,the electric spark taken in alkaline air is red1 as it is in common inflammable air4 ,though alkaline air be inflammable1 it appeared1 by the following experiment1 to be heavier than the common inflammable air1 as well as to contract no union with it4 ,into a vessel containing a quantity of inflammable air1 ,i put half as much alkaline air1 and then about the same quantity of acid air4 ,these immediately formed a white cloud1 but it did not rise within the space that was occupied by the inflammable air2 so that this latter had kept its place above the alkaline air1 and had not mixed with it4 ,that alkaline air is lighter than acid air is evident from the appearances that attend the mixture1 which are indeed very beautiful4 ,when acid air is introduced into a vessel containing alkaline air1 the white cloud which they form appears at the bottom only1 and ascends gradually4 ,but when the alkaline air is put to the acid1 the whole becomes immediately cloudy1 quite to the top of the vessel4 ,in the last place1 ,i shall observe that alkaline air1 as well as acid1 dissolves ice as fast as a hot fire can do it4 ,this was tried when both the kinds of air1 and every instrument made use of in the experiment1 had been exposed to a pretty intense frost several hours4 ,in both cases1 also1 the water into which the ice was melted dissolved more ice1 to a considerable quantity4 ,,section ,,ii4 ,of ,,common ,,air diminished and made noxious by various processes4 ,it will have been observed that1 in the first publication of my papers1 ,i confined myself chiefly to the narration of the new facts which ,i had discovered1 barely mentioning any hypotheses that occurred to me1 and never seeming to lay much stress upon them4 ,the reason why ,i was so much upon my guard in this respect was1 left1 in consequence of attaching myself to any hypothesis too soon1 the success of my future inquiries might be obstructed4 ,but subsequent experiments having thrown great light upon the preceding ones and having confirmed the few conjectures ,i then advanced1 ,i may now venture to speak of my hypotheses with a little less diffidence4 ,still1 however1 ,i shall be ready to relinquish any notions ,i may now entertain1 if new facts should hereafter appear not to favour them4 ,in a great variety of cases ,i have observed that there is a remarkable diminution of common1 or respirable air1 in proportion to which it is always rendered unfit for respiration1 indisposed to effervesce with nitrous air1 and incapable of farther diminution from any other cause4 ,the circumstances which produce this effect ,i had then observed to be the burning of candles1 the respiration of animals1 the putrefaction of vegetables or animal substances1 the effervescence of iron filings and brimstone1 the calcination of metals1 the fumes of charcoal1 the effluvia of paint made of white-lead and oil1 and a mixture of nitrous air4 ,all these processes1 ,i observed1 agree in this one circumstance1 and ,i believe in no other1 that the principle which the chemists call phlogiston is set loose2 and therefore ,i concluded that the diminution of the air was1 in some way or other1 the consequence of the air becoming overcharged with phlogiston1#aa and that water1 and growing vegetables1 tend to restore this air to a state fit for respiration1 by imbibing the superfluous phlogiston4 ,several experiments which ,i have since made tend to confirm this supposition4 ,common air1 ,i find1 is diminished1 and rendered noxious1 by liver of sulphur1 which the chemists say exhales phlogiston1 and nothing else4 ,the diminution in this case was one fifth of the whole1 and afterwards1 as in other similar cases1 it made no effervescence with nitrous air4 ,i found also1 after ,dr4 ,hales1 that air is diminished by ,homberg's pyrophorus4 ,the same effect is produced by firing gunpowder in air4 ,this ,i tried by firing the gunpowder in a receiver half exhausted1 by which the air was rather more injured than it would have been by candles burning in it4 ,air is diminished by a cement made with one half common coarse turpentine and half bees-wax4 ,this was the result of a very casual observation4 ,having1 in an air-pump of ,mr4 ,smeaton's construction1 closed that end of the syphon-gage1 which is exposed to the outward air1 with this cement 7which ,i knew would make it perfectly air-light7 instead of sealing it hermetically2 ,i observed that1 in a course of time1 the quicksilver in that leg kept continually rising1 so that the measures ,i marked upon it were of no use to me2 and when ,i opened that end of the tube1 and closed it again1 the same consequence always took place4 ,at length1 suspecting that this effect must have arisen from the bit of cement diminishing the air to which it was exposed1 ,i covered all the inside of a glass tube with it1 and one end of it being quite closed with the cement1 ,i set it perpendicular1 with its open end immersed in a bason of quicksilver2 and was presently satisfied that my conjecture was well founded3 for1 in a few days1 the quicksilver rose so much within the tube1 that the air in the inside appeared to be diminished about one sixth4 ,to change this air ,i filled the tube with quicksilver1 and pouring it out again1 ,i replaced the tube in its former situation2 when the air was diminished again1 but not so fast as before4 ,the same lining of cement diminished the air a third time4 ,how long it will retain this power ,i cannot tell4 ,this cement had been made several months before ,i made this experiment with it4 ,i must observe1 however1 that another quantity of this kind of cement1 made with a finer and more liquid turpentine1 had not the power of diminishing air1 except in a very small proportion4 ,also the common red cement has this property in the same small degree4 ,common air1 however1 which had been confined in a glass vessel lined with this cement about a month1 was so far injured that a candle would not burn in it4 ,in a longer time it would1 ,i doubt not1 have become thoroughly noxious4 ,iron that has been suffered to rust in nitrous air diminishes common air very fast1 as ,i shall have occasion to mention when ,i give a continuation of my experiments on nitrous air4 ,lastly1 the same effect1 ,i find1 is produced by the electric spark1 though ,i had no expectation of this event when ,i made the experiment4 ,this experiment1 however1 and those which ,i have made in pursuance of it1 has fully confirmed another of my conjectures1 which relates to the manner in which air is diminished by being overcharged with phlogiston1 viz4 the phlogiston having a nearer affinity with some of the constituent parts of the air than the fixed air which enters into the composition of it1 in consequence of which the fixed air is precipitated4 ,this ,i first imagined from perceiving that lime-water became turbid by burning candles over it1 p4 #dd4 ,this was also the case with lime-water confined in air in which an animal substance was putrefying1 or in which an animal died1 p4 #gi4 and that in which charcoal was burned1 p4 #ha4 ,but1 in all these cases1 there was a possibility of the fixed air being discharged from the candle1 the putrefying substance1 the lungs of the animal1 or the charcoal4 ,that there is a precipitation of lime when nitrous air is mixed with common air1 ,i had not then observed1 but ,i have since found it to be the case4 ,that there was no precipitation of lime when brimstone was burned1 ,i observed1 p4 #de4 might be owing to the fixed air and the lime uniting with the vitriolic acid1 and making a salt1 which was soluble in water2 which salt ,i1 indeed1 discovered by the evaporation of the water4 ,i also observed1 p4 #df1 #aje4 that diminished air being rather lighter than common air is a circumstance in favour of the fixed1 or the heavier part of the common air1 having been precipitated4 ,it was upon this idea1 together with others similar to it1 that ,i took so much pains to mix fixed air with air diminished by respiration or putrefaction1 in order to make it fit for respiration again2 and ,i thought that ,i had1 in general1 succeeded to a considerable degree1 p4 #ii1 c4 ,i will add1 also1 what ,i did not mention before1 that ,i once endeavoured1 but without effect1 to preserve mice alive in the same unchanged air1 by supplying them with fixed air1 when the air in which they were confined began to be injured by their respiration4 ,without effect1 also1 ,i confined for some months1 a quantity of quick lime in a given quantity of common air1 thinking it might extract the fixed air from it4 ,the experiments which ,i made with electricity were solely intended to ascertain what has often been attempted1 but1 as far as ,i know1 had never been fully accomplished1 viz4 to change the blue colour of liquors1 tinged with vegetable juices1 red4 ,for this purpose ,i made use of a glass tube1 about one tenth of an inch diameter in the inside1 as in fig4 #af4 ,in one end of this ,i cemented a piece of wire b1 on which ,i put a brass ball4 ,the lower part from a was filled with water tinged blue1 or rather purple1 with the juice of turnsole1 or archil4 ,this is easily done by an air-pump1 the tube being set in a vessel of the tinged water4 ,things being thus prepared1 ,i perceived that1 after ,i had taken the electric spark1 between the wire b1 and the liquor at a1 about a minute1 the upper part of it began to look red1 and in about two minutes it was very manifestly so2 and the red part1 which was about a quarter of an inch in length1 did not readily mix with the rest of the liquor4 ,i observed also1 that if the tube lay inclined while ,i took the sparks1 the redness extended twice as far on the lower side as on the upper4 ,the most important1 though the least expected observation1 however1 was that1 in proportion as the liquor became red1 it advanced nearer to the wire1 so that the space of air in which the sparks were taken was diminished2 and at length ,i found that the diminution was about one fifth of the whole space2 after which more electrifying produced no sensible effect4 ,to determine whether the cause of the change of colour was in the air1 or in the electric matter1 ,i expanded the air which had been diminished in the tube by means of an air-pump1 till it expelled all the liquor1 and admitted fresh blue liquor into its place2 but after that1 electricity produced no sensible effect1 either on the air1 or on the liquor2 so that it was evident that the electric matter had decomposed the air1 and had made it deposite something that was of an acid nature4 ,in order to determine whether the wire had contributed any thing to this effect1 ,i used wires of different metals1 iron1 copper1 brass1 and silver2 but the result was the very same with them all4 ,it was also the same when1 by means of a bent glass tube1 ,i made the electric spark without any wire at all1 in the following manner4 ,each leg of the tube1 fig4 #ai4 stood in a bason of quicksilver2 which1 by means of an air-pump1 was made to ascend as high as a1 a1 in each leg1 while the space between a and b in each contained the blue liquor1 and the space between b and b contained common air4 ,things being thus disposed1 ,i made the electric spark perform the circuit from one leg to the other1 passing from the liquor in one leg of the tube to the liquor in the other leg1 through the space of air4 ,the effect was1 that the liquor1 in both the legs1 became red1 and the space of air between them was contracted1 as before4 ,air thus diminished by electricity makes no effervescence with1 and is no farther diminished by a mixture of nitrous air2 so that it must have been in the highest degree noxious1 exactly like air diminished by any other process4 ,in order to determine what the acid was1 which was deposited by the air1 and which changed the colour of the blue liquor1 ,i exposed a small quantity of the liquor so changed to the common air1 and found that it recovered its blue colour1 exactly as water1 tinged with the same blue1 and impregnated with fixed air1 will do4 ,but the following experiment was still more decisive to this purpose4 ,taking the electric spark upon lime-water1 instead of the blue liquor1 the lime was precipitated as the air diminished4 ,from these experiments it pretty clearly follows1 that the electric matter either is1 or contains phlogiston2 since it does the very same thing that phlogiston does4 ,it is also probable1 from these experiments1 that the sulphureous smell1 which is occasioned by electricity1 being very different from that of fixed air1 the phlogiston in the electric matter itself may contribute to it4 ,it was now evident that common air diminished by any one of the processes above-mentioned being the same thing1 as ,i have observed1 with air diminished by any other of them 7since it is not liable to be farther diminished by any other7 the loss which it sustains1 in all the cases1 is1 in part1 that of the fixed air which entered into its constitution4 ,the fixed air thus precipitated from common air by means of phlogiston unites with lime1 if any lime water be ready to receive it1 unless there be some other substance at hand1 with which it has a greater affinity1 as the calces of metals4 ,if the whole of the diminution of common air was produced by the deposition of fixed air1 it would be easy to ascertain the quantity of fixed air that is contained in any given quantity of common air4 ,but it is evident that the whole of the diminution of common air by phlogiston is not owing to the precipitation of fixed air1 because a mixture of nitrous air will make a great diminution in all kinds of air that are fit for respiration1 even though they never were common air1 and though nothing was used in the process for generating them that can be supposed to yield fixed air4 ,indeed1 it appears1 from some of the experiments1 that the diminution of some of these kinds of air by nitrous air is so great1 and approaches so nearly to the quantity of the diminution of common air by the same process1 as to shew that1 unless they be very differently affected by phlogiston1 very little is to be allowed to the loss of fixed air in the diminution of common air by nitrous air4 ,the kinds of air on which this experiment was made were inflammable air1 nitrous air diminished by iron filings and brimstone1 and nitrous air itself2 all of which are produced by the solution of metals in acids2 and also on common air diminished and made noxious1 and therefore deprived of its fixed air by phlogistic processes2 and they were restored to a great degree of purity by agitation in water1 out of which its own air had been carefully boiled4 ,to five parts of inflammable air1 which had been agitated in water till it was diminished about one half 7at which time part of it fired with a weak explosion7 ,i put one part of nitrous air1 which diminished it one eighth of the whole4 ,this was done in lime-water1 without any precipitation of lime4 ,to compare this with common air1 ,i mixed the same quantity1 viz4 five parts of this1 and one part of nitrous air3 when considerable crust of lime was formed upon the surface of the lime water1 though the diminution was very little more than in the former process4 ,it is possible1 however1 that the common air might have taken more nitrous air before it was fully saturated1 so as to begin to receive an addition to its bulk4 ,i agitated in water a quantity of nitrous air phlogisticated with iron filings and brimstone1 and found it to be so far restored1 that three fourths of an ounce measure of nitrous air being put to two ounce measures of it1 made no addition to it4 ,but the most remarkable of these experiments is that which ,i made with nitrous air itself which ,i had no idea of the possibility of reducing to a state fit for respiration by any process whatever1 at the time of my former publication on this subject4 ,this air1 however1 itself1 without any previous phlogistication1 is purified by agitation in water till it is diminished by fresh nitrous air1 and to a very considerable degree4 ,in a pretty long time ,i agitated nitrous air in water1 supplying it from time to time with more1 as the former quantity diminished1 till only one eighteenth of the whole quantity remained2 in which state it was so wholesome1 that a mouse lived in two ounce measures of it more than ten minutes1 without shewing any sign of uneasiness2 so that ,i concluded it must have been about as good as air in which candles had burned out4 ,after agitating it again in water1 ,i put one part of fresh nitrous air to five parts of this air1 and it was diminished one ninth part4 ,i then agitated it a third time1 and putting more nitrous air to it1 it was diminished again in the same proportion1 and so a fourth time2 so that1 by continually repeating the process1 it would1 ,i doubt not1 have been all absorbed4 ,these processes were made in lime-water1 without forming any incrustation on the surface of it4 ,lastly1 ,i took a quantity of common air1 which had been diminished and made noxious by phlogistic processes2 and when it had been agitated in water1 ,i found that it was diminished by nitrous air1 though not so much as it would have been at the first4 ,after cleansing it a second time1 it was diminished again by the same means2 and1 after that1 a third time2 and thus there can be no doubt but that1 in time1 the whole quantity would have disappeared4 ,for ,i have never found that agitation in water1 deprived of its own air1 made any addition to a quantity of noxious air2 though1 a priori1 it might have been imagined that1 as a saturation with phlogiston diminishes air1 the extraction of phlogiston would increase the bulk of it4 ,on the contrary1 agitation in water always diminished noxious air a little2 indeed1 if water be deprived of all its own air1 it is impossible to agitate any kind of air in it without some loss4 ,also1 when noxious air has been restored by plants1 ,i never perceived that it gained any addition to its bulk by that means4 ,there was no incrustation of the lime-water in the above-mentioned experiment4 ,it is not a little remarkable1 that those kinds of air which never had been common air1 as inflammable air1 phlogisticated nitrous air1 and nitrous air itself1 when rendered wholesome by agitation in water1 should be more diminished by fresh nitrous air1 than common air which had been made noxious1 and restored by the same process2 and yet1 from the few trials that ,i have made1 ,i could not help concluding that this is the case4 ,in this course of experiments ,i was very near deceiving myself1 in consequence of transferring the nitrous air which ,i made use of in a bladder1 in the manner described1 p4 #ae4 fig4 #i4 so as to conclude that there was a precipitation of lime in all the above-mentioned cases1 and that even nitrous air itself produced that effect4 ,but after repeated trials1 ,i found that there was no precipitation of lime1 except1 in the first diminution of common air1 when the nitrous air was transferred in a glass vessel4 ,that the calces of metals contain air1 of some kind or other1 and that this air contributes to the additional weight of the calces1 above that of the metals from which they are made1 had been observed by ,dr4 ,hales2 and ,mr4 ,hartley had informed me1 that when red-lead is boiled in linseed oil1 there is a prodigious discharge of air before they incorporate4 ,i had likewise found1 that no weight is either gained or lost by the calcination of tin in a close glass vessel2 but ,i purposely deferred making any more experiments on the subject1 till we should have some weather in which ,i could make use of a large burning lens1 which ,i had provided for that and other purposes2 but1 in the mean time1 ,i was led to the discovery in a different manner4 ,having1 by the last-recited experiments1 been led to consider the electric matter as phlogiston1 or something containing phlogiston1 ,i was endeavouring to revivify the calx of lead with it2 when ,i was surprized to perceive a considerable generation of air4 ,it occurred to me1 that possibly this effect might arise from the heat communicated to the red-lead by the electric sparks1 and therefore ,i immediately filled a small phial with the red-lead1 and heating it with a candle1 ,i presently expelled from it a quantity of air about four or five times the bulk of the lead1 the air being received in a vessel of quicksilver4 ,how much more air it would have yielded1 ,i did not try4 ,along with the air1 a small quantity of water was likewise thrown out2 and it immediately occurred to me1 that this water and air together must certainly be the cause of the addition of weight in the calx4 ,it still remained to examine what kind of air this was2 but admitting water to it1 ,i found that it was imbibed by it1 exactly like fixed air1 which ,i therefore immediately concluded it must be#ab4 ,after this1 ,i found that ,mr4 ,lavoisier had completely discovered the same thing1 though his apparatus being more complex1 and less accurate than mine1 he concluded that more of the air discharged from the calces of metals was immiscible with water than ,i found it to be4 ,it appeared to me that ,i had never obtained fixed air more pure4 ,it being now pretty clearly determined1 that common air is made to deposit the fixed air which entered into the constitution of it1 by means of phlogiston1 in all the cases of diminished air1 it will follow1 that in the precipitation of lime1 by breathing into lime-water the fixed air1 which incorporates with lime1 comes not from the lungs1 but from the common air1 decomposed by the phlogiston exhaled from them1 and discharged1 after having been taken in with the aliment1 and having performed its function in the animal system4 ,thus my conjecture is more confirmed1 that the cause of the death of animals in confined air is not owing to the want of any pabulum vit1 which the air had been supposed to contain1 but to the want of a discharge of the phlogistic matter1 with which the system was loaded2 the air1 when once saturated with it1 being no sufficient menstruum to take it up4 ,the instantaneous death of animals put into air so vitiated1 ,i still think is owing to some stimulus1 which1 by causing immediate1 universal and violent convulsions1 exhausts the whole of the vis vit at once2 because1 as ,i have observed1 the manner of their death is the very same in all the different kinds of noxious air4 ,to this section on the subject of diminished1 and noxious air1 or as it might have been called phlogisticated air1 ,i shall subjoin a letter which ,i addressed to ,sir ,john ,pringle1 on the noxious quality of the effluvia of putrid marshes1 and which was read at a meeting of the ,royal ,society1 ,december #af1 #aggc4 ,this letter which is printed in the ,philosophical ,transactions1 ,vol4 #gd1 p4 #ij4 is immediately followed by another paper1 to which ,i would refer my reader4 ,it was written by ,dr4 ,price1 who has so greatly distinguished himself1 and done such eminent service to his country1 and to mankind1 by his calculations relating to the probabilities of human life1 and was suggested by his hearing this letter read at the ,royal ,society4 ,it contains a confirmation of my observations on the noxious effects of stagnant waters by deductions from ,mr4 ,muret's account of the ,bills of ,mortality for a parish situated among marshes1 in the district of ,vaud1 belonging to the ,canton of ,bern in ,switzerland4 ,to ,sir ,,john ,,pringle1 ,baronet4 ,,dear ,,sir1 ,having pursued my experiments on different kinds of air considerably farther1 in several respects1 than ,i had done when ,i presented the last account of them to the ,royal ,society2 and being encouraged by the favourable notice which the ,society has been pleased to take of them1 ,i shall continue my communications on this subject2 but1 without waiting for the result of a variety of processes1 which ,i have now going on1 or of other experiments1 which ,i propose to make1 ,i shall1 from time to time1 communicate such detached articles1 as ,i shall have given the most attention to1 and with respect to which1 ,i shall have been the most successful in my inquiries4 ,since the publication of my papers1 ,i have read two treatises1 written by ,dr4 ,alexander1 of ,edinburgh1 and am exceedingly pleased with the spirit of philosophical inquiry1 which they discover4 ,they appear to me to contain many new1 curious1 and valuable observations2 but one of the conclusions1 which he draws from his experiments1 ,i am satisfied1 from my own observations1 is ill founded1 and from the nature of it1 must be dangerous4 ,i mean his maintaining1 that there is nothing to be apprehended from the neighbourhood of putrid marshes4 ,i was particularly surprised1 to meet with such an opinion as this1 in a book inscribed to yourself1 who have so clearly explained the great mischief of such a situation1 in your excellent treatise on the diseases of the army4 ,on this account1 ,i have thought it not improper1 to address to you the following observations and experiments1 which ,i think clearly demonstrate the fallacy of ,dr4 ,alexander's reasoning1 indisputably establish your doctrine1 and indeed justify the apprehensions of all mankind in this case4 ,i think it probable enough1 that putrid matter1 as ,dr4 ,alexander has endeavoured to prove1 will preserve other substances from putrefaction2 because1 being already saturated with the putrid effluvium1 it cannot readily take any more2 but ,dr4 ,alexander was not aware1 that air thus loaded with putrid effluvium is exceedingly noxious when taken into the lungs4 ,i have lately1 however1 had an opportunity of fully ascertaining how very noxious such air is4 ,happening to use at ,calne1 a much larger trough of water1 for the purpose of my experiments1 than ,i had done at ,leeds1 and not having fresh water so near at hand as ,i had there1 ,i neglected to change it1 till it turned black1 and became offensive1 but by no means to such a degree1 as to deter me from making use of it4 ,in this state of the water1 ,i observed bubbles of air to rise from it1 and especially in one place1 to which some shelves1 that ,i had in it1 directed them2 and having set an inverted glass vessel to catch them1 in a few days ,i collected1 a considerable quantity of this air1 which issued spontaneously from the putrid water2 and putting nitrous air to it1 ,i found that no change of colour or diminution ensued1 so that it must have been1 in the highest degree1 noxious4 ,i repeated the same experiment several times afterwards1 and always with the same result4 ,after this1 ,i had the curiosity to try how wholesome air would be affected by this water2 when1 to my real surprise1 ,i found1 that after only one minute's agitation in it1 a candle would not burn in it2 and1 after three or four minutes1 it was in the same state with the air1 which had issued spontaneously from the same water4 ,i also found1 that common air1 confined in a glass vessel1 in contact only with this water1 and without any agitation1 would not admit a candle to burn in it after two days4 ,these facts certainly demonstrate1 that air which either arises from stagnant and putrid water1 or which has been for some time in contact with it1 must be very unfit for respiration2 and yet ,dr4 ,alexander's opinion is rendered so plausible by his experiments1 that it is very possible that many persons may be rendered secure1 and thoughtless of danger1 in a situation in which they must necessarily breathe it4 ,on this account1 ,i have thought it right to make this communication as early as ,i conveniently could2 and as ,dr4 ,alexander appears to be an ingenuous and benevolent man1 ,i doubt not but he will thank me for it4 ,that air issuing from water1 or rather from the soft earth1 or mud1 at the bottom of pits containing water1 is not always unwholesome1 ,i have also had an opportunity of ascertaining4 ,taking a walk1 about two years ago1 in the neighbourhood of ,wakefield1 in ,yorkshire1 ,i observed bubbles of air to arise1 in remarkably great plenty1 from a small pool of water1 which1 upon inquiry1 ,i was informed had been the place1 where some persons had been boring the ground1 in order to find coal4 ,these bubbles of air having excited my curiosity1 ,i presently returned1 with a bason1 and other vessels proper for my purpose1 and having stirred the mud with a long stick1 ,i soon got about a pint of this air2 and1 examining it1 found it to be good1 common air2 at least a candle burned in it very well4 ,i had not then discovered the method of ascertaining the goodness of common air1 by a mixture of nitrous air4 ,previous to the trial1 ,i had suspected that this air would have been found to be inflammable4 ,i shall conclude this letter with observing1 that ,i have found a remarkable difference in different kinds of water1 with respect to their effect on common air agitated in them1 and which ,i am not yet able to account for4 ,if ,i agitate common air in the water of a deep well1 near my house in ,calne1 which is hard1 but clear and sweet1 a candle will not burn in it after three minutes4 ,the same is the case with the rain-water1 which ,i get from the roof of my house4 ,but in distilled water1 or the water of a spring-well near the house1 ,i must agitate the air about twenty minutes1 before it will be so much injured4 ,it may be worth while1 to make farther experiments with respect to this property of water4 ,in consequence of using the rain-water1 and the well-water above mentioned1 ,i was very near concluding1 contrary to what ,i have asserted in this treatise1 that common air suffers a decomposition by great rarefaction4 ,for when ,i had collected a considerable quantity of air1 which had been rarefied about four hundred times1 by an excellent pump made for me by ,mr4 ,smeaton1 ,i always found1 that if ,i filled my receivers with the water above mentioned1 though ,i did it so gradually as to occasion as little agitation as possible1 a candle would not burn in the air that remained in them4 ,but when ,i used distilled water1 or fresh spring-water1 ,i undeceived myself4 ,i think myself honoured by the attention1 which1 from the first1 you have given to my experiments1 and am1 with the greatest respect1 ,dear ,sir1 ,your most obliged ,humble ,servant1 ,london1 #g ,dec4 #aggc4 ,j4 ,,priestley4 ,,postscript4 ,i cannot help expressing my surprize1 that so clear and intelligible an account1 of ,mr4 ,,smeaton',s air-pump1 should have been before the public so long1 as ever since the publication of the forty-seventh volume of the ,philosophical ,transactions1 printed in #ageb1 and yet that none of our philosophical instrument-makers should use the construction4 ,the superiority of this pump1 to any that are made upon the common plan1 is1 indeed1 prodigious4 ,few of them will rarefy more than #ajj times1 and1 in a general way1 not more than #fj or #gj times2 whereas this instrument must be in a poor state indeed1 if it does not rarefy #bjj or #cjj times2 and when it is in good order1 it will go as far as #ajjj times1 and sometimes even much farther than that2 besides1 this instrument is worked with much more ease1 than a common air-pump1 and either exhausts or condenses at pleasure4 ,in short1 to a person engaged in philosophical pursuits1 this instrument is an invaluable acquisition4 ,i shall have occasion to recite some experiments1 which ,i could not have made1 and which1 indeed1 ,i should hardly have dared to attempt1 if ,i had not been possessed of such an air-pump as this4 ,it is much to be wished1 that some person of spirit in the trade would attempt the construction of an instrument1 which would do great credit to himself1 as well as be of eminent service to philosophy4 ,,footnotes3 #aa ,on this account1 if it was thought convenient to introduce a new term 7or rather make a new application of a term already in use among chemists7 it might not be amiss to call air that has been diminished1 and made noxious by any of the processes above mentioned1 or others similar to them1 by the common appellation of phlogisticated air2 and1 if it was necessary1 the particular process by which it was phlogisticated might be added2 as common air phlogisticated by charcoal1 air phlogisticated by the calcination of metals1 nitrous air phlogisticated with the liver of sulphur1 c4 #ab ,here it becomes me to ask pardon of that excellent philosopher ,father ,beccaria of ,turin1 for conjecturing that the phlogiston1 with which he revivified metals1 did not come from the electric matter itself1 but from what was discharged from other pieces of metal with which he made the experiment4 ,see ,history of ,electricity1 p4 #bgg1 c4 ,this revivification of metals by electricity completes the proof of the electric matter being1 or containing phlogiston4 ,,section ,,iii4 ,of ,,nitrous ,,air4 ,since the publication of my former papers ,i have given more attention to the subject of nitrous air than to any other species of air2 and having been pretty fortunate in my inquiries1 ,i shall be able to lay before my reader a more satisfactory account of the curious phenomena occasioned by it1 and also of its nature and constitution1 than ,i could do before1 though much still remains to be investigated concerning it1 and many new objects of inquiry are started4 ,with a view to discover where the power of nitrous air to diminish common air lay1 ,i evaporated to dryness a quantity of the solution of copper in diluted spirit of nitre2 and having procured from it a quantity of a green precipitate1 ,i threw the focus of a burning-glass upon it1 when it was put into a vessel of quicksilver1 standing inverted in a bason of quicksilver4 ,in this manner ,i procured air from it1 which appeared to be1 in all respects1 nitrous air2 so that part of the same principle which had escaped during the solution1 in the form of air1 had likewise been retained in it1 and had not left it in the evaporation of the water4 ,with great difficulty ,i also procured a small quantity of the same kind of air from a solution of iron in spirit of nitre1 by the same process4 ,having1 for a different purpose1 fired some paper1 which had been dipped in a solution of copper in diluted spirit of nitre1 in nitrous air1 ,i found there was a considerable addition to the quantity of it2 upon which ,i fired some of the same kind of paper in quicksilver and presently observed that air was produced from it in great plenty4 ,this air1 at the first1 seemed to have some singular properties1 but afterwards ,i found that it was nothing more than a mixture of nitrous air1 from the precipitate of the solution1 and of inflammable air1 from the paper2 but that the former was predominant4 ,in the mixture of this kind of air with common air1 in a trough of water which had been putrid1 but which at that time seemed to have recovered its former sweetness 7for it was not in the least degree offensive to the smell7 a phenomenon sometimes occurred1 which for a long time exceedingly delighted and puzzled me2 but which was afterwards the means of letting me see much farther into the constitution of nitrous air than ,i had been able to see before4 ,when the diminution of the air was nearly completed1 the vessel in which the mixture was made began to be filled with the most beautiful white fumes1 exactly resembling the precipitation of some white substance in a transparent menstruum1 or the falling of very fine snow2 except that it was much thicker below than above1 as indeed is the case in all chemical precipitations4 ,this appearance continued two or three minutes4 ,at other times ,i went over the same process1 as nearly as possible in the same manner1 but without getting this remarkable appearance1 and was several times greatly disappointed and chagrined1 when ,i baulked the expectations of my friends1 to whom ,i had described1 and meant to have shewn it4 ,this made me give all the attention ,i possibly could to this experiment1 endeavouring to recollect every circumstance1 which1 though unsuspected at the time1 might have contributed to produce this new appearance2 and ,i took a great deal of pains to procure a quantity of this air from the paper above mentioned for the purpose1 which1 with a small burning lens1 and an uncertain sun1 is not a little troublesome4 ,but all that ,i observed for some time was1 that ,i stood the best chance of succeeding when ,i warmed the vessel in which the mixture was made1 and agitated the air during the effervescence4 ,finding1 at length1 that1 with the same preparation and attentions1 ,i got the same appearance from a mixture of nitrous and common air in the same trough of water1 ,i concluded that it could not depend upon any thing peculiar to the precipitate of the copper contained in the paper from which the air was procured1 as ,i had at first imagined1 but upon what was common to it1 and pure nitrous air4 ,afterwards1 having1 7with a view to observe whether any crystals would be formed by the union of volatile alkali1 and nitrous air1 similar to those formed by it and fixed air1 as described by ,mr4 ,smeth in his ,dissertation on fixed ,air7 opened the mouth of a phial which was half filled with a volatile alkaline liquor1 in a jar of nitrous air 7in the manner described p4 #aa4 fig4 #d47 ,i had an appearance which perfectly explained the preceding4 ,all that part of the phial which was above the liquor1 and which contained common air1 was filled with beautiful white clouds1 as if some fine white powder had been instantly thrown into it1 and some of these clouds rose within the jar of nitrous air4 ,this appearance continued about a minute1 and then intirely disappeared1 the air becoming transparent4 ,withdrawing the phial1 and exposing it to the common air1 it there also became turbid1 and soon after the transparency returned4 ,introducing it again into the nitrous air1 the clouds appeared as before4 ,in this manner the white fumes1 and transparency1 succeeded each other alternately1 as often as ,i chose to repeat the experiment1 and would no doubt have continued till the air in the jar had been thoroughly diluted with common air4 ,these appearances were the same with any substance that contained volatile alkali1 fluid or solid4 ,when1 instead of the small phial1 ,i used a large and tall glass jar1 this appearance was truly fine and striking1 especially when the water in the trough was very transparent4 ,for ,i had only to put the smallest drop of a volatile alkaline liquor1 or the smallest bit of the solid salt1 into the jar1 and the moment that the mouth of it was opened in a jar of nitrous air1 the white clouds above mentioned began to be formed at the mouth1 and presently descended to the bottom1 so as to fill the whole1 were it ever so large1 as with fine snow4 ,in considering this experiment1 ,i soon perceived that this curious appearance must have been occasioned by the mixture of the nitrous and common air1 and therefore that the white clouds must be nitrous ammoniac1 formed by the acid of the nitrous air1 set loose in the decomposition of it by common air1 while the phlogiston1 which must be another constituent part of nitrous air1 entering the common air1 is the cause of the diminution it suffers in this process2 as it is the cause of a similar diminution1 in a variety of other processes4 ,i would observe1 that it is not peculiar to nitrous air to be a test of the fitness of air for respiration4 ,any other process by which air is diminished and made noxious answers the same purpose4 ,liver of sulphur for instance1 the calcination of metals1 or a mixture of iron filings and brimstone will do just the same thing2 but the application of them is not so easy1 or elegant1 and the effect is not so soon perceived4 ,in fact1 it is phlogiston that is the test4 ,if the air be so loaded with this principle that it can take no more1 which is seen by its not being diminished in any of the processes above mentioned1 it is noxious2 and it is wholesome in proportion to the quantity of phlogiston that it is able to take4 ,this1 ,i have no doubt1 is the true theory of the diminution of common air by nitrous air1 the redness of the appearance being nothing more than the usual colour of the fumes1 of spirit of nitre1 which is now disengaged from the superabundant phlogiston with which it was combined in the nitrous air1 and ready to form another union with any thing that is at hand1 and capable of it4 ,with the volatile alkali it forms nitrous ammoniac1 water imbibes it like any other acid1 even quicksilver is corroded by it2 but this action being slow1 the redness in this mixture of nitrous and common air continues much longer when the process is made in quicksilver1 than when it is made in water1 and the diminution1 as ,i have also observed2 is by no means so great4 ,i was confirmed in this opinion when ,i put a bit of volatile alkaline salt into the jar of quicksilver in which ,i made the mixture of nitrous and common air4 ,in these circumstances1 the vessel being previously filled with the alkaline fumes1 the acid immediately joined them1 formed the white clouds above mentioned1 and the diminution proceeded almost as far as when the process was made in water4 ,that it did not proceed quite so far1 ,i attribute chiefly to the small quantity of calx formed by the slight solution of mercury with the acid fumes not being able to absorb all the fixed air that is precipitated from the common air by the phlogiston4 ,in part1 also1 it may be owing to the small quantify of surface in the quicksilver in the vessels that ,i made use of2 in consequence of which the acid fumes could act upon it only in a slow succession1 so that part of them1 as well as of the fixed air1 had an opportunity of forming another union with the diminished air4 ,this1 as ,i have observed before1 was so much the case when the process was made in quicksilver1 without any volatile alkali1 that when water was admitted to it1 after some time1 it was not capable of dissolving that union1 tho' it would not have taken place if the process had been in water from the first4 ,in diversifying this experiment1 ,i found that it appeared to very great advantage when ,i suspended a piece of volatile salt in the common air1 previous to the admission of nitrous air to it1 inclosing it in a bit of gauze1 muslin1 or a small net of wire4 ,for1 presently after the redness of the mixture begins to go off1 the white cloud1 like snow1 begins to descend from the salt1 as if a white powder was shaken out of the bag that contains it4 ,this white cloud presently fills the whole vessel1 and the appearance will last about five minutes4 ,if the salt be not put to the mixture of these two kinds of air till it has perfectly recovered its transparency1 the effervescence being completely over1 no white cloud will be formed2 and1 what is rather more remarkable1 there is nothing of this appearance when the salt is put into the nitrous air itself4 ,the reason of this must be1 that the acid of the nitrous air has a nearer affinity with its phlogiston than with the volatile alkali2 though the phlogiston having a nearer affinity with something in the common air1 the acid being thereby set loose1 will unite with the alkaline vapour1 if it be at hand to unite with it4 ,there is also very little1 if any white cloud formed upon holding a piece of the volatile salt within the mouth of a phial containing smoking spirit of nitre4 ,also when ,i threw the focus of a burning mirror upon some sal ammoniac in nitrous air1 and filled the whole vessel with white fumes which arose from it1 they were soon dispersed1 and the air was neither diminished nor altered4 ,i was now fully convinced1 that the white cloud which ,i casually observed1 in the first of these experiments1 was occasioned by the volatile alkali emitted from the water1 which was in a slight degree putrid2 and that the warming1 and agitation of the vessels1 had promoted the emission of the putrid1 or alkaline effluvium4 ,i could not perceive that the diminution of common air by the mixture of nitrous air was sensibly increased by the presence of the volatile alkali4 ,it is possible1 however1 that1 by assisting the water to take up the acid1 something less of it may be incorporated with the remaining diminished air than would otherwise have been2 but ,i did not give much attention to this circumstance4 ,when the phial in which ,i put the alkaline salts contained any kind of noxious air1 the opening of it in nitrous air was not followed by any thing of the appearance above mentioned4 ,this was the case with inflammable air4 ,but when1 after agitating the inflammable air in water1 ,i had brought it to a state in which it was diminished a little by the mixture of nitrous air1 the cloudy appearance was in the same proportion2 so that this appearance seems to be equally a test of the fitness of air for respiration1 with the redness which attends the mixture of it with nitrous air only4 ,having generally fastened the small bag which contained the volatile salt to a piece of brass wire in the preceding experiment1 ,i commonly found the end of it corroded1 and covered with a blue substance4 ,also the salt itself1 and sometimes the bag was died blue4 ,but finding that this was not the case when ,i used an iron wire in the same circumstances1 but that it became red1 ,i was satisfied that both the metals had been dissolved by the volatile alkali4 ,at first ,i had a suspicion that the blue might have come from the copper1 out of which the nitrous air had been made4 ,but when the nitrous air was made from iron1 the appearances were1 in all respects1 the same4 ,i have observed1 in the preceding section1 that if nitrous air be mixed with common air in lime-water1 the surface of the water1 where it is contiguous to that mixture1 will be covered with an incrustation of lime1 shewing that some fixed air had been deposited in the process4 ,it is remarkable1 however1 as ,i there also just mentioned1 that this is the case when nitrous air alone is put to a vessel of lime-water1 after it has been kept in a bladder1 or only transferred from one vessel to another by a bladder1 in the manner described1 p4 #ae4 fig4 #i4 ,as ,i had used the same bladder for transferring various kinds of air1 and among the rest fixed air1 ,i first imagined that this effect might have been occasioned by a mixture of this fixed air with the nitrous air1 and therefore took a fresh bladder2 but still the effect was the same4 ,to satisfy myself farther1 that the bladder had produced this effect1 ,i put one into a jar of nitrous air1 and after it had continued there a day and a night1 ,i found that the nitrous air in this jar1 though it was transferred in a glass vessel1 made lime-water turbid4 ,whether there was any thing in the preparation of these bladders that occasioned their producing this effect1 ,i cannot tell4 ,they were such as ,i procure from the apothecaries4 ,the thing seems to deserve farther examination1 as there seems1 in this case1 to be the peculiar effect of fixed air from other causes1 or else a production of fixed air from materials that have not been supposed to yield it1 at least not in circumstances similar to these4 ,as fixed air united to water dissolves iron1 ,i had the curiosity to try whether fixed air alone would do it2 and as nitrous air is of an acid nature1 as well as fixed air1 ,i1 at the same time1 exposed a large surface of iron to both the kinds2 first filling two eight ounce phials with nails1 and then with quicksilver1 and after that displacing the quicksilver in one of the phials by fixed air1 and in the other by nitrous air2 then inverting them1 and leaving them with their mouths immersed in basons of quicksilver4 ,in these circumstances the two phials stood about two months1 when no sensible change at all was produced in the fixed air1 or in the iron which had been exposed to it1 but a most remarkable1 and most unexpected change was made in the nitrous air2 and in pursuing the experiment1 it was transformed into a species of air1 with properties which1 at the time of my first publication on this subject1 ,i should not have hesitated to pronounce impossible1 viz4 air in which a candle burns quite naturally and freely1 and which is yet in the highest degree noxious to animals1 insomuch that they die the moment they are put into it2 whereas1 in general1 animals live with little sensible inconvenience in air in which candles have burned out4 ,such1 however1 is nitrous air1 after it has been long exposed to a large surface of iron4 ,it is not less extraordinary1 that a still longer continuance of nitrous air in these circumstances 7but how long depends upon too many1 and too minute circumstances to be ascertained with exactness7 makes it not only to admit a candle to burn in it1 but enables it to burn with an enlarged flame1 by another flame 7extending every where to an equal distance from that of the candle1 and often plainly distinguishable from it7 adhering to it4 ,sometimes ,i have perceived the flame of the candle1 in these circumstances1 to be twice as large as it is naturally1 and sometimes not less than five or six times larger2 and yet without any thing like an explosion1 as in the firing of the weakest inflammable air4 ,nor is the farther progress in the transmutation of nitrous air1 in these circumstances1 less remarkable4 ,for when it has been brought to the state last mentioned1 the agitation of it in fresh water almost instantly takes off that peculiar kind of inflammability1 so that it extinguishes a candle1 retaining its noxious quality4 ,it also retains its power of diminishing common air in a very great degree4 ,but this noxious quality1 like the noxious quality of all other kinds of air that will bear agitation in water1 is taken out of it by this operation1 continued about five minutes2 in which process it suffers a farther and very considerable diminution4 ,it is then itself diminished by fresh nitrous air1 and animals live in it very well1 about as well as in air in which candles have burned out4 ,lastly1 ,one quantity of nitrous air1 which had been exposed to iron in quicksilver1 from ,december #ah to ,january #bj1 and which happened to stand in water till ,january #ca 7the iron still continuing in the phial7 was fired with an explosion1 exactly like a weak inflammable air4 ,at the same time another quantity of nitrous air1 which had likewise been exposed to iron1 standing in quicksilver1 till about the same time1 and had then stood in water only1 without iron1 only admitted a candle to burn in it with an enlarged flame1 as in the cases above mentioned4 ,but whether the difference ,i have mentioned in the circumstances of these experiments contributed to this difference in the result1 ,i cannot tell4 ,nitrous air treated in the manner above mentioned is diminished about one fourth by standing in quicksilver2 and water admitted to it will absorb about half the remainder2 but if water only1 and no quicksilver1 be used from the beginning1 the nitrous air will be diminished much faster and farther2 so that not more than one fourth1 one sixth1 or one tenth of the original quantity will remain4 ,but ,i do not know that there is any difference in the constitution of the air which remains in these two cases4 ,the water which has imbibed this nitrous air exposed to iron is remarkably green1 also the phial containing it becomes deeply1 and1 ,i believe1 indelibly tinged with green2 and if the water be put into another vessel1 it presently deposits a considerable quantity of matter1 which when dry appears to be the earth or ochre of iron2 from which it is evident1 that the acid of the nitrous air dissolves the iron2 while the phlogiston1 being set loose1 diminishes nitrous air1 as in the process of the iron filings and brimstone4 ,upon this hint1 instead of using iron1 ,i introduced a pot of liver of sulphur into a jar of nitrous air1 and presently found1 that what ,i had before done by means of iron in six weeks1 or two months1 ,i could do by liver of sulphur 7in consequence1 no doubt1 of its giving its phlogiston more freely7 in less than twenty-four hours1 especially when the process was kept warm4 ,it is remarkable1 however1 that if the process with liver of sulphur be suffered to proceed1 the nitrous air will be diminished much farther4 ,at one time not more than one twentieth of the original quantity remained1 and how much farther it right have been diminished1 ,i cannot tell4 ,in this great diminution1 it does not admit a candle to burn in it at all2 and ,i generally found this to be the case whenever the diminution had proceeded beyond three fourths of the original quantity#ac4 ,it is something remarkable1 that though the diminution of nitrous air by iron filings and brimstone very much resembles the diminution of it by iron only1 or by liver of sulphur1 yet the iron filings and brimstone never bring it to such a state as that a candle will burn in it2 and also that1 after this process1 it is never capable of diminishing common air4 ,but when it is considered that these properties are destroyed by agitation in water1 this difference in the result of processes1 in other respects similar1 will appear less extraordinary2 and they agree in this1 that long agitation in water makes both these kinds of nitrous air equally fit for respiration1 being equally diminished by fresh nitrous air4 ,it is possible that there would have been a more exact agreement in the result of these processes1 if they had been made in equal degrees of heat2 but the process with iron was made in the usual temperature of the atmosphere1 and that with liver of sulphur generally near a fire4 ,it may clearly1 ,i think1 be inferred from these experiments1 that all the difference between fresh nitrous air1 that state of it in which it is partially inflammable1 or wholly so1 that in which it again extinguishes candles1 and that in which it finally becomes fit for respiration1 depends upon some difference in the mode of the combination of its acid with phlogiston1 or on the proportion between these two ingredients in its composition2 and it is not improbable but that1 by a little more attention to these experiments1 the whole mystery of this proportion and combination may be explained4 ,i must not omit to observe that there was something peculiar in the result of the first experiment which ,i made with nitrous air exposed to iron2 which was that1 without any agitation in water1 it was diminished by fresh nitrous air1 and that a candle burned in it quite naturally4 ,to what this difference was owing ,i cannot tell4 ,this air1 indeed1 had been exposed to the iron a week or two longer than in any of the other cases1 but ,i do not imagine that this circumstance could have produced that difference4 ,when the process is in water with iron1 the time in which the diminution is accomplished is exceedingly various2 being sometimes completed in a few days1 whereas at other times it has required a week or a fortnight4 ,some kinds of iron also produced this effect much sooner than others1 but on what circumstances this difference depends ,i do not know4 ,what are the varieties in the result of this experiment when it is made in quicksilver ,i cannot tell1 because1 on account of its requiring more time1 ,i have not repeated it so often2 but ,i once found that nitrous air was not sensibly changed by having been exposed to iron in quicksilver nine days2 whereas in water a very considerable alteration was always made in much less than half that time4 ,it may just deserve to be mentioned1 that nitrous air extremely rarified in an air-pump dissolves iron1 and is diminished by it as much as when it is in its native state of condensation4 ,it is something remarkable1 though ,i never attended to it particularly before ,i made these last experiments1 and it may tend to throw some light upon them1 that when a candle is extinguished1 as it never fails to be1 in nitrous air1 the flame seems to be a little enlarged at its edges1 by another bluish flame added to it1 just before its extinction4 ,it is proper to observe in this place1 that the electric spark taken in nitrous air diminishes it to one fourth of its original quantity1 which is about the quantity of its diminution by iron filings and brimstone1 and also by liver of sulphur without heat4 ,the air is also brought by electricity to the same state as it is by iron filings and brimstone1 not diminishing common air4 ,if the electric spark be taken in it when it is confined by water tinged with archil1 it is presently changed from blue to red1 and that to a very great degree4 ,when the iron nails or wires1 which ,i have used to diminish nitrous air1 had done their office1 ,i laid them aside1 not suspecting that they could be of any other philosophical use2 but after having lain exposed to the open air almost a fortnight2 having1 for some other purpose1 put some of them into a vessel containing common air1 standing inverted1 and immersed in water1 ,i was surprized to observe that the air in which they were confined was diminished4 ,the diminution proceeded so fast1 that the process was completed in about twenty-four hours2 for in that time the air was diminished about one fifth1 so that it made no effervescence with nitrous air1 and was1 therefore1 no doubt1 highly noxious1 like air diminished by any other process4 ,this experiment ,i have repeated a great number of times1 with the same phials1 filled with nails or wires that have been suffered to rust in nitrous air1 but their power of diminishing common air grows less and less continually4 ,how long it will be before it is quite exhausted ,i cannot tell4 ,this diminution of air ,i conclude must arise from the phlogiston1 either of the nitrous air or the iron1 being some way entangled in the rust1 in which the wires were encrusted1 and afterwards getting loose from it4 ,to the experiments upon iron filings and brimstone in nitrous air1 ,i must add1 that when a pot full of this mixture had absorbed as much as it could of a jar of nitrous air 7which is about three fourths of the whole7 ,i put fresh nitrous air to it1 and it continued to absorb1 till three or four jars full of it disappeared2 but the absorption was exceedingly slow at the last4 ,also when ,i drew this pot through the water1 and admitted fresh nitrous air to it1 it absorbed another jar full1 and then ceased4 ,but when ,i scraped off the outer surface of this mixture1 which had been so long exposed to the nitrous air1 the remainder absorbed more of the air4 ,when ,i took the top of the mixture which ,i had scraped off and threw upon it the focus of a burning-glass1 the air in which it was confined was diminished1 and became quite noxious2 yet when ,i endeavoured to get air from this matter in a jar full of quicksilver1 ,i was able to procure little or nothing4 ,it is not a little remarkable that nitrous air diminished by iron filings and brimstone1 which is about one fourth1 cannot1 by agitation in water1 be diminished much farther2 whereas pure nitrous air may1 by the same process1 be diminished to one twentieth of its whole bulk1 and perhaps much more4 ,this is similar to the effect of the same mixture1 and of phlogiston in other cases1 on fixed air2 for it so far changes its constitution1 that it is afterwards incapable of mixing with water4 ,it is similar also to the effect of phlogiston in acid air1 which of itself is almost instantly absorbed by water2 but by this addition it is first converted into inflammable air1 which does not readily mix with water1 and which1 by long agitation in water1 becomes of another constitution1 still less miscible with water4 ,i shall close this section with a few other observations of a miscellaneous nature4 ,nitrous air is as much diminished both by iron filings1 and also by liver of sulphur1 when confined in quicksilver1 as when it is exposed to water4 ,distilled water tinged blue with the juice of turnsole becomes red on being impregnated with nitrous air2 but by being exposed a week or a fortnight to the common atmosphere1 in open and shallow vessels1 it recovers its blue colour2 though1 in that time1 the greater part of the water will be evaporated4 ,this shews that in time nitrous air escapes from the water with which it is combined1 just as fixed air does1 though by no means so readily#ad4 ,having dissolved silver1 copper1 and iron in equal quantities of spirit of nitre diluted with water1 the quantities of nitrous air produced from them were in the following proportion2 from iron #h1 from copper #f-a_/d1 from silver #f4 ,in about the same proportion also it was necessary to mix water with the spirit of nitre in each case1 in order to make it dissolve these metals with equal rapidity1 silver requiring the least water1 and iron the most4 ,phosphorus gave no light in nitrous air1 and did not take away from its power of diminishing common air2 only when the redness of the mixture went off1 the vessel in which it was made was filled with white fumes1 as if there had been some volatile alkali in it4 ,the phosphorus itself was unchanged4 ,there is something remarkable in the effect of nitrous air on insects that are put into it4 ,i observed before that this kind of air is as noxious as any whatever1 a mouse dying the moment it is put into it2 but frogs and snails 7and therefore1 probably1 other animals whose respiration is not frequent7 will bear being exposed to it a considerable time1 though they die at length4 ,a frog put into nitrous air struggled much for two or three minutes1 and moved now and then for a quarter of an hour1 after which it was taken out1 but did not recover4 ,wasps always died the moment they were put into the nitrous air4 ,i could never observe that they made the least motion in it1 nor could they be recovered to life afterwards4 ,this was also the case in general with spiders1 flies1 and butterflies4 ,sometimes1 however1 spiders would recover after being exposed about a minute to this kind of air4 ,considering how fatal nitrous air is to insects1 and likewise its great antiseptic power1 ,i conceived that considerable use might be made of it in medicine1 especially in the form of clysters1 in which fixed air had been applied with some success2 and in order to try whether the bowels of an animal would bear the injection of it1 ,i contrived1 with the help of ,mr4 ,hey1 to convey a quantity of it up the anus of a dog4 ,but he gave manifest signs of uneasiness1 as long as he retained it1 which was a considerable time1 though in a few hours afterwards he was as lively as ever1 and seemed to have suffered nothing from the operation4 ,perhaps if nitrous air was diluted either with common air1 or fixed air1 the bowels might bear it better1 and still it might be destructive to worms of all kinds1 and be of use to check or correct putrefaction in the intestinal canal1 or other parts of the system4 ,i repeat it once more that1 being no physician1 ,i run no risk by such proposals as these2 and ,i cannot help flattering myself that1 in time1 very great medicinal use will be made of the application of these different kinds of air to the animal system4 ,let ingenious physicians attend to this subject1 and endeavour to lay hold of the new handle which is now presented them1 before it be seized by rash empiricks2 who1 by an indiscriminate and injudicious application1 often ruin the credit of things and processes which might otherwise make an useful addition to the materia and ars medica4 ,in the first publication of my papers1 having experienced the remarkable antiseptic power of nitrous air1 ,i proposed an attempt to preserve anatomical preparations1 c4 by means of it2 but ,mr4 ,hey1 who made the trial1 found that1 after some months1 various animal substances were shriveled1 and did not preserve their natural forms in this kind of air4 ,,footnotes3 #ac ,the result of several of these experiments ,i had the pleasure of trying in the presence of the celebrated ,mr4 ,de ,luc of ,geneva1 when he was upon a visit to ,lord ,shelburne in ,wiltshire4 #ad ,i have not repeated this experiment with that variation of circumstances which an attention to ,mr4 ,bewley's observation will suggest4 ,,section ,,iv4 ,of ,,marine ,,acid ,,air4 ,in my former experiments on this species of air ,i procured it from spirit of salt1 but ,i have since hit upon a much less expensive method of getting it1 by having recourse to the process by which the spirit of salt is itself originally made4 ,for this purpose ,i fill a small phial with common salt1 pour upon it a small quantity of concentrated oil of vitriol1 and receive the fumes emitted by it in a vessel previously filled with quicksilver1 and standing in a bason of quicksilver1 in which it appears in the form of a perfectly transparent air1 being precisely the same thing with that which ,i had before expelled from the spirit of salt4 ,this method of procuring acid air is the more convenient1 as a phial1 once prepared in this manner1 will suffice1 for common experiments1 many weeks2 especially if a little more oil of vitriol be occasionally put to it4 ,it only requires a little more heat at the last than at the first4 ,indeed1 at the first1 the heat of a person's hand will often be sufficient to make it throw out the vapour4 ,in warm weather it will even keep smoking many days without the application of any other heat4 ,on this account1 it should be placed where there are no instruments1 or any thing of metal1 that can be corroded by this acid vapour4 ,it is from dear-bought experience that ,i give this advice4 ,it may easily be perceived when this phial is throwing out this acid vapour1 as it always appears1 in the open air1 in the form of a light cloud2 owing1 ,i suppose1 to the acid attracting to itself1 and uniting with1 the moisture that is in the common atmosphere4 ,by this process ,i even made a stronger spirit of salt than can be procured in any other way4 ,for having a little water in the vessel which contains the quicksilver1 it imbibes the acid vapour1 and at length becomes truly saturated with it4 ,having1 in this manner1 impregnated pure water with acid air1 ,i could afterwards expel the same air from it1 as from common spirit of salt4 ,i observed before that this acid vapour1 or air1 has a strong affinity with phlogiston1 so that it decomposes many substances which contain it1 and with them forms a permanently inflammable air1 no more liable to be imbibed by water than inflammable air procured by any other process1 being in fact the very same thing2 and that1 in some cases1 it even dislodges spirit of nitre and oil of vitriol1 which in general appear to be stronger acids than itself4 ,i have since observed that1 by giving it more time1 it will extract phlogiston from substances from which ,i at first concluded that it was not able to do it1 as from dry wood1 crusts of bread not burnt1 dry flesh1 and what is more extraordinary from flints4 ,as there was something peculiar to itself in the process or result of each of these experiments1 it may not be improper to mention them distinctly4 ,pieces of dry cork wood being put to the acid air1 a small quantity remained not imbibed by water1 and was inflammable4 ,very dry pieces of oak1 being exposed to this air a day and a night1 after imbibing a considerable quantity of it1 produced air which was inflammable indeed1 but in the slightest degree imaginable4 ,it seemed to be very nearly in the state of common air4 ,a piece of ivory imbibed the acid vapour very slowly4 ,in a day and a night1 however1 about half an ounce measure of permanent air was produced1 and it was pretty strongly inflammable4 ,the ivory was not discoloured1 but was rendered superficially soft1 and clammy1 tasting very acid4 ,pieces of beef1 roasted1 and made quite dry1 but not burnt1 absorbed the acid vapour slowly2 and when it had continued in this situation all night1 from five ounce measures of the air1 half a measure was permanent1 and pretty strongly inflammable4 ,this experiment succeeded a second time exactly in the same manner2 but when ,i used pieces of white dry chicken-flesh though ,i allowed the same time1 and in other respects the process seemed to go on in the same manner1 ,i could not perceive that any part of the remaining air was inflammable4 ,some pieces of a whitish kind of flint1 being put into a quantity of acid air1 imbibed but a very little of it in a day and a night2 but of #b-a_/b ounce measures of it1 about half a measure remained unabsorbed by water1 and this was strongly inflammable1 taking fire just like an equal mixture of inflammable and common air4 ,at another time1 however1 ,i could not procure any inflammable air by this means1 but to what circumstance these different results were owing ,i cannot tell4 ,that inflammable air is produced from charcoal in acid air ,i observed before4 ,i have since found that it may likewise be procured from pit coal1 without being charred4 ,inflammable air ,i had also observed to arise from the exposure of spirit of wine1 and various oily substances1 to the vapour of spirit of salt4 ,i have since made others of a similar nature1 and as peculiar circumstances attended some of these experiments1 ,i shall recite them more at large4 ,essential oil of mint absorbed this air pretty fast1 and presently became of a deep brown colour4 ,when it was taken out of this air it was of the consistence of treacle1 and sunk in water1 smelling differently from what it did before2 but still the smell of the mint was predominant4 ,very little or none of the air was fixed1 so as to become inflammable2 but more time would probably have produced this effect4 ,oil of turpentine was also much thickened1 and became of a deep brown colour1 by being saturated with acid air4 ,ether absorbed acid air very fast1 and became first of a turbid white1 and then of a yellow and brown colour4 ,in one night a considerable quantity of permanent air was produced1 and it was strongly inflammable4 ,having1 at one time1 fully saturated a quantity of ether with acid air1 ,i admitted bubbles of common air to it1 through the quicksilver1 by which it was confined1 and observed that white fumes were made in it1 at the entrance of every bubble1 for a considerable time4 ,at another time1 having fully saturated a small quantity of ether with acid air1 and having left the phial in which it was contained nearly full of the air1 and inverted1 it was by some accident overturned2 when1 instantly1 the whole room was filled with a visible fume1 like a white cloud1 which had very much the smell of ether1 but peculiarly offensive4 ,opening the door and window of the room1 this light cloud filled a long passage1 and another room4 ,in the mean time the ether was seemingly all vanished1 but some time after the surface of the quicksilver in which the experiment had been made was covered with a liquor that tasted very acid2 arising1 probably1 from the moisture in the atmosphere attracted by the acid vapour with which the ether had been impregnated4 ,this visible cloud ,i attribute to the union of the moisture in the atmosphere with the compound of the acid air and ether4 ,i have since saturated other quantities of ether with acid air1 and found it to be exceedingly volatile1 and inflammable4 ,its exhalation was also visible1 but not in so great a degree as in the case above mentioned4 ,camphor was presently reduced into a fluid state by imbibing acid air1 but there seemed to be something of a whitish sediment in it4 ,after continuing two days in this situation ,i admitted water to it2 immediately upon which the camphor resumed its former solid state1 and1 to appearance1 was the very same substance that it had been before2 but the taste of it was acid1 and a very small part of the air was permanent1 and slightly inflammable4 ,the acid air seemed to make no impression upon a piece of ,derbyshire spar1 of a very dark colour1 and which1 therefore1 seemed to contain a good deal of phlogiston4 ,as the acid air has so near an affinity with phlogiston1 ,i expected that the fumes of liver of sulphur1 which chemists agree to be phlogistic1 would have united with it1 so as to form inflammable air2 but ,i was disappointed in that expectation4 ,this substance imbibed half of the acid air to which it was introduced3 one fourth of the remainder1 after standing one day in quicksilver1 was imbibed by water1 and what was left extinguished a candle4 ,this experiment1 however1 seems to prove that acid air and phlogiston may form a permanent kind of air that is not inflammable4 ,perhaps it may be air in such a state as common air loaded with phlogiston1 and from which the fixed air has been precipitated4 ,or rather1 it may be the same thing with inflammable air1 that has lost its inflammability by long standing in water4 ,it well deserves a farther examination4 ,the following experiments are those in which the stronger acids were made use of1 and therefore they may assist us farther to ascertain their affinities with certain substances1 with respect to this marine acid in the form of air4 ,i put a quantity of strong concentrated oil of vitriol to acid air1 but it was not at all affected by it in a day and a night4 ,in order to try whether it would not have more power in a more condensed state1 ,i compressed it with an additional atmosphere2 but upon taking off this pressure1 the air expanded again1 and appeared to be not at all diminished4 ,i also put a quantity of strong spirit of nitre to it without any sensible effect4 ,we may conclude1 therefore1 that the marine acid1 in this form of air1 is not able to dislodge the other acids from their union with water4 ,blue vitriol1 which is formed by the union of the vitriolic acid with copper1 turned to a dark green the moment that it was put to the acid air1 which it absorbed1 though slowly4 ,two pieces1 as big as small nuts1 absorbed three ounce measures of the air in about half an hour4 ,the green colour was very superficial2 for it was easily wiped or washed off4 ,green copperas turned to a deeper green upon being put into acid air1 which it absorbed slowly4 ,white copperas absorbed this air very fast1 and was dissolved in it4 ,sal ammoniac1 being the union of spirit of salt with volatile alkali1 was no more affected with the acid air than1 as ,i have observed before1 common salt was4 ,i also introduced to the acid air various other substances1 without any particular expectation2 and it may be worth while to give an account of the results1 that the reader may draw from them such conclusions as he shall think reasonable4 ,borax absorbed acid air about as fast as blue vitriol1 but without any thing else that was observable4 ,fine white sugar absorbed this air slowly1 was thoroughly penetrated with it1 became of a deep brown colour1 and acquired a smell that was peculiarly pungent4 ,a piece of quick lime being put to about twelve or fourteen ounce measures of acid air1 and continuing in that situation about two days1 there remained one ounce measure of air that was not absorbed by water1 and it was very strongly inflammable1 as much so as a mixture of half inflammable and half common air4 ,very particular care was taken that no common air mixed with the acid air in this process4 ,at another time1 from about half the quantity of acid air above mentioned1 with much less quick-lime1 and in the space of one day1 ,i got half an ounce measure of air that was inflammable in a slight degree only4 ,this experiment proves that some part of the phlogiston which escapes from the fuel1 in contact with which the lime is burned1 adheres to it4 ,but ,i am very far from thinking that the causticity of quick-lime is at all owing to this circumstance4 ,i have made a few more experiments on the mixture of acid air with other kinds of air1 and think that it may be worth while to mention them1 though nothing of consequence1 at least nothing but negative conclusions1 can be drawn from them4 ,a quantity of common air saturated with nitrous air was put to a quantity of acid air1 and they continued together all night1 without any sensible effect4 ,the quantity of both remained the same1 and water being admitted to them1 it absorbed all the acid air1 and left the other just as before4 ,a mixture of two thirds of air diminished by iron filings and brimstone1 and one third acid air1 were mixed together1 and left to stand four weeks in quicksilver4 ,but when the mixture was examined1 water presently imbibed all the acid air1 and the diminished air was found to be just the same that it was before4 ,i had imagined that the acid air might have united with the phlogiston with which the diminished air was overcharged1 so as to render it wholsome2 and ,i had read an account of the stench arising from putrid bodies being corrected by acid fumes4 ,the remaining experiments1 in which the acid air was principally concerned1 are of a miscellaneous nature4 ,i put a piece of dry ice to a quantity of acid air 7as was observed in the section concerning alkaline air7 taking it with a forceps1 which1 as well as the air itself1 and the quicksilver by which it had been confined2 had been exposed to the open air for an hour1 in a pretty strong frost4 ,the moment it touched the air it was dissolved as fast as it would have been by being thrown into a hot fire1 and the air was presently imbibed4 ,putting fresh pieces of ice to that which was dissolved before1 they were also dissolved immediately1 and the water thus procured did not freeze again1 though it was exposed a whole night1 in a very intense frost4 ,flies and spiders die in acid air1 but not so quickly as in nitrous air4 ,this surprized me very much2 as ,i had imagined that nothing could be more speedily fatal to all animal life than this pure acid vapour4 ,as inflammable air1 ,i have observed1 fires at one explosion in the vapour of smoking spirit of nitre1 just like an equal mixture of inflammable and common air1 ,i thought it was possible that the fume which naturally rises from common spirit of salt might have the same effect1 but it had not4 ,for this purpose ,i treated the spirit of salt1 as ,i had before done the smoking spirit of nitre2 first filling a phial with it1 then inverting it in a vessel containing a quantity of the same acid2 and having thrown the inflammable air into it1 and thereby driven out all the acid1 turning it with its mouth upwards1 and immediately applying a candle to it4 ,acid air not being so manageable as most of the other kinds of air1 ,i had recourse to the following peculiar method1 in order to ascertain its specific gravity4 ,having filled an eight ounce phial with this air1 and corked it up1 ,i weighed it very accurately2 and then1 taking out the cork1 ,i blew very strongly into it with a pair of bellows1 that the common air might take place of the acid2 and after this ,i weighed it again1 together with the cork1 but ,i could not perceive the least difference in the weight4 ,i conclude1 however1 from this experiment1 that the acid air is heavier than the common air1 because the mouth of the phial and the inside of it were evidently moistened by the water which the acid vapour had attracted from the air1 which moisture must have added to the weight of the phial4 ,,section ,v4 ,of ,,inflammable ,,air4 ,it will have appeared from my former experiments1 that inflammable air consists chiefly1 if not wholly1 of the union of an acid vapour with phlogiston2 that as much of the phlogiston as contributes to make air inflammable is imbibed by the water in which it is agitated2 that in this process it soon becomes fit for respiration1 and by the continuance of it comes at length to extinguish flame4 ,these observations1 and others which ,i have made upon this kind of air1 have been confirmed by my later experiments1 especially those in which ,i have connected electrical experiments with those on air4 ,the electric spark taken in any kind of oil produces inflammable air1 as ,i was led to observe in the following manner4 ,having found1 as will be mentioned hereafter1 that ether doubles the quantity of any kind of air to which it is admitted2 and being at that time engaged in a course of experiments to ascertain the effect of the electric matter on all the different kinds of air1 ,i had the curiosity to try what it would do with common air1 thus increased by means of ether4 ,the very first spark1 ,i observed1 increased the quantity of this air very considerably1 so that ,i had very soon six or eight times as much as ,i began with2 and whereas water imbibes all the ether that is put to any kind of air1 and leaves it without any visible change1 with respect to quantity or quality1 this air1 on the contrary1 was not imbibed by water4 ,it was also very little diminished by the mixture of nitrous air4 ,from whence it was evident1 that it had received an addition of some other kind of air1 of which it now principally consisted4 ,in order to determine whether this effect was produced by the wire1 or the cement by which the air was confined 7as ,i thought it possible that phlogiston might be discharged from them7 ,i made the experiment in a glass syphon1 fig4 #ai1 and by that means ,i contrived to make the electric spark pass from quicksilver through the air on which ,i made the experiment1 and the effect was the same as before4 ,at one time there happened to be a bubble of common air1 without any ether1 in one part of the syphon1 and another bubble with ether in another part of it2 and it was very amusing to observe how the same electric sparks diminished the former of these bubbles1 and increased the latter4 ,it being evident that the ether occasioned the difference that was observable in these two cases1 ,i next proceeded to take the electric spark in a quantity of ether only1 without any air whatever2 and observed that every spark produced a small bubble2 and though1 while the sparks were taken in the ether itself1 the generation of air was slow1 yet when so much air was collected1 that the sparks were obliged to pass through it1 in order1 to come to the ether and the quicksilver on which it rested1 the increase was exceedingly rapid2 so that1 making the experiment in small tubes1 as fig4 #af1 the quicksilver soon receded beyond the striking distance4 ,this air1 by passing through water1 was diminished to about one third1 and was inflammable4 ,one quantity of air produced in this manner from ether ,i suffered to stand two days in water1 and after that ,i transferred it several times through the water1 from one vessel to another1 and still found that it was very strongly inflammable2 so that ,i have no doubt of its being genuine inflammable air1 like that which is produced from metals by acids1 or by any other chemical process4 ,air produced from ether1 mixed both with common and nitrous air1 was likewise inflammable2 but in the case of the nitrous air1 the original quantity bore a very small proportion to the quantity generated4 ,concluding that the inflammable matter in this air came from the ether1 as being of the class of oils1 ,i tried other kinds of oil1 as oil of olives1 oil of turpentine1 and essential oil of mint1 taking the electric spark in them1 without any air to begin with1 and found that inflammable air was produced in this manner from them all4 ,the generation of air from oil of turpentine was the quickest1 and from the oil of olives the slowest in these three cases4 ,by the same process ,i got inflammable air from spirit of wine1 and about as copiously as from the essential oil of mint4 ,this air continued in water a whole night1 and when it was transferred into another vessel was strongly inflammable4 ,in all these cases the inflammable matter might be supposed to arise from the inflammable substances on which the experiments were made4 ,but finding that1 by the same process ,i could get inflammable air from the volatile spirit of sal ammoniac1 ,i conclude that the phlogiston was in part supplied by the electric matter itself4 ,for though1 as ,i have observed before1 the alkaline air which is expelled from the spirit of sal ammoniac be inflammable1 it is so in a very slight degree1 and can only be perceived to be so when there is a considerable quantity of it4 ,endeavouring to procure air from a caustic alkaline liquor1 accurately made for me by ,mr4 ,lane1 and also from spirit of salt1 ,i found that the electric spark could not be made visible in either of them2 so that they must be much more perfect conductors of electricity than water1 or other fluid substances4 ,this experiment well deserves to be prosecuted4 ,i observed before that inflammable air1 by standing long in water1 and especially by agitation in water1 loses its inflammability2 and that in the latter case1 after passing through a state in which it makes some approach to common air 7just admitting a candle to burn in it7 it comes to extinguish a candle4 ,i have since made another observation of this kind1 which well deserves to be recited4 ,it relates to the inflammable air generated from oak the #bgth of ,july #agga1 of which ,i have made mention before4 ,this air ,i have observed to have been but weakly inflammable some months after it was generated1 and to have been converted into pretty good or wholesome air by no great degree of agitation in water2 but on the #bgth of ,march #aggc1 ,i found the remainder of it to be exceedingly good air4 ,a candle burned in it perfectly well1 and it was diminished by nitrous air almost as much as common air4 ,i shall conclude this section with a few miscellaneous observations of no great importance4 ,inflammable air is not changed by being made to pass many times through a red-hot iron tube4 ,it is also no more diminished or changed by the fumes of liver of sulphur1 or by the electric spark1 than ,i have before observed it to have been by a mixture of iron filings and brimstone4 ,when the electric spark was taken in it1 it was confined by a quantity of water tinged blue with the juice of archil1 but the colour remained unchanged4 ,i put two wasps into inflammable air1 and let them remain there a considerable time1 one of them near an hour4 ,they presently ceased to move1 and seemed to be quite dead for about half an hour after they were taken into the open air2 but then they came to life again1 and presently after seemed to be as well as ever they had been4 ,,section ,,vi4 ,of ,,fixed ,,air4 ,the additions ,i have made to my observations on fixed air are neither numerous nor considerable4 ,the most important of them is a confirmation of my conjecture1 that fixed air is capable of forming an union with phlogiston1 and thereby becoming a kind of air that is not miscible with water4 ,i had produced this effect before by means of iron filings and brimstone1 fermenting in this kind of air2 but ,i have since had a much more decisive and elegant proof of it by electricity4 ,for after taking a small electric explosion1 for about an hour1 in the space of an inch of fixed air1 confined in a glass tube one tenth of an inch in diameter1 fig4 #af1 ,i found that when water was admitted to it1 only one fourth of the air was imbibed4 ,probably the whole of it would have been rendered immiscible in water1 if the electrical operation had been continued a sufficient time4 ,this air continued several days in water1 and was even agitated in water without any farther diminution4 ,it was not1 however1 common air1 for it was not diminished by nitrous air4 ,by means of iron filings and brimstone ,i have1 since my former experiments1 procured a considerable quantity of this kind of air in a method something different from that which ,i used before4 ,for having placed a pot of this mixture under a receiver1 and exhausted it with a pump of ,mr4 ,smeaton's construction1 ,i filled it with fixed air1 and then left it plunged under water2 so that no common air could have access to it4 ,in this manner1 and in about a week1 there was1 as near as ,i can recollect1 one sixth1 or at least one eighth of the whole converted into a permanent air1 not imbibed by water4 ,from this experiment ,i expected that the same effect would have been produced on fixed air by the fumes of liver of sulphur2 but ,i was disappointed in that expectation1 which surprised me not a little2 though this corresponds in some measure1 to the effect of phlogiston exhaled from this substance on acid air4 ,perhaps more time may be requisite for this purpose1 for this process was not continued more than a day and a night4 ,iron filings and brimstone1 ,i have observed1 ferment with great heat in nitrous air1 and ,i have since observed that this process is attended with greater heat in fixed air than in common air4 ,though fixed air incorporated with water dissolves iron1 fixed air without water has no such power1 as ,i observed before4 ,i imagined that1 if it could have dissolved iron1 the phlogiston would have united with the air1 and have made it immiscible with water1 as in the former instances2 but after being confined in a phial full of nails from the #aeth of ,december to the #dth of ,october following1 neither the iron nor the air appeared to have been affected by their mutual contact4 ,having exposed equal quantities of common and fixed air1 in equal and similar cylindrical glass vessels1 to equal degrees of heat1 by placing them before a fire1 and frequently changing their situations1 ,i observed that they were expanded exactly alike1 and when removed from the fire they both recovered their former dimensions4 ,having had some small suspicion that liver of sulphur1 besides emitting phlogiston1 might also yield some fixed air 7which is known to be contained in the salt of tartar from which it is made7 ,i mixed the two ingredients1 viz4 salt of tartar and brimstone1 and putting them into a thin phial1 and applying the flame of a candle to it1 so as to form the liver of sulphur1 ,i received the air that came from it in this process in a vessel of quicksilver4 ,in this manner ,i procured a very considerable quantity of fixed air1 so that ,i judged it was all discharged from the tartar4 ,but though it is possible that a small quantity of it may remain in liver of sulphur1 when it is made in the most perfect manner1 it is not probable that it can be expelled without heat4 ,,section ,,vii4 ,,miscellaneous ,,experiments4 #a4 ,it is something extraordinary that1 though ether1 as ,i found1 cannot be made to assume the form of air 7the vapour arising from it by heat1 being soon condensed by cold1 even in quicksilver7 yet that a very small quantity of ether put to any kind of air1 except the acid1 and alkaline1 which it imbibes1 almost instantly doubles the apparent quantity of it2 but upon passing this air through water1 it is presently reduced to its original quantity again1 with little or no change of quality4 ,i put about the quantity of half a nut-shell full of ether1 inclosed in a glass tube1 through a body of quicksilver1 into an ounce measure of common air1 confined by quicksilver2 upon which it presently began to expand1 till it occupied the space of two ounce measures4 ,it then gradually contracted about one sixth of an ounce measure4 ,putting more ether to it1 it again expanded to two ounce measures2 but no more addition of ether would make it expand any farther4 ,withdrawing the quicksilver1 and admitting water to this air1 without any agitation1 it began to be absorbed2 but only about half an ounce measure had disappeared after it had stood an hour in the water4 ,but by once passing it through water the air was reduced to its original dimensions4 ,being tried by a mixture of nitrous air1 it appeared not to be so good as fresh air1 though the injury it had received was not considerable4 ,all the phenomena of dilatation and contraction were nearly the same1 when1 instead of common air1 ,i used nitrous air1 fixed air1 inflammable air1 or any species of phlogisticated common air4 ,the quantity of each of these kinds of air was nearly doubled while they were kept in quicksilver1 but fixed air was not so much increased as the rest1 and phlogisticated air less2 but after passing through the water1 they appeared not to have been sensibly changed by the process4 #b4 ,spirit of wine yields no air by means of heat1 the vapours being soon condensed by cold1 like the vapour of water2 yet when1 in endeavouring to procure air from it1 ,i made it boil1 and catched the air which had rested on the surface of the spirit1 and which had been expelled by the heat together with the vapour1 in a vessel of quicksilver1 and afterwards admitted acid air to it1 the vessel was filled with white fumes1 as if there had been a mixture of alkaline air along with it4 ,to what this appearance was owing ,i cannot tell1 and indeed ,i did not examine into it4 #c4 ,having been informed by ,dr4 ,small and ,mr4 ,bolton of ,birmingham1 that paper dipped in a solution of copper in spirit of nitre would take fire with a moderate heat 7a fact which ,i afterwards found mentioned in the ,philosophical ,transactions7 it occurred to me that this would be very convenient for experiments relating to ignition in different kinds of air2 and indeed ,i found that it was easily fired1 either by a burning lens1 or the approach of red-hot iron on the outside of the phial in which it was contained1 and that any part of it being once fired1 the whole was presently reduced to ashes2 provided it was previously made thoroughly dry1 which1 however1 it is not very easy to do4 ,with this preparation1 ,i found that this paper burned freely in all kinds of air1 but not in vacuo1 which is also the case with gunpowder2 and1 as ,i have in effect observed before1 all the kinds of air in which this paper was burned received an addition to their bulk1 which consisted partly of nitrous air1 from the nitrous precipitate1 and partly of inflammable air1 from the paper4 ,as some of the circumstances attending the ignition of this paper in some of the kinds of air were a little remarkable1 ,i shall just recite them4 ,firing this paper in inflammable air1 which it did without any ignition of the inflammable air itself1 the quantity increased regularly1 till the phial in which the process was made was nearly full2 but then it began to decrease1 till one third of the whole quantity disappeared4 ,a piece of this paper being put to three ounce measures of acid air1 a great part of it presently turned yellow1 and the air was reduced to one third of the original quantity1 at the same time becoming reddish1 exactly like common air in a phial containing smoking spirit of nitre4 ,after this1 by the approach of hot iron1 ,i set fire to the paper2 immediately upon which there was a production of air which more than filled the phial4 ,this air appeared1 upon examination1 to be very little different from pure nitrous air4 ,i repeated this experiment with the same event4 ,paper dipped in a solution of mercury1 zinc1 or iron1 in nitrous acid1 has1 in a small degree1 the same property with paper dipped in a solution of copper in the same acid4 #d4 ,gunpowder is also fired in all kinds of air1 and1 in the quantity in which ,i tried it1 did not make any sensible change in them1 except that the common air in which it was fired would not afterwards admit a candle to burn in it4 ,in order to try this experiment ,i half exhausted a receiver1 and then with a burning-glass fired the gunpowder which had been previously put into it4 ,by this means ,i could fire a greater quantity of gunpowder in a small quantity of air1 and avoid the hazard of blowing up1 and breaking my receiver4 ,i own that ,i was rather afraid of firing gunpowder in inflammable air1 but there was no reason for my fear2 for it exploded quite freely in this air1 leaving it1 in all respects1 just as it was before4 ,in order to make this experiment1 and indeed almost all the experiments of firing gunpowder in different kinds of air1 ,i placed the powder upon a convenient stand within my receiver1 and having carefully exhausted it by a pump of ,mr4 ,smeaton's construction1 ,i filled the receiver with any kind of air by the apparatus described1 p4 #ai1 fig4 #ad1 taking the greatest care that the tubes1 c4 which conveyed the air should contain little or no common air4 ,in the experiment with inflammable air a considerable mixture of common air would have been exceedingly hazardous3 for1 by that assistance1 the inflammable air might have exploded in such a manner1 as to have been dangerous to the operator4 ,indeed1 ,i believe ,i should not have ventured to have made the experiment at all with any other pump besides ,mr4 ,smeaton's4 ,sometimes1 ,i filled a glass vessel with quicksilver1 and introduced the air to it1 when it was inverted in a bason of quicksilver4 ,by this means ,i intirely avoided any mixture of common air2 but then it was not easy to convey the gunpowder into it1 in the exact quantity that was requisite for my purpose4 ,this1 however1 was the only method by which ,i could contrive to fire gunpowder in acid or alkaline air1 in which it exploded just as it did in nitrous or fixed air4 ,i burned a considerable quantity of gunpowder in an exhausted receiver 7for it is well known that it will not explode in it7 but the air ,i got from it was very inconsiderable1 and in these circumstances was necessarily mixed with common air4 ,a candle would not burn in it4 ,,section ,,viii4 ,,queries1 ,,speculations1 and ,,hints4 ,i begin to be apprehensive lest1 after being considered as a dry experimenter1 ,i should pass1 with many of my readers1 into the opposite character of a visionary theorist4 ,a good deal of theory has been interspersed in the course of this work1 but1 not content with this1 ,i am now entering upon a long section1 which contains nothing else4 ,the conjectures that ,i have ventured to advance in the body of the work will1 ,i hope1 be found to be pretty well supported by facts2 but the present section will1 ,i acknowledge1 contain many random thoughts4 ,i have1 however1 thrown them together by themselves1 that readers of less imagination1 and who care not to advance beyond the regions of plain fact1 may1 if they please1 proceed no farther1 that their delicacy be not offended4 ,in extenuation of my offence1 let it1 however1 be considered1 that theory and experiment necessarily go hand in hand1 every process being intended to ascertain some particular hypothesis1 which1 in fact1 is only a conjecture concerning the circumstances or the cause of some natural operation2 consequently that the boldest and most original experimenters are those1 who1 giving free scope to their imaginations1 admit the combination of the most distant ideas2 and that though many of these associations of ideas1 will be wild and chimerical1 yet that others will have the chance of giving rise to the greatest and most capital discoveries2 such as very cautious1 timid1 sober1 and slow-thinking people would never have come at4 ,sir ,isaac ,newton himself1 notwithstanding the great advantage which he derived from a habit of patient thinking1 indulged bold and excentric thoughts1 of which his ,queries at the end of his book of ,optics are a sufficient evidence4 ,and a quick conception of distant analogies1 which is the great key to unlock the secret of nature1 is by no means incompatible with the spirit of perseverance1 in investigations calculated to ascertain and pursue those analogies4 #a4 ,speculations concerning the ,,constituent ,,principles of the different kinds of ,,air1 and the ,,constitution and ,,origin of the ,,atmosphere1 c4 ,all the kinds of air that appear to me to be essentially distinct from each other are fixed air1 acid and alkaline2 for these1 and another principle1 called phlogiston1 which ,i have not been able to exhibit in the form of air1 and which has never yet been exhibited by itself in any form1 seem to constitute all the kinds of air that ,i am acquainted with4 ,acid air and phlogiston constitute an air which either extinguishes flame1 or is itself inflammable1 according1 probably1 to the quantity of phlogiston combined in it1 or the mode of combination4 ,when it extinguishes flame1 it is probably so much charged with the phlogistic matter1 as to take no more from a burning candle1 which must1 therefore1 necessarily go out in it4 ,when it is inflammable1 it is probably so much charged with phlogiston1 that the heat communicated by a burning candle makes it immediately separate itself from the other principle with which it was united1 in which separation heat is produced1 as in other cases of ignition2 the action and reaction1 which necessarily attends the separation of the constituent principles1 exciting probably a vibratory motion in them4 ,since inflammable1 air1 by agitation in water1 first comes to lose its inflammability1 so as to be fit for respiration1 and even to admit a candle to burn in it1 and then comes to extinguish a candle2 it seems probable that water imbibes a great part of this extraordinary charge of phlogiston4 ,and that water can be impregnated with phlogiston1 is evident from many of my experiments1 especially those in which metals were calcined over it4 ,water having this affinity with phlogiston1 it is probable that it always contains a considerable portion of it2 which phlogiston having a stronger affinity with the acid air1 which is perhaps the basis of common air1 may by long agitation be communicated to it1 so as to leave it over saturated1 in consequence of which it will extinguish a candle4 ,it is possible1 however1 that inflammable air and air which extinguishes a candle may differ from one another in the mode of the combination of these two constituent principles1 as well as in the proportional quantity of each2 and by agitation in water1 or long standing1 that mode of combination may change4 ,this we know to be the case with other substances1 as with milk1 from which1 by standing only1 cream is separated2 which by agitation becomes butter4 ,also many substances1 being at rest1 putrefy1 and thereby become quite different from what they were before4 ,if this be the case with inflammable air1 the water may imbibe either of the constituent parts1 whenever any proportion of it is spontaneously separated from the rest2 and should this ever be that phlogiston1 with which air is but slightly overcharged1 as by the burning of a candle1 it will be recovered to a state in which a candle may burn in it again4 ,it will be observed1 however1 that it was only in one instance that ,i found that strong inflammable air1 in its transition to a state in which it extinguishes a candle1 would admit a candle to burn in it1 and that was very faintly2 that then the air was far from being pure1 as appeared by the test of nitrous air2 and that it was only from a particular quantity of inflammable air which ,i got from oak1 and which had stood a long time in water1 that ,i ever got air which was as pure as common air4 ,indeed1 it is much more easy to account for the passing of inflammable air into a state in which it extinguishes candles1 without any intermediate state1 in which it will admit a candle to burn in it1 than otherwise4 ,this subject requires and deserves farther investigation4 ,it will also be well worth while to examine what difference the agitation of air in natural or artificial sea-water will occasion4 ,since acid air and phlogiston make inflammable air1 and since inflammable air is convertible into air fit for respiration1 it seems not to be improbable1 that these two ingredients are the only essential principles of common air4 ,for this change is produced by agitation in water only1 without the addition of any fixed air1 though this kind of air1 like various other things of a foreign nature1 may be combined with it4 ,considering also what prodigious quantities of inflammable air are produced by the burning of small pieces of wood or pit-coal1 it may not be improbable but that the volcanos1 with which there are evident traces of almost the whole surface of the earth having been overspread1 may have been the origin of our atmosphere1 as well as 7according to the opinion of some7 of all the solid land4 ,the superfluous phlogiston of the air1 in the state in which it issues from volcanos1 may have been imbibed by the waters of the sea1 which it is probable originally covered the surface of the earth1 though part of it might have united with the acid vapour exhaled from the sea1 and by this union have made a considerable and valuable addition to the common mass of air2 and the remainder of this over-charge of phlogiston may have been imbibed by plants as soon as the earth was furnished with them4 ,that an acid vapour is really exhaled from the sea1 by the heat of the sun1 seems to be evident from the remarkably different states of the atmosphere1 in this respect1 in hot and cold climates4 ,in ,hudson's bay1 and also in ,russia1 it is said1 that metals hardly ever rust1 whereas they are remarkably liable to rust in ,barbadoes1 and other islands between the tropics4 ,see ,ellis's ,voyage1 p4 #bhh4 ,this is also the case in places abounding with salt-springs1 as ,nantwich in ,cheshire4 ,that mild air should consist of parts of so very different a nature as an acid vapour and phlogiston1 one of which is so exceedingly corrosive1 will not appear surprising to a chemist1 who considers the very strong affinity which these two principles are known to have with each other1 and the exceedingly different properties which substances composed by them possess4 ,this is exemplified in common sulphur1 which is as mild as air1 and may be taken into the stomach with the utmost safety1 though nothing can be more destructive than one of its constituent parts1 separately taken1 viz4 oil of vitriol4 ,common air1 therefore1 notwithstanding its mildness1 may be composed of similar principles1 and be a real sulphur4 ,that the fixed air which makes part of the atmosphere is not presently imbibed by the waters of the sea1 on which it rests1 may be owing to the union which this kind of air also appears to be capable of forming with phlogiston4 ,for fixed air is evidently of the nature of an acid2 and it appears1 in fact1 to be capable of being combined with phlogiston1 and thereby of constituting a species of air not liable to be imbibed by water4 ,phlogiston1 however1 having a stronger affinity with acid air1 which ,i suppose to be the basis of common air1 it is not surprising that1 uniting with this1 in preference to the fixed air1 the latter should be precipitated1 whenever a quantity of common air is made noxious by an over-charge of phlogiston4 ,the fixed air with which our atmosphere abounds may also be supplied by volcanos1 from the vast masses of calcareous matter lodged in the earth1 together with inflammable air4 ,also a part of it may be supplied from the fermentation of vegetables upon the surface of it4 ,at present1 as fast as it is precipitated and imbibed by one process1 it may be set loose by others4 ,whether there be1 upon1 the whole1 an increase or a decrease of the general mass of the atmosphere is not easy to conjecture1 but ,i should imagine that it rather increases4 ,it is true that many processes contribute to a great visible diminution of common air1 and that when by other processes it is restored to its former wholesomeness1 it is not increased in its dimensions2 but volcanos and fires still supply vast quantities of air1 though in a state not yet fit for respiration2 and it will have been seen in my experiments1 that vegetable and animal substances1 dissolved by putrefaction1 not only emit phlogiston1 but likewise yield a considerable quantity of permanent elastic air1 overloaded indeed with phlogiston1 as might be expected1 but capable of being purified by those processes in nature by which other noxious air is purified4 ,that particles are continually detaching themselves from the surfaces of all solid bodies1 even the metallic ones1 and that these particles constitute the most permanent part of the atmosphere1 as ,sir ,isaac ,newton supposed1 does not appear to me to be at all probable4 ,my readers will have observed1 that not only is common air liable to be diminished by a mixture of nitrous air1 but likewise air originally produced from inflammable air1 and even from nitrous air itself1 which never contained any fixed air4 ,from this it may be inferred1 that the whole of the diminution of common air by phlogiston is not owing to the precipitation of fixed air1 but from a real contraction of its dimensions1 in consequence of its union with phlogiston4 ,perhaps an accurate attention to the specific gravity of air procured from these different materials1 and in these different states1 may determine this matter1 and assist us in investigating the nature of phlogiston4 ,in what manner air is diminished by phlogiston1 independent of the precipitation of any of its constituent parts1 is not easy to conceive2 unless air thus diminished be heavier than air not diminished1 which ,i did not find to be the case4 ,it deserves1 however1 to be tried with more attention4 ,that phlogiston should communicate absolute levity to the bodies with which it is combined1 is a supposition that ,i am not willing to have recourse to1 though it would afford an easy solution of this difficulty4 ,i have likewise observed1 that a mouse will live almost as long in inflammable air1 when it has been agitated in water1 and even before it has been deprived of all its inflammability1 as in common air2 and yet that in this state it is not1 perhaps1 so much diminished by nitrous air as common air is4 ,in this case1 therefore1 the diminution seems to have been occasioned by a contraction of dimensions1 and not by a loss of any constituent part2 so that the air is really better1 that is1 more fit for respiration1 than1 by the test of nitrous air1 it would seem to be4 ,if this be the case 7for it is not easy to judge with accuracy by experiments with small animals7 nitrous air will be an accurate test of the goodness of common air only1 that is1 air containing a considerable proportion of fixed air4 ,but this is the most valuable purpose for which a test of the goodness of air can be wanted4 ,it will still1 indeed1 serve for a measure of the goodness of air that does not contain fixed air2 but1 a smaller degree of diminution in this case1 must be admitted to be equivalent to a greater diminution in the other4 ,as ,i could never1 by means of growing vegetables1 bring air which had been thoroughly noxious to so pure a state as that a candle would burn in it1 it may be suspected that something else besides vegetation is necessary to produce this effect4 ,but it should be considered1 that no part of the common atmosphere can ever be in this highly noxious state1 or indeed in a state in which a candle will not burn in it2 but that even air reduced to this state1 either by candles actually burning out in it1 or by breathing it1 has never failed to be perfectly restored by vegetation1 at least so far that candles would burn in it again1 and1 to all appearance1 as well1 and as long as ever2 so that the growing vegetables1 with which the surface of the earth is overspread1 may1 for any thing that appears to the contrary1 be a cause of the purification of the atmosphere sufficiently adequate to the effect4 ,it may likewise be suspected1 that since agitation in water injures pure common air1 the agitation of the sea may do more harm than good in this respect4 ,but it requires a much more violent and longer continued agitation of air in water than is ever occasioned by the waves of the sea to do the least sensible injury to it4 ,indeed a light agitation of air in putrid water injures it very materially2 but if the water be sweet1 this effect is not produced1 except by a long and tedious operation1 whereas it requires but a very short time1 in comparison1 to restore a quantity of any of the most noxious kinds of air to a very great degree of wholesomeness by the same process4 ,dr4 ,hales found that he could breathe the same air much longer when1 in the course of his respiration1 it was made to pass through several folds of cloth dipped in vinegar1 in a solution of sea-salt1 or in salt of tartar1 especially the last4 ,statical ,essays1 vol4 #a4 p4 #bff4 ,the experiment is valuable1 and well deserves to be repeated with a greater variety of circumstances4 ,i imagine that the effect was produced by those substances1 or by the water which they attracted from the air1 imbibing the phlogistic matter discharged from the lungs4 ,perhaps the phlogiston may unite with the watery part of the atmosphere1 in preference to any other part of it1 and may by that means be more easily transferred to such salts as imbibe moisture4 ,sir ,isaac ,newton defines flame to be fumus candens1 considering all smoke as being of the same nature1 and capable of ignition4 ,but the smoke of common fuel consists of two very different things4 ,that which rises first is mere water1 loaded with some of the grosser parts of the fuel1 and is hardly more capable of becoming red hot than water itself2 but the other kind of smoke1 which alone is capable of ignition1 is properly inflammable air1 which is also loaded with other heterogeneous matter1 so as to appear like a very dense smoke4 ,a lighted candle soon shews them to be essentially different from each other4 ,for one of them instantly takes fire1 whereas the other extinguishes a candle4 ,it is remarkable that gunpowder will take fire1 and explode in all kinds of air1 without distinction1 and that other substances which contain nitre will burn freely in those circumstances4 ,now since nothing can burn1 unless there be something at hand to receive the phlogiston1 which is set loose in the act of ignition1 ,i do not see how this fact can be accounted for1 but by supposing that the acid of nitre1 being peculiarly formed to unite with phlogiston1 immediately receives it4 ,and if the sulphur1 which is thereby formed1 be instantly decomposed again1 as the chemists in general say1 thence comes the explosion of gunpowder1 which1 however1 requires the reaction of some incumbent atmosphere1 and without which the materials will only melt1 and be dispersed without explosion4 ,nitrous air seems to consist of the nitrous acid vapour united to phlogiston1 together1 perhaps1 with some small portion of the metallic calx2 just as inflammable air consists of the vitriolic or marine acid1 and the same phlogistic principle4 ,it should seem1 however1 that phlogiston has a stronger affinity with the marine acid1 if that be the basis of common air2 for nitrous air being admitted to common air1 it is immediately decomposed2 probably by the phlogiston joining with the acid principle of the common air1 while the fixed air which it contained is precipitated1 and the acid of the nitrous air is absorbed by the water in which the mixture is made1 or unites with any volatile alkali that happens to be at hand4 ,this1 indeed1 is hardly agreeable to the hypothesis of most chemists1 who suppose that the nitrous acid is stronger than the marine1 so as to be capable of dislodging it from any base with which it may be combined2 but it agrees with my own experiments on marine acid air1 which shew that1 in many cases1 this weaker acid1 as it is called1 is capable of separating both the vitriolic and the nitrous acids from the phlogiston with which they are combined4 ,on the other hand1 the solution of metals in the different acids seems to shew1 that the nitrous acid forms a closer union with phlogiston than the other two2 because the air which is formed by the nitrous acid is not inflammable1 like that which is produced by the oil of vitriol1 or the spirit of salt4 ,also1 the same weight of iron does not yield half the quantity of nitrous air that it does of inflammable4 ,the great diminution of nitrous air by phlogiston is not easily accounted for1 unless we suppose that its superabundant acid1 uniting more intimately with the phlogiston1 constitutes a species of sulphur that is not easily perceived or catched2 though1 in the process with iron1 and also in that with liver of sulphur1 part of the redundant phlogiston forms such an union with the acid as gives it a kind of inflammability4 ,it appears to me to be very probable1 that the spirit of nitre might be exhibited in the form of air1 if it were possible to find any fluid by which it could be confined2 but it unites with quicksilver as well as with water1 so that when1 by boiling the spirit of nitre1 the fumes are driven through the glass tube1 fig4 #h1 they instantly seize upon the quicksilver through which they are to be conveyed1 and uniting with it1 form a substance that stops up the tube3 a circumstance which has more than once exposed me to very disagreeable accidents1 in consequence of the bursting of the phials4 ,i do not know any inquiry more promising than the investigation of the properties of nitre1 the nitrous acid1 and nitrous air4 ,some of the most wonderful phenomena in nature are connected with them1 and the subject seems to be fully within our reach4 #b4 ,speculations arising from the consideration of the similarity of the ,,electric ,,matter and ,,phlogiston4 ,there is nothing in the history of philosophy more striking than the rapid progress of electricity4 ,nothing ever appeared more trifling than the first effects which were observed of this agent in nature1 as the attraction and repulsion of straws1 and other light substances4 ,it excited more attention by the flashes of light which it exhibited4 ,we were more seriously alarmed at the electrical shock1 and the effects of the electrical battery2 and we were astonished to the highest degree by the discovery of the similarity of electricity with lightning1 and the aurora borealis1 with the connexion it seems to have with water-spouts1 hurricanes1 and earthquakes1 and also with the part that is probably assigned to it in the system of vegetation1 and other the most important processes in nature4 ,yet1 notwithstanding all this1 we have been1 within a few years1 more puzzled than ever with the electricity of the torpedo1 and of the anguille temblante of ,surinam1 especially since that most curious discovery of ,mr4 ,walsh's1 that the former of these wonderful fishes has the power of giving a proper electrical shock2 the electrical matter which proceeds from it performing a real circuit from one part of the animal to the other2 while both the fish which performs this experiment and all its apparatus are plunged in water1 which is known to be a conducting substance4 ,perhaps1 however1 by considering this fact in connexion with a few others1 and especially with what ,i have lately observed concerning the identity of electricity and phlogiston1 a little light may be thrown upon this subject1 in consequence of which we may be led to consider electricity in a still more important light4 ,many of my readers1 ,i am aware1 will smile at what ,i am going to advance2 but the apprehension of this shall not interrupt my speculations1 how chimerical soever they may be thought to be4 ,the facts1 the consideration of which ,i would combine with that of the electricity of the torpedo1 are the following4 ,first1 ,the remarkable electricity of the feathers of a paroquet1 observed by ,mr4 ,hartmann1 an account of which may be seen in ,mr4 ,rozier's ,journal for ,sept4 #agga4 p4 #fi4 ,this bird never drinks1 but often washes itself2 but the person who attended it having neglected to supply it with water for this purpose1 its feathers appeared to be endued with a proper electrical virtue1 repelling one another1 and retaining their electricity a long time after they were plucked from the body of the bird1 just as they would have done if they had received electricity from an excited glass tube4 ,secondly1 ,the electric matter directed through the body of any muscle forces it to contract4 ,this is known to all persons who attend to what is called the electrical shock2 which certainly occasions a proper convulsion1 but has been more fully illustrated by ,father ,beccaria4 ,see my ,history of ,electricity1 p4 #djb4 ,lastly1 ,let it be considered that the proper nourishment of an animal body1 from which the source and materials of all muscular motion must be derived1 is probably some modification of phlogiston4 ,nothing will nourish that does not contain phlogiston1 and probably in such a state as to be easily separated from it by the animal functions4 ,that the source of muscular motion is phlogiston is still more probable1 from the consideration of the well known effects of vinous and spirituous liquors1 which consist very much of phlogiston1 and which instantly brace and strengthen the whole nervous and muscular system2 the phlogiston in this case being1 perhaps1 more easily extricated1 and by a less tedious animal process1 than in the usual method of extracting it from mild aliments4 ,since1 however1 the mildest aliments do the same thing more slowly and permanently1 that spirituous liquors do suddenly and transiently1 it seems probable that their operation is ultimately the same4 ,this conjecture is likewise favoured by my observation1 that respiration and putrefaction affect common air in the same manner1 and in the same manner in which all other processes diminish air and make it noxious1 and which agree in nothing but the emission of phlogiston4 ,if this be the case1 it should seem that the phlogiston which we take in with our aliment1 after having discharged its proper function in the animal system 7by which it probably undergoes some unknown alteration7 is discharged as effete by the lungs into the great common menstruum1 the atmosphere4 ,my conjecture suggested 7whether supported or not7 by these facts1 is1 that animals have a power of converting phlogiston1 from the state in which they receive it in their nutriment1 into that state in which it is called the electrical fluid2 that the brain1 besides its other proper uses1 is the great laboratory and repository for this purpose2 that by means of the nerves this great principle1 thus exalted1 is directed into the muscles1 and forces them to act1 in the same manner as they are forced into action when the electric fluid is thrown into them ab extra4 ,i farther suppose1 that the generality of animals have no power of throwing this generated electricity any farther than the limits of their own system2 but that the torpedo1 and animals of a similar construction1 have likewise the power1 by means of an additional apparatus1 of throwing it farther1 so as to affect other animals1 and other substances at a distance from them4 ,in this case1 it should seem that the electric matter discharged from the animal system 7by which it is probably more exhausted and fatigued than by ordinary muscular motion7 would never return to it1 at least so as to be capable of being made use of a second time1 and yet if the structure of these animals be such as that the electric matter shall dart from one part of them only1 while another part is left suddenly deprived of it1 it may make a circuit1 as in the ,leyden phial4 ,as to the manner in which the electric matter makes a muscle contract1 ,i do not pretend to have any conjecture worth mentioning4 ,i only imagine that whatever can make the muscular fibres recede from one another farther than the parts of which they consist1 must have this effect4 ,possibly1 the light which is said to proceed from some animals1 as from cats and wild beasts1 when they are in pursuit of their prey in the night1 may not only arise1 as it has hitherto been supposed to do1 from the friction of their hairs or bristles1 c4 but that violent muscular exertion may contribute to it4 ,this may assist them occasionally to catch their prey2 as glow-worms1 and other insects1 are provided with a constant light for that purpose1 to the supply of which light their nutriment may also contribute4 ,i would not even say that the light which is said to have proceeded from some human bodies1 of a particular temperament1 and especially on some extraordinary occasions1 may not have been of the electrical kind1 that is1 produced independently of friction1 or with less friction than would have produced it in other persons2 as in those cases related by ,bartholin in his treatice ,de luce animalium4 ,see particularly what he says concerning ,theodore king of the ,goths1 p4 #ed1 concerning ,gonzaga duke of ,mantua1 p4 #eg1 and ,gothofred ,antonius1 p4 #abc3 ,but ,i would not have my readers suppose that ,i lay much stress upon stories no better authenticated than these4 ,the electric matter in passing through non-conducting substances always emits light4 ,this light ,i have been sometimes inclined to suspect might have been supplied from the substance through which it passes4 ,but ,i find that after the electric spark has diminished a quantity of air as much as it possibly can1 so that it has no more visible effect upon it1 the electric light in that air is not at all lessened4 ,it is probable1 therefore1 that electric light comes from the electric matter itself2 and this being a modification of phlogiston1 it is probable that all light is a modification of phlogiston also4 ,indeed1 since no other substances besides such as contain phlogiston are capable of ignition1 and consequently of becoming luminous1 it was on this account pretty evident1 prior to these deductions from electrical phenomena1 that light and phlogiston are the same thing1 in different forms or states4 ,it appears to me that heat has no more proper connexion with phlogiston than it has with water1 or any other constituent part of bodies2 but that it is a state into which the parts of bodies are thrown by their action and reaction with respect to one another2 and probably 7as the ,english philosophers in general have supposed7 the heated state of bodies may consist of a subtle vibratory motion of their parts4 ,since the particles which constitute light are thrown from luminous bodies with such amazing velocity1 it is evident that1 whatever be the cause of such a projection1 the reaction consequent upon it must be considerable4 ,this may be sufficient not only to keep up1 but also to increase the vibration of the parts of those bodies in which the phlogiston is not very firmly combined2 and the difference between the substances which are called inflammable and others which also contain phlogiston may be this1 that in the former the heat1 or the vibration occasioned by the emission of their own phlogiston1 may be sufficient to occasion the emission of more1 till the whole be exhausted2 that is1 till the body be reduced to ashes4 ,whereas in bodies which are not inflammable1 the heat occasioned by the emission of their own phlogiston may not be sufficient for this purpose1 but an additional heat ab extra may be necessary4 ,some philosophers dislike the term phlogiston2 but1 for my part1 ,i can see no objection to giving that1 or any other name1 to a real something1 the presence or absence of which makes so remarkable difference in bodies1 as that of metallic calces and metals1 oil of vitriol and brimstone1 c4 and which may be transferred from one substance to another1 according to certain known laws1 that is1 in certain definite circumstances4 ,it is certainly hard to conceive how any thing that answers this description can be only a mere quality1 or mode of bodies1 and not substance itself1 though incapable of being exhibited alone4 ,at least1 there can be no harm in giving this name to any thing1 or any circumstance that is capable of producing these effects4 ,if it should hereafter appear not to be a substance1 we may change our phraseology1 if we think proper4 ,on the other hand ,i dislike the use of the term fire1 as a constituent principle of natural bodies1 because1 in consequence of the use that has generally been made of that term1 it includes another thing or circumstance1 viz4 heat1 and thereby becomes ambiguous1 and is in danger of misleading us4 ,when ,i use the term phlogiston1 as a principle in the constitution of bodies1 ,i cannot mislead myself or others1 because ,i use one and the same term to denote only one and the same unknown cause of certain well-known effects4 ,but if ,i say that fire is a principle in the constitution of bodies1 ,i must1 at least1 embarrass myself with the distinction of fire in a state of action1 and fire inactive1 or quiescent4 ,besides ,i think the term phlogiston preferable to that of fire1 because it is not in common use1 but confined to philosophy2 so that the use of it may be more accurately ascertained4 ,besides1 if phlogiston and the electric matter be the same thing1 though it cannot be exhibited alone1 in a quiescent state1 it may be exhibited alone under one of its modifications1 when it is in motion4 ,and if light be also phlogiston1 or some modification or subdivision of phlogiston1 the same thing is capable of being exhibited alone in this other form also4 ,in my paper on the conducting power of charcoal1 7,see ,philosophical ,transactions1 vol4 #fj4 p4 #bba7 ,i observed that there is a remarkable resemblance between metals and charcoal2 as in both these substances there is an intimate union of phlogiston with an earthy base2 and ,i said that1 had there been any phlogiston in water1 ,i should have concluded1 that there had been no conducting power in nature1 but in consequence of an union of this principle with some base2 for while metals have phlogiston they conduct electricity1 but when they are deprived of it they conduct no longer4 ,now the affinity which ,i have observed between phlogiston and water leads me to conclude that water1 in its natural state1 does contain some portion of phlogiston2 and according to the hypothesis just now mentioned they must be intimately united1 because water is not inflammable4 ,i think1 therefore1 that after this state of hesitation and suspence1 ,i may venture to lay it down as a characteristic distinction between conducting and non-conducting substances1 that the former contain phlogiston intimately united with some base1 and that the latter1 if they contain phlogiston at all1 retain it more loosely4 ,in what manner this circumstance facilitates the passing of the electric matter through one substance1 and obstructs its passage through another1 ,i do not pretend to say4 ,but it is no inconsiderable thing to have advanced but one step nearer to an explanation of so very capital a distinction of natural bodies1 as that into conductors and non-conductors of electricity4 ,i beg leave to mention in this place1 as favourable to this hypothesis1 a most curious discovery made very lately by ,mr4 ,walsh1 who being assisted by ,mr4 ,de ,luc to make a more perfect vacuum in the double or arched barometer1 by boiling the quicksilver in the tube1 found that the electric spark or shock would no more pass through it1 than through a stick of solid glass4 ,he has also noted several circumstances that affect this vacuum in a very extraordinary manner4 ,but supposing that vacuum to be perfect1 ,i do not see how we can avoid inferring from the fact1 that some substance is necessary to conduct electricity2 and that it is not capable1 by its own expansive power1 of extending itself into spaces void of all matter1 as has generally been supposed1 on the idea of there being nothing to obstruct its passage4 ,indeed if this was the case1 ,i do not see how the electric matter could be retained within the body of the earth1 or any of the planets1 or solid orbs of any kind4 ,in nature we see it make the most splendid appearance in the upper and thinner regions of the atmosphere1 just as it does in a glass tube nearly exhausted2 but if it could expand itself beyond that degree of rarity1 it would necessarily be diffused into the surrounding vacuum1 and continue and be condensed there1 at least in a greater proportion than in or near any solid body1 as ,newton supposed concerning his ether4 ,if that mode of vibration which constitutes heat be the means of converting phlogiston from that state in which it makes a part of solid bodies1 and eminently contributes to the firmness of their texture into that state in which it diminishes common air2 may not that peculiar kind of vibration by which ,dr4 ,hartley supposes the brain to be affected1 and by which he endeavours to explain all the phenomena of sensation1 ideas1 and muscular motion1 be the means by which the phlogiston1 which is conveyed into the system by nutriment1 is converted into that form or modification of it of which the electric fluid consists4 ,these two states of phlogiston may be conceived to resemble1 in some measure1 the two states of fixed air1 viz4 elastic1 or non-elastic2 a solid1 or a fluid4 ,,the ,,appendix4 ,in this ,appendix ,i shall present the reader with the communications of several of my friends on the subject of the preceding work4 ,among them ,i should with pleasure have inserted some curious experiments1 made by ,dr4 ,hulme of ,halifax1 on the air extracted from ,buxton water1 and on the impregnation of several fluids1 with different kinds of air2 but that he informs me he proposes to make a separate publication on the subject4 ,,number ,i4 ,,experiments made by ,mr4 ,hey to prove that there is no ,,oil of ,,vitriol in water impregnated with ,,fixed ,,air4 ,it having been suggested1 that air arising from a fermenting mixture of chalk and oil of vitriol might carry up with it a small portion of the vitriolic acid1 rendered volatile by the act of fermentation2 ,i made the following experiments1 in order to discover whether the acidulous taste1 which water impregnated with such air affords1 was owing to the presence of any acid1 or only to the fixed air it had absorbed4 ,,experiment ,i4 ,i mixed a tea-spoonful of syrup of violets with an ounce of distilled water1 saturated with fixed air procured from chalk by means of the vitriolic acid2 but neither upon the first mixture1 nor after standing #bd hours1 was the colour of the syrup at all changed1 except by its simple dilution4 ,,experiment ,,ii4 ,a portion of the same distilled water1 unimpregnated with fixed air1 was mixed with the syrup in the same proportion3 not the least difference in colour could be perceived betwixt this and the above-mentioned mixture4 ,,experiment ,,iii4 ,one drop of oil of vitriol being mixed with a pint of the same distilled water1 an ounce of this water was mixed with a tea-spoonful of the syrup4 ,this mixture was very distinguishable in colour from the two former1 having a purplish cast1 which the others wanted4 ,,experiment ,,iv4 ,the distilled water impregnated with so small a quantity of vitriolic acid1 having a more agreeable taste than when alone1 and yet manifesting the presence of an acid by means of the syrup of violets2 ,i subjected it to some other tests of acidity4 ,it formed curds when agitated with soap1 lathered with difficulty1 and very imperfectly2 but not the least ebullition could be discovered upon dropping in spirit of sal ammoniac1 or solution of salt of tartar1 though ,i had taken care to render the latter free from causticity by impregnating it with fixed air4 ,,experiment ,v4 ,the distilled water saturated with fixed air neither effervesced1 nor shewed any clouds1 when mixed with the fixed or volatile alkali4 ,,experiment ,,vi4 ,no curd was formed by pouring this water upon an equal quantity of milk1 and boiling them together4 ,,experiment ,,vii4 ,when agitated with soap1 this water produced curds1 and lathered with some difficulty2 but not so much as the distilled water mixed with vitriolic acid in the very small proportion above-mentioned4 ,the same distilled water without any impregnation of fixed air lathered with soap without the least previous curdling4 ,river-water1 and a pleasant pump-water not remarkably hard1 were compared with these4 ,the former produced curds before it lathered1 but not quite in so great a quantity as the distilled water impregnated with fixed air3 the latter caused a stronger curd than any of the others above-mentioned4 ,,experiment ,,viii4 ,apprehending that the fixed air in the distilled water occasioned the coagulation1 or separation of the oily part of the soap1 only by destroying the causticity of the lixivium1 and thereby rendering the union less perfect betwixt that and the tallow1 and not by the presence of any acid2 ,i impregnated a fresh quantity of the same distilled water with fixed air1 which had passed through half a yard of a wide barometer-tube filled with salt of tartar2 but this water caused the same curdling with soap as the former had done1 and appeared in every respect to be exactly the same4 ,,experiment ,,ix4 ,distilled water saturated with fixed air formed a white cloud and precipitation1 upon being mixed with a solution of saccharum saturni4 ,i found likewise1 that fixed air1 after passing through the tube filled with alkaline salt1 upon being let into a phial containing a solution of the metalic salt in distilled water1 caused a perfect separation of the lead1 in the form of a white powder2 for the water1 after this precipitation1 shewed no cloudiness upon a fresh mixture of the substances which had before rendered it opaque4 ,,number ,,ii4 ,a ,letter from ,mr4 ,,hey to ,dr4 ,,priestley1 concerning the ,effects of fixed ,air applied by way of ,clyster4 ,leeds1 ,feb4 #aeth1 #aggb4 ,reverend ,sir1 ,having lately experienced the good effects of fixed air in a putrid fever1 applied in a manner1 ,i believe not heretofore made use of1 ,i thought it proper to inform you of the agreeable event1 as the method of applying this powerful corrector of putrefaction took its rise principally from your observations and experiments on factitious air2 and now1 at your request1 ,i send the particulars of the case ,i mentioned to you1 as far as concerns the administration of this remedy4 ,january #h1 #aggb1 ,mr4 ,lightbowne1 a young gentleman who lives with me1 was seized with a fever1 which1 after continuing about ten days1 began to be attended with those symptoms that indicate a putrescent state of the fluids4 #ahth1 ,his tongue was black in the morning when ,i first visited him1 but the blackness went off in the day-time upon drinking3 ,he had begun to doze much the preceding day1 and now he took little notice of those that were about him3 ,his belly was loose1 and had been so for some days3 his pulse beat #aaj strokes in a minute1 and was rather low3 he was ordered to take twenty-five grains of ,peruvian bark with five of tormentil-root in powder every four hours1 and to use red wine and water cold as his common drink4 #aith1 ,i was called to visit him early in the morning1 on account of a bleeding at the nose which had come on3 he lost about eight ounces of blood1 which was of a loose texture3 the hmorrhage was suppressed1 though not without some difficulty1 by means of tents made of soft lint1 dipped in cold water strongly impregnated with tincture of iron1 which were introduced within the nostrils quite through to their posterior apertures2 a method which has never yet failed me in like cases4 ,his tongue was now covered with a thick black pellicle1 which was not diminished by drinking3 his teeth were furred with the same kind of sordid matter1 and even the roof of his mouth and sauces were not free from it3 his looseness and stupor continued1 and he was almost incessantly muttering to himself3 he took this day a scruple of the ,peruvian bark with ten grains of tormentil every two or three hours3 a starch clyster1 containing a drachm of the compound powder of bole1 without opium1 was given morning and evening3 a window was set open in his room1 though it was a severe frost1 and the floor was frequently sprinkled with vinegar4 #bjth1 ,he continued nearly in the same state3 when roused from his dozing1 he generally gave a sensible answer to the questions asked him2 but he immediately relapsed1 and repeated his muttering4 ,his skin was dry1 and harsh1 but without petechi4 ,he sometimes voided his urine and fces into the bed1 but generally had sense enough to ask for the bed-pan3 as he now nauseated the bark in substance1 it was exchanged for ,huxham's tincture1 of which he took a table spoonful every two hours in a cup full of cold water3 he drank sometimes a little of the tincture of roses1 but his common liquors were red wine and water1 or rice-water and brandy acidulated with elixir of vitriol3 before drinking1 he was commonly requested to rinse his mouth with water to which a little honey and vinegar had been added4 ,his looseness rather increased1 and the stools were watery1 black1 and foetid3 ,it was judged necessary to moderate this discharge1 which seemed to sink him1 by mixing a drachm of the theriaca ,andromachi with each clyster4 #bast4 ,the same putrid symptoms remained1 and a subsultus tendinum came on3 his stools were more foetid2 and so hot1 that the nurse assured me she could not apply her hand to the bed-pan1 immediately after they were discharged1 without feeling pain on this account3 ,the medicine and clysters were repeated4 ,reflecting upon the disagreeable necessity we seemed to lie under of confining this putrid matter in the intestines1 lest the evacuation should destroy the vis vit before there was time to correct its bad quality1 and overcome its bad effects1 by the means we were using2 ,i considered1 that1 if this putrid ferment could be more immediately corrected1 a stop would probably be put to the flux1 which seemed to arise from1 or at least to be encreased by it2 and the fomes of the disease would likewise be in a great measure removed4 ,i thought nothing was so likely to effect this1 as the introduction of fixed air into the alimentary canal1 which1 from the experiments of ,dr4 ,macbride1 and those you have made since his publication1 appears to be the most powerful corrector of putrefaction hitherto known4 ,i recollected what you had recommended to me as deserving to be tried in putrid diseases1 ,i mean1 the injection of this kind of air by way of clyster1 and judged that in the present case such a method was clearly indicated4 ,the next morning ,i mentioned my reflections to ,dr4 ,hird and ,dr4 ,crowther1 who kindly attended this young gentleman at my request1 and proposed the following method of treatment1 which1 with their approbation1 was immediately entered upon4 ,we first gave him five grains of ipecacuanha1 to evacuate in the most easy manner part of the putrid colluvies3 he was then allowed to drink freely of brisk orange-wine1 which contained a good deal of fixed air1 yet had not lost its sweetness4 ,the tincture of bark was continued as before2 and the water which he drank along with it1 was impregnated with fixed air from the atmosphere of a large vat of fermenting wort1 in the manner ,i had learned from you4 ,instead of the astringent clyster1 air alone was injected1 collected from a fermenting mixture of chalk and oil of vitriol3 he drank a bottle of orange-wine in the course of this day1 but refused any other liquor except water and his medicine3 two bladders full of air were thrown up in the afternoon4 #bc;d4 ,his stools were less frequent2 their heat likewise and peculiar foetor were considerably diminished2 his muttering was much abated1 and the subsultus tendinum had left him4 ,finding that part of the air was rejected when given with a bladder in the usual way1 ,i contrived a method of injecting it which was not so liable to this inconvenience4 ,i took the flexible tube of that instrument which is used for throwing up the fume of tobacco1 and tied a small bladder to the end of it that is connected with the box made for receiving the tobacco1 which ,i had previously taken off from the tube3 ,i then put some bits of chalk into a six ounce phial until it was half filled2 upon these ,i poured such a quantity of oil of vitriol as ,i thought capable of saturating the chalk1 and immediately tied the bladder1 which ,i had fixed to the tube1 round the neck of the phial3 the clyster-pipe1 which was fastened to the other end of the tube1 was introduced into the anus before the oil of vitriol was poured upon the chalk4 ,by this method the air passed gradually into the intestines as it was generated2 the rejection of it was in a great measure prevented2 and the inconvenience of keeping the patient uncovered during the operation was avoided4 #bdth1 ,he was so much better1 that there seemed to be no necessity for repeating the clysters3 the other means were continued4 ,the window of his room was now kept shut4 #beth1 ,all the symptoms of putrescency had left him2 his tongue and teeth were clean2 there remained no unnatural blackness or foetor in his stool1 which had now regained their proper consistence2 his dozing and muttering were gone off2 and the disagreeable odour of his breath and perspiration was no longer perceived4 ,he took nourishment to-day1 with pleasure2 and1 in the afternoon1 sat up an hour in his chair4 ,his fever1 however1 did not immediately leave him2 but this we attributed to his having caught cold from being incautiously uncovered1 when the window was open1 and the weather extremely severe2 for a cough1 which had troubled him in some degree from the beginning1 increased1 and he became likewise very hoarse for several days1 his pulse1 at the same time1 growing quicker3 but these complaints also went off1 and he recovered1 without any return of the bad symptoms above-mentioned4 ,i am1 ,reverend ,sir1 ,your obliged humble ,servant1 ,,wm4 ,,hey4 ,,postscript ,october #bi1 #aggb4 ,fevers of the putrid kind have been so rare in this town1 and in its neighbourhood1 since the commencement of the present year1 that ,i have not had an opportunity of trying again the effects of fixed air1 given by way of clyster1 in any case exactly similar to ,mr4 ,lightbowne's4 ,i have twice given water saturated with fixed air in a fever of the putrescent kind1 and it agreed very well with the patients4 ,to one of them the arial clysters were administred1 on account of a looseness1 which attended the fever1 though the stools were not black1 nor remarkably hot or foetid4 ,these clysters did not remove the looseness1 though there was often a greater interval than usual betwixt the evacuations1 after the injection of them4 ,the patient never complained of any uneasy distention of the belly from the air thrown up1 which1 indeed1 is not to be wondered at1 considering how readily this kind of air is absorbed by aqueous and other fluids1 for which sufficient time was given1 by the gradual manner of injecting it4 ,both those patients recovered though the use of fixed air did not produce a crisis before the period at which such fevers usually terminate4 ,they had neither of them the opportunity of drinking such wine as ,mr4 ,lightbowne took1 after the use of fixed air was entered upon2 and this1 probably1 was some disadvantage to them4 ,i find the methods of procuring fixed air1 and impregnating water with it1 which you have published1 are preferable to those ,i made use of in ,mr4 ,lightbowne's case4 ,the flexible tube used for conveying the fume of tobacco into the intestines1 ,i find to be a very convenient instrument in this case1 by the method before-mentioned 7only adding water to the chalk1 before the oil of vitriol is instilled1 as you direct7 the injection of air may be continued at pleasure1 without any other inconvenience to the patient1 than what may arise from his continuing in one position during the operation1 which scarcely deserves to be mentioned1 or from the continuance of the clyster-pipe within the anus1 which is but trifling1 if it be not shaken much1 or pushed against the rectum4 ,when ,i said in my letter1 that fixed air appeared to be the greatest corrector of putrefaction hitherto known1 your philosophical researches had not then made you acquainted with that most remarkably antiseptic property of nitrous air4 ,since you favoured me with a view of some astonishing proofs of this1 ,i have conceived hopes1 that this kind of air may likewise be applied medicinally to great advantage4 ,w4 ,h4 ,,number ,,iii4 ,observations on the ,,medicinal ,,uses of ,,fixed ,,air4 ,by ,,thomas ,,percival1 ,m4 ,d4 ,fellow of the ,,royal ,,society1 and of the ,,society of ,,antiquaries in ,,london4 ,these ,observations on the ,,medicinal ,,uses ,,of ,,fixed ,,air have been before published in the ,second ,volume of my ,essays2 but are here reprinted with considerable additions4 ,they form a part of an experimental inquiry into this interesting and curious branch of ,physics2 in which the friendship of ,dr4 ,priestley first engaged me1 in concert with himself4 ,manchester1 ,march #af1 #aggd4 ,in a course of ,experiments1 which is yet unfinished1 ,i have had frequent opportunities of observing that ,,fixed ,,air may in no inconsiderable quantity be breathed without danger or uneasiness4 ,and it is a confirmation of this conclusion1 that at ,bath1 where the waters copiously exhale this mineral spirit1#ae the bathers inspire it with impunity4 ,at ,buxton also1 where the ,bath is in a close vault1 the effects of such effluvia1 if noxious1 must certainly be perceived4 ,encouraged by these considerations1 and still more by the testimony of a very judicious ,physician at ,stafford1 in favour of this powerful antiseptic remedy1 ,i have administered fixed air in a considerable number of cases of the ,,phthisis ,,pulmonalis1 by directing my patients to inspire the steams of an effervescing mixture of chalk and vinegar2 or what ,i have lately preferred1 of vinegar and potash4 ,the hectic fever has in several instances been considerably abated1 and the matter expectorated has become less offensive1 and better digested4 ,i have not yet been so fortunate in any one case1 as to effect a cure2 although the use of mephitic air has been accompanied with proper internal medicines4 ,but ,dr4 ,withering1 the gentleman referred to above1 informs me1 that he has been more successful4 ,one ,phthisical patient under his care has by a similar course intirely recovered2 another was rendered much better2 and a third1 whose case was truly deplorable1 seemed to be kept alive by it more than two months4 ,it may be proper to observe that fixed air can only be employed with any prospect of success1 in the latter stages of the phthisis pulmonalis1 when a purulent expectoration takes place4 ,after the rupture and discharge of a ,,vomica also1 such a remedy promises to be a powerful palliative4 ,antiseptic fumigations and vapours have been long employed1 and much extolled in cases of this kind4 ,i made the following experiment1 to determine whether their efficacy1 in any degree1 depends on the separation of fixed air from their substance4 ,one end of a bent tube was fixed in a phial full of lime-water2 the other end in a bottle of the tincture of myrrh4 ,the junctures were carefully luted1 and the phial containing the tincture of myrrh was placed in water1 heated almost to the boiling point1 by the lamp of a tea-kettle4 ,a number of air-bubbles were separated1 but probably not of the mephitic kind1 for no precipitation ensued in the lime water4 ,this experiment was repeated with the tinct4 tolutan1 ph4 ed4 and with sp1 vinos4 camp4 and the result was entirely the same4 ,the medicinal action therefore of the vapours raised from such tinctures1 cannot be ascribed to the extrication of fixed air2 of which it is probable bodies are deprived by chemical solution as well as by mixture4 ,if mephitic air be thus capable of correcting purulent matter in the lungs1 we may reasonably infer it will be equally useful when applied externally to foul ,,ulcers4 ,and experience confirms the conclusion4 ,even the sanies of a ,,cancer1 when the carrot poultice failed1 has been sweetened by it1 the pain mitigated1 and a better digestion produced4 ,the cases ,i refer to are now in the ,manchester infirmary1 under the direction of my friend ,mr4 ,white1 whose skill as a surgeon1 and abilities as a writer are well known to the public4 ,two months have elapsed since these observations were written1#af and the same remedy1 during that period1 has been assiduously applied1 but without any further success4 ,the progress of the cancers seems to be checked by the fixed air2 but it is to be feared that a cure will not be effected4 ,a palliative remedy1 however1 in a disease so desperate and loathsome1 may be considered as a very valuable acquisition4 ,perhaps ,,nitrous ,,air might be still more efficacious4 ,this species of factitious air is obtained from all the metals except zinc1 by means of the nitrous acid2 and ,dr4 ,priestley informs me1 that as a sweetener and antiseptic it far surpasses fixed air4 ,he put two mice into a quantity of it1 one just killed1 the other offensively putrid4 ,after twenty-five days they were both perfectly sweet4 ,in the ,,ulcerous ,,sore ,,throat much advantage has been experienced from the vapours of effervescing mixtures drawn into the fauces#ag4 ,but this remedy should not supersede the use of other antiseptic applications4#ah ,a physician#ai who had a very painful ,,apthous ,,ulcer at the point of his tongue1 found great relief1 when other remedies failed1 from the application of fixed air to the part affected4 ,he held his tongue over an effervescing mixture of potash and vinegar2 and as the pain was always mitigated1 and generally removed by this vaporisation1 he repeated it1 whenever the anguish arising from the ulcer was more than usually severe4 ,he tried a combination of potash and oil of vitriol well diluted with water2 but this proved stimulant and increased his pain2 probably owing to some particles of the acid thrown upon the tongue1 by the violence of the effervescence4 ,for a paper stained with the purple juice of radishes1 when held at an equal distance over two vessels1 the one containing potash and vinegar1 the other the same alkali and ,spiritus vitrioli tenuis1 was unchanged by the former1 but was spotted with red1 in various parts1 by the latter4 ,in ,,malignant ,,fevers wines abounding with fixed air may be administered1 to check the septic ferment1 and sweeten the putrid colluvies in the prim vi4 ,if the laxative quality of such liquors be thought an objection to the use of them1 wines of a greater age may be given1 impregnated with mephitic air1 by a simple but ingenious contrivance of my friend ,dr4 ,priestley4#bj ,the patient's common drink might also be medicated in the same way4 ,a putrid ,,diarrh,,oe,a frequently occurs in the latter stage of such disorder1 and it is a most alarming and dangerous symptom4 ,if the discharge be stopped by astringents1 a putrid fomes is retained in the body1 which aggravates the delirium and increases the fever4 ,on the contrary1 if it be suffered to take its course1 the strength of the patient must soon be exhausted1 and death unavoidably ensue4 ,the injection of mephitic air into the intestines1 under these circumstances1 bids fair to be highly serviceable4 ,and a case of this deplorable kind1 has lately been communicated to me1 in which the vapour of chalk and oil of vitriol conveyed into the body by the machine employed for tobacco clysters1 quickly restrained the diarrhoea1 corrected the heat and foetor of the stools1 and in two days removed every symptom of danger#ba4 ,two similar instances of the salutary effects of mephitic air1 thus administered1 have occurred also in my own practice1 the history of which ,i shall briefly lay before the reader4 ,may we not presume that the same remedy would be equally useful in the ,,dysentery8 ,the experiment is at least worthy of trial4 ,mr4 ,w----1 aged forty-four years1 corpulent1 inactive1 with a short neck1 and addicted to habits of intemperance1 was attacked on the #gth of ,july #aggb1 with symptoms which seemed to threaten an apoplexy4 ,on the #hth1 a bilious looseness succeeded1 with a profuse hoemorrhage from the nose4 ,on the #ith1 ,i was called to his assistance4 ,his countenance was bloated1 his eyes heavy1 his skin hot1 and his pulse hard1 full1 and oppressed4 ,the diarrhoea continued2 his stools were bilious and very offensive2 and he complained of griping pains in his bowels4 ,he had lost1 before ,i saw him1 by the direction of ,mr4 ,hall1 a surgeon of eminence in ,manchester1 eight ounces of blood from the arm1 which was of a lax texture2 and he had taken a saline mixture every sixth hour4 ,the following draught was prescribed1 and a dose of rhubarb directed to be administered at night4 ,rx4 ,aq4 ,cinnam4 ten4 oz4 j4 ,succ4 ,limon4 recent4 oz4 4 ,salis ,nitri gr4 xij4 ,syr4 ,succo ,limon4 dr4 j4 ,m4 f4 ,haust4 #dtis horis sumendus4 ,july #aa4 ,the ,diarrhoea was more moderate2 his griping pains were abated2 and he had less stupor and dejection in his countenance4 ,pulse #ij1 not so hard or oppressed4 ,as his stools continued to be foetid1 the dose of rhubarb was repeated2 and instead of simple cinnamon-water1 his draughts were prepared with an infusion of columbo root4 #ab4 ,the ,diarrhoea continued2 his stools were involuntary2 and he discharged in this way a quantity of black1 grumous1 and foetid blood4 ,pulse hard and quick2 skin hot2 tongue covered with a dark fur2 abdomen swelled2 great stupor4 ,ten grains of columbo root1 and fifteen of the ,gummi rubrum astringens were added to each draught4 ,fixed air1 under the form of clysters1 was injected every second or third hour2 and directions were given to supply the patient plentifully with water1 artificially impregnated with mephitic air4 ,a blister was also laid between his shoulders4 #ac4 ,the ,diarrhoea continued1 with frequent discharges of blood2 but the stools had now lost their foetor4 ,pulse #abj2 great flatulence in the bowels1 and fulness in the belly4 ,the clysters of fixed air always diminished the tension of the ,abdomen1 abated flatulence1 and made the patient more easy and composed for some time after their injection4 ,they were directed to be continued1 together with the medicated water4 ,the nitre was omitted1 and a scruple of the ,confect4 ,damocratis was given every fourth hour1 in an infusion of columbo root4 #ad4 ,the ,diarrhoea was how checked1 ,his other symptoms continued as before4 ,blisters were applied to the arms2 and a drachm and a half of the ,tinctura ,serpentari was added to each draught4 #ae4 ,his pulse was feeble1 quicker and more irregular4 ,he dosed much2 talked incoherently2 and laboured under a slight degree of ,dyspna4 ,his urine1 which had hitherto assumed no remarkable appearance1 now became pale4 ,though he discharged wind very freely1 his belly was much swelled1 except for a short time after the injection of the air-clysters4 ,the following draughts were then prescribed4 ,rx ,camphor mucilag4 ,g4 ,arab1 solut gr4 viij4 ,infus4 ,rad4 ,columbo oz4 jfs ,tinct4 ,serpent4 dr4 ij ,confect4 ,card4 scruple j ,syr4 ,cort4 ,aurant dr4 i m4 f4 ,haust4 #dtis horis sumendus4 ,directions were given to foment his feet frequently with vinegar and warm water4 #af4 ,he has had no stools since the #adth4 ,his ,abdomen is tense4 ,no change in the other symptoms4 ,the ,tinct4 ,serpent4 was omitted in his draughts1 and an equal quantity of ,tinct4 ,rhi ,sp4 substituted in its place4 ,in the evening he had a motion to stool1 of which he was for the first time so sensible1 as to give notice to his attendants4 ,but the discharge1 which was considerable and slightly offensive1 consisted almost entirely of blood1 both in a coagulated and in a liquid state4 ,his medicines were therefore varied as follows3 ,rx4 ,decoct4 ,cort4 ,peruv4 oz4 iss ,tinct4 ,cort4 ejusd4 dr4 ij4 ,confect4 ,card4 scruple j ,gum4 ,rubr4 ,astring4 gr4 xv4 ,pulv4 ,alnmin4 gr4 vij4 m4 f4 ,haustus #dtis horis sumendus4 ,red ,port wine was now given more freely in his medicated water2 and his nourishment consisted of sago and salep4 ,in this state1 with very little variation1 he continued for several days2 at one time ostive1 and at another discharging small quantities of fces1 mixed with grumous blood4 ,the air-clysters were continued1 and the astringents omitted4 #bj4 ,his urine was now of an amber colour1 and deposited a slight sediment4 ,his pulse was more regular1 and although still very quick1 abated in number ten strokes in a minute4 ,his head was less confused1 and his sleep seemed to be refreshing4 ,no blood appeared in his stools1 which were frequent1 but small in quantity2 and his ,abdomen was less tense than usual4 ,he was extremely deaf2 but gave rational answers to the few questions which were proposed to him2 and said he felt no pain4 #ba4 ,he passed a very restless night2 his delirium recurred2 his pulse beat #abe strokes in a minute2 his urine was of a deep amber colour when first voided2 but when cold assumed the appearance of cow's whey4 ,the ,abdomen was not very tense1 nor had he any further discharge of blood4 ,directions were given to shave his head1 and to wash it with a mixture of vinegar and brandy2 the quantity of wine in his drink was diminished2 and the frequent use of the pediluvium was enjoined4 ,the air-clysters were discontinued1 as his stools were not offensive1 and his ,abdomen less distended4 #bb4 ,his pulse was now small1 irregular1 and beat #acj strokes in a minute4 ,the ,dyspnoea was greatly increased2 his skin was hot1 and bedewed with a clammy moisture2 and every symptom seemed to indicate the approach of death4 ,in this state he continued till evening1 when he recruited a little4 ,the next day he had several slight convulsions4 ,his urine which was voided plentifully1 still put on the appearance of whey when cold4 ,cordial and antispasmodic draughts1 composed of camphor1 tincture of castor1 and ,sp4 vol4 aromat4 were now directed2 and wine was liberally administered4 #bd4 ,he rose from his bed1 and by the assistance of his attendants walked across the chamber4 ,soon after he was seized with a violent convulsion1 in which he expired4 ,to adduce a case which terminated fatally as a proof of the efficacy of any medicine1 recommended to the attention of the public1 may perhaps appear singular2 but cannot be deemed absurd1 when that remedy answered the purposes for which it was intended4 ,for in the instance before us2 fixed air was employed1 not with an expectation that it would cure the fever1 but to obviate the symptoms of putrefaction1 and to allay the uneasy irritation in the bowels4 ,the disease was too malignant1 the nervous system too violently affected1 and the strength of the patient too much exhausted by the discharges of blood which he suffered1 to afford hopes of recovery from the use of the most powerful antiseptics4 ,but in the succeeding case the event proved more fortunate4 ,elizabeth ,grundy1 aged seventeen1 was attacked on the #ajth of ,december #aggb1 with the usual symptoms of a continued fever4 ,the common method of cure was pursued2 but the disease increased1 and soon assumed a putrid type4 ,on the #bc;d ,i found her in a constant delirium1 with a subsultus tendinum4 ,her skin was hot and dry1 her tongue black1 her thirst immoderate1 and her stools frequent1 extremely offensive1 and for the most part involuntary4 ,her pulse beat #acj strokes in a minute2 she dosed much2 and was very deaf4 ,i directed wine to be administered freely2 a blister to be applied to her back2 the pediluvium to be used several times in the day2 and mephitic air to be injected under the form of a clyster every two hours4 ,the next day her stools were less frequent1 had lost their foetor1 and were no longer discharged involuntarily2 her pulse was reduced to #aaj strokes in the minute2 and her delirium was much abated4 ,directions were given to repeat the clysters1 and to supply the patient liberally with wine4 ,these means were assiduously pursued several days2 and the young woman was so recruited by the #bhth1 that the injections were discontinued4 ,she was now quite rational1 and not averse to medicine4 ,a decoction of ,peruvian bark was therefore prescribed1 by the use of which she speedily recovered her health4 ,i might add a third history of a putrid disease1 in which the mephitic air is now under trial1 and which affords the strongest proof both of the antiseptic1 and of the tonic powers of this remedy2 but as the issue of the case remains yet undetermined 7though it is highly probable1 alas6 that it will be fatal7 ,i shall relate only a few particulars of it4 ,master ,d4 a boy of about twelve years of age1 endowed with an uncommon capacity1 and with the most amiable dispositions1 has laboured many months under a hectic fever1 the consequence of several tumours in different parts of his body4 ,two of these tumours were laid open by ,mr4 ,white1 and a large quantity of purulent matter was discharged from them4 ,the wounds were very properly treated by this skilful surgeon1 and every suitable remedy1 which my best judgment could suggest1 was assiduously administered4 ,but the matter became sanious1 of a brown colour1 and highly putrid4 ,a ,diarrhoea succeeded2 the patient's stools were intolerably offensive1 and voided without his knowledge4 ,a black fur collected about his teeth2 his tongue was covered with ,aphth2 and his breath was so foetid1 as scarcely to be endured4 ,his strength was almost exhausted2 a subsultus tendinum came on2 and the final period of his sufferings seemed to be rapidly approaching4 ,as a last1 but almost hopeless1 effort1 ,i advised the injection of clysters of mephitic air4 ,these soon corrected the foetor of the patient's stools2 restrained his ,diarrhoea2 and seemed to recruit his strength and spirits4 ,within the space of twenty-four hours his wounds assumed a more favourable appearance2 the matter discharged from them became of a better colour and consistence2 and was no longer so offensive to the smell4 ,the use of this remedy has been continued several days1 but is now laid aside4 ,a large tumour is suddenly formed under the right ear2 swallowing is rendered difficult and painful2 and the patient refuses all food and medicine4 ,nourishing clysters are directed2 but it is to be feared that these will renew the looseness1 and that this amiable youth will quickly sink under his disorder#bb4 ,the use of wort from its saccharine quality1 and disposition to ferment1 has lately been proposed as a remedy for the ,,sea ,,scurvy4 ,water or other liquors1 already abounding with fixed air in a separate state1 should seem to be better adapted to this purpose2 as they will more quickly correct the putrid disposition of the fluids1 and at the same time1 by their gentle stimulus#bc increase the powers of digestion1 and give new strength to the whole system4 ,dr4 ,priestley1 who suggested both the idea and the means of executing it1 has under the sanction of the ,college of ,physicians1 proposed the scheme to the ,lords of the ,admiralty1 who have ordered trial to be made of it1 on board some of his ,majesty's ships of war4 ,might it not however give additional efficacy to this remedy1 if instead of simple water1 the infusion of malt were to be employed8 ,i am persuaded such a medicinal drink might be prescribed also with great advantage in ,,scrophulous ,,complaints1 when not attended with a hectic fever2 and in other disorders in which a general acrimony prevails1 and the crasis of the blood is destroyed4 ,under such circumstances1 ,i have seen vibices which spread over the body1 disappear in a few days from the use of wort4 ,a gentleman who is subject to a scorbutic eruption in his face1 for which he has used a variety of remedies with no very beneficial effect1 has lately applied the fumes of chalk and oil of vitriol to the parts affected4 ,the operation occasions great itching and pricking in the skin1 and some degree of drowsiness1 but evidently abates the serous discharge1 and diminishes the eruption4 ,this patient has several symptoms which indicate a genuine scorbutic ,,diathesis2 and it is probable that fixed air1 taken internally1 would be an useful medicine in this case4 ,the saline draughts of ,riverius are supposed to owe their antiemetic effects to the air1 which is separated from the salt of wormwood during the act of effervescence4 ,and the tonic powers of many mineral waters seem to depend on this principle4 ,i was lately desired to visit a lady who had most severe convulsive ,,reachings4 ,various remedies had been administered without effect1 before ,i saw her4 ,she earnestly desired a draught of malt liquor1 and was indulged with half a pint of ,burton beer in brisk effervescence4 ,the vomitings ceased immediately1 and returned no more4 ,fermenting liquors1 it is well known1 abound with fixed air4 ,to this1 and to the cordial quality of the beer1 the favourable effect which it produced1 may justly be ascribed4 ,but ,i shall exceed my design by enlarging further on this subject4 ,what has been advanced it is hoped1 will suffice to excite the attention of physicians to a remedy which is capable of being applied to so many important medicinal purposes4 ,,number ,,iv4 ,extract of a ,letter from ,,william ,,falconer1 ,m4,d4 of ,,bath4 ,jan #f1 #aggd1 ,reverend ,sir1 ,i once observed the same taste you mention 7,philosophical ,transactions1 p4 #aef4 of this ,volume1 p4 #ce47 viz4 like tar water1 in some water that ,i impregnated with fixed air about three years ago4 ,i did not then know to what to attribute it1 but your experiment seems to clear it up4 ,i happened to have spent all my acid for raising effervescence1 and to supply its place ,i used a bottle of dulcified spirit of nitre1 which ,i knew was greatly under-saturated with spirit of wine2 from which1 as analogous to your observation1 ,i imagine the effect proceeded4 ,as#bd to the coagulation of the blood of animals by fixed ,air1 ,i fear it will scarce stand the test of experiment1 as ,i this day gave it1 ,i think1 a fair trial1 in the following manner4 ,a young healthy man1 at #bj years old1 received a contusion by a fall1 was instantly carried to a neighbouring surgeon1 and1 at my request1 bled in the following manner4 ,i inserted a glass funnel into the neck of a large clear phial about oz4 x4 contents1 and bled him into it to about oz4 viii4 ,by these means the blood was exposed to the air as little a time as possible1 as it flowed into the bottle as it came from the orifice4 ,as soon as the quantity proposed was drawn1 the bottle was carefully corked1 and brought to me4 ,it was then quite fluid1 nor was there the least separation of its parts4 ,on the surface of this ,i conveyed several streams of fixed air 7having first placed the bottle with the blood in a bowl of water1 heated as nearly to the human heat as possible7 from the mixture of the vitriolic acid and lixiv4 tartar1 which ,i use preferably to other alkalines1 as being 7as ,dr4 ,cullen observes7 in the mildest state1 and therefore most likely to generate most air4 ,i shook the phial often1 and threw many streams of air on the blood1 as ,i have often practised with success for impregnating water2 but could not perceive the smallest signs of coagulation1 although it stood in an atmosphere of fixed air #bj minutes or more4 ,i then uncorked the bottles1 and poured off about oz4 ii to which ,i added about #f or #g gtts of spirit of vitriol1 which coagulated it immediately4 ,i set the remainder in a cold place and it coagulated1 as near as ,i could judge1 in the same time that blood would have done newly drawn from the vein4 ,p4 #hb4 ,perhaps the circumilance of putrid vegetables yielding all fixed and no inflammable air may be the causes of their proving so antiseptic1 even when putrid1 as appears by ,mr4 ,alexander's ,experiments4 ,p4 #hf4 ,perhaps the putrid air continually exhaled may be one cause of the luxuriancy of plants growing on dunghills or in very rich soils4 ,p4 #adf4 ,your observation that inflammable air consists of the union of some acid vapour with phlogiston1 puts me in mind of an old observation of ,dr4 ,cullen1 that the oil separated from soap by an acid was much more inflammable than before1 resembling essential oil1 and soluble in ,v4 sp4 ,i have tried fixed air as an antiseptic taken in by respiration1 but with no great success4 ,in one case it seemed to be of service1 in two it seemed indifferent1 and in one was injurious1 by exciting a cough4 ,,number ,v4 ,extract of a ,letter from ,mr4 ,,william ,,bewley1 of ,,great ,,massingham1 ,,norfolk4 ,march #bc1 #aggd4 ,dear ,sir1 ,when ,i first received your paper1 ,i happened to have a process going on for the preparation of nitrous ether1 without distillation4#be ,i had heretofore always taken for granted that the elastic fluid generated in that preparation was fixed air3 but on examination ,i found this combination of the nitrous acid with inflammable spirits1 produced an elastic fluid that had the same general properties with the air that you unwillingly1 though very properly1 in my opinion1 term nitrous2 as ,i believe it is not to be procured without employing the nitrous acid1 either in a simple state1 or compounded1 as in aqua regia4 ,i shall suggest1 however1 by and by some doubts with respect to it's title to the appellation of air4 ,water impregnated with your nitrous air certainly1 as you suspected from it's taste1 contains the nitrous acid4 ,on saturating a quantity of this water with a fixed alcali1 and then evaporating1 c4 ,i have procured two chrystals of nitre4 ,but the principal observations that have occurred to me on the subject of nitrous air are the following4 ,my experiments have been few and made by snatches1 under every disadvantage as to apparatus1 c4 and with frequent interruptions2 and yet ,i think they are to be depended upon4 ,my first remark is1 that nitrous air does not give water a sensibly acid impregnation1 unless it comes into contact1 or is mixed with a portion of common or atmospherical air3 and my second1 that nitrous air principally consists of the nitrous acid itself1 reduced to the state of a permanent vapour not condensable by cold1 like other vapours1 but which requires the presence and admixture of common air to restore it to its primitive state of a liquid4 ,i am beholden for this idea1 you will perceive1 to your own very curious discovery of the true nature of ,mr4 ,cavendish's marine vapour4 ,when ,i first repeated your experiment of impregnating water with nitrous air1 the water1 ,i must own tasted acid2 as it did in one1 or perhaps two trials afterwards2 but1 to my great astonishment1 in all the following experiments1 though some part of the factitious air1 or vapour1 was visibly absorbed by the water1 ,i could not perceive the latter to have acquired any sensible acidity4 ,i at length found1 however1 that ,i could render this same water very acid1 by means only of the nitrous air already included in the phial with it4 ,taking the inverted phial out of the water1 ,i remove my finger from the mouth of it1 to admit a little of the common air1 and instantly replace my finger4 ,the redness1 effervescence1 and diminution take place4 ,again taking off my finger1 and instantly replacing it1 more common1 air rushes in1 and the same phenomena recur4 ,the process sometimes requires to be seven or eight times repeated1 before the whole of the nitrous vapour 7as ,i shall venture to call it7 is condensed into nitrous acid1 by the successive entrance of fresh parcels of common air after each effervescence2 and the water becomes evidently more and more acid after every such fresh admission of the external air1 which at length ceases to enter1 when the whole of the vapour has been condensed4 ,no agitation of the water is requisite1 except a gentle motion1 just sufficient to rince the sides of the phial1 in order to wash off the condensed vapour4 ,the acidity which you 7and ,i likewise1 at first7 observed in the water agitated with nitrous air alone1 ,i account for thus4 ,on bringing the phial to the mouth1 the common air meeting with the nitrous vapour in the neck of the phial1 condenses it1 and impregnates the water with the acid1 in the very act of receiving it upon the tongue4 ,on stopping the mouth of the phial with my tongue for a short time and afterwards withdrawing it a very little1 to suffer the common air to rush past it into the phial1 the sensation of acidity has been sometimes intolerable3 but taking a large gulph of the water at the same time1 it has been found very slightly acid4--,the following is one of the methods by which ,i have given water a very strong acid impregnation1 by means of a mixture of nitrous and common air4 ,into a small phial1 containing only common air1 ,i force a quantity of nitrous air at random1 out of a bladder1 and instantly clap my finger on the mouth of the bottle4 ,i then immerse the neck of it into water1 a small quantity of which ,i suffer to enter1 which squirts into it with violence2 and immediately replacing my finger1 remove the phial4 ,the water contained in it is already very acid1 and it becomes more and more so 7if a sufficient quantity of nitrous air was at first thrown in7 on alternately stopping the mouth of the phial1 and opening it1 as often as fresh air will enter4 ,since ,i wrote the above1 ,i have frequently converted a small portion of water in an ounce phial into a weak ,aqua fortis1 by repeated mixtures of common and nitrous air2 throwing in alternately the one or the other1 according to the circumstances2 that is1 as long as there was a superabundance of nitrous air1 suffering the common air to enter and condense it2 and1 when that was effected1 forcing in more nitrous air from the bladder1 to the common air which now predominated in the phial--and so alternately4 ,i have wanted leisure1 and conveniences1 to carry on this process to its maximum1 or to execute it in a different and better manner2 but from what ,i have done1 ,i think we may conclude that nitrous air consists principally of the nitrous acid1 phlogisticated1 or otherwise so modified1 by a previous commenstruation with metals1 inflammable spirits1 c4 as to be reduced into a durably elastic vapour3 and that1 in order to deprive it of its elasticity1 and restore it to its former state1 an addition of common air is requisite1 and1 as ,i suspect1 of water likewise1 or some other fluid3 as in the course of my few trials1 ,i have not yet been able to condense it in a perfectly dry bottle4 ,,number ,,vi4 ,a ,letter from ,dr4 ,,franklin4 ,craven ,street1 ,april #aj1 #aggd4 ,dear ,sir1 ,in compliance with your request1 ,i have endeavoured to recollect the circumstances of the ,american experiments ,i formerly mentioned to you1 of raising a flame on the surface of some waters there4 ,when ,i passed through ,new ,jersey in #agfd1 ,i heard it several times mentioned1 that by applying a lighted candle near the surface of some of their rivers1 a sudden flame ,would catch and spread on the water1 continuing to burn for near half a minute4 ,but the accounts ,i received were so imperfect that ,i could form no guess at the cause of such an effect1 and rather doubted the truth of it4 ,i had no opportunity of seeing the experiment2 but calling to see a friend who happened to be just returned home from making it himself1 ,i learned from him the manner of it2 which was to choose a shallow place1 where the bottom could be reached by a walking-stick1 and was muddy2 the mud was first to be stirred with the stick1 and when a number of small bubbles began to arise from it1 the candle was applied4 ,the flame was so sudden and so strong1 that it catched his ruffle and spoiled it1 as ,i saw4 ,new-,jersey having many pine-trees in different parts of it1 ,i then imagined that something like a volatile oil of turpentine might be mixed with the waters from a pine-swamp1 but this supposition did not quite satisfy me4 ,i mentioned the fact to some philosophical friends on my return to ,england1 but it was not much attended to4 ,i suppose ,i was thought a little too credulous4 ,in #agfe1 the ,reverend ,dr4 ,chandler received a letter from ,dr4 ,finley1 ,president of the ,college in that province1 relating the same experiment4 ,it was read at the ,royal ,society1 ,nov4 #ba1 of that year1 but not printed in the ,transactions2 perhaps because it was thought too strange to be true1 and some ridicule might be apprehended if any member should attempt to repeat it in order to ascertain or refute it4 ,the following is a copy of that account4 ,a worthy gentleman1 who lives at a few miles distance1 informed me that in a certain small cove of a mill-pond1 near his house1 he was surprized to see the surface of the water blaze like inflamed spirits4 ,i soon after went to the place1 and made the experiment with the same success4 ,the bottom of the creek was muddy1 and when stirred up1 so as to cause a considerable curl on the surface1 and a lighted candle held within two or three inches of it1 the whole surface was in a blaze1 as instantly as the vapour of warm inflammable spirits1 and continued1 when strongly agitated1 for the space of several seconds4 ,it was at first imagined to be peculiar to that place2 but upon trial it was soon found1 that such a bottom in other places exhibited the same phenomenon4 ,the discovery was accidentally made by one belonging to the mill4 ,i have tried the experiment twice here in ,england1 but without success4 ,the first was in a slow running water with a muddy bottom4 ,the second in a stagnant water at the bottom of a deep ditch4 ,being some time employed in stirring this water1 ,i ascribed an intermitting fever1 which seized me a few days after1 to my breathing too much of that foul air which ,i stirred up from the bottom1 and which ,i could not avoid while ,i stooped in endeavouring to kindle it4--,the discoveries you have lately made of the manner in which inflammable air is in some cases produced1 may throw light on this experiment1 and explain its succeeding in some cases1 and not in others4 ,with the highest esteem and respect1 ,i am1 ,dear ,sir1 ,your most obedient humble servant1 ,b4 ,,franklin4 ,,number ,,vii4 ,extract of a ,letter from ,mr4 ,,henry of ,manchester4 ,it is with great pleasure ,i hear of your intended publication on air1 and ,i beg leave to communicate to you an experiment or two which ,i lately made4 ,dr4 ,percival had tried1 without effect1 to dissolve lead in water impregnated with fixed air4 ,i however thought it probable1 that the experiment might succeed with nitrous air4 ,into a quantity of water impregnated with it1 ,i put several pieces of sheet-lead1 and suffered them1 after agitation1 to continue immersed about two hours4 ,a few drops of vol4 tincture of sulphur changed the water to a deep orange colour1 but not so deep as when the same tincture was added to a glass of the same water1 into which one drop of a solution of sugar of lead had been instilled4 ,the precipitates of both in the morning1 were exactly of the same kind2 and the water in which the lead had been infused all night1 being again tried by the same test1 gave signs of a still stronger saturnine impregnation--,whether the nitrous air acts as an acid on the lead1 or in the same manner that fixed air dissolves iron1 ,i do not pretend to determine4 ,syrup of violets added to the nitrous water became of a pale red1 but on standing about an hour1 grew of a turbid brown cast4 ,though the nitrous acid is not often found1 except produced by art1 yet as there is a probability that nitre may be formed in the earth in large towns1 and indeed fossile nitre has been actually found in such situations1 it should be an additional caution against the use of leaden pumps4 ,i tried to dissolve mercury by the same means1 but without success4 ,i am1 with the most sincere esteem1 ,dear ,sir1 ,your obliged and obedient servant1 ,,tho4 ,,henry4 ,,finis4 ,,footnotes3 #ae ,see ,dr4 ,falconer's very useful and ingenious treatise on the ,bath water1 #b;d edit4 p4 #cac4 #af ,may1 #aggb4 #ag ,vid4 ,mr4 ,white's useful treatise on the management of pregnant and lying-in women1 p4 #bgi4 #ah ,see the author's observations on the efficacy of external applications in the ulcerous sore throats1 ,essays medical and experimental1 ,vol4 ,i4 #b;d edit4 p4 #cgg4 #ai ,the author of these observations4 #bj ,directions for impregnating water with fixed air1 in order to communicate to it the peculiar spirit and virtues of ,pyrmont water1 and other mineral waters of a similar nature4 #ba ,referring to the case communicated by ,mr4 ,hey4 #bb ,he languished about a week1 and then died4 #bc ,the vegetables which are most efficacious in the cure of the scurvy1 possess some degree of a stimulating power4 #bd ,this refers1 to an experiment mentioned in the first publication of these papers in the ,philosophical ,transactions1 but omitted in this volume4 #be ,the first account of this curious process was1 ,i believe1 given in the ,mem4 de l',ac4 de ,sc4 de ,paris for #agdb4 ,though seemingly less volatile than the vitriolic ether1 it boils with a much smaller degree of heat4 ,one day last summer1 it boiled in the coolest room of my house2 as it gave me notice by the explosion attending its driving out the cork4 ,to save the bottle1 and to prevent the total loss of the liquor by evaporation1 ,i found myself obliged instantly to carry it down to my cellar4 ,,errata4 ,p4 #ae4 l4 #ac4 for it to read to it p4 #bd4 l4 #bj4 ---- has ---- had p4 #fj4 l4 #bb4 ---- inflammable ---- in inflammable p4 #hd4 l4 #e4 ---- experiments ---- experiment p4 #ade4 l4 #af4 ---- with ---- of p4 #aec4 l4 #a4 ---- that is ---- this air p4 #aii4 l4 #ag4 ---- ingenious ---- ingenuous p4 #baa4 l4 #bc4 ---- of ---- 1 if p4 #bdc4 l4 #bg4 ---- diminishing ---- diminished p4 #bgb4 l4 #ba4 ---- seem ---- seems p4 #cja4 l4 #ca4 ---- ---- ---- one end p4 #cjc4 l4 #e4 ---- ---- ---- the nitrous p4 #cjd4 l4 #ba4 ---- deslrium ---- delirium p4 #cjf4 l4 #b4 ---- recet4 ---- recent4 p4 #cjh4 l4 #g4 ---- per ---- ,peruv4 p4 #cac4 l4 #bg4 ---- usual ---- useful p4 #cjj4 to #cad4 passim ---- ,diarrha ---- ,diarrhoea p4 #caf4 l4 #aa4 ---- remains ---- remainder p4 #ebd4 l4 #ae4 ---- it ---- iron4 ,a ,,catalogue of ,,books written by ,,joseph ,,priestley1 ,,ll4,d4 ,f4,r4,s41 ,and printed for ,j4 ,,johnson1 ,,bookseller1 at ,no4 #gb1 ,st4 ,paul's ,church-,yard1 ,london4 #a4 ,the ,,history and ,,present ,,state of ,,electricity1 with original ,experiments1 illustrated with ,copper ,plates4 #dth ,edit1 corrected and enlarged1 #dto4 #al4 #as4 #b4 ,a ,,familiar ,,introduction to the ,,study of ,,electricity1 #b;d ,edit4 #hvo4 #bs4 #f;d4 #c4 ,the ,,history and ,,present ,,state of ,,discoveries relating to ,,vision1 ,,light1 and ,,colours1 #b vols4 #dto4 illustrated with a great ,number of ,copper ,plates1 #al4 #aas4 #f;d4 in ,boards4 #d4 ,a ,,familiar ,,introduction to the ,,theory and ,,practice of ,,perspective1 with ,copper ,plates1 #es4 in ,boards4 #e4 ,,directions for impregnating ,water with ,,fixed ,,air1 in order to communicate to it the peculiar ,spirit and ,virtues of ,,pyrmont ,,water1 and other ,mineral ,waters of a similar ,nature1 #as4 #f4 ,experiments and ,observations on different ,kinds of ,air1 with ,copper ,plates1 #b;d ,edit4 #es4 in ,boards4 #g4 ,a ,,new ,,chart of ,,history1 containing a ,view of the principal ,revolutions of ,empire that have taken ,place in the ,world2 with a ,book describing it1 containing an ,epitome of ,universal ,history1 #ajs4 #f;d4 #h4 ,a ,,chart of ,,biography1 with a ,book1 containing an ,explanation of it1 and a ,catalogue of all the ,names inserted in it1 #dth ,edit1 very much improved1 #ajs4 #f;d4 #i4 ,an ,essay on a ,course of liberal ,education for ,civil and ,active ,life2 with ,plans of ,lectures on1 #a4 ,the ,study of ,history and general ,policy4 #b4 ,the ,history of ,england4 #c4 ,the ,constitution and ,laws of ,england4 ,to which are added ,remarks on ,dr4 ,browne's proposed ,code of ,education4 #aj4 ,the ,,rudiments of ,,english ,,grammar1 adapted to the ,use of ,schools1 #as4 #f;d4 #aa4 ,the above ,,grammar1 with ,notes and ,observations1 for the ,use of those who have made some ,proficiency in the ,language1 #dth ,ed4 #cs4 #ab4 ,an ,,essay on the ,,first ,,principles of ,,government1 and on the ,nature of ,,political1 ,,civil1 and ,,religious ,,liberty1 #b;d ,edit1 much enlarged1 #es4 #ac4 ,,institutes of ,,natural and ,,revealed ,,religion1 ,vol4 ,i4 containing the ,elements of ,natural ,religion2 to which is prefixed1 ,an ,essay on the best ,method of communicating religious ,knowledge to the ,members of ,christian ,societies1 #bs4 #f;d4 sewed4--,vol4 ,,ii4 containing the ,evidences of the ,jewish and ,christian ,revelation1 #cs4 sewed4--,vol4 ,,iii4 containing the ,doctrines of ,revelation1 #bs4 #f;d4 sewed4--,preparing for the ,press 7,march #agge7 the fourth and last ,part of this ,work1 containing a ,view of the ,corruptions of ,christianity4 #ad4 ,an ,examination of ,dr4 ,reid's ,enquiry into the ,human ,mind1 on the ,principles of ,common ,sense1 ,dr4 ,beattie's ,essay on the ,nature and ,immutability of ,truth1 and ,dr4 ,oswald's ,appeal to ,common ,sense in behalf of ,religion4 ,to which is added the ,correspondence of ,dr4 ,beattie and ,dr4 ,oswald with the ,author1 #b;d ,edit4 #es4 unbound4 #ae4 ,a ,,free ,,address to ,,protestant ,,dissenters1 on the ,subject of the ,lord's ,supper1 the third ,edition with ,additions1 #bs4 #af4 ,the ,additions to the ,above may be had alone1 #as4 #ag4 ,an ,,address to ,,protestant ,,dissenters1 on the ,subject of giving the ,lord's ,supper to ,children1 #as4 #ah4 ,,considerations on ,,differences of ,,opinion among ,christians2 with a ,letter to the ,rev4 ,mr4 ,,venn1 in ,answer to his ,examination of the ,address to ,protestant ,dissenters1 #as4 #f;d4 #ai4 ,a ,,catechism for ,,children and ,,young ,,persons1 #b;d ,edit4 #c;d4 #bj4 ,a ,,scripture ,,catechism1 consisting of a ,series of ,questions1 with ,references to the ,scriptures instead of ,answers1 #c;d4 #ba4 ,a ,serious ,,address to ,,masters of ,,families1 with ,forms of ,family ,prayer1 #b;d ,edit4 #f;d4 #bb4 ,a ,view of the ,,principles and ,,conduct of the ,,protestant ,,dissenters1 with respect to the ,civil and ,ecclesiastical ,constitution of ,england1 #b;d ,edit4 #as4 #f;d4 #bc4 ,a ,free ,,address to ,,protestant ,,dissenters1 on the ,subject of ,,church ,,discipline2 with a ,preliminary ,discourse concerning the ,spirit of ,christianity1 and the ,corruption of it by false ,notions of ,religion1 #bs4 #f;d4 #bd4 ,a ,,sermon preached before the ,congregation of ,,protestant ,,dissenters1 at ,mill ,hill ,chapel1 in ,leeds1 ,may #af1 #aggc1 on ,occasion of his resigning the ,pastoral ,office among them1 #as4 #be4 ,a ,,free ,,address to ,,protestant ,,dissenters1 as such4 ,by a ,dissenter4 ,a new ,edition1 enlarged and corrected1 #as4 #f;d4--,an ,allowance is made to those who buy this ,pamphlet to give away4 #bf4 ,letters to the ,author of ,remarks on several late ,publications relative to the ,dissenters1 in a ,letter to ,dr4 ,priestley1 #as4 #bg4 ,an ,,appeal to the serious and candid ,professors of ,christianity on the following ,subjects1 viz4 #a4 ,the ,use of ,reason in ,matters of ,religion4 #b4 ,the ,power of ,man to do the ,will of ,god4 #c4 ,original ,sin4 #d4 ,election and ,reprobation4 #e4 ,the ,divinity of ,christ4 ,and1 #f4 ,atonement for ,sin by the ,death of ,christ1 #dth ,edit4 #a;d4 #bh4 ,a ,,familiar ,,illustration of certain ,passages of ,scripture relating to the same ,subject4 #d;d4 or #cs4 #f;d4 per ,dozen4 #bi4 ,the ,,triumph of ,,truth2 being an ,account of the ,trial of ,mr4 ,e4 ,elwall1 for ,heresy and ,blasphemy1 at ,stafford ,assizes1 before ,judge ,denton1 c4 #b;d ,edit4 #a;d4 #cj4 ,,considerations for the ,,use of ,,young ,,men1 and the ,parents of ,,young ,,men1 #b;d4 ,also1 published under the ,direction of ,dr4 ,,priestley1 ,,the ,,theological ,,repository4 ,consisting of original ,essays1 ,hints1 ,queries1 c4 calculated to promote religious ,knowledge1 in #c ,volumes1 #hvo1 ,price #ahs4 in ,boards4 ,among other ,articles1 too many to be enumerated in an ,advertisement1 these three ,volumes will be found to contain such original and truly valuable ,observations on the ,doctrine of the ,atonement1 the ,pre-existence of ,christ1 and the ,inspiration of the ,scriptures1 more especially respecting the ,harmony of the ,evangelists1 and the ,reasoning of the ,apostle ,paul1 as cannot fail to recommend them to those ,persons1 who wish to make a truly free ,enquiry into these important ,subjects4 ,in the ,first ,volume1 which is now reprinted1 several ,articles are added1 particularly ,,two ,,letters from ,dr4 ,,thomas ,,shaw to ,dr4 ,,benson1 relating to the ,passage of the ,israelites through the ,red ,sea4 ,illustration3 ,to face the last page4