,transcriber's notes ,italics in the original work are transcribed between underscores2 small-capitals have been transcribed as all capitals4 ,more transcriber's notes and a list of corrections made may be found at the end of this text4 ,illustration3 ,,fig4 #a ,a ,,practical ,,treatise ,,on ,,gas-,,light2 ,,exhibiting ,a ,,summary ,,description ,,of ,,the ,,apparatus ,,and ,,machinery ,,best ,,calculated ,,for ,,illuminating ,,streets1 ,,houses1 ,,and ,,manufactories1 ,,with ,,carburetted ,,hydrogen1 ,,or ,,coal-,,gas1 ,,with ,,remarks ,,on ,,the ,,utility1 ,,safety1 ,,and ,,general ,,nature ,,of ,,this ,,new ,,branch ,,of ,,civil ,,economy4 ,,by ,,fredrick ,,accum1 ,,operative ,,chemist1 ,,lecturer ,,on ,,practical ,,chemistry1 ,,on ,,mineralogy1 ,,and ,,on ,,chemistry ,,applied ,,to ,,the ,,arts ,,and ,,manufactures2 ,,member ,,of ,,the ,,royal ,,irish ,,academy1 ,,fellow ,,of ,,the ,,linn,n ,,society1 ,,member ,,of ,,the ,,royal ,,academy ,,of ,,sciences ,,of ,,berlin1 c4 c4 ,,with ,,seven ,,coloured ,,plates4 ,london3 ,,printed ,,by ,g4 ,,hayden1 ,,brydges-,,street1 ,,covent ,,garden2 ,,for ,r4 ,,ackermann1 #aja1 ,,strand2 ,,longman1 ,,hurst1 ,,rees1 ,,orme1 ,,and ,,brown2 ,,and ,,sherwood1 ,,neely1 ,,and ,,jones1 ,,paternoster ,,row2 ,,and ,j4 ,,hatchard1 ,,piccadilly4 ,price--,twelve ,shillings in ,boards4 #ahae4 ,,ex ,,fumo ,,dare ,,lucem4 ,,hor4 ,,preface4 #aa1 ,compton ,street ,soho4 ,the following pages are intended to exhibit a summary view of the new art of procuring light1 by means of carburetted hydrogen gas obtained from pit-coal1 and which of late has been employed with unparalelled success1 as a substitute for candles and lamps1 and is known by the name of ,,gas-,,light4 ,to accomplish this object1 ,i have given1 in the first part of this ,essay1 a concise and popular view of the chemical theory and production of artificial light--,i have explained the action of candles and lamps--,i have shown the methods of measuring the comparative illuminating power of artificial light of different kinds1 so as to appreciate their economical value--,i have stated the proportions of combustible materials requisite for producing a light of a certain strength2 with such other preliminary facts and observations as were deemed necessary to enable the reader to understand fully the nature of the new art of illumination1 which it is the object of this ,essay to describe4 ,these positions are followed by a chemical view of the general nature and composition of coal--the chemical changes which this substance suffers1 when employed in the production of gas-light--the different products it furnishes--the modes of obtaining them--their properties and applications in the various arts of life4 ,i have given a description of the apparatus and machinery by means of which the coal-gas is prepared1 and the methods employed for distributing and applying it as a substitute for candles and lamps to illuminate houses1 streets and manufactories2--,i have furnished the data for calculating the expense that must attend the application of this species of light under different circumstances1 so as to determine the relative cost or value of gas-lights1 when compared with the lights now in use--together with such other practical directions and facts as will enable the reader to form a proper estimate of the gas-light illumination1 and to put this art into practice4 ,i have stated the leading objects of public and private utility to which the new system of lighting may be successfully applied1 candidly pointing out those in which it cannot be made use of to advantage4 ,i have detailed the most obvious effects which the discovery of lighting with coal-gas must inevitably produce upon the arts and upon domestic economy2 its primary advantages--its views--its limits1 and the resources it presents to industry and public economy4 ,i have endeavoured to show how far its application is safe1 and in what respect it is entitled to public approbation and national encouragement4 ,it may not be improper1 before concluding1 to inform the reader1 that my qualifications for the task ,i have undertaken are founded upon many years experience1 during which time1 ,i possessed peculiar opportunities to witness and verify the most extended series of operations that ever have been made for the purpose of ascertaining the practicability1 safety1 and general nature of the art of applying coal-gas as a substitute for tallow and oil2 and which have1 as it were1 fixed the fate of this art4 ,the numerous experiments ,i instituted1 upon a large scale1 by desire of the ,gas-,light ,company1 for the purpose of adducing them in my evidence before the ,house of ,commons1 and ,house of ,lords1 on a former occasion1 have enabled me to collect such information as could not have been obtained by other means4 ,the substance of these results 7which are printed by order of ,government17 are incorporated in this ,treatise1 together with such other facts and observations as have presented themselves in the routine of my profession elsewhere4 ,to generalize the results of my observations1 and to make them practically useful to the public1 is the aim of the present publication1 and ,i need scarcely add1 that their suffrages to the zeal and industry1 at least1 with which ,i have endeavoured to attain my object1 will be a source of infinite satisfaction4 ,,fredrick ,,accum ,contents4 ,,introductory ,,observation4 ,page #a4 ,progress of the arts4--,influence of it upon the morals and condition of man4--,beneficial tendency of chemical and mechanical improvements4 --,state of pre-eminence of people with regard to civilization4--,how to be estimated4--,flourishing state of those nations which have shown the greatest activity in cultivating the useful arts1 and establishing useful enterprises4--,general observations on this subject4--,extra- ordinary discoveries of modern times4--,new art of procuring light4-- ,object of the treatise4 ,,part ,i4 ,,production ,,of ,,artificial ,,light1 c4 #h4 ,production of the flame generated during the combustion of certain bodies4--,characters of flame when perfect4--,most luminous flame1 how produced with the least consumption of combustible matter4--,conditions necessary for that purpose4--,importance of this subject1 with regard to the production and supply of artificial light4--,the flame of bodies may be tinged4--,blue flame1 red flame1 green flame1 c4--,opinion concerning the origin of light emitted by bodies burning with flame4-- ,philosophy of the subject4--,theory of the action of the instruments of illumination4--,rude method of procuring light employed in some countries4--,chemical action of candles1 and lamps4--,agency of the tallow1 oil1 c4--,office of the wick4--,reason why tallow candles require snuffing1 and wax candles snuff themselves--,further observations on the subject4 ,,method ,,of ,,ascertaining ,,the ,,illuminating ,,power ,,of ,,candles1 ,,lamps1 ,,and ,,other ,,luminous ,,bodies4 #bb4 ,optical principle assumed as law for determining the relative strength of lights of different kinds4--,admeasurement of the intensities of light4--,quantity of wax1 tallow1 oil1 c4 requisite for producing a light of a certain strength4--,method of increasing the light of tallow candles1 and to obviate the necessity of snuffing them4--,a tallow candle placed in an inclined position gives more light than when placed perpendicularly and snuffed with an instrument4--,explanation of the fact4--,further observations on this subject4--,comparative cost of the light obtained by burning tallow candles of different sorts and sizes4 ,,part ,,ii4 ,,gas-,,light4 #dg4 ,encouragement given by the legislature to the new system of procuring light4--,gas-light company1 incorporated by charter1 to apply the new art of illumination by way of experiment1 on a large scale1 to illuminate the streets and houses of the metropolis4--,power and authorities granted to this corporate body4--are very restricted1 and do not prevent other individuals from entering into competition with them4--,boundaries of their experiments4--limit of capital employed by them4--,power of ,his ,majesty with regard to the gas-light charter4 ,,theory ,,of ,,the ,,combustion ,,of ,,coal ,,in ,,elucidation ,,of ,,the ,,nature ,,of ,,gas- ,,light4 #di4 ,natural history of pit-coal4--,immediate constituent parts of coal4-- ,their relative quantities--are different in different kinds of coal4-- ,phenomena1 which happen during the combustion of coal4--,analysis of coal by distillation4--,great waste of matter capable of producing light and heat1 in the usual mode of burning coal4--,proofs of this statement4--,theory of the production of gas-light1 compared with the production of light obtained by candles and lamps4--,place which the discovery of lighting with gas occupies in the philosophical order of knowledge4 ,,historical ,,sketch ,,of ,,the ,,rise ,,and ,,progress ,,of ,,the ,,application ,,of ,,coal- ,,gas ,,as ,a ,,substitute ,,for ,,procuring ,,artificial ,,light4 #ee4 ,the discovery of the inflammable nature and application of coal-gas for the production of artificial light1 cannot be claimed by any body now living4--,early notices of the inflammable property of the gas obtained by distilling coal4--,attempts to substitute it for tallow and oil4--,experiments made with coal-gas by ,dr4 ,,clayton1 ,dr4 ,,hales1 and the ,bishop of ,llandaff4--,first successful attempt of lighting manu- factories with gas4--,creditor and debtor account concerning the expence of this mode of illumination1 when compared with the light obtained by tallow candles4--,claims of ,mr4 ,,murdoch with regard to the economical application of coal-gas4--,claims of ,mr4 ,,winsor4--,experi- ments of ,mr4 ,,northern1 ,mr4 ,,clegg1 ,mr4 ,,cook1 ,mr4 ,,ackermann4--,economical statements of the gas-light illumination when compared with the cost of the same quantity of light obtained by means of candles and lamps4 ,,theory ,,of ,,the ,,production ,,of ,,gas-,,light2 ,,and ,,description ,,of ,a ,,portable ,,apparatus ,,for ,,illustrating1 ,,in ,,the ,,small ,,way1 ,,the ,,general ,,nature ,,of ,,the ,,new ,,system ,,of ,,procuring ,,light4 #gg4 ,philosophy of the production of coal-gas4--,characters of the various products which the gas-light process affords1 their quantities1 and modes of obtaining them4--,quantity of gas obtainable from a given weight of coal4--,illuminating power of a given bulk of coal-gas compared with the illuminating power of a given weight of tallow candles4--,practical directions with regard to the production of the gas from coal4--,its chemical constitution and analysis4--,pit-coal is not the only substance which affords carburetted hidrogen gas4--,this gas exists ready formed in nature4--,mode of collecting it when found native4--,is given out by all kinds of vegetable matter1 submitted to distillation in close vessels4--,other sources of obtaining this gazeous fluid4--,practical directions with regard to the method of obtaining from coal1 this gazeous substance1 as best suited for illumination4--,chemical constitution of coal-gas4--,how ascertained4 ,,utility ,,of ,,the ,,gas-,,light ,,illumination ,,with ,,regard ,,to ,,public ,,and ,,private ,,economy4 #ii4 ,objects to which the new system of lighting with gas may be beneficially applied4--,capital advantages of the gas-light illumina- tion4--,places and public edifices lighted with coal-gas in this metro- polis4--,situations best suited for the application of gas-lights4-- places where it cannot be used to advantage4--,illumination of barracks1 arsenals1 dock yards1 c4 with coal-gas4--,further observa- tions on this subject4--,great heat produced by gas-lights4--,reason why the flame of coal-gas produces more heat than the flame of candles and lamps4--,admeasurement of the comparative degrees of heat produced by gas-lights1 oil lamps1 tallow and wax candles1 c4--,gas lamps and burners1 various kinds of4--,ornamental chandeliers and candelabras1 for applying coal-gas as a substitute for oil4--,other products obtain- able from coal besides gas4--,coke4--,its nature4--,combustion of it4-- ,produces a more strong and lasting heat than coal4--,explanation of this fact4--,advantages resulting from the use of coke as fuel4--,disad- vantages of its application in certain circumstances4--,relative effect of heat produced by equal quantities of coke and charcoal4--,method of measuring the comparative effect of different kinds of fuel in pro- ducing heat4--,capital advantages resulting from the application of coke1 as fuel1 in the art of burning lime4--,plaster of ,paris1 bricks1 c4--,quantity of coke obtainable from a certain quantity of pit-coal4 --,kind of coke best suited for metallurgical operations4--,mode of obtaining it in the gas-light process4--,sort of coke best adapted for kitchen and parlour fires4--,manufacture of it4--,coal tar4--,how obtained4--,its properties4--,earl of ,dundonald's method of manufac- turing tar from coal4--,quantity of coal-tar produced in the gas-light process from a given quantity of coal4--,characters of coal tar obtained from ,newcastle coal1 differ from that produced from canel coal4--,coal pitch4--,process for obtaining it4--,properties of coal- pitch4--,use of it in the arts4--quantity of coal-pitch obtainable from a given quantity of tar4--,ammoniacal liquor produced during the distillation of coal4--,its chemical constitution4--,quantity obtained from a given quantity of coal4--,general observation respecting the scheme of applying coal-gas as a substitute for candles and lamps4-- ,effects which it must produce upon the arts and upon domestic economy4 --,its views4--,primary advantages4--,resources which it presents to industry and public economy4--,in what respect it is entitled to public approbation and national encouragement4--,effects of prejudice against the introduction of new and useful discoveries4--,have operated strongly in retarding the gas-light illumination4--,remarkable slowness with which improvements of extended utility make their way into common use1 contrasted with the rapid adoption of fashionable changes4--,other causes unfavourable to the adoption of new and useful plans4--,further observations on this subject4--,the new system of lighting with coal- gas can never supersede the use of candles and moveable lights4--,gas- light illumination cannot prove injurious to the ,greenland fishery-- nor can it diminish the coal trade--must prove beneficial to it4--,the price of coal even when it is the highest cannot materially affect the beneficial application of gas-lights4--,striking advantages to be derived from the introduction of gas-lights into manufactories4-- ,principal expense which must always attend the gas-light illumination4 --,is the dead capital employed for erecting the machinery4--,floating capital is small4--,advice to private individuals with regard to the erection of a gas-light apparatus calculated for their own use4-- ,expence which must attend the application of the new system of lighting under different circumstances4--,entire new scheme of illuminating streets1 or small towns1 with gas-lights2 which would save all the main pipes for conveying the gas through the streets as well as the branch pipes which conduct the gas to the lamps4--,manage- ment of the gas-light machinery is extremely simple and easy4--,the apparatus not liable to be out of order4--,observations on the safety of the gas-light illumination4--,misapprehension of the public con- cerning it4--,causes that have alarmed the public concerning the application of the new lights4--,gas-lights cannot give rise to those accidents which have so often arisen from the careless snuffing of candles1 c4--,produce no embers or sparks4--,cannot fall1 or be dis- turbed without becoming extinguished4--,are the safest of all lights4-- ,impossibility of streets or towns lighted with gas to be thrown suddenly into darkness by the fracture of the gas-pipes conveying the gas to the lamps--or by the destruction of one or more of the gas- light machineries employed for preparing the gas4--,illustration showing the absurdity of such mistaken notions4--,curious self-ex- tinguishing lamp1 invented by ,mr4 ,,clegg4--,his machine which measures and registers in the absence of the observer1 the quantity of gas delivered by a pipe communicating with a gas-light main4--,leading characters of the new lights4--,objects and views which this art embraces4--,it must lessen the consumption of oil4--,occasion a defalcation in the revenue4 ,,tabular ,,view1 ,exhibiting the quantity of ,,gas1 ,,coke1 ,,tar1 ,,pitch1 ,,essential ,,oil1 and ,,ammoniacal ,,liquor1 obtainable from a given quantity of ,,coal3 together with an estimate of the quantity of ,coal necessary to produce a quantity of ,gas1 capable of yielding a ,light equal in duration of time and intensity to that produced by ,tallow ,candles of different kinds4 #afd4 ,,description ,,of ,,the ,,gas-,,light ,,apparatus4 #aff4 ,,method of correcting the relative pressure of the ,gasometer1 so as to cause the gas which it contains to be uniformly of an equal density4 #aha4 ,,directions ,,to ,,workmen ,,attending ,,the ,,gas-,,light ,,apparatus4 #ahb4 ,,estimate of the price of a ,gas-,light ,apparatus4 #ahe4 ,,london ,price ,list of the most essential articles employed in the erection of a ,gas-light ,apparatus4 #ahf4 ,,errata4 ,page #bd1 line #aa1 for too1 read two4 #dh1 #bb1 for corporated1 read incorporated4 #ec1 #g1 for this combustion1 read the combustion4 #fd1 #bd1 for ,,cleg1 read ,,clegg4 ibid #be1 for communicates1 read communicated4 #fe1 erase the 99 and put it after the word ,,clegg1 line #bd1 p4 #fd4 ibid #ag1 for attemps1 read attempts4 #abe1 #bc1 for degree1 read degrees4 #acb1 #be1 for coal1 read coal-tar4 ,,directions ,,to ,,the ,,binder3 ,plate ,i4 facing the title2 plate ,,ii4 facing page #gi2 plate ,,iii4 facing page #aae2 plate ,,iv4 facing page #aai2 plate ,v4 facing page #abj2 and plates ,,vi4 and ,,vii4 at the end of the book4 ,a ,,practical ,,treatise ,,on ,,gas-,,light4 ,,introductory ,,observation4 ,,influence ,,of ,,the ,,progress ,,of ,,the ,,arts ,,upon ,,the ,,morals ,,and ,,condition ,,of ,,man4 ,it is an undoubted truth1 that the successive improvements in the condition of man1 from a state of ignorance and barbarism1 to that of the highest cultivation and refinement1 are usually effected by the aid of machinery and expedients1 calculated to procure the necessaries1 the comforts1 and the elegancies of life2 and that the pre-eminence of any people in civilization is1 and ought ever to be1 estimated by the proportional state of industry1 and useful labour existing among them4 ,in proof of this great and striking truth1 no other argument requires to be offered1 than an immediate reference to the experience of all ages and places3 the various nations of the earth1 the provinces of each nation1 the towns1 and even the villages of the same province1 differ from each other in their accommodations2 and are in every respect more flourishing1 the greater their activity in establishing new channels of useful employ1 calculated to procure the necessaries and comforts of life4 ,hence the nations which have shewn the most ingenuity in this way1 are not only the richest1 but also the most populous and the best defended3 the provinces of those nations1 are seen to flourish likewise in proportion to their respective degrees of activity in this respect1 ,and from these exertions it is1 as ,,smith#a emphatically remarks1 that 8the accommodation of an ,european prince does not always so much exceed that of an industrious and frugal peasant1 as the accommodation of the latter exceeds that of many an ,african king1 the absolute master of the lives and liberties of ten thousand naked savages40 #a ,wealth of ,nations1 chap4 #a4 ,it was a strange notion of ,rousseau to maintain that mankind were happier when they resembled wild beasts1 than with all the expanded knowledge of civilized life2 and that the cultivation of their understanding had tended to degenerate their virtues4 ,there can be no virtue but what is founded on a comprehensive estimate of the effects of human actions1 and an animal under the guidance of instinct can form no such estimate4 ,the variety of production1 of wants1 and fabrication of a civilized society1 has given rise to barter or exchange2 mutual supply has increased the sub-division of labour1 and improved the means of conveyance4 ,streams1 roads1 ships1 and carriages have extended their beneficial intercourse2 confidence between man and man has advanced the moral principles of society1 and afforded a progression1 of which the past gradation may indeed be traced1 but to the future part of which the imagination can scarcely form a probable outline4 ,and as the moral and physical powers of man expand1 new resources and new agencies are made subservient to our commands1 which1 in an earlier state of society1 would have appeared altogether visionary4 ,who among the ancients would have listened to the extraordinary scheme of writing books with such rapidity1 that one man1 by this new art1 should perform the work of twenty thousand amanuenses8 ,what philosopher would have given credit to the daring project of navigating the widest ocean8--or imagined the astonishing effect of gun-powder--or the extended application of the steam engine8 ,what mortal would have dared to dive to the bottom of the sea--or to soar aloft into the air--or bid defiance to the thunder of the clouds8 ,discoveries which have changed1 as it were1 the course of human affairs1 and the effects of which have already carried the intellectual operations of the human mind1 to a height they could by no other means have attained4 ,the men of those early ages1 in the confidence of their own wisdom1 might have derided these discoveries as impossible1 or rejected them as visionary2 but to those1 who enjoy the full effects of such1 and numerous other successful inventions1 it becomes a duty to reason upon different principles1 and to exert all means in their power to give effect to the progress of useful knowledge4 ,the artificial production and supply of light during the absence of the sun1 unquestionably holds a distinguished rank among the most important arts of civilized life4 ,if we could for a moment suppose the privation of artificial light1 it would follow as an immediate consequence that the greatest part of the globe on which we dwell1 would cease to be the habitation of man4 ,whether he could ensnare or overtake those animals upon whose unprepared remains he would then be compelled to feed--whether he might store the fruits of the earth for his winter supply--what might be the physical and moral consequences of a state of such desolation1 may perhaps be conjectured2 but no estimate can show its dreadful magnitude4 ,how much do our comforts1 and how greatly does the extent of our powers1 in the common affairs of life1 depend upon the production and supply of artificial light4 ,the flame of a single candle animates a family1 every one follows his occupation1 and no dread is felt of the darkness of night4 ,it might be a curious speculation to enquire how far1 and in what respects1 the morals of men would become degraded by the want of this contrivance4 ,but it is sufficient on the present occasion1 that1 previous to entering upon a dissertation respecting a new art of illumination1 a train of ideas has slightly been hinted at1 which cannot fail to show its magnitude and importance4 ,the methods of procuring and distributing light1 during the absence of the sun1 have not hitherto attained the extent of their possible perfection3 there is yet a wide field for improvement in the construction of the instruments of illumination1 and the subject is highly deserving the attention of every individual4 ,the scheme of lighting houses1 streets1 and manufactories1 by means of the inflammable gas1 obtainable by distillation from common pit-coal1 professes to increase the wealth of the nation1 by adding to the number of its internal resources1 and on this ground it is entitled1 at least1 to a candid examination4 ,the apparent slight that has been thrown upon this new breach of civil economy by some individuals1 who appear to be incapable of judging of its nature1 has contributed to deter sensible and well disposed persons from wishing it success4 ,it is the more necessary to state this fact1 because1 when a mistaken notion once becomes diffused1 concerning the nature of a new project1 persons of the best intention are liable to become affected with wrong impressions on their mind4 ,i am neither a share holder1 nor a governor1 nor am ,i directly or indirectly concerned in any gas-light association4 ,the object of the succeeding pages1 simply is to rescue the art of illumination with coal-gas from misconception and misrepresentation1 and by a fair1 and not overcharged statement of its merits and its disadvantages1 to appeal from prejudice and ignorance1 to the good sense of the community4 ,,part ,i4 ,,production ,,of ,,artificial ,,light2 ,,and ,,theory ,,of ,,the ,,action ,,of ,,candles ,,and ,,lamps4 ,the flame of burning bodies consists of such inflammable matter in the act of combustion as is capable of existing in a gazeous state4 ,when all circumstances are favorable to the complete combustion of the products1 the flame is perfect2 if this is not the case1 part of the combustible body1 capable of being converted into the gazeous state1 passes through the luminous flame unburnt1 and exhibits the appearance of smoke4 ,soot therefore always indicates an imperfect combustion4 ,hence flame is produced from those inflammable substances only1 which are either totally volatile when heat is applied to them1 so as not to alter their chemical habitudes--or which contain a quantity of combustible matter that is readily volatilized into vapour by heat1 or the elements necessary for producing such vapour or gazeous products1 when the chemical constitution of the body is altered by an increase of temperature4 ,and hence the flame of bodies is nothing else than the inflammable product1 either in a vaporous or in a permanently elastic gazeous state4 ,thus originates the flame of wood and coal1 when they are burned in their crude state4 ,they contain the elements of a quantity of inflammable matter1 which is capable of assuming the gazeous state by the application of heat1 and subsequent new chemical arrangements of their constituent parts4 ,as the artificial light of lamps and candles is afforded by the flame they exhibit1 it seems a matter of considerable importance to society1 to ascertain how the most luminous flame may be produced with the least consumption of combustible matter4 ,there does not appear to be any danger of error in concluding1 that the light emitted will be greatest when the matter is completely consumed in the shortest time4 ,it is therefore necessary1 that the stream of volatilized combustible gazeous matter should pass into the atmosphere with a certain determinate velocity4 ,if the quantity of this stream should not be duly proportioned2 that is to say1 if it be too large1 its internal parts will not be completely burned for want of contact with the air4 ,if its temperature be below that of ignition1 it will not1 in many cases1 burn when it comes into the open air4 ,and there is a certain velocity at which the quantity of atmospherical air which comes in contact with the vapour will be neither too great nor too small2 for too much air will diminish the temperature of the stream of combustible matter so much as very considerably to impede the desired effect1 and too little will render the combustion languid4 ,we have an example of a flame too large in the mouths of the chimneys of furnaces1 where the luminous part is merely superficial1 or of the thickness of about an inch or two1 according to circumstances1 and the internal part1 though hot1 will not set fire to paper passed into it through an iron tube2 the same defect of air preventing the combustion of the paper1 as prevented the interior fluid itself from burning4 ,and in the lamp of ,argand we see the advantage of an internal current of air1 which renders the combustion perfect by the application of air on both sides of a thin flame4 ,so likewise a small flame is always whiter and more luminous than a larger2 and a short snuff of a candle giving out less combustible matter in proportion to the circumambient air2 the quantity of light becomes increased to eight or ten times what a long snuff would have afforded4 ,the light of bodies burning with flame1 exists previously either combined with the combustible body1 or with the substance which supports the combustion4 ,we know that light exists in some bodies as a constituent part1 since it is disengaged from them when they enter into new combinations1 but we are unable to obtain in a separate state the basis with which it was combined4 ,that in many cases the light evolved by artificial means is derived from the combustible body1 is obvious1 if we recollect that the colour of the light emitted during the process of combustion varies1 and that this variation usually depends not upon the medium which supports the process of combustion1 but upon the combustible body itself4 ,hence the colour of the flame of certain combustibles1 even of the purest kind may be tinged by the admixture of various substances4 ,the flame of a common candle is far from being of an uniform colour4 ,the lowest part is always blue2 and when the flame is sufficiently elongated1 so as to be just ready to smoke1 the tip is red or brown4 ,as for the colours of flames that arise from coals1 wood1 and other usual combustibles1 their variety1 which hardly amounts to a few shades of red or purple1 intermixed with the bright yellow light1 seems principally to arise from the greater or less admixture of aqueous vapour1 dense smoke1 or1 in short1 of other incombustible products which pass through the luminous flame unburnt4 ,spirit of wine burns with a blueish flame4 ,the flame of sulphur has nearly the same tinge4 ,the flame of zinc is of a bright greenish white4 ,the flame of most of the preparations of copper1 or of the substances with which they are mixed1 is vivid green4 ,spirit of wine1 mixed with common salt1 when set on fire1 burns with a very unpleasant effect1 as may be experienced by looking at the spectators who are illuminated by such light4 ,if a spoonful of spirit of wine and a little boracic acid1 or nitrate of copper be stirred together in a cup1 and then be set on fire1 the flame will be beautifully green4 ,if spirit of wine be mixed with nitrate of strontia1 it will1 afterwards1 on being inflamed1 burn with a carmine red colour4 ,muriate of lime tinges the flame of burning spirit of wine of an orange colour4#b #b ,see ,chemical ,amusement1 comprising minute instructions for performing a series of striking and interesting chemical experiments1 p4 #h1 c4 ,before we consider the general nature of ,gas-,light1 it will be necessary to give a short sketch of the theory and action of the instruments of illumination employed for supplying light1 together with some other facts connected with the artificial production and distribution of light2 such a proceeding will enable us to understand the general nature of the new system of illumination which it is the object of this ,essay to explain4 ,to procure light for the ordinary purposes of life1 we are acquainted with no other ready means than the process of combustion4 ,the rude method of illumination consists1 as is sufficiently known1 in successively burning certain masses of fuel in the solid state3 common fires answer this purpose in the apartments of houses1 and in some light-houses4 ,small fires of resinous wood1 and the bituminous fossil1 called canel-coal1 are in some countries applied to the same end1 but the most general and useful contrivance is that in which fat1 or oil1 of an animal or vegetable kind is burned by means of a wick1 and these contrivances comprehend candles and lamps4 ,in the lamp the combustible substance must be one of those which retain their fluidity at the ordinary temperature of the atmosphere4 ,the candle is formed of a material which is not fusible but at a temperature considerably elevated4 ,all these substances must be rendered volatile before they can produce a flame1 but for this purpose it is sufficient to volatilize a small quantity of any of them1 successively2 for this small quantity will suffice to give a useful light1 and hence we must admire the simple1 yet wonderful contrivance of a common candle or lamp4 ,these bodies contain a considerable quantity of the combustible substance1 sufficient to last several hours2 they have likewise1 in a particular place1 a slender piece of spongy vegetable substance1 called the wick1 which in fact is the fire-place1 or laboratory where the whole operation is conducted4 ,there are three articles which demand our attention in the lamp--the oil1 the wick1 and the supply of air4 ,it is required that the oil should be readily inflammable2 the office of the wick appears to be chiefly1 if not solely1 to convey the oil by capillary attraction to the place of combustion2 as the oil is decomposed into carburetted hydrogen gas and other products1 other oil succeeds1 and in this way a continual current and maintenance of flame is effected4 ,when a candle is for the first time lighted1 a degree of heat is given to the wick1 sufficient first to melt1 and next to decompose the tallow surrounding its lower surface2 and just in this part the newly generated gas and vapour is1 by admixture with the air1 converted into a blue flame2 which1 almost instantaneously encompassing the whole body of the vapour1 communicates so much heat to it1 as to make it emit a yellowish white light4 ,the tallow now liquefied1 as fast as it boils away at the top of the wick1 is1 by the capillary attraction of the same wick1 drawn up to supply the place of what is consumed by the cotton4 ,the congeries of capillary tubes1 which form the wick1 is black1 because it is converted into coal2 a circumstance common to it with all other vegetable and animal substances1 when part of the carbon and hydrogen which enter into their composition having been acted on by combustion1 the remainder and other fixed parts are by any means whatever covered and defended from the action of the air4 ,in this case1 the burning substance owes its protection to the surrounding flame4 ,for when the wick1 by the continual wasting of the tallow1 becomes too long to support itself in a perpendicular situation1 the top of it projects out of the cone formed by the flame1 and thus being exposed to the action of the air1 is ignited1 loses its blackness1 and is converted into ashes2 but that part of the combustible which is successively rendered volatile by the heat of the flame is not all burnt1 but part of it escapes in the form of smoke through the middle of the flame1 because that part cannot come in contact with the oxygen of the surrounding atmosphere2 hence it follows1 that with a large wick and a large flame1 this waste of combustible matter is proportionately much greater than with a small wick and a small flame4 ,in fact1 when the wick is not greater than a single thread of cotton1 the flame1 though very small1 is1 however1 peculiarly bright1 and free from smoke2 whereas in lamps1 with very large wicks1 such as are often suspended before butchers' shops1 or with those of the lamp-lighters1 the smoke is very offensive1 and in great measure eclipses the light of the flame4 ,a candle differs from a lamp in one very essential circumstance2 viz4 that the oil or tallow is liquefied1 only as it comes into the vicinity of the combustion2 and this fluid is retained in the hollow of the part1 which is still concrete1 and forms a kind of cup4 ,the wick1 therefore1 should not1 on this account1 be too thin1 because if this were the case1 it would not carry off the material as fast as it becomes fused2 and the consequence would be1 that it would gutter or run down the sides of the candle3 and as this inconvenience arises from the fusibility of the tallow it is plain that a more fusible candle will require a larger wick2 or that the wick of a wax candle may be made thinner than that of one of tallow4 ,the flame of a tallow candle will of course be yellow1 smoky1 and obscure1 except for a short time after snuffing4 ,when a candle with a thick wick is first lighted1 and the wick snuffed short1 the flame is perfect and luminous1 unless its diameter be very great2 in which last case1 there is an opake part in the middle1 where the combustion is impeded for want of air4 ,as the wick becomes longer1 the interval between its upper extremity and the apex of the flame is diminished2 and consequently the tallow which issues from that extremity1 having a less space of ignition to pass through1 is less completely burned1 and passes off partly in smoke4 ,this evil increases1 until at length the upper extremity of the wick projects beyond the flame and forms a support for an accumulation of soot which is afforded by the imperfect combustion1 and which retains its figure1 until1 by the descent of the flame1 the external air can have access to the upper extremity2 but in this case1 the requisite combustion which might snuff it1 is not effected2 for the portion of tallow emitted by the long wick is not only too large to be perfectly burned1 but also carries off much of the heat of the flame1 while it assumes the elastic state4 ,by this diminished combustion1 and increased afflux of half decomposed oil1 a portion of coal or soot is deposited on the upper part of the wick1 which gradually accumulates1 and at length assumes the appearance of a fungus4 ,the candle then does not give more than one-tenth of the light which the due combustion of its materials would produce2 and1 on this account1 tallow candles require continual snuffing4 ,but if we direct our attention to a wax candle1 we find that as its wick lengthens1 the light indeed becomes less4 ,the wick1 however1 being thin and flexible1 does not long occupy its place in the centre of the flame2 neither does it1 even in that situation1 enlarge the diameter of the flame1 so as to prevent the access of air to its internal part4 ,when its length is too great for the vertical position1 it bends on one side2 and its extremity1 coming in contact with air1 is burned to ashes2 excepting such a portion as is defended by the continual afflux of melted wax1 which is volatilized1 and completely burned1 by the surrounding flame4 ,hence it appears1 that the difficult fusibility of wax renders it practicable to burn a large quantity of fluid by means of a small wick1 and that this small wick1 by turning on one side in consequence of its flexibility1 performs the operation of snuffing itself1 in a much more accurate manner than can ever be performed mechanically4 ,from the above statement it appears1 that the important object to society of rendering tallow candles equal to those of wax1 does not at all depend on the combustibility of the respective materials1 but upon a mechanical advantage in the cup1 which is afforded by the inferior degree of fusibility in the wax3 and that1 in order to obtain this valuable object1 one of the following effects must be produced3 either the tallow must be burned in a lamp1 to avoid the gradual progression of the flame along the wick2 or some means must be devised to enable the candle to snuff itself1 as the wax-candle does2 or the tallow itself must be rendered less fusible by some chemical process4 ,the object is1 in a commercial point of view1 entitled to assiduous and extensive investigation4 ,chemists in general suppose the hardness or less fusibility of wax to arise from oxygen4 ,mr4 ,,nicholson#c is led by various considerations to imagine1 that the spontaneous snuffing of candles made of tallow or other fusible materials1 will scarcely be effected but by the discovery of some material for the wick1 which shall be voluminous enough to absorb the tallow1 and at the same time sufficiently flexible to bend on one side4 #c ,philosophical ,journal1 #dto ,series1 ,vol4 ,i4 p4 #gj4 ,,method ,,of ,,ascertaining ,,the ,,illuminating ,,power ,,of ,,candles1 ,,lamps1 ,,gas-,,lights1 ,,and ,,other ,,luminous ,,bodies4 ,though the eye is not fitted to judge of the proportional force of different lights1 it can distinguish1 in many cases with great precision1 when two similar surfaces1 presented together1 are equally illuminated4 ,but as the lucid particles are darted in right lines1 they must spread uniformly1 and hence their density will diminish in the duplicate ratio of their distance4 ,from the respective situations1 therefore1 of the centres of divergency1 when the contrasted surfaces become equally bright1 we may easily compute their relative degrees of intensity4 ,for this purpose it is assumed as a principle1 that the same quantity of light1 diverging in all directions from a luminous body1 remains undiminished in all distances from the centre of divergency4 ,thus we must suppose1 that the quantity of light falling on every body1 is the same as would have fallen on the places occupied by the shadow2 and if there were any doubt of the truth of the supposition1 it might be confirmed by some simple experiment4 ,therefore1 it follows1 that1 since the shadow of a square inch of any surface occupies at twice the distance of the surface from the luminous point the space of four square inches1 the intensity of the light diminishes as the square of the distance increases4 ,if1 consequently1 we remove two sources of light to such distances from an object that they may illuminate it in equal degrees1 we may conclude that their original intensities are inversely as the squares of the distances4 ,hence1 if two lights of unequal illuminating powers shine upon the same surface at equal obliquities1 and an opake body be interposed between them and the illuminated surface1 the two shadows produced1 must differ in blackness or intensity in the same degree4 ,for the shadow formed by intercepting the greater light1 will be illuminated by the smaller light only1 and reversely the other shadow will be illuminated by the greater light3 that is to say1 the stronger light will be attended with the deeper shadow4 ,now it is easy1 by removing the stronger light to a greater distance1 to render the shadow which it produces at the common surface equal to that afforded by the less4 ,experiments of this kind may be conveniently made by fastening a sheet of white paper against the wall of a room2 the two lights1 of whatever nature they are1 intended to be compared1 must then be placed so that the ray of light from each shall fall with nearly the same angle of incidence upon the middle of the paper4 ,in this situation1 if a book or other object be held to intercept part of the light which would have fallen on the paper1 the two shadows may be made to appear as in this figure2 ,illustration where ,a represents the surface illuminated by one of the lights only2 ,b1 the surface illuminated by the other light2 ,c1 the perfect shadow from which both lights are excluded4 ,it will easily be understood that the lights about ,d and ,e1 near the angle ,f1 will fall with equal incidences when the double shadow is made to occupy the middle of the paper2 and consequently1 if one or both of the lights be removed directly towards or from the paper1 as the appearances may require1 until the two shadows at ,e and ,d have the same intensity1 the quantities of light emitted by each will be as the squares of the distances from the paper4 ,by some experiments made in this way1 the degree of illumination of different lights may readily be ascertained to the tenth part of the whole4 ,and1 by experiments of this kind1 many useful particulars may be shewn4 ,for1 since the cost and duration of candles1 and the consumption of oil in lamps1 are easily ascertainable1 it may be shewn whether more or less light is obtained at the same expence during a given time1 by burning a number of small candles instead of one or more of greater thickness4 ,it will therefore be easy to compare the power of different kinds of lamps or candles1 or gas lights1 so as to determine the relative cost of each particular kind of the combustible substance employed for furnishing light3--for example1 if a candle and a gas-burner supplying coal-gas1 adjusted by a stop-cock1 produce the same darkness of shadow1 at the same distance from the wall1 the strength or intensity of light is the same4 ,an uniform degree of intensity of the gas-light may readily be produced1 by opening or shutting the stop-cock1 if more or less be required1 and the candle is carefully snuffed to produce the most regular and greatest quantity of light4 ,the size of the flame in experiments of this kind of course becomes unnecessary1 and will vary very much with the quality of the coal gas4 ,the bulk of the gas consumed1 and the quantity of tallow used1 by weighing the candle before and after the experiment1 furnish the data for ascertaining the relative costs of tallow and gas-light1 when compared with each other4 ,from experiments made by ,count ,,rumford1 concerning the quantity of materials requisite for producing a light of a certain intensity for a given time3 it was found that we must burn of wax #ajj1 of tallow #aja1 of oil1 in an ,argand's lamp1 #abi1 of an ill-snuffed tallow candle #bbi parts1 by weight4 ,and with regard to the quantity of carburetted hydrogen1 or coal-gas1 ,i have found that from #ah to #bj cubic feet 7according to the purity of the gas7 are required to give a light equal in duration and in illuminating powers to #alb4 of tallow candles1 six to the pound1 provided they were set up and burnt out one after another4#d #d #aablbs4 of ,newcastle coal1 called ,tanfield ,moor1 produce1 upon an average1 from #bej to #cjj cubic feet of gas1 fit for illumination4 ,,further ,,illustrations ,,of ,,the ,,mode ,,of ,,computing ,,the ,,relative ,,cost ,,or ,,value ,,of ,,light1 ,,emitted ,,by ,,means ,,of ,,candles1 ,,lamps1 ,,other ,,bodies4 ,it is sufficiently known that the light of a candle1 which is so exceedingly brilliant when first snuffed1 is very speedily diminished to one-half and is usually not more than one-fifth or one-sixth before the uneasiness of the eye induces us to snuff it4#e ,whence it follows1 that if candles could be made so as not to require snuffing1 the average quantity of light afforded by the same quantity of combustible matter would be more than doubled4 #e ,ezekiel ,walker4--,nicholson's ,journal1 ,vol4 ,,iv4 #hvo4 ,series4 ,when a lighted candle is so placed as neither to require snuffing or produce smoke1 it is reasonable to conclude that the whole of the combustible matter which is consumed is converted to the purpose of generating light2 and that the intensities of light afforded in a given time1 by candles of different dimensions1 are in proportion to the quantity of matter consumed4 ,that is to say2 when candles are made of the same materials1 if one candle produce twice as much light as another1 the former will in the same time lose twice as much weight as the latter4 ,to prove the truth of this position1 ,mr4 ,walker made the experiments contained in the following ,,table4 ---------------------------------------- -------------- ,weight of the ,distance ,no4 of ,no4 of ,time of ,candles ,strength of the the the burning4 consumed of ,candles ,experiment4,candles4 in a ,light4 from the given ,wall4 time4 ---------------------------------------- -------------- h4 oz4 dr4 ,feet4 #a #c #j #j #ae #a #g #a #c #c #j #a #a #a #g ,mould #c #j #j #ae #a #g ---------------------------------------- -------------- #a #b #ee #j #ae #a #h #b #c #b #ee #a #j #a #h ,mould #b #ee #j #ae #a #h ---------------------------------------- -------------- #a #c #j #j #ae #a #h #c #c #c #j #a #b #a #h ,mould #c #j #j #j #a #i ---------------------------------------- -------------- #d #e #c #j #a #e #a4ah #h ,mould #c #j #a #a #a4 #h ---------------------------------------- -------------- ,these experiments1 ,mr4 ,walker informs us1 were made in the following manner3-- ,three candles1 the dimensions of which are given in the table1 against #a1 #c1 and mould4 ,these were first weighed1 and then lighted at the same instant4 ,at the end of the time inserted in the third column of the above table1 they were extinguished and weighed again1 and the loss of weight of each candle is contained in the fourth column4 ,the three first experiments were made under such favourable circumstance1 that there was little doubt of their results being more accurate than what practical utility requires1 but the fourth experiment cannot be depended on so much1 in consequence of the variable light of ,no4 #e4 ,this candle was moved so often to keep the two shadows equal1 that it was found necessary to set down its mean distance from the wall by estimation2 but as this was done before the candles were weighed1 the experimenter's mind could not be under the influence of partiality for a system4 ,the method which ,mr4 ,walker employed in comparing one light with another in each experiment1 was that which has been described page #bd4 #a4 ,the experiments were made at different times1 and the light of the mould candle was made the standard1 with which the lights of the others were compared2 but it must not be understood1 that this candle gave the same strength of light in every experiment4 #b4 ,the sign in the #eth column1 signifies that the candle against which it is placed1 gave a stronger light than the others4 ,from the experiments contained in the table1 it appears to be an established law1 where combustion is complete1 that the quantities of light produced by tallow candles1 are in the complicate ratio of their times of burning and weights of matter consumed4 ,for if their quantities of matter be equal1 and times of burning the same1 they will give equal quantities of light1 by the experiments4 ,and if the times of burning be equal1 the quantities of light will be directly as their weights of matter expended4 ,therefore the light is universally in the compound ratio of the time of burning and weight of matter consumed4 ,if the law which ,mr4 ,walker has endeavoured to prove1 both by reason and experiment1 be admitted1 we have a standard with which we may compare the strength of any other light4 ,let a small mould candle1 when lighted1 be so placed as neither to produce smoke nor require snuffing1 and it will lose an ounce of its weight in three hours4 ,let this quantity of light produced under these circumstances1 be represented by #a4jj4 ,then should this candle at any other time1 lose more or less of its weight in three hours than an ounce1 the quantity of light will be still known1 because the quantity of light in a given time is directly as the weight of the candle consumed4#f #f ,to investigate rules for this purpose1 #a4 ,let ,m represent the mould candle1 a its distance from the wall1 on which the shadows were compared1 x its quantity of matter consumed in a given time1 7t7 and ,q the quantity of light emitted by ,m in the same time3 #b4 ,let m represent any other candle1 b its distance from the same wall1 and y its quantity of matter consumed1 in the time t4 ,then as the intensities of light are directly as the squares of the distances of the two candles from the wall1 we have as a 3 ,q b 3 7b ,q7_/a the quantity of light1 emitted by m in the time4 ,then let us suppose that the quantities of light are directly as the quantities of matter consumed in the time t1 and we have1 ,as x 3 ,q y 3 7y ,q7_/x the quantity of light emitted by m in that time1 by hypothesis4 ,now1 when 7b ,q7_/a 7,theo4 #a47 is 7,y ,q7_/,x 7,theo4 #b47 the quantities of light of ,m and m are directly as their quantities of matter consumed in any given time4 ,,method ,,of ,,increasing ,,the ,,light ,,of ,,tallow ,,candles1 ,,and ,,to ,,obviate ,,the ,,necessity ,,of ,,snuffing ,,them4 ,mr4 ,,ezekiel ,,walker has shewn that1 if a trifling alteration be made in the method of using common tallow candles1 they will become excellent substitutes for those of wax4 ,a common candle1 weighing one-tenth of a pound1 containing fourteen single threads of fine cotton1 placed so as to form an angle of #cj degrees#g with the perpendicular1 and lighted1 requires no snuffing2 and what is much more valuable for some purposes1 it gives a light that is nearly uniform in strength without the least smoke4 ,these effects are thus produced3 #g ,candlesticks may be made to hold the candle at this angle1 or they may be so contrived as to hold the candle at any angle at pleasure4 ,when a candle burns in an inclined position1 most part of the flame rises perpendicularly from the upper side of the wick1 and when viewed in a certain direction1 it appears in the form of an obtuse angled triangle4 ,and as the end of the wick projects beyond the flame at the obtuse angle1 it meets with the air1 and is completely burnt to ashes3 hence it is rendered incapable of acting as a conductor to carry off part of the combustible matter in the form of smoke4 ,by this spontaneous mode of snuffing1 that part of the wick which is acted upon by the flame continues of the same length1 and the flame itself very nearly of the same strength and magnitude#h4 #h ,the wick's not being uniformly twisted throughout1 may occasion a little variation in the dimensions of the flame4 ,the advantages which may be derived from candles that require no snuffing and afford no smoke1 may be readily understood2 but these candles have another property which ought not to be passed over in silence4 ,a candle snuffed by an instrument gives a very fluctuating light1 which1 in viewing near objects is highly injurious to the eye2 and this is an inconvenience which no shade can remove4 ,but when a candle is snuffed spontaneously1 it gives a light so perfectly steady and so uniformly bright1 that the adjustments of the eye remain at rest1 and distinct vision is performed without pain1 and without uneasiness4 ,candles1 on which ,mr4 ,,walker has made experiments1 are described in the following ,,table4 ---------------------------------------- --- ,no4 of candles ,no4 of single ,no4 to the pound ,length inthreads of fine avoirdupoise inches4 cotton in the weight4 wick4 ---------------------------------------- --- #a #ad #h4e #aj #b #ac #i4 #ab #c #aj #i4gd #ad #d #h #aj4 #bj #e #f #aj4be #bd ,mould #f #ac4 ---------------------------------------- --- ,number #a1 #b1 and #c4 ,these candles1 when lighted and placed to form an angle of #cj with the perpendicular1 require no snuffing3 they give lights which are nearly equal1 and combustion proceeds so regularly1 that no part of the melted tallow escapes unconsumed1 except from accidental causes4 ,no4 #d1 placed at the angle mentioned above1 and lighted1 requires no snuffing3 it gives a light very little stronger than ,no4 #a1 but its colour is not quite so white1 nor its flame so steady4 ,no4 #e4 ,this candle1 placed at an angle of #cj1 and lighted1 requires no snuffing2 its flame is rather fluctuating1 and not so white as ,no4 #d1 nor is its strength of light much greater than ,no4 #a4 ,the melted tallow sometimes overflows when the air in the room is put in motion2 yet the light of this candle is much improved by being placed in an inclined position4 ,the mould candle1 treated in the same manner1 affords a very pure steady flame1 without smoke and without snuffing1 and its strength of light is about equal to that of ,no4 #a4 ,the experiments have not been sufficiently numerous to determine with precision which of these candles affords the most light at a given expence1 but the few experiments which have been made seem to indicate1 that the quantity of light is nearly as the quantity of combustible matter consumed1 and thus a candle which is used in the manner pointed out gives more light than a candle of the same dimension set perpendicularly and snuffed1 because one part of a candle that is snuffed1 is thrown away1 and another part flies off in the form of smoke4 ,and this is not the only inconvenience that attends the using candles in this manner1 and which the other method is free from1 for the light which it gives is of a bad quality1 on account of its being variable and undulating4 ,from the time that a candle is snuffed till it wants snuffing again1 its strength of light scarcely continues the same for a single minute4 ,and that variation which frequently takes place in the height of the flame1 is a matter of still more serious consequence4 ,the flame of a long candle placed vertically when it is snuffed burns steadily1 is about two inches high1 but it very frequently rises to the height of four inches or upwards2 drops down again in a moment1 till it is less than three inches1 and then rises again4 ,in this manner the flame continues in motion for some time before it returns to its original dimensions4 ,but it does not continue long in a quiescent state before it begins a new series of undulations4 ,in this manner the candle burns till the top of the wick is seen near the apex of the flame1 carrying off clouds of smoke4 ,in this state of things the eye becomes uneasy for want of light1 and the snuffers are applied to remove the inconvenience4 ,mr4 ,,walker further observes1 that it is these sudden changes1 and not the nature of candle-light itself1 that do so much injury to the eye of the student and artist2 and that that injury may be easily prevented1 by laying aside the snuffers1 and in the place of one large candle1 let two small ones be used in the manner stated4 ,the following observations on this subject are copied from the ,monthly ,magazine1 #ahje1 p4 #bjf4 8,it is scarcely necessary to observe1 that the combustion of candles proceeds the quicker in proportion as the inclination is greater4 ,from the experiments which ,i have made1 ,i should consider an angle of forty degrees with the perpendicular as the maximum of inclination1 beyond which several considerable inconveniencies would occur2 and ,i should take #be degrees as the minimum of inclination1 less than which does not sufficiently expose the point of the wick to the action of the air4 8,by those who are much in the habit of reading or writing by candle-light1 it will also be esteemed no inconsiderable addition to the advantages already mentioned1 that the trouble of seeking and applying the snuffers is superseded4 ,a candle of common size in a vertical position1 requires the application of the snuffers forty-five times during its complete consumption4 8,but ,i found an obstacle to the adoption of ,mr4 ,,walker's plan1 which1 from the inclined position of the candle1 it did not immediately occur to me by what means to counteract4 ,any agitation of the air of the room1 occasioned either by the opening or shutting of a door1 or by the quick passage of a person near the candle1 caused the melted tallow to run over1 or1 in more familiar language1 caused the candle to gutter2 which1 with the candle in this position1 became an insuperable bar to the use of it4 8,for the prevention of this inconvenience1 ,i have had a wire skeleton-shade adapted to a rod bearing the same inclination as the candle1 and which at bottom joins the candlestick in an horizontal line of about two inches1 terminating in a nozzle fitting that of the candlestick4--,the distance of this rod from the candlestick1 or1 which is the same thing1 the length of the foot or horizontal line1 is of course to be determined by the distance between the two circles which form the upper and lower apertures of the shade4--,it may serve1 perhaps1 more familiarly to describe this part of the apparatus1 to state1 that it bears a perfect resemblance to the two first strokes of the written figure #d2 and the third stroke1 if carried up as high as the first1 and made sloping instead of upright1 will very well represent the situation of the candle4 8,when a strong light1 for the purposes of reading or writing1 be required1 a white silk or paper may be used1 as is common1 over the skeleton2 but when it be required that the light should be dispersed over the room1 a glass of a similar shape may be adopted1 for the purpose of preventing the flame from being influenced by any agitation of the air of the room4 ,if the upper circle of the shade be four inches in diameter1 the apex of the flame will be within it during more than half the time of the complete consumption of the candle2 the shade will not1 therefore1 require adjusting for the purpose of preventing injury to the silk1 or whatever else may be used over the skeleton1 more than once during that time4 8,being myself much averse to the interruptions which a candle used in a vertical position occasions1 and which1 though short1 may1 under some circumstances1 be highly vexatious1 ,i wish to extend to others a benefit which ,i prize rather highly40 ,lord ,,stanhope#i has published a simple method of manufacturing candles1 which1 according to his ,lordship's statement1 is superior to the method usually employed4 ,the principles upon which the process depends are the following3--,first1 the wick of the candle is to have only three-fourths of the usual number of cotton threads1 if the candle be of wax or spermaceti2 and only two-thirds of the usual number1 if the candle be of tallow4 ,secondly1 it is required that the wick in all cases be perfectly free from moisture1 a circumstance seldom attended to in the manufacturing of candles2 and thirdly1 to deprive the wick of wax candles1 of all the air which is entangled in its fibres1 and this may conveniently be done1 by boiling it in melted wax1 till no more air bubbles1 or froth appear on the surface of the fluid4 #i ,repository of ,arts1 ,vol4 ,i1 p4 #hf4 ,if these circumstances be attended to1 three candles of any size thus prepared1 last as long as four of the same size manufactured in the common way4 ,the light which they afford is superior and more steady than the light of common candles2 and lastly1 candles made in this manner1 whether of wax1 spermaceti1 or tallow1 do not require to be snuffed as often4 ,besides all this1 they flame much less1 and are consequently better for writing1 reading1 working and drawing1 than candles made by the common method4 ,the following observations will enable any person who is willing to try the candles manufactured according to ,lord ,stanhope's plan1 to ascertain the real value of the improvements suggested by his ,lordship4 ,it shews also the result of some experiments1 made to ascertain the expence of burning oil in lamps with wicks of various sizes4 ,a taper lamp1 with eight threads of cotton1 will consume in one hour #bbe_/ajjj oz4 of spermaceti oil3 at six shillings per gallon1 the expence of burning twelve hours is #ac4ga farthings4 ,at seven shillings1 it is #ae4iie farthings4 ,at eight shillings1 it is #ah4bhj farthings4 ,n4 ,b4 ,this gives as good a light as tallow candles of eight and ten in the pound4 ,this lamp seldom wants snuffing1 and casts a steady and strong light4 ,a taper1 chamber1 or watch lamp1 with four ordinary threads of cotton in the wick1 consumes #a4ffd oz4 of spermaceti oil in one hour3 the oil at seven shillings per gallon1 the expence of burning twelve hours1 #g4jb farthings4 ,at eight shillings1 it is #h4jbb farthings4 ,at nine shillings1 it is #i4jbd farthings4 ,,table1 ,exhibiting a series of experiments1 made with a view to determine the real and comparative expence of burning candles of different sorts and sizes4 ---------------------------------------- ---------------------- ,number of ,weight of ,time one,the time ,the expence in candles one candle4 candle that one twelve hours when in one lasted4pound willcandles are at pound4 last4 #abs4 per dozen1 which also shews the proportion of expence at any price1 per dozen4 ---------------------------------------- --------------- ,farthings and ,oz4 ,dr4 ,hr4 ,min4 ,hr4 ,min4 hundredth parts4 ,a small #ah #j #ad #c #ae #ei #bf #i4gj wick4 #ai #j #ac #b #dj #ej #cd #aa4dj ,a large #af #j #ae #b #dj #dd #b #ac4jh wick4 #ab #a #e #c #bg #da #bd #ac4ib #aj #a #h #c #cf #ch #bd #ae4jj #g #b #a #d #i #cb #ab #ag4hh #h #b #j #d #ae #cd #j #af4id #e #b #ac #e #ai #cj #ae #ai4jf ,mould ,moulds at #ad;d4 candles4 ,each4 per dozen4 ,with #c #b #ab #g #bj #db #ci #ae4gd wax'd #d #d #j #i #c #cf #bj #ah4ef wick4 #c #e #b #ag #cj #eb #cj #af4hbe ---------------------------------------- ---------------------- ,the time each candle lasted1 was taken from an average of several trials on each size4 ,it has been suggested by ,dr4 ,,franklin1 that the flame of two candles joined1 gives a much stronger light than both of them separately4 ,the same1 has been observed by ,mr4 ,,warren1 to be the case with flames of gas-lights1 which1 when combined1 give a much stronger light than they would afford1 when in a separate state4 ,indeed1 in all cases1 where flames for producing light are placed near to each other1 it is always beneficial to preserve the heat of the flame as much as possible4 ,one of the most simple methods of doing this1 is no doubt1 the placing of the several flames together1 and as near as possible to each other without touching1 in order that they may mutually cover and defend each other against the powerful cooling influence of the surrounding cold bodies4 ,this principle is now employed in the ,liverpool lamp1 which acts by several flat or ribband wicks placed in the form of a cylinder4 ,the power of illumination of this lamp is superior in effect and more economical than any other lamp in use--and as flame is perfectly transparent to the light of another flame which passes through it1 there is no danger of loss of light on account of the flames covering each other4 ,,part ,,ii4 ,,gas-,,light4 ,,preliminary ,,observation4 ,a new art of procuring artificial light1 which consists in burning the gazeous fluid obtained by distillation from common pit-coal1 has of late engaged the attention of the public1 under the name of gas-light4 ,the encouragement that has been given for some years past by the legislature to this system of lighting1 has induced certain individuals to apply the coal-gas light for the illumination of streets1 houses1 roads1 and public edifices4 ,and it is sufficiently known that a company has been incorporated by charter under the name of the 8,gas ,light and ,coke ,company10 to apply this new art of procuring light1 by way of experiment1 on a large scale1 in lighting the streets of the metropolis4#aj #aj ,an ,act for granting certain powers and authorities to a company to be incorporated by charter1 called the 8,gas ,light and ,coke ,company10 for making inflammable air for the lighting of the streets of the metropolis1 c4--,session #ahaj1 #ejth ,geo4 ,,iii4 ,the power and authorities granted to this corporate body are very restricted and moderate4 ,the individuals composing it have no exclusive privilege2 their charter does not prevent other persons from entering into competition with them4 ,their operations are confined to the metropolis where they are bound to furnish not only a stronger and better light to such streets and parishes as chuse to be lighted with gas1 but also at a cheaper price than shall be paid for lighting the said streets with oil in the usual manner4 ,the corporation is not permitted to traffic in machinery for manufacturing or conveying the gas into private houses1 their capital or joint stock is limited to #bjj1jjjl4 and ,his ,majesty has the power of declaring the gas-light charter void1 if the company fail to fulfil the terms of it4 ,,theory ,,of ,,the ,,combustion ,,of ,,coal ,,in ,,elucidation ,,of ,,the ,,nature ,,and ,,production ,,of ,,gas ,,light4 ,pit-coal exists in this island in strata1 which1 as far as concerns many hundred generations after us1 may be pronounced inexhaustible2 and is so admirably adapted1 both for domestic purposes and the uses of the arts1 that it is justly regarded as a most essential constituent of our national wealth4 ,like all other bituminous substances1 it is composed of a fixed carbonaceous base or bitumen1 united to more or less earthy and saline matter constituting the ashes left behind when this substance is burnt4 ,the proportions of these parts differ considerably1 in different kinds of coal2 and according to the prevalency of one or other of them1 so the coal is more or less combustible1 and possesses the characters of perfect pit-coal2 and by various shades1 passes from the most inflammable canel-coal1 into blind1 ,kilkenny1 or stone-coal2 and1 lastly1 into a variety of earthy or stony substances2 which1 although they are inflammable1 do not merit the appellation of coal4 ,every body knows that when pit-coals are burning in our grates1 a flame more or less luminous issues from them1 and that they frequently emit beautiful streams of flame remarkably bright4 ,but besides the flame1 which is a peculiar gas in the state of combustion1 heat expels from coal an aqueous vapour1 loaded with several kinds of ammoniacal salts1 a thick viscid fluid resembling tar1 and some gases that are not of a combustible nature4 ,the consequence of which is1 that the flame of a coal-fire is continually wavering and changing1 both in shape1 as well as brilliance and in colour1 so that what one moment gave a beautiful bright light1 in the next1 perhaps1 is obscured by a stream of thick smoke4 ,but if coals1 instead of being suffered to burn in this way1 are submitted to distillation in close vessels1 all its immediate constituent parts may be collected4 ,the bituminous part is melted out in the form of tar4 ,there is disengaged at the same time1 a large quantity of an aqueous fluid1 contaminated with a portion of oil1 and various ammoniacal salts4 ,a large quantity of carburetted hidrogen1 and other uninflammable gases1 make their appearance1 and the fixed base of the coal remains behind in the distillatory apparatus in the form of a carbonaceous substance1 called coke4 ,all these products may be separately collected in different vessels4 ,the carburetted hidrogen1 or coal-gas1 may be freed from the non-inflammable gases1 and afterwards forced in streams out of small appertures1 which1 when lighted1 may serve as the flame of a candle to illuminate a room or any other place4 ,it is thus1 that from pit-coal a native production of this country1 we may procure a pure1 lasting1 and copious light2 which1 in other cases1 must be derived from expensive materials1 in part imported from abroad4 ,it is chiefly upon the power of collecting the products afforded by coal1 with convenience and cheapness1 that the promoters of the gas-light illumination found their claims to public encouragement4 ,they conceive that the flame which pit-coal yields1 as it is now consumed1 is turned to very little advantage3 it is not only confined to one place1 where a red heat is more wanted than a brilliant flame1 but it is obscured1 and sometimes entirely smothered1 by the quantity of incombustible materials that ascend along with it and pollute the atmosphere4 ,that much inflammable matter is thus lost1 is evident from facts that come under our daily observation4 ,we often see a flame suddenly burst from the densest smoke1 and as suddenly disappear2 and if a light be applied to the little jets that issue from the bituminous parts of the coal1 they will catch fire1 and burn with a bright flame4 ,a considerable quantity of a gazeous fluid1 capable of affording light and heat continually escapes up the chimney1 whilst another part is occasionally ignited1 and exhibits the phenomena of the flame and light of the fire4 ,the theory of the production of gas-light is therefore analogous to the action of a lamp or candle4 ,the wick of a candle being surrounded by the flame1 is in the same situation of the pit-coal exposed to distillation4 ,the office of the wick is chiefly to convey tallow1 by capillary attraction1 to the place of combustion4 ,as it is decomposed into carburetted hidrogen gas it is consumed and flies off1 another portion succeeds2 and in this way a continued current of tallow and maintenance of flame are effected4 ,see page #ae4 ,the combustion of oil by means of a lamp depends on similar circumstances4 ,the tubes formed by the wick serve the same office as a retort placed in a heated furnace through which the inflammable liquid is transmitted4 ,the oil is drawn up into these ignited tubes1 and is decomposed into carburetted hidrogen gas1 and from the combustion of this gas the illumination proceeds4 ,see p4 #ae4 ,what then does the gas-light system attempt8 ,nothing more than to generate1 by means of sufficient furnaces and a reservoir of sufficient capacity1 desired quantities of the gas1 which is the same material of the flame of candles or lamps2 and then by passing it through pipes to any desired distance1 to exhibit it there at the mouths of the conducting tubes1 so that it may be ignited for any desired purpose4 ,the only difference between this process and that of an ordinary candle or lamp1 consists in having the furnace at the manufactory1 instead of its being in the wick of the candle or lamp--in having the inflammable material distilled at the station1 instead of its present exhibitions in oil1 wax1 or tallow1 and then in transmitting the gas to any required distance1 and igniting it at the orifice of the conducting pipe instead of igniting it at the apex of the wick4 ,the principle is rational1 and justified by the universal mode in which all light is produced4 ,indeed1 this discovery ranks among the numerous recent applications of chemical science to the purposes of life1 which promise to be of the most general utility4 ,it is evident from the outline here given of the production and application of coal-gas1 that all the uses of pit-coal are not exhausted2 it will be sufficient to observe1 that the complete analysis of coal1 which has been hitherto confined to the laboratory of the chemist1 requiring skill and nicety in the operator1 and attended with great trouble and expence1 is now so far simplified1 that many chaldrons of coals may be decomposed by one gas-light apparatus in the space of six hours1 and all the component parts produced in their most useful shape1 at an expence out of all proportion below the value of the products4 ,,sketch ,,of ,,the ,,rise ,,and ,,progress ,,of ,,the ,,discovery ,,and ,,application ,,of ,,coal-,,gas1 ,,as ,a ,,substitute ,,for ,,procuring ,,artificial ,,light4 ,to assist the reader in comprehending the nature and object of substituting coal-gas for tallow or oil1 for the purpose of obtaining light1 it may be proper to touch slightly upon the successive discoveries that have been made as to the decomposition of coal1 and the application of its different ingredients4 ,such a sketch will add to the many examples that occur in the history of science and art1 showing the slow progress of mankind in following up known principles1 or extracting from acknowledged facts every possible advantage4 ,in the ,philosophical ,transactions of the ,royal ,society1 ,v4 ,,xli4 so long ago as the year #agci1 is recorded a paper1 exhibiting an account of some experiments made by ,dr4 ,james ,clayton1 from which it appears that the inflammable nature of coal-gas was then already known4 ,dr4 ,clayton having distilled ,newcastle coal1 obtained1 as products of the process1 an aqueous fluid1 a black oil1 and an inflammable gas1 which he caught in bladders1 and by pricking these he was enabled to inflame the gas at pleasure4 ,it is further known1 that in the beginning of the last century1 ,dr4 ,hales#aa on submitting pit-coal to a chemical examination1 found1 that during the ignition of this fossil in close vessels1 nearly one-third of the coal became volatilized in the form of an inflammable vapour4 ,hence the discovery of the inflammable nature of coal-gas can no longer be claimed by any person now living4 #aa ,vegetab4 ,statics1 vol4 ,i4 ,in the year #agfg1 the ,bishop of ,llandaff#ab examined the nature of the vapour and gazeous products evolved during the distillation of pit-coal4 ,this learned philosopher noticed1 that the volatile product is not only inflammable as it issues from the distillatory vessel1 but that it also retained its inflammability after having been made to pass through water1 and suffered to ascend through two high curved tubes4 ,the solid matters obtained by this venerable prelate1 were1 an aqueous ammoniacal fluid1 a tenaceous oil1 resembling tar1 an ammoniacal liquor1 and a spongy coal1 or coke4 #ab ,watson's ,chemical ,essays1 vol4 ,,ii4 ,the first discovery and application of the use of coal-gas for the purpose of illumination is claimed by ,mr4 ,murdoch4 ,dr4 ,w4 ,henry of ,manchester1 has published the following account#ac of this discovery4 #ac ,thompson's ,system of ,chemistry1 vol4 ,i4 p4 #eb4 8,in the year #agib1 at which time ,mr4 ,murdoch resided at ,redruth1 in ,cornwall1 he commenced a series of experiments upon the quantity and quality of the gases contained in different substances4 ,in the course of these he remarked1 that the gas obtained by distillation from coal1 peat1 wood1 and other inflammable substances1 burnt with great brilliancy upon being set fire to2 and it occurred to him1 that by confining and conducting it through tubes1 it might be employed as an economical substitute for lamps and candles4 ,the distillation was performed in iron retorts1 and the gas conducted through tinned iron and copper tubes to the distance of #gj feet4 ,at this termination1 as well as at intermediate points1 the gas was set fire to1 as it passed through apertures of different diameters and forms1 purposely varied with a view of ascertaining which would answer best4 ,in some the gas issued through a number of small holes like the head of a watering pan2 in others it was thrown out in thin long sheets2 and again in others in circular ones1 upon the principle of ,argand's lamp4 ,bags of leather and of varnished silk1 bladders1 and vessels of tinned iron1 were filled with the gas1 which was set fire to1 and carried about from room to room1 with a view of ascertaining how far it could be made to answer the purpose of a moveable or transferable light4 ,trials were likewise made of the different quantities and qualities of gas produced by coals of various descriptions1 such as the ,swansea1 ,haverfordwest1 ,newcastle1 ,shropshire1 ,staffordshire1 and some kinds of ,scotch coals4 8,mr4 ,murdoch's constant occupations prevented his giving farther attention to the subject at that time2 but he again availed himself of a moment of leisure to repeat his experiments upon coal and peat at ,old ,cumnock1 in ,ayrshire1 in #agig2 and it may be proper to notice that both these1 and the former ones1 were exhibited to numerous spectators1 who1 if necessary1 can attest them4 ,in #agih1 he constructed an apparatus at ,soho ,foundry1 which was applied during many successive nights to the lighting of the building2 when the experiments upon different apertures were repeated and extended upon a large scale4 ,various methods were also practised of washing and purifying the air1 to get rid of the smoke and smell4 ,these experiments were continued1 with occasional interruptions1 until the epoch of the peace in the spring of #ahjb1 when the illumination of the ,soho manufactory afforded an opportunity of making a public display of the new lights2 and they were made to constitute a principal feature in that exhibition40 ,in the year #ahjc and #ahjd1 ,mr4 ,winsor exhibited at the ,lyceum in ,london the general nature of this new mode of illumination though the machinery for procuring1 and the manner of purifying the gas1 he kept a secret4 ,he exhibited the mode of conducting the gas through the house1 and a number of devices for chandeliers1 lamps1 and burners1 by which it might be applied4 ,among these he proposed long flexible tubes suspended from the ceiling1 or wall of the room1 and at the end communicating with burners or lamps of different kinds4 ,this gentleman showed also by experiment1 that the flame of the gas-light1 produced no smoke2 that it was not so dangerous as the flame of candles or lamps2 that it could not produce sparks2 and that it was not so readily extinguished by gusts of wind or torrents of rain4 ,mr4 ,,winsor's display of gas-lights took place more than two years before ,mr4 ,,murdoch's priority of right was heard of4 ,in stating these facts ,i do not mean to say that ,mr4 ,,murdoch derived the hint of applying the coal-gas from the previous exhibition of ,mr4 ,,winsor1 because it is quite within the bounds of probability that the ideas of ,mr4 ,,murdoch may have arisen totally independent of all acquaintance with ,mr4 ,,winsor's4 ,the claims of invention1 or the determination of the right of priority1 concerns the public only so far as the honour and estimation of any useful discovery conferred on the inventor may induce other individuals to devote their talents to similar pursuits2 by means of which1 more discoveries may be made1 and the subject of human invention become extended1 or rendered more useful4 ,for as the mere benefits which mankind may derive from any particular discovery1 they are certainly more indebted to the person who first applied the discovery to actual practice1 than to him who first made it1 and merely illustrated it by barren experiments4 ,mr4 ,,winsor certainly pressed on the mind of the public with unremitted perseverance and diligence the extensive application of gas-light in the year #ahjb1 but he made no new discovery with regard to the composition of coal2 he did not even invent the mode of conducting the gas through tubes2 and if he has pointed out the particulars of the process1 he has made a very important1 though not the most brilliant improvement in this line of business4 ,mr4 ,,winsor's publications are1 perhaps1 but ill adapted to promote his cause2 and the exaggerated calculation which the sanguine mind of a discoverer is naturally disposed to indulge in1 have1 to superficial observers1 thrown an air of ridicule and improbability on the whole scheme of lighting with gas4 ,it may1 however1 be safely affirmed1 that if the same facts had come forward1 under the sanction of some great name in the chemical or philosophical world1 the public incredulity would long since have been subdued2 and the plan1 which for many years has been struggling for existence1 would have been eagerly adopted as a national object4 ,on the #ahth of ,may1 #ahjd1 ,mr4 ,,frederick ,,albert ,,winsor1 took out a patent for combining the saving and purifying of the inflammable gas 7for producing light and heat71 the ammonia1 tar1 and other products of pit-coal1 with the manufacture of a superior kind of coke 7see ,repertory1 #b;d ,series1 v4 #agb74 ,and1 lately1 the same gentleman has taken out a second patent1 for further improvements in these processes4 ,in the year #ahje1 ,mr4 ,,northern1 of ,leeds1 also directed the attention of the public to the application of coal-gas1 as a substitute for tallow light1 as will be seen by the following extract of the ,monthly ,magazine for ,april1 #ahje4 8,i distilled in a retort1 #ej ounces of pit-coal in a red heat1 which gave #f ounces of a liquid matter covered with oil1 more or less fluid as the heat was increased or diminished4 ,about #bf ounces of cinder remained in the retort2 the rest came over in the form of air1 as it was collected in the pneumatic apparatus4 ,i mixed part of it with atmospherical air1 and fired it with the electric spark with a tolerable explosion1 which proves it to be hydrogene4--,whether any of the other gases were mixed with it1 ,i did not then determine4 ,in the receiver ,i found a fluid of an acid taste1 with a great quantity of oil1 and1 at the bottom1 a substance resembling tar4 8,the apparatus ,i make use of for producing light is a refiner's crucible1 the top of which 7after filling with coal7 ,i close with a metal cover1 luted with clay or other luting1 so as to prevent the escape of the gas2 a metal pipe is soldered into the cover1 bent so as to come under the shelf in the pneumatic trough1 over which ,i place a jar with a stop-cock and a small tube2 the jar being previously filled with water1 the crucible ,i place on the common or other fire as is most convenient2 and as the heat increases in it1 the gas is forced rapidly through the water into the jar1 and regularly displaces it4 ,i then open the cock and put fire to the gas1 which makes its escape through the small tube1 and immediately a most beautiful flame ensues1 perfectly free from smoke or smell of any kind4 ,a larger light1 but not so vivid or clear1 will be produced without passing the gas through water1 but attended with a smoke somewhat greater than that of a lamp charged with common oil4 8,i have great hopes that some active mechanic or chemist will1 in the end1 hit on a plan to produce light for large factories1 and other purposes1 at a much less expence1 by the above or similar means1 than is at present produced from oil40 ,soon afterwards1 ,mr4 ,,samuel ,,clegg#ad of ,manchester1 ,engineer1 communicated an account of his method of lighting up manufactories with gas-light to the ,society of ,arts1 for which he received the silver medal4 #ad ,this gentleman is at present engineer to the ,gas-,light ,company4 ,since that time1 the application of gas-light has spread rapidly1 and numerous manufactories and other establishments have been lighted by coal-gas4 ,in ,france1 the application of gas-lights to economical purposes1 was pointed out long before it was publicly introduced into this country4 ,m4 ,,le ,,bon had a house fitted up in ,paris1 in the winter of #ahjb1 so as to be entirely illuminated by gas-lights1 which was seen by thousands with admiration2 and had a brevet d'invention 7patent7 granted to him by the ,french government1 for the art of producing light from wood1 ignited in close vessels4 ,many other attempts have been made to derive advantage from the different ingredients of coal2 but they are too obscure to merit particular enumeration4 ,in the year #ahjh1 ,mr4 ,,murdoch presented to the ,royal ,society his account of the application of gas-light1 and was complimented with ,count ,,romford's medal for the same4 ,the following statement is taken from ,mr4 ,,murdoch's paper4 8,the whole of the rooms of the cotton mill of ,mr4 ,,lee1 at ,manchester1 which is ,i believe the most extensive in the ,united ,kingdom1 as well as its counting-houses and store-rooms1 and the adjacent dwelling house of ,mr4 ,,lee1 are lighted with the gas from coal4 ,the total quantity of light used during the hours of burning has been ascertained1 by a comparison of shadows1 7see page #bc7 to be about equal to the light which #bejj mould candles1 of six to the pound1 would give2 each of the candles with which the comparison was made consuming at the rate of #d-ajths of an ounce 7#age grains7 of tallow per hour4 8,the gas-burners are of two kinds3 the one is upon the principle of the ,argand lamp1 and resembles it in appearance2 the other is a small curved tube with a conical end1 having three circular apertures or perforations1 of about a thirtieth of an inch in diameter1 one at the point of the cone1 and two lateral ones1 through which the gas issues1 forming three divergent jets of flame1 somewhat like a fleur-de-lis4 ,the shape and general appearance of this tube has procured it1 among the workmen1 the name of the cockspur burner4 8,the number of burners employed in all the buildings amounts to #bga ,argand1 and #fec cockspurs1 each of the former giving a light equal to that of four candles of the description above-mentioned2 and each of the latter a light equal to two and a quarter of the same candles2 making therefore the total of the gas-light a little more than equal to that of #bejj candles1 six to the pound4 ,when thus regulated1 the whole of the above burners require an hourly supply of #abej cubic feet of the gas produced from cannel-coal2 the superior quality and quantity of the gas produced from that material having given it a decided preference in this situation over every other coal1 notwithstanding its higher price4 8,the time during which the gas-light is used may1 upon an average of the whole year1 be stated at least at two hours per day of #bd hours4 ,in some mills1 where there is over work1 it will be three hours2 and in the few where night work is still continued nearly #ab hours4 ,but taking two hours per day as the common average throughout the year1 the consumption in ,messrs4 ,philips and ,lee's mill will be #abej #b #bejj cubic feet of gas per day2 to produce which #gjj weight of cannel-coal is required in the retort4 ,the price of the best ,wiggan cannel-coal 7the sort used7 is #ac;d4 per cwt4 7#bbs4 #f;d4 per ton7 delivered at the mill1 or say about eight shillings for the seven hundred weight4 ,multiplying by the number of working days in the year 7#cac17 the annual consumption of coal will be #aaj tons1 and its cost #abel4 8,about one-third of the above quantity1 or say forty tons of good common coal1 value ten shillings per ton1 is required for fuel to heat the retorts1 the annual amount of which is #bjl4 8,the #aaj tons of cannel-coal1 when distilled1 produce about #gj tons of good coke1 which is sold upon the spot at #as4 #d;d4 per cwt4 and will therefore amount annually to the sum of #icl4 8,the quantity of tar produced from each ton of cannel-coal is from #aa to #ab ale gallons1 making a total annual produce of about #abej ale gallons1 which not having been yet sold1 it cannot yet be determined its value4 8,the interest of the capital expended in the necessary apparatus and buildings1 together with what is considered as an ample allowance for wear and tear1 is stated by ,mr4 ,,lee at about #eejl4 per annum1 in which some allowance is made for this apparatus being made upon a scale adequate to the supply of a still greater quantity of light1 than he has occasion to make use of4 8,mr4 ,,lee is of opinion that the cost of attendance upon candles would be as much1 if not more1 than upon the gas apparatus2 so that1 in forming the comparison1 nothing need be stated upon that score1 on either side4 8,the economical statement for one year1 then1 stands thus3 ,cost of #aaj tons of cannel coal #abe ,ditto of #dj tons of common ditto1 to carbonise #bj ---- ,in all #ade ---- ,deduct the value of #gj tons of coke #ic ,the annual expenditure in coal1 after deducting the value of the coke1 and without allowing any thing for the tar1 is therefore #eb ,and the interest of capital sunk1 and wear and tear of apparatus #eej ,making the total expence of the gas apparatus per annum1 about #fjj 8,that of candles1 to give the same light1 would be about #bjjjl4 ,for each candle1 consuming at the rate of #d-ajths of an ounce of tallow per hour1 the #bejj candles burning1 upon an average of the year1 two hours per day1 would1 at one shilling per pound1 the present price1 amount to nearly the sum of money above-mentioned4 8,if the comparison were made upon an average of three hours per day1 as in most cases1 would perhaps be nearer to the truth1 and the tear and wear remaining nearly the same as on the former case1 the whole cost would not exceed #fejl4 while that of the tallow would be #cjjjl40 ,mr4 ,,ackerman in this metropolis1 has shown that the art of gas-light illumination is not confined to great manufactories1 but that its advantages are equally applicable to those on a moderate scale4 ,the whole of ,mr4 ,,ackerman's establishment1 his public library1 warehouse1 printing-offices and work-shops1 together with his dwelling house1 from the kitchen to the drawing-room1 has1 for these four years past1 been lighted with gas1 to the total exclusion of all other lights4 ,the result of the whole of this proceeding will be obvious from the following letter3 ,to ,,mr4 ,,accum4 ,,sir1 8,in answer to your request with regard to my gas-lights1 which ,i now have in my house1 ,i take this mode of informing you1 that ,i charge two retorts with #bdjlbs4 of coal1 half cannel and half ,newcastle1 from which ,i extract #ajjj cubic feet of gas4 ,to obtain this quantity of gas1 when the retorts are cold1 ,i use from #ajj to #aajlb4 of common coals2 but when they are in a working state1 that is to say1 when they are once red hot1 the carbonising fuel amounts to about #belb4 per retort4 ,the bulk of gas thus obtained supplies #dj ,argand's lamps1 of the large size1 for four hours per night1 during the long winter evenings1 together with eight ,argand's lamps and about #bb single cockspur burners1 for three hours per night3 in addition to which my printers employ #af cockspur burners for ten hours per day to heat their plates instead of charcoal fire4 ,in the depth of winter we charge two retorts per day3 but1 upon an average1 we work #cfe retorts in #cfe days4 ,now #cfe retorts containing #abjlb4 of coal each1 make #dchjjlb4 which is equal to ten chaldrons of ,newcastle and eight tons of cannel coal4 #aj chaldrons of ,newcastle coals1 at #fes4 make #cb #aj #j #h tons of cannel coal1#ae 7this coal is sold by weight7 at #ajjs4 per ton #dj #j #j #g chaldrons of common coals for carbonising1 at #ees4 #ai #e #j ,to wages paid the servant for attending the gas apparatus #cj #j #j ,interest of money sunk #cj #j #j ,the wear and tear of the gas-light apparatus ,i consider to be equal to the wear and tear of lamps1 candlesticks1 c4 employed for oil1 tallow1 c4 ----------- ,total expence of the gas lights #aea #ae #j ,,deduct #bc chaldrons of coke1 at #fjs4 per chaldron #fi ,ammoniacal liquor #e ,tar #f ,charcoal employed by the copper-plate printers to heat their plates1 which is now done with the gas- light flame1 cost1 annua #be ,two chaldrons of coals minus used as fuel1 for warming the house1 since the adoption of the gas- lights1 at #fes4 per chaldron #f #aj ------ #aaa #aj #j ---------- ,nett expences of the gas-lights #dj #e #j ---------- ,the lights used in my ,establishment1 prior to the gas- lights1 amounted annually to #afj #j #j ,my present system of lighting with gas costs1 per ann4 #dj #e #j ---------- ,balance in favor of the gas for one year #aai #ae #j ,such is the simple statement of my present system of lighting1 the brilliancy of which1 when contrasted with our former lights1 bears the same comparison to them as a bright summer sun-shine does to a murky ,november day3 nor are we1 as formerly1 almost suffocated with the effluvia of charcoal and fumes of candles and lamps4 ,in addition to this1 the damage sustained by the spilling of oil and tallow upon prints1 drawings1 books and paper1 c4 amounted annually to upwards of #ejl4 ,all the workmen employed in my establishment consider their gas-lights as the greatest blessing2 and ,i have only to add1 that the light we now enjoy1 were it to be produced by means of ,argand's lamps or candles1 would cost at least #cejl4 per annum4 ,i am1 with respect1 ,yours1 ,strand1 ,march #ac1 #ahae4 ,r4 ,,ackerman40 #ae ,although cannel-coal sells at nearly double the price of ,newcastle coal1 ,i use it in preference to the latter1 because it affords a larger portion of gas1 and gives a much more brilliant light4 ,another manufacturer who was one of the first that adopted the use of this method of illumination in the small way1 and who gave a statement of its advantages to the public1 is ,mr4 ,,cook1 a manufacturer of metal toys1 at ,birmingham1 a clear-headed1 prudent man1 not apt to be dazzled by a fanciful speculation1 but governed in his transactions by a simple balance of profit and loss4 ,there is a navet in his own account of the process which will amuse as well as instruct the reader4 8,my apparatus is simply a small cast-iron pot1 of about eight gallons1 with a cast-iron cover1 which ,i lute to it with sand4 ,into this pot ,i put my coal4 ,i pass the gas through water into the gasometer or reservoir1 which holds about #djj gallons2 and1 by means of old gun-barrels1 convey it all round my shops4 ,now1 from twenty or twenty-five pounds of coal1 ,i make perhaps six hundred gallons#af of gas2 for1 when my reservoir is full1 we are forced to burn away the overplus in waste1 unless we have work to use it as it is made3 but1 in general1 we go on making and using it1 so that ,i cannot tell to fifty or a hundred gallons2--and1 in fact1 a great deal depends on the coals1 some coals making much more than others4 ,these twenty-five pounds of coal put into the retort1 and say twenty-five pounds more to heat the retort1 which is more than it does take one time with another1 but ,i am willing to say the utmost1 are worth four-pence per day4 ,from this four-pence we burn eighteen or twenty lights during the winter season40 #af ,a wine-gallon is equal to #bca cubic inches4 ,thus are the candles which ,mr4 ,,cook used to employ1 and which cost him three shillings a day1 entirely superseded4 ,but1 besides his expence in candles1 oil and cotton for soldering1 used to cost him full #cjl4 a year2 which is entirely saved1 as he now does all his soldering by the gas flame only4 ,for 8in all trades in which the blow-pipe is used with oil and cotton1 or where charcoal is employed to produce a moderate heat1 the gas flame will be found much superior1 both as to quickness and neatness in the work3 the flame is sharper1 and is constantly ready for use2 while1 with oil and cotton or charcoal1 the workman is always obliged to wait for his lamp or coal getting up2 that is1 till it is sufficiently on fire to do his work4 ,thus1 a great quantity of oil is always burned away useless2 but1 with the gas1 the moment the stop-cock is turned1 the lamp is ready1 and not a moment is lost40 ,we must refer to ,mr4 ,,cook's letter for the details of expence1 which he gives with faithful minuteness1 and always leaning to the side unfavourable to the gas4 ,the result of the whole is1 that he saves #cjl4 out of the #ejl4 which his lights formerly cost him3 and1 when we consider that his calculation allows the gas-lights to burn the whole year1 and the candles only twenty weeks1 there can be little doubt1 that the savings in this case follow nearly the same proportion as in the former4 ,if the apparatus be erected even on a smaller scale1 8the saving10 ,mr4 ,,cook assures us1 8will still be considerable3 for the poor man1 who lights only six candles1 or uses one lamp1 if the apparatus is put up in the cheapest way possible1 will find it only cost him #ajl4 or #abl4 which he will nearly1 if not quite1 save the first year40 ,mr4 ,,ackerman having1 in this town1 set the example of lighting his establishment with gas1 several other individuals soon followed the attempt4 ,the following statement will show1 that this species of light may be made use of with the greatest advantage1 upon a still smaller scale1 where no great nicety with regard to the apparatus for procuring gas is required4 ,the following report ,i have received from ,messrs4 ,,lloyd1 of ,queen ,street1 ,southwark1 thimble manufacturers and whitesmiths1 who have used the gas-light for soldering and other purposes these five years past4 ,from #d pecks or #a bushel of coals1 weighing #filbs4 for which we now pay 7#ahji7 #as4 we produce #d pecks of coke and peck of coal not carbonised remains in the distilling pot1 which together with the coke weighs #ehlbs4 #f oz4 value at #as4 per bushel #j #a #d we procure #flbs4 #d oz4 of tar which we use as pith--it saves us #j #a #j ---------- #j #b #d ,deduct for coal #j #a #j ---------- ,profit on coke and tar #j #a #j ---------- ,the gas yielded by the #d pecks of coals in the pot1 make #db brilliant lights1 which burn #g hours4 ,to keep #db tallow candles which were formerly used in the manufactory burning for the same time1 required #glbs4 which at #as4 per lb4 cost #j #g #j ,to this1 add profits on coke and tar #j #a #j ---------- ,gained out of every bushel of coal #j #h #j ---------- 8,the gas-burners made use of in our manufactory produce jets of flame1 which in our business1 where much soldering with the blow-pipe must be done1 have a decided superiority over ,argand's lamps4 ,we are not nice concerning the quality of the gas--a great part of it is burned from the gasometer1 without allowing it to purify itself in the gasometer1 because our gasometer is not large enough to store up the whole quantity of gas we want for use40 ,,theory ,,of ,,the ,,production ,,of ,,gas-,,light1 ,,and ,,description ,,of ,a ,,portable ,,apparatus ,,for ,,exhibiting1 ,,in ,,the ,,small ,,way1 ,,the ,,general ,,nature ,,of ,,this ,,species ,,of ,,light4 ,to obtain carburetted hidrogen1 or coal-gas1 from common pit-coal1 and to apply it for the purposes of illumination1 the coal is introduced into large iron cylinders1 called retorts1 to the apertures of which iron pipes are adapted1 terminating in a vessel1 or vessels1 destined to purify and collect the gas4 ,the retorts charged with coals and made air-tight1 are placed upon the fire1 the action of which extricates the gazeous products from the coals1 together with an aqueous ammoniacal vapour1 and a tenaceous bituminous fluid1 or tar1 c4 ,the liquid substances are conveyed into proper vessels1 and the gazeous products are conducted1 by means of pipes1 under the gasometer1 where the gas is again washed1 and remains ready for use4 ,there are also other pipes leading from the gasometer1 which branch out into smaller ramifications1 until they terminate at the places where the lights are wanted4 ,the extremities of the pipes have small apertures1 out of which the gas issues1 and the streams of gas being lighted at those apertures burn with a clear and steady flame as long as the supply of gas continues4 ,all the pipes which come from the gasometer are furnished at their extremities with stop-cocks to regulate the admission of the gas4 ,the burners are formed in various ways1 either a tube ending with a simple orifice1 at which the gas issues in a stream1 and if once lighted will continue to burn with the most steady and regular light imaginable1 as long as the gas is supplied2 or two concentric tubes of brass1 or sheet-iron1 are placed at a distance of a small fraction of an inch from each other1 and closed at the bottom4 ,the gas which enters between these cylinders1 when lighted1 forms an ,argand lamp1 which is supplied by an internal and external current of air in the usual manner4 ,or the two concentric tubes are closed at the top with a ring having small perforations1 out of which the gas alone can issue1 thus forming small distinct streams of light4 ,illustration ,the gas-apparatus1 plate #b1 will be found very convenient for exhibiting1 in the small way1 the general nature of this new art of illumination1 whilst at the same time it may serve to ascertain1 at a trifling expence1 the comparative value of different kinds of coals intended to be employed for the production of this species of light1 as well as other occasional purposes connected with the gas-light system of illumination4 ,it consists of three distinct apparatus3--namely1 a portable furnace1 fig4 #a1 plate #b1 by means of which the gas is prepared--fig4 #b1 a purifyer1 or condenser1 which separates and purifies the products obtained from the coal1 so as to render the gas fit for the purpose of illumination--fig4 #c1 a gasometer1 or reservoir for receiving and preserving the purified stock of gas1 and from which it may be transferred and distributed as occasion may require4 ,the following statement will explain more fully the general nature of this portable chamber apparatus3--a1 represents a cast iron retort1 such as is used for chemical operations in the small way4 ,this retort rests upon a tripod of hammered iron1 placed upon the bars of the grate of the chemical furnace4 ,into this retort the coals are put for furnishing the gas4 ,it is provided with a solid iron stopper ground air-tight into the mouth of the retort1 and the stopper is secured in its place by an iron wedge passing over it in the centre2 by means of which the mouth of the retort when charged with coal is readily made air-tight1 and the stopper may easily be removed by knocking out the iron wedge4 b4 is a metal pipe which conveys all the distillatory products from the retort into the purifier fig4 #b4 ,this tube is bent at right angles at the extremity where it enters the intermediate vessel fig4 #b4 ,the purifier fig4 #b1 is divided into three compartments marked c4 d4 e4 ,the first compartment is filled with water1 and by means of it an air-tight communication is established with the retort which furnishes the gas4 ,the second compartment1 d1 contains a solution of caustic pot-ash composed of about #b parts of caustic pot-ash and #af of water1 or a mixture of quick-lime and water of the consistence of very thin cream4 ,the object of this compartment is to separate the non-inflammable gases and other products evolved during the distillation of the coal1 from the carburetted hidrogen or coal-gas1 so as to render it fit for use4 ,the third compartment e is left empty to receive the tar and other liquid products4 ,into the first compartment c1 all the gazeous and liquid products are delivered1 as they become evolved during the distillation1 by means of the pipe b4 ,the compartment d1 of the purifier1 or alcali vessel1 is furnished with a wide perpendicular pipe1 which serves to make an air-tight communication with the retort1 by allowing the tube b1 to pass readily through it4 ,from the chamber c1 the liquid and gazeous products pass to the tar-chamber1 or compartment e1 by means of the descending pipe f4 ,the tar and other condensible substances are therefore deposited at e1 whilst the gazeous products alone ascend from the tar-chamber e1 by the pipe g1 and down again the pipe h1 7which is closed at the top7 into the compartment d1 of the vessel or purifier1 fig4 #b4 ,the gas being thus made to pass from the compartment e1 up into the pipe g1 and down the pipe h1 7which is closed at the top7 into the purifier d1 is brought into contact with the liquor in that vessel1 where it is opposed to a pressure in proportion to the perpendicular height of the column of liquid which it contains4 ,the funnel in the compartment c1 is considerably higher than the purifying apparatus1 it therefore allows the liquid which it contains1 when pressed upon by the gas1 to ascend into it1 without overflowing the apparatus1 and to descend again as the pressure diminishes--i is another wide-mouth funnel1 by means of which the chamber d1 is filled with the alcaline solution1 or mixture of lime and water4 ,the carbonic acid gas and sulphuretted hidrogen1 evolved during the distillation of the coal1 are thus made to combine with the alcali or lime1 in the compartment d1 of the purifier1 forming carbonate and hidro-sulphuret of lime4 ,the carburetted hidrogen1 being left more or less pure1 is conveyed through the pipe k1 into the gasometer1 fig4 #c4 ,the communication of the purifier1 fig4 #b1 with the gasometer1 is made by means of the well-known water-valve l1 placed so that the communicating tube k1 may be easily removed at pleasure--m1 is a cock for drawing off the tar1 c4 n1 a gauge-cock for ascertaining the height of the liquid in the chamber d4 ,the gasometer1 fig4 #c1 the object of which is to store up the gas1 consists of two principal parts--namely1 a large interior vessel designed to contain the gas1 and an outer cistern or vessel1 of rather greater capacity1 in which the former is suspended1 designed to contain the water by which the gas is confined4 ,the interior vessel which contains the gas is suspended by chains or cords hung over pullies1 to which weights are attached1 so as to nearly equipoise it4 o is a pipe1 which communicates with the water-valve l1 and by means of which the gas passes from the purifier1 fig4 #b1 into the gasometer4 ,the upper end of this pipe is covered1 in the manner of a hood1 by a cylindrical vessel p1 open at bottom1 but partially immersed beneath the surface of the water contained in the outer cistern of the gasometer1 and perforated round near the lower edge with a number of small holes4 ,the gas displaces the water from this receiver p1 and escapes through the small holes1 rising in bubbles through the water1 so as to expose a large surface to its action1 that it may be properly washed1 c4 ,after rising through the water the gas enters the gasometer1 which is suspended to move up and down by the chains1 pullies1 and balance-weights1 q4 ,from the centre of the gasometer a tube1 r1 descends1 which includes a pipe1 s1 fixed perpendicular from the bottom of the cistern4 ,the fixed pipe r1 forms a guide to keep the gasometer always perpendicular4 t is also an iron pipe made fast in the centre of the inner vessel1 and communicates with the upright tube1 s1 in the outer vessel4 ,this contrivance obliges the gas to pass into the pipe t1 whilst it also serves to keep the gasometer steady when nearly out of the outer cistern4 ,when the operation commences1 the gasometer is sunk down nearly to a level with the surface of the water in the outer cistern1 and is consequently filled with water2 but as the gas enters1 it rises up to receive it4 ,it is to be noted1 that the balance-weights q q1 should not be quite so heavy as the gasometer1 in order that some pressure may be exerted1 to force the gas out of the burners with a proper jet4 ,the gas which issues from the retort enters the purifier as stated already1 and ascends the pipe o1 into the vessel1 p1 from which it displaces the water1 and passes out at the small holes1 as before described1 rising through the water into the gasometer1 and raising it up3 the gas then passes away to the burners1 u u4 ,in this manner the process proceeds until the whole of the volatile products of the coal in the retort is evaporated4 ,the use of the gasometer is1 to equalize the emission of the gas which comes from the retort more quickly at some time than others4 ,when this happens1 the interior vessel rises up to receive it1 and when the stream from the retort diminishes1 the weight of the gasometer expels its contents4 ,when the process is finished1 the retort is suffered to cool1 and its ground stopper is then removed to replenish it with coal4 ,the residue found in the retort is coke4 v v are cocks to let off any liquid that may collect in the pipe o or t2 for if the smallest portion of liquid were to obstruct the free passage of the gas to the burners1 the consequence would be1 that the lights would not burn steadily--they would1 as it is called1 dance1 or become extinguished4 x is the main stop-cock which communicates with the burners--these1 of course1 may be placed as convenience may require4 z z are two projecting parts in the top of the gasometer2 they are intended to receive the hood p1 and the upper extremity of the pipe t1 so as to allow the gasometer to be wholly immersed into the cistern4 ,the wheels or pullies of the gasometer have a groove to allow the links of the chain to pass freely4 ,in this apparatus there is no provision made for the unequal pressure which the gas suffers1 accordingly as the gasometer is more or less immersed in water4 ,it will be observed that1 in this apparatus1 the weight of the interior vessel is constantly increasing1 in proportion as it fills with gas1 and rises out of the water1 and consequently1 if a constant1 uniform1 counterpoising weight1 equal only to that of the gasometer in the first moment of its rise1 be employed1 the gas becomes gradually more and more compressed by that part of the weight of the gasometer which is not counterpoised1 and if its pressure or quantity be then estimated by the bulk which it occupies1 without making allowance for the increasing pressure1 a material error must arise1 and this1 in the large way1 would give rise to insurmountable difficulties with regard to the regulation of the size of the flames2 which could not be rendered uniform4 ,suppose the cistern or exterior vessel full of water1 and the gasometer partly filled with gas and partly with water1 it is evident that the balance-weight may be so adjusted1 as to occasion an exact equilibrium1 so that the external air shall not tend to enter into the gasometer nor the gas to escape from it2 and in this case the water will stand exactly at the same level both within the gasometer and within the outer cistern4 ,on the contrary1 if the balance-weights be diminished1 the gasometer will then press downwards from its own gravity1 and the water will stand lower in the gasometer than it does in the cistern2 in this case1 the included air or gas will suffer a degree of compression above that experienced by the external air1 exactly proportioned to the weight of a column of water1 equal to the difference of the external and internal surfaces of the water4 ,to compensate for this increasing weight of the gasometer1 and render a scale of equal graduations accurate1 some have ingeniously adopted the plan of a spiral pulley to the chain1 which has the effect of gradually avoiding the evil1 but the best way of accomplishing it will be stated hereafter4 ,with regard to the philosophy or the production of coal-gas1 it proves that pit-coal contains solid hidrogen1 carbon1 and oxigen4 ,when the intensity of the heat has reached a certain degree1 a part of the carbon unites with part of the oxigen and produces carbonic acid1 which by means of caloric is melted into the gazeous state and forms carbonic acid gas2 at the same time1 part of the hidrogen of the coal combines with another portion of carbon and caloric1 and forms the carburetted hidrogen gas1 which varies considerably in its constitution1 according to the circumstances under which it is produced2 a portion of olifiant gas1 carbonic oxid1 hidrogen1 and sulphuretted hidrogen1 is also produced during the process4 ,the quantities of these products vary according to the nature of the coal employed in the process4 ,pit-coal is not the only substance which affords carburetted hydrogen2 this gazeous fluid may be obtained in a great variety of ways1 and with very considerable differences in specific gravity and proportion of ingredients4 ,it is found plentifully native or ready formed on the surface of stagnant waters1 marshes1 wet ditches1 c4 through which1 if examined closely1 large bubbles will be seen to rise in hot weather1 and may be increased at pleasure by stirring the bottom or mud with a stick4 ,in close still evenings if a lighted candle is held over the surface1 flashes of blue lambent flame may sometimes be perceived spreading to a considerable distance4 ,all that is not fabulous concerning the ignis fatuus is probably derived from this source4 ,this species of gas is termed for distinction the carburetted hydrogen of marshes4 ,in the purest form in which it can be collected it is mixed with about #bj per cent4 of azot or nitrogen4 ,to procure the gas for the purpose of philosophical amusement1 fill a wide-mouthed bottle with the water of the ditch1 and keep it inverted therein with a large funnel in its neck1 then with a stick stir the mud at the bottom just under the funnel1 so as to cause the bubbles of air which rise from the mud to enter into the bottle2 when by thus stirring the mud in various places1 the air may be catched in the bottle4 ,carburetted hidrogen gas is also given out very abundantly by all kinds of vegetable matter when subjected to a scorching heat sufficient to decompose them4 ,when heated in close vessels much more gas is obtained than when burnt in the open air4 ,if moistened charcoal be put into an earthen retort and heat be applied till the retort becomes ignited2 gas will be evolved1 consisting partly of carbonic acid1 and partly of carburetted hidrogen4 ,a gas of similar properties is obtained by causing steam to pass through a tube filled with red-hot charcoal2 by passing spirit of wine1 or camphor1 through red-hot tubes2 by distilling oils1 wood1 bones1 wax and tallow1 or any animal or vegetable body whatever4 ,indeed it would be endless to enumerate the various sources of this gazeous fluid4 ,a most curious variety of carburetted hidrogen gas has been discovered by the associated ,dutch chemists 7,,van ,,dieman1 ,,troostwyck1 and others7 which is procured from ether or alcohol1 and has the remarkable property of generating a heavy oil when in contact with chlorine gas4 ,hence it has been termed oily carburetted hidrogen1 or olifiant gas--it consists of carburetted hydrogen1 supersaturated with carbon4 ,the oil generated is heavier than water1 whitish1 and semi-transparent4 ,by keeping1 it becomes yellow and limpid2 its smell is highly fragrant and penetrating--its taste somewhat sweet--it is partly soluble in water1 imparting to it1 its peculiar smell4 ,a portion of this gas always accompanies the common carburetted hidrogen obtained from coal1 and those sorts of coal that afford the largest quantity of it are best suited for the production of gas-light4 ,the nature of carburetted hidrogen obtained from coal varies considerably according to the conditions under which it is obtained4 ,the first part is always much heavier than the last1 though still lighter than common air1 and holds in solution a portion of oil1 for on standing for some time over water it becomes lighter1 and is found to require less oxygen for saturation than before4 ,the oil which it held suspended1 then becomes precipitated4 ,the average specific gravity of the first and last gas mixed1 which may be taken as an average of the whole specific gravity is to that of common air as #b to #c--aablb4 of common cannel coal produce at its minimum1 from #cej to #cfj cubic feet of carburetted hidrogen gas2 but the same quantity of the best ,newcastle coal1 that is to say1 such as coke1 which1 when laid on the fire readily undergoes a kind of semi-fusion1 and sends out brilliant streams of flame1 produces upon an average from #cjj to #cfj cubic feet of this gazeous fluid1 besides a large portion of sulphuretted hidrogen1 carbonic oxid and carbonic acid4 ,half a cubic foot of this carburetted hidrogen1 fresh prepared1 that is to say1 holding in solution or suspension1 a portion of the essential oil1 which is generated during the evolution of the gas1 is equal in illuminating power to from #agj to #ahj grains of tallow1 7being the quantity consumed by a candle six to the pound in one hour47 ,now1 one pound avoirdupoise is equal to #gjjj grains1 and consequently one pound of candles of six in the pound1 burning one at a time in succession1 would last 7if we take #age grains of tallow to be consumed in an hour7 #gjjj_/age #dj hours4 ,to produce the same light we must burn one half of a cubic foot of coal-gas per hour2 therefore1 one-half multiplied by forty hours is equal to twenty cubic feet of gas in #dj hours1 consequently equal to one pound of candles1 six to the pound1 provided they were burnt one after another4 ,one hundred and twelve pounds of cannel-coal1 produce1 at its minimum1 three hundred and fifty cubic feet of gas2 and are equal to three hundred and fifty1 divided by twenty1 which last is equivalent to one pound of tallow1 making one hundred and twelve pounds of cannel-coal1 equal to #cej_/bj #aglbs4 of tallow4 ,further1 one hundred and twelve pounds of cannel-coal1 divided by seventeen and a half of tallow make six and four-tenths of cannel-coal1 equal to one pound of tallow4 ,with regard to ,newcastle coals#ag1 it may be stated that one chaldron of ,wall's-,end coal may be made to produce in the large way upwards of #aa1jjj cubic feet of crude gas2 which1 when properly purified1 diminishes to nearly #aj1jjj cubic feet4 #ag ,one chaldron of ,newcastle coal weighs from #bhej to upwards of #bighlb4 ,the production of carburetted hydrogen1 both with regard to quantity and quality from the same kind of coal depends much upon the degree of temperature employed in the distillatory process4 ,if the tar and oil produced during the evolution of the gas in its nascent state1 be made to come in contact with the sides of the red hot retorts1 or if it be made to pass through an iron cylinder or other vessel heated red hot1 a large portion becomes decomposed into carburetted hydrogen gas and olifiant gas1 and thus a much larger quantity of gas is produced than would be obtained without such precaution from the same quantity of coal4#ah #ah ,one pound of coal-tar produces #ae cubic feet of carburetted hidrogen abounding in olifiant gas4 ,the distillation of the coal1 7if gas be the chief object7 should therefore not be carried on too rapidly4 ,most of the retorts used in the large way1 are calculated for containing about one hundred weight of coal1 and in general1 when previously heated1 produce from two and one-half to three cubic feet of gas1 in four hours for each pound of coal they contain2 but when the layer of coals in them does not exceed four inches in depth1 three and one-half to four feet of gas may be obtained in the same time4 ,the retorts best calculated for large gas-light works are seven or eight foot long 7without the mouth-piece7 and twelve inches in diameter1 tapering down to ten inches--if they are larger the coal which they contain cannot be heated properly4 ,the advantages that may be derived from the circumstances before stated are of greater value in the gas-light manufacture than is often imagined1 and the quantity as well as the quality of the gas is very much influenced by such circumstances4 ,if coal be distilled with a very low red heat scarcely observable by daylight1 the gas produced gives a feeble light--if the temperature be increased so that the distillatory vessel is of a dull redness1 the light is more brilliant and of a better colour--if a bright or cherry-red heat be employed the gas produced1 burns with a brilliant white flame1 and if the heat be increased so far that the retort is almost white hot1 and consequently in danger of melting1 the gas given out1 has little illuminating power1 and burns with a clear blueish flame2#ai or if the coal abounds in pyrites or sulphuret of iron1 as is sometimes the case with ,newcastle coal1 a large quantity of sulphuretted hidrogen is likewise evolved1 which although it increases the illuminating power of the coal-gas1 has the capital disadvantage1 of producing an intolerable suffocating odour1 when the gas is burnt which is particularly perceptible in low rooms illuminated with such gas4 #ai ,it is chiefly a mixture of carbonic oxid1 and hydrogen gas4 ,these observations also apply to the distillation of tar1 which when distilled either in a vaporous or nascent state1 during its first production from coal in the ordinary process1 or if it be submitted to a second distillation1 mingled with a fresh portion of pit-coal1 a practice usually had recourse to when this product cannot be disposed of more advantageously4 ,the best depth of coal in the retort for procuring excellent gas1 and at the same time for yielding the greatest quantity from the same weight in the shortest possible time1 is about six inches4 ,the brightness of the coal-gas flame is rather diminished when the gas has been long kept over water1 and hence for illumination it should be used as soon as prepared1 but of course properly purified4 ,the quantity of gas taken up by water is affected by temperature1 because the temperature increases its elasticity2 the quantity of gas absorbed1 diminishes as the temperature increases1 and increases as the temperature diminishes4 #g part of its own bulk of pure coal-gas is absorbed by the water over which it is confined in the gazometer4 ,the chemical constitution of this gazeous fluid is best ascertained by burning it in a vessel of oxygen gas1 over lime-water in a pneumatic reservoir1 by means of a bladder and bent brass pipe4 ,two products are then obtained1 viz4 water and carbonic acid4 ,that water is produced1 may be shown by burning a very small stream of the gas in a long funnel-shaped tube open at both ends4 ,the formation of carbonic acid is evinced1 by the copious precipitation of the lime-water in the foregoing experiment4 ,if carburetted hydrogen be mixed with a sufficient quantity of oxygen gas or common air and fired by the electric spark1 or by any other method1 an explosion takes place more or less violent according to the quantity of carbonaceous matter condensed in the hydrocarbonat2 and the remaining gas consists of carbonic acid1 together with any unconsumed gas1 or excess of oxygen1 whilst the water condenses in drops on the sides of the vessel4 ,a few cubic inches of the mixed airs is as much as can be conveniently managed at a single explosion2 and when any portion of olefiant gas is present1 even this quantity will endanger very thick glass jars4 ,a very vivid red flame appears at the moment of the explosion1 and a great enlargement takes place in an instant1 after which the bulk is suddenly reduced to much less than the original quantity4 ,when the carbonic acid is absorbed by lime-water1 if the gasses have been properly proportioned1 no gazeous residue is left1 except accidental impurities4 ,though carburetted hydrogen gas1 is sometimes naturally produced in coal-mines1 and occasionally mixes with common air1 producing dreadful explosions1 yet when coal-gas is mixed with common air1 it does not explode unless the gas be to the air as #a to #aj nearly4 ,such are the leading chemical habitudes of this gazeous product4 ,the varieties of carburetted hydrogen gas all agree in being inflammable2 but they possess this property in various degrees1 as is evinced by the variable brightness of the flame which they yield when set on fire4 8,messrs4 ,,sobolewsky and ,,horrer1 of ,st4 ,petersburgh1 have employed wood for the purpose of producing carburetted hydrogen gas4 ,the pyroligneous acid obtained in this operation1 when freed from the empyreumatic oil with which it is mixed1 becomes acetous acid1 and is applicable to all the uses of vinegar4 ,a cubic cord of wood equal to #b4acc ,french metres 7a metre being rather more than an ,english yard71 yields #bee ,paris pounds of charcoal1 and #gj buckets of acid4 ,the latter gives #cj pounds of tar1 after the extraction of it #ej buckets of good vinegar remain4 ,the same quantity of wood furnishes #ej1jjj cubic feet of gas1 sufficient for the supply of #djjj lamps for five hours40#bj #bj ,see ,repository of ,arts1 ,vol4 ,,xi4 ,no4 #cf1 p4 #cda4 ,,utility ,,of ,,the ,,gas-,,light ,,illumination1 ,,with ,,regard ,,to ,,public ,,and ,,private ,,economy4 ,from what has been stated in the preceding pages it becomes obvious1 that a substance yielding an artificial light may be obtained from common coal in immense quantities4 ,the attempt to derive advantage from so valuable a discovery is surely no idle speculation4 ,let us therefore now consider to what objects of public and private utility this mode of procuring light may be applied with effect4 ,it is obvious that coal-gas may be preserved in a reservoir for any length of time and that it may be conveyed by means of tubes to any distance flowing equably and regularly like water4 ,those1 indeed1 who have not seen the contrivance will find it difficult to imagine with what ease it is managed4 ,the gas may be distributed through an infinity of ramifications of tubes with the utmost facility4 ,near the termination of each of the tubes through which it flows1 it is confined by a valve or stop-cock1 upon turning which1 when required to be lighted1 it flows out in an equable stream and ascends by its specific levity4 ,there is nothing to indicate its presence2 no noise at the opening of the stop-cock or valve--no disturbance in the transparency of the atmosphere--it instantly bursts on the approach of a lighted taper1 into a brilliant1 noiseless1 steady and beautiful flame4 ,its purity is attested by its not blacking or soiling in the least degree the metallic orifice from which it issues1 nor even a sheet of white paper1 or polished surface brought in contact with it4 ,there is no escape of combustible matter unconsumed1 which is so great a nuisance in all our common lights4 ,the products of the combustion are water and carbonic acid gas#ba4 ,the accurate and elegant experiments of ,dr4 ,w4 ,,henry have shewn in the most satisfactory manner1 that considerably less carbonic acid is produced by the flame of coal-gas1 than by that of oil1 tallow1 or wax#bb1 which sufficiently refutes the absurd notions that have been circulated respecting the pernicious effects of gas-lights4 ,but if the gas from ,newcastle coal is badly prepared1 or not deprived of the portion of sulphuretted hydrogen1 which it usually contains1 it then emits fiery sparks and produces a portion of sulphureous acid by virtue of the union of the oxygen of the air with the sulphur dissolved in the gas1 the consequence of which is1 a suffocating odour1 which is particularly observable in the higher stratum of the air of apartments in which the gas is burnt4 ,such gas likewise tarnishes all metallic bodies--it discolours the paintings effected with metallic oxids1 and always produces a suffocating odour very noxious to health4 ,it is freed from the sulphuretted hydrogen and may be rendered fit for illumination by passing it repeatedly through very dilute solutions of sub-acetate of lead1 green sulphate of iron1 quicklime and water1 or hyper-oxymuriate of lime4 #ba ,the water 7which passes off in imperceptible vapour7 is generated by part of the oxygen of the air uniting with part of the hydrogen1 which forms the great bulk of the coal-gas3 and the carbonic acid gas is produced by the union of another portion of the oxygen uniting with the smaller portion of carbon1 which is the other component part of the coal-gas4 #bb #ajj ,cubic inches of carburetted hydrogen from coal1 require for burning #bbj cubic inches of oxygen and produce #ajj cubic inches of carbonic acid--#ajj cubic inches of the same gas obtained from wax1 require for burning #bhj cubic inches of oxygen and produce #acg cubic inches of carbonic acid--#ajj cubic inches of the same gas procured from lamp-oil1 require #aij cubic inches of oxygen for burning1 and produce #abd cubic inches of carbonic acid4 ,the following lines relating to the salubrity of the gas-light illumination are copied from ,mr4 ,lee's evidence in the ,house of ,commons1 when examined on that subject4 ,question--8,is the health of your manufacturers at all affected by the use of gas8--,answer--,not in the least1 or ,i would not have adopted it4 ,i believe ,i explained to the ,committee1 that ,i used the gas-lights in my own house first40 ,q4 8,you have not seen the smallest alteration in the health of your workmen8--,a4 ,not in the least1 for had ,i seen it1 it would have been a fatal objection to it40 ,q4 8,and you say the same in regard to the use of the gas-lights in your own family8--,a4 ,certainly ,i do40 ,as to the brilliancy of the flame1 an appeal may be made to every one who has witnessed the gas-light illumination1 whether it be not superior to the best wax candle-light1 or the light of ,argand's lamps4 ,it may be described as a rich compact flame1 burning with a white and agreeable light4 ,it is also perfectly steady1 when the flame is limited to a moderate size3 in large masses1 it is subject to that undulation which is common to it with all flames of certain dimensions1 and is caused by the agitation of the surrounding atmosphere4 ,the gas flame is entirely free from smell4 ,the coal-gas itself certainly has a disagreeable foetid odour before it is burnt1 so has the vapour of wax1 oil1 and tallow1 as it comes from a lamp or candle newly blown out4 ,this concession proves nothing against the flame of gas which is perfectly inodorous1 a white handkerchief1 passed repeatedly through it and applied to the nose1 excites no odour4 ,another peculiar advantage of the gas flame is1 that it may be applied in any direction we please1 as there is nothing to spill and the gas is propelled by a certain force which is always the same1 it will burn equally well in an almost horizontal as in an upright position2 and we can thus obviate two great objections to all our artificial lights1 that their least luminous end is directed downwards where the light is generally most wanted1 and that a shade is cast below by the stand or support of the combustible matter4 ,the size1 shape and intensity of the gas-flame may be regulated by simply turning a stop-cock which supplies the gas to the burner4 ,it may at command be made to burn with an intensity sufficient to illuminate every corner of a room1 or so low and dim as barely to be perceived4 ,it is unnecessary to point out how valuable such lights may be in nurseries1 stables1 warehouses1 in the chambers of the sick1 c4 ,from the facility with which the gas-flame can be conveyed in any direction1 from the diversified application1 size and shape which the flame can be made to assume1 there is no other kind of light so well calculated for being made the subject of splendid illuminations4 ,where lustres are required in the middle of a room1 the best mode of conducting the gas to the chandelier1 is to pass the gas-pipe through the ceiling from the room above1 immediately over the lustre4 ,this can be easily done without injury to the apartment4 ,where side-lights and chandeliers are required the tubes need never appear in sight1 but may be concealed in the wall or floor of the house4 ,when transparencies are wanted as decorations for halls1 lobbies1 c4 more than light1 recesses may be filled with different coloured media1 or paintings1 and any intensity of light may be thrown on the object4 ,if a number of minute holes are made in the end of a gas pipe1 it forms as many jets de feu1 which have a very brilliant appearance2 these may sometimes be placed in the focus of a parabolic reflector4 ,in cases where the light is required to be thrown to a distance1 other burners are constructed upon the same principle as the ,argand lamp1 forming a cylinder of flame1 and admitting a current of air both to the inside and outside4 ,on comparing the flame of a gas-light with the flame of a candle whatever its size may be1 it appears just as yellow and dull as the flame of a common lamp appears when compared with that of a lamp of ,argand4 ,the beautiful whiteness of gas-light never fails to excite the surprize and admiration of those who behold it for the first time4 ,a large edifice or manufactory lighted by gas1 contrasted with one of the same kind lighted by candles or lamps1 resembles a street on the night of a general illumination1 compared with the glimmering light of its ordinary parish lamps4 ,the intensity of one of the parish gas-light lamps1 now exhibited in the streets of this metropolis1 will bear ample testimony of this assertion2 the light of the parish gas-lamps1 is to the intensity of the parish oil lamps as #a to #ab4 ,one of the most obvious applications of the gas-light illumination unquestionably consists in lighting streets1 shops and houses2 and let it be observed that as this is found safe and economical1 it proves all that the most ardent friends of the gas-light system can desire4 ,for in contending with the common mode of lighting the streets and shops1 the new lights must beat out of the market the cheapest of all artificial lights2 and as it has succeeded in doing this it shews in the most satisfactory point of view1 the prodigious advantages of gas-lights when compared with the materials of tallow and oil4 ,the original expence of laying the pipes for conveying the gas1 together with the cost of the machinery1 is all that is required2 the preparation of the gas being itself a lucrative process1 no doubt will pay all its expences besides the interest of capital1 and leave a surplus of profit4 ,indeed the application of the coal-gas1 as a substitute for tallow and oil1 to illuminate houses1 shops1 c4 is no longer problematical1 a considerable extent of this capital1 together with numerous shops and houses being already supplied with this species of light4#bc #bc ,the ,liberty of ,norton ,falgate1 as far as ,bishopgate-street1 is lighted with gas-light1 from the ,chartered ,company's station at ,norton ,falgate2 and gas-light pipes are laid from that station as far as the west end of ,cheapside1 and in all the streets north of that great thoroughfare4 ,in the ,west end of the ,town1 the main pipes for supplying the streets and houses with light from the ,gas-,light ,company1 extend through the most eligible parts2 from their ,establishment in ,peter-street1 ,westminster1 along the line from ,pall ,mall to ,temple-bar1 compleatly surrounding the parish of ,st4 ,martin's in the ,field4 ,main pipes are also placed in the ,hay-market1 ,coventry-street1 ,long-,acre1 ,st4 ,martin's-lane2 and in the principal parts of the parishes of ,st4 ,james and ,st4 ,ann4 ,in the ,east end of the metropolis1 the gas-light mains extend from ,cornhill to ,st4 ,paul's1 ,wood-street1 ,fore-street1 c4--,consent has also been given to the incorporated ,gas-,light ,company for laying their pipes in the parish of ,st4 ,stephen's in the ,field2 ,st4 ,paul ,covent-garden2 ,st4 ,mary-le-,strand2 ,st4 ,clement ,danes2 ,st4 ,george's1 ,bloomsbury2 ,st4 ,giles's in the ,fields2 ,st4 ,andrew's1 ,holborn1 above the bars2 part of the parish of ,st4 ,mary-la-bonne2 besides several other districts1 comprehending the whole of the city and suburbs of ,westminster4 ,enough therefore1 has been done to prove the possibility of lighting houses1 and streets1 with gas1 which would have been regarded twenty years ago as an extravagant paradox4#bd #bd ,i am informed by ,mr4 ,,clegg1 the engineer of the ,chartered ,gas-,light ,company1 under whose direction the new system of lighting is carried on1 that the total length of pipe laid down1 as mains1 in the streets of ,london amounts already to nearly #ae miles4 ,in the ,eastern part of ,london1 the same ,company is engaged to lay their pipes in the principal parts of ,whitechapel1 ,spitalfields1 ,st4 ,luke's1 and the adjoining neighbourhood4 ,one part of the city of ,london1 extending from ,temple-bar to the ,west end of ,cheapside2 from ,newgate-street to ,holborn ,bars1 together with the intervening streets1 is also provided with pipes laid down by another gas-light association1 who have opened a new ,establishment in ,water-lane1 ,fleet-street1 but are unconnected with the ,chartered ,company4 ,a third company is projected in ,southwark1 and a fourth in the ,eastern district of ,london1 creating by a rivalry of interest1 that laudable competition which always proves beneficial to the public at large1 and which cannot fail to accelerate the progress of this new art of procuring light4 ,the ,church of ,st4 ,john the ,evangelist in this metropolis has been illuminated with gas-lights for upwards of two years3 the lights employed in this edifice is equal to #cfj tallow candles eight to the pound4 ,the avenues to the ,house of ,lords and ,house of ,commons1 ,westminster-hall1 ,westminster-bridge2 the house and offices of the ,speaker of the ,house of ,commons1 the ,mansion-house1 and many other places1 deserve to be named1 as having already adopted this species of illumination4 ,another advantageous application of the gas-light must be the supplying of light-houses4 ,from the splendour and distinguishing forms which the gas-light flame is capable of assuming1 no light is better calculated for signal-lights than this4 ,by means of one single furnace as much gas might readily be procured as would furnish a flame of sufficient intensity1 during the longest winter night1 exceeding in brilliancy or intensity of light any light-house in ,britain or elsewhere4 ,if every light-house round this island were possessed of a gas-light furnace1 one-half part of the enormous expence which they at present require would furnish a much more brilliant light4 ,the cheapness of this light and its efficacy for the purpose1 would soon multiply the number of light-houses1 and thus most essentially contribute to the security of navigation on our coast4 ,the gas may be made to issue from tubes by long narrow slips1 and a surface of flame produced of any given dimensions1 and free from all smoke that would obscure the reflectors4 ,the ease with which the largest gas-light flame is instantly extinguished by shutting the stop-cock1 and the readiness with which a long line of gas catches fire by applying a lighted taper to one extremity1 are properties that cannot fail to recommend it for the purposes of telegraphic communications by night4 ,another application of the gas unquestionably might be the lighting of barracks1 arsenals1 dock-yards1 and other establishments where much light is wanted in a small place4 ,the annual expence of lighting the barracks of ,great ,britain is said to fall little short of #ej1jjjl4 a small part of which on the new plan1 would supply them with a much purer and safer light4 ,the uses of the gas-lights already enumerated must of themselves1 justify us in attaching great importance to the discovery1 and if reduced to practice all over the kingdom1 would employ a large capital in a way the most advantageous and productive4 ,but the utility of this light will be almost indefinitely increased to the use of private families4 ,that such an application is practicable1 in all towns of ,great ,britain1 is obvious1 from what has been done already1 and that it would be highly economical and ornamental1 there can be little doubt4 ,by means of gas we may have a pure and agreeable light at command in every room of our house1 just as we have the command of water1 with this singular advantage1 that these lights may burn for hours within an inch of the most combustible substance without danger1 because they neither can burn down like a candle nor emit sparks4 ,these properties make the gas-lights a most desirable light on board our ships of war1 where severe regulations are necessary to prevent danger from fire1 which after all are frequently evaded4 ,the gas-light might be used in the store-rooms1 and even in the powder magazine1 and the captain would completely command the supply of light by the possession of the key which opens and shuts the stop-cock4 ,a small apparatus which may be erected at a trifling expence would be sufficient for that purpose4 ,in shops1 counting-houses1 and public offices1 the advantages are a white light1 nearly equal to day-light1 a warmth which almost supersedes the use of fires1 a total absence of smoke1 smell1 and vapour1 and great economy of labour4 ,the heat produced by gas-lights must be observed by every one who has had an opportunity of attending to it in the most superficial manner1 and the reason why gas-lights produce more heat than oil or candle-light will not appear strange to our chemical readers 7and who is there now that does not know something of chemistry87 when it is considered that the gas-light flame condenses more air than the flame of oil and tallow1 and consequently must produce more heat4 ,the flame of gas may be produced in so large a surface1 as to be applied to heat the most spacious apartments as well as to light them4 ,if the gas is made to issue by a circular rim of about twelve inches diameter2 it forms a sort of an ,argand lamp on a great scale1 and it is manifest that a circumference of three feet of flame will heat the air very rapidly1 and with such uniformity that we need no longer be exposed to the partial heating occasioned by the strong draft of a large fire4 ,a lamp of this description in the centre of a large room1 with a very small fire to secure a gradual renewal of the air would enable us to enjoy the most healthful and agreeable temperature4 ,from trials made on this subject1 ,i am enabled to state1 that three ,argand's lamps1 consuming five cubic feet of gas per hour1 are sufficient to keep a room #aj feet square at a temperature of #ee ,fahr4 when the air without doors has a temperature of freezing4#be #be ,mr4 ,,dalton's method of ascertaining the comparative quantity or effects of heat evolved during the combustion of different inflammable gases1 and other substances capable of burning with flame1 as stated in his ,system of ,chemistry1 vol4 ,i4 p4 #gf1 deserves to be recommended to those who are more immediately interested in this subject4 ,the process1 which is simple1 easy1 and accurate1 is as follows3 ,take a bladder of any size1 7let us suppose for the sake of illustration1 the bladder to hold or to be equal in capacity to #cj1jjj grains of water17 and having furnished it with a stop-cock and a small jet pipe1 fill it with the combustible gas the heating power of which is to be tried4 ,take also a tinned iron vessel with a concave bottom of the same capacity1 pour into it as much water as will make the vessel and water together equal to the above stated bulk of water in the bladder1 viz4 #cj1jjj grains4 ,this being done1 set fire to the gas at the orifice of the pipe1 and bring the point of the flame under the bottom of the tinned vessel1 and suffer it to burn there1 by squeezing the bladder till the whole of the gas is consumed4 ,the increase of temperature of the water in the tinned vessel being carefully noticed before and after the experiment1 gives very accurately the heating power of the given bulk of the inflammable gas4 ,it was thus proved that-- ,olefiant gas raises an equal volume of water #ad ,carburetted hidrogen1 or coal gas #aj ,carbonic oxid #d ,hidrogen #e ,spermaceti oil #aj grains burnt in a lamp raised #cj1jjj grains of water #e ,tallow #e ,wax #e1ge ,oil of turpentine #c ,spirit of wine #b ,in all processes of the arts where a moderate heat is wanted the gas-light flame will be found very advantageous--even on a large scale this flame may be used with profit4 ,it possesses advantages which cannot be obtained from flaming fuel1 where much nicety is required2 because no fuel can be managed like the flame of coal-gas4 ,for it is well known1 that when too little air be given to flaming fuel it produces no flame1 but sooty vapour2 and if too much air be admitted to make those vapours break out into flame1 the heat is often too violent4 ,it is a fact1 that flame1 when produced in great quantity1 and made to burn violently1 by mixing with a proper portion of fresh air1 driving it on the subject1 and throwing it into whirls and eddies1 thereby mixing the air with every part of the hot vapour1 produces a very intense heat4 ,the great power of a gas-flame does not appear when we try small quantities of it1 and allow it to burn quietly1 because the air is not intimately brought into contact with it1 but acts only on the outside2 and the quantity of burning matter in the surface of a small flame is too minute to produce much effect4 ,illustration ,but when the flame is produced in large quantity and is freely brought forward into contact and agitated with air1 its power to heat bodies is immensely increased4 ,it is therefore peculiarly proper for heating large quantities of matter to a violent degree1 especially if the contact of solid fuel with such matter is inconvenient4 ,as the gas-flame may be made to assume any shape and intensity1 and as there is nothing to spill1 it may be exhibited under such variety of forms and designs1 as cannot fail to give rise to the most tasteful ornamental illumination4 ,,plates ,,iii4 ,,iv4 and ,v4 exhibit such designs of different kinds of gas-lamps1 chandeliers1 lustres1 candelabras1 c4 as are already in use in this ,metropolis4 ,,plate ,,iii4 fig4 #a1 represents a ,rod ,lamp4 ,the gas passes through the rod a1 to the ,argand burner1 which is surrounded by a cylindrical chimney1 c1 swelling out at the lower extremity4 ,the construction of the ,argand burner we have mentioned already1 p4 #gh4 ,in all the gas-light burners1 constructed on ,argand's plan1 care should be taken that the flame be in contact with the air on all sides1 and that the current of air be directed towards the upper extremity of the flame4 ,this may be effected by causing a current of air to rise up perpendicular from the bottom of the chimney glass1 and to pass out again through the contracted part1 or upper extremity of the chimney2 but no other current of air should ever be permitted to come near the gas-flame1 or enter the glass chimney which covers or defends the light2 for if more air be permitted to mix with the flame than is sufficient for the compleat combustion of the coal-gas1 it necessarily diminishes the heat1 and consequently reduces the quantity of light4 ,fig4 #b4 ,a ,rod ,gas ,lamp1 with branches4 ,the gas passes through the hollow rod1 a1 and part of the hollow branch1 b1 to the burner of the lamp4 ,the cylindrical shaped glass1 c1 exhibited in this figure1 is not so well adapted for the compleat combustion of coal-gas1 as the belly-shaped chimney1 c1 represented in fig4 #a1 #c1 #e1 #f1 because the ascending current of fresh air is not turned out of its perpendicular course1 and thrown immediately in a concentrated state1 into the upper part of the flame where the combustion of the gas is less perfect4 ,the exterior current of air which enters at the bottom into the lamp1 rises merely with a velocity proportioned to the length of the cylinder1 and to the rarefaction of the air in the same1 but without being propelled to the apex of the flame1 as it should do1 and is made to do1 in the bellied glass adapted to the lamp1 fig4 #a4 ,fig4 #c4 ,a ,bracket ,lamp4 a1 the tube which conveys the gas to the burner2 b1 the stop-cock of the tube4 ,fig4 #d4 ,a ,pendent ,rod ,lamp2 in which the gas is supposed to come from a pipe above1 through the ceiling1 into the pipe1 a1 to supply the burners4 ,the tulip-shaped chimney1 b1 of this lamp1 is likewise ill adapted for gas-light burners4 ,fig4 #e4 ,a pendent double-bracket ,lamp4 ,the gas passing through the perpendicular tube1 a1 into the brackets1 b b2 c shows the ,argand burner4 ,fig4 #f4 ,a swing ,bracket ,lamp4 a1 the gas-pipe with its stop-cock2 b1 a brass ball1 communicating with the pipe1 a2 c1 the conducting tube1 ground air-tight into the ball1 b1 and communicating with the burner of the lamp1 so as to allow it to have an horizontal motion4 ,fig4 #g4 ,shews the construction of the ball b1 and pipe1 c1 of the lamp1 fig4 #f4 ,fig4 #h4 ,a ,swing ,cockspur ,lamp1 constructed upon the same plan as fig4 #f4 ,these two lamps are very convenient for desks in counting-houses1 c4 ,fig4 #i4 ,a stop-cock with ball and socket1 which1 when adapted to a gas-light pipe1 allows it to have an universal motion1 so that the light may be turned in any direction4 ,fig4 #aj4 ,section of the stop-cock1 with ball and socket4 ,fig4 #aa4 ,shows the ball and socket1 fig4 #i1 in perspective4 ,illustration ,,plate ,,iv1#bf fig4 #a4 ,a ,candelabrum2 the gas pipe ascending from the floor of the apartment1 through the column a1 and terminating in the burner of the lamp4 #bf ,the gas-lamps exhibited in this plate1 are employed in the library1 counting-house1 warehouse1 and offices of ,mr4 ,,ackerman1 and1 by whose permission1 they are copied on this occasion4 ,fig4 #b4 ,a fancy pendent ,cockspur ,lamp4 ,the gas being transmitted to the burners1 c c1 by means of the pipe1 a4 ,fig4 #c4 ,a ,pedestal ,argand ,lamp4 a1 the pipe and stop-cock1 which transmits to1 and shuts off the gas from the burner of the lamp4 ,fig4 #d4 ,a ,pedestal ,cockspur ,lamp4 a1 the stop-cock and gas-pipe4 ,fig4 #e4 ,a fancy bracket ,cockspur ,lamp1 intended merely to show that the coal-gas1 as it passes to the burner1 is perfectly devoid of colour1 and invisible4 a is a glass vessel furnished at its orifice with a brass cap1 c1 and perforated ball1 out of which the gas-flame proceeds4 b1 the pipe which conveys the gas into the glass vessel1 a4 ,fig4 #f4 ,a ,bracket ,argand ,lamp4 a and b1 the gas pipe communicating with the burner4 ,fig4 #g and #h4 ,a ,horizontal ,bracket ,lamp4 a1 the gas pipe1 supposed to be concealed in the ceiling4 b1 the communicating pipe1 which1 together with c1 branches out at right angles at d d4 e e1 are the burners of the lamp4 ,,plate ,v4 fig4 #a4 ,a ,candelabrum1 into which the gas-pipe ascends from the floor of the apartment1 the lateral branches communicating with the central tube4 ,fig4 #b4 ,an ,arabesque ,chandelier4 ,the gas enters from the ceiling of the room into the rope-shaped pipe1 a1 from which it proceeds through one of the arched ribs1 b b1 into the horizontal hoop1 or pipe1 c4 ,fig4 #c4 ,a ,roman ,chandelier4 ,the gas enters through the inflexible hollow chain1 a1 into the central tube1 b1 from whence the burners are supplied by the lateral branches1 c c4 ,fig4 #d4 ,a ,gothic ,chandelier4 ,the gas is transmitted to the burners through the rope1 a1 which includes a tube1 and the communication with the burners is established through the lateral branches4 ,fig4 #e4 ,a ,pedestal ,figure ,lamp4 ,the gas is here made to pass by means of a pipe through the body of the figure into the lattice-work plateau1 constructed of hollow and perforated brass tubes4 ,illustration ,fig4 #f4 ,a ,pedestal ,vase ,lamp4 ,the gas-tube enters through one of the claw-feet of the altar-shaped pedestal1 into the glass vase1 a1 at the bottom of which it joins the tubes communicating with the metallic corn-ears1 b1 at the upper extremities of which it forms jets de feu4 ,fig4 #g4 ,a ,girandole4 ,the gas enters through the bracket1 a1 and is conveyed to the burners by the descending tubes1 b b4 ,fig4 #h4 ,a ,candelabrum1 having a central pipe1 through which the gas is conducted to the burner at the top4 ,,other ,,products ,,obtainable ,,from ,,coal3 ,,namely1 ,,coke1 ,,tar1 ,,essential ,,oil1 c4 ,having thus far considered the nature of coal-gas as a substitute for the lights now in use1 it will be necessary to attend more particularly to some other products which are obtained during the production of this species of light3 namely1 coke1 tar1 ammoniacal liquor1 c4 ,coke4--,the substance called coke1 which constitutes the skeleton of the coal1 or its carbonaceous base1 is left behind in the retort1 after all the evaporable products have been expelled from the coal by heat4--,see page #he4 ,it is sufficiently known1 that coke is a more valuable fuel than the coal from which it is obtained4 ,hence1 immense quantities are prepared in the large way1 but the gazeous and other substances are lost in the process employed for carbonizing the coal4#bg ,in the manufacture of coal-gas1 the coke comes from the retort1 enlarged in size1 and greatly diminished in weight1 when compared with the original coal4 ,in whatever state the coal may be when introduced into the retort1 the coke is uniformly taken out in large masses1 so that the refuse coal1 or dust1 and sweepings of the pit1 which are now thrown away1 may be employed and converted into an excellent fuel4 ,coke is decidedly superior to coal for all domestic1 and more especially for culinary purposes2 the heat which it throws out being more uniform1 more intense1 and more durable4 ,no flame1 indeed1 accompanies it1 and it seldom needs the application of the poker1--that specific for the ennui of ,englishmen2 but these deficiences are more than balanced by the valuable property of emitting no sparks1 of giving more heat1 and burning free from dust and smoke4 #bg ,the preparation of coke is as follows3--,a quantity of large coal is placed on the ground in a round heap1 of from #ab to #ae feet in diameter1 and about two feet in height2 as many as possible of the large pieces are placed on their ends1 to form passages for the air2 above them are thrown the smaller pieces and coal dust1 and in the midst of this circular heap1 is left1 a vacancy of a foot wide where a few faggots are deposited to kindle it4 ,four or five apertures of this kind are formed round the ring1 particularly on the side exposed to the wind2 there is1 however1 seldom occasion to light it with wood1 for other masses being generally on fire1 the workmen most frequently use a few shovels of coal already burning1 which acts more rapidly than wood1 and soon kindles the surrounding pile2 as the fire spreads1 the mass increases in bulk1 puffs up1 becomes spongy and light1 cakes into one body1 and at length loses its volatile parts1 and emits no more smoke4 ,it then acquires an uniform red colour1 inclining a little to white1 in which state it begins to break into gaps and chinks1 and assumes the appearance of the under part of a mushroom2 at this moment the heap must be quickly covered with ashes1 of which there is always a sufficient provision around the numerous fires1 where the coke is prepared4 ,that coke must give out more heat during its combustion than coal1 will at once become obvious1 when we consider that the quantity of matter which1 in the combustion of coal is changed from a solid to a state of elastic fluidity1 must necessarily carry off a portion of caloric1 which then becomes converted in a latent state without producing heat1 whilst the glow of the coke radiates caloric with an intensity unimpaired by any demand of this kind4 ,it is thus that coke1 though somewhat more difficult of ignition than common coal1 always gives out a more steady1 a more lasting1 and a more intense heat4 ,the only inconveniences that attend the use of coke is1 that1 as it consumes1 it leaves much more ashes than common coal1 charcoal1 or wood2 and these much heavier too1 which are1 therefore1 liable to collect in such quantity as to obstruct the free passage of air through the fire2 and further1 that when the heat is very intense1 these ashes are disposed to melt or vitrify into a tenacious drossy substance1 which clogs the grate1 the sides of the furnace and the vessels4 ,this last inconvenience is only troublesome1 however1 when the heat required is very great4 ,in ordinary heats1 such as are produced by kitchen or parlour grates1 the ashes do not melt1 and though they are more copious and heavy than those of charcoal or wood1 they do not choke up the fire1 unless the bars of the grate be too close together4 ,the relative effects of heat produced by coke and coal are as follows3-- ,six hundred pounds of pit-coal are capable of evaporating #aj cubic feet of water in #bj hours1 and #dcjlb4 of coke are capable of evaporating #ag cubic feet of water in #ab hours and a half4#bh #bh ,in order to learn the relative effect of different kinds of fuel1 with regard to their capability of producing heat1 chemistry teaches that equal quantities of fuel alike expended1 will raise the temperature of a given quantity of water through the same number of degrees2 whence1 by knowing the original quantity and temperature of water1 together with the quantity of fuel expended to raise the water to the boiling point1 the result sought may be expressed by stating the quantity of water at #cj degrees1 which would have been raised #ahj degrees by one pound of the fuel employed2 or in the form of a rule1 ,multiply the quantity of water by the number expressing the degrees actually raised2 multiply the number of pounds of fuel expended by #ahj degrees4 ,divide the first product by the latter1 and the quotient will express the water which would have been raised #ahj degrees by one pound of the fuel4 ,or equal quantities of water may be compleatly evaporated under equal surfaces and circumstances1 with the different kinds of fuel1 the nature of which is to be examined2 the quantities of fuel expended for that purpose give the relative effect of the different kinds of fuel1 with regard to their power of producing heat4 ,the ,earl of ,dundonald has shown that1 in the application for burning lime1 a quantity of coke uniformly burns a given portion of lime-stone in one-third part of the time that the quantity of coal from which the coke had been made could do4 ,this effect is to be accounted for from having previously freed the coal1 or rather its coke1 from the moisture and the tar1 which it sends out during combustion1 and which condenses on the middle and upper strata of stratified limestone and coal in the lime kiln1 and impedes the whole mass of materials from coming into a rapid and compleat ignition2 because the greater the quantity of materials1 and the sooner the whole is ignited1 the better and more economically the lime is burned1 both as to coals and time2 the saving of which last is a material object1 especially at lime-kilns where there is in the summer time a great demand for lime1 the coke occasioning the kilns to hold a third more lime at the same time4 ,in the art of making bricks1 in the smelting of metallic ores1 and the drying of malt1 the advantages of coke over coal1 are sufficiently known4 ,the following account given by ,mr4 ,davis1#bi shows that the advantages that may be derived in the processes of burning lime1 plaster of paris1 and bricks1 by means of coke1 are greater than at first sight might be imagined4 #bi ,philosophical ,magazine1 ,vol4 #cc1 p4 #dce4 8,the coke obtained in the gas process is so valuable1 that it appears inexplicable that men should not avail themselves of this mode of procuring light1 to the almost total exclusion of all other methods now in use4 ,as a landholder1 placed among an industrious but wholly illiterate society of men1 ,i have had the more opportunity of trying this species of fuel or coke1 which ,i could not otherwise procure in this sequestered spot1 at a tolerably cheap rate1 for purposes to which it has not1 as far as ,i know1 been hitherto employed4 ,i must tell you that ,i am my own lime-burner1 plaster of paris baker1 and brick-maker2 and that in these processes of rural economy ,i have derived the greatest benefits from this species of fuel1 which ,i now prepare at a cheap rate1 although ,i waste almost the whole of the light of the coal gas intentionally4 ,the coal which ,i employed formerly for the burning of limestone into lime1 is a very inferior kind of small coal1 called here ,welsh culm4 ,the kiln for burning the limestone into lime is a cup-shaped concavity1 surrounded with solid brick-work1 open at the top1 and terminating below by an iron grate4 ,it has a stone door that may be opened and closed for charging and emptying the furnace when required4 ,this furnace ,i formerly charged with alternate strata or layers of small coal and limestone1 the latter being broken previously into pieces not larger than a man's fist1 until the kiln was completely filled4 ,the stone is thus slowly decomposed2 the upper part of the charge descends1 and when it has arrived at the bottom of the furnace new strata are super-imposed1 so as to keep the furnace continually full during a period of #ej hours4 ,the quantity of lime ,i procured with small coal formerly amounted to #he bushels4 ,the strata of coal necessary for the production of this quantity of lime require to be four inches thick1 and the time necessary for calcination was1 as stated already1 #ej hours4 8,on applying coke instead of coal1 the produce of lime may be increased to nearly #cj per cent4 from the same furnace1 and the time required to effect the calcination of this quantity of lime-stone is reduced to #ci hours3 it also requires less attendance and less labour1 and the whole saving1 thus accomplished1 amounts to more than #ej per cent4 on the lime-kiln4 8,i have lately also employed coke for the burning of bricks4 ,my bricks are burnt in clamps1 made of bricks themselves4 ,the place for the fuel1 or fire-place1 is perpendicular1 about three feet high4 ,the flues are formed by gathering or arching the bricks over1 so as to leave a space between each of a brick's breadth2 and as the whole of the coal1 if this fuel be employed1 must1 on account of the construction of the pile1 be put in at once1 the charge of the bricks is not1 and never can be1 burnt properly throughout2 and the interference of the legislature1 with regard to the measurement of the clamp1 is a sufficient inducement for the manufacturer to allow no more space for coal than he can possibly spare4 8,if coke be applied instead of coal1 the arches1 or empty spaces in the clamp or pile1 as well as the strata of the fuel1 may be considerably smaller3 the heat produced in this case is more uniform and more intense1 and a saving of #cj per cent4 at least is gained4 8,in the baking my own plaster-stone ,i also employ coke4 ,the calcination of the stone for manure ,i perform in a common reverberatory furnace1 and the men who conduct the process 7who are otherwise averse to every thing new7 are much pleased with the steadiness of the fire1 and little attendance which the process requires1 when coke is used instead of coal4 8,these are the few facts ,i wish to state1 with regard to the useful application of this species of fuel1 which1 no doubt1 hereafter will become an object of economy of incalculable advantage to individuals1 if its nature be better understood than it is at present40 ,the quantity of coke obtainable from a given quantity of coal varies according to the nature of the coal employed4 ,one chaldron of ,newcastle coal produced1 upon an average1 in the gas-light manufacture1 from one chaldron and a quarter to one chaldron and a half of well formed coke4 ,if the carbonization of the coal has been carried to its utmost point1 the coke produced1 has a brilliant silvery lustre4 ,such coke is excellent for metallurgical operations1 because it stands the powerful blast of the bellows1 but for culinary and other purposes of domestic economy1 the carbonization should not be carried so far1 because1 the coke then produced1 kindles more readily and makes a more cheerful fire4 ,coal-tar1 ,oil1 and ,pitch4--,another1 valuable product obtainable from pit-coal1 is coal-tar4#cj ,this substance is deposited1 in the purification of the coal-gas1 in a separate vessel destined to receive it4 #cj ,in the year #affe1 ,becher1 a ,german chemist1 brought to ,england his discovery for extracting tar from coal1 this distillation he performed in close vessels4 ,it is not mentioned in the records of the time1 whether ,becher obtained1 or rather collected1 any other articles than the tar4 ,the coal-tar is so called from its resembling common tar in its appearance1 and most of its qualities4 ,several works have been1 at different times1 erected both in ,england and on the continent1 to procure from coal a substitute for tar2 but they turned out unprofitable speculations4 ,in #agha1 the ,earl of ,dundonald invented a mode of distilling coal in the large way1 which enabled him not only to form coke1 but1 at the same time1 to save and collect the tar4 ,even this process however1 for which a patent was taken out1 has gained very little ground4 ,its object was still too limited2 for though some of the ingredients of coal were procured1 they were procured at an expense that nearly balanced the profits2 and no attention whatever was paid to the coal gas1 which constitutes the most important part of coal4 ,coal-tar may be used with advantage for painting and securing wood that is exposed to the action of air or water4 ,the wood being warmed1 the tar is applied cold1 and penetrating into the pores1 gives the timber an uncommon degree of hardness and durability4 ,one chaldron of ,newcastle coal produces in the gas-light manufacture from #aej to #ahjlb of tar1 according to the circumstances under which it is produced4 ,see page #id4 ,the tar obtained from ,newcastle coal-tar is specifically heavier than that produced from cannel-coal2 hence it sinks in water1 whereas the latter swims on the surface of that fluid4 ,to render the tar fit for use1 it requires to be evaporated to give it a sufficient consistence4 ,if this process be performed in close vessels1 a portion of an essential oil is obtained1 which is known to colourmen by the name of oil of tar4 ,to obtain this oil1 a common still is filled with the coal-tar1 and1 being properly luted1 the fire is kindled and kept up very moderate1 for the tar is very apt to boil up in the early part of the process4 ,the first product that distils over is principally a brown ammoniacal fluid1 mixed however with a good deal of oil4 ,as the process advances1 and the heat is increased1 the quantity of ammoniacal liquor lessens1 and that of oil increases1 and towards the end of the distillation the product is chiefly oil4 ,the oil and ammoniacal water which distil over do not mix1 so that they may be easily separated by decantation4 ,the oil is a yellowish inferior kind of oil of turpentine1 which is very useful in painting ships1 for making varnishes1 and other coarse out-door work4 ,two hundred pounds of tar produce1 upon an average1 fifty-three pounds of essential oil4 ,if the coal-tar is wanted to be converted into pitch1 without obtaining the oil which it is capable of furnishing1 the evaporation of it may be performed in a common boiler2 but as it is extremely liable to boil over1 the greatest precaution is necessary in conducting the evaporation4 ,a boiler constructed on the following plan is very convenient for the conversion of coal-tar into pitch4 ,the contrivance consists in adding a spout1 or rim1 to the common boiler1 into which the tar spreads itself as it rises1 and by this means becomes cooled1 and the boiling over is checked4 ,illustration3 ,kettle for boiling ,tar4 #ajjjlb4 of coal-tar produce1 upon an average1 from #dfj to #dhjlb4 of pitch4 ,a subsequent fusion1 with a gentle heat1 converts the coal-pitch into a substance possessing all the characters of asphaltum4 ,ammoniacal ,fluid4--,the properties of the ammoniacal liquor1 which accompanies the tar1 and which is deposited in the tar-cistern1 has not yet been fully investigated4 ,it is employed already in the manufacture of muriate of ammonia 7sal ammoniac74 ,one chaldron of coal affords from #bbj to #bdjlb4 of this ammoniacal fluid1 which is composed chiefly of sulphate1 and carbonate of ammonia4--,such are the products obtainable from coal4 ,however certain the practicability of extending the new lights to the dwelling houses of every town and village is1 it cannot be expected that such an event should take place speedily and generally4 ,to eradicate prejudice1 and to alter established habits1 is a work which nothing but time can effect2 because prejudice is the effect of habit1 and can seldom be eradicated from the minds of such individuals as consider the ready occurrence of a proposition as a test of its truth4 ,to establish a new philosophical theory has1 in every instance1 required time sufficient to educate an entire generation of men4 ,the rejection of the ,aristotelian philosophy--the adoption of experimental research--the substitution of the doctrine of gravitation instead of that of vortices1 and the rejection of phlogiston by modern chemists1 are sufficiently illustrative of this assertion4 ,new arts1 and new practices1 are still more difficult to be introduced4 ,the new art of bleaching need merely be mentioned to prove this assertion4 ,the new grammar--the new rudiments of science--the new stile--or the new instrument1 however superior to the old in simplicity1 facility1 and truth1 must be less valuable to the ordinary teacher or artisan1 whose memory is familiarized with the precepts of the latter1 and whose only ambition is to earn his subsistence with the least possible exertion4 ,the slowness with which improvements of every kind1 make their way into common use1 and especially such discoveries as are most calculated to be of an extended or general utility is very remarkable1 and forms a striking contrast to the extreme avidity with which those unmeaning changes are adopted1 which folly and caprice are continually sending forth into the world under the auspices of fashion4 ,on the first view of the subject it appears very extraordinary1 that any person should neglect1 or refuse to avail himself of a proposed invention1 or improvement1 which is evidently calculated to economise his labour1 and to encrease his comforts2 but when we reflect on the power of habit1 and consider how difficult it is for a person even to perceive the disadvantages or imperfections of former modes to which he has been accustomed from his early youth1 our surprize will be diminished1 or vanish altogether4 ,many other circumstances1 besides prejudice1 are unfavourable to the introduction of new and useful discoveries4 ,among these jealousy1 malice1 envy1 and revenge1 have too often their share in obstructing the progress of real improvement1 and in preventing the adoption of plans evidently calculated to promote the public good4 ,a plan like the present1 which proposes not only to trench upon domestic habits1 but to give an entire new direction to a portion of the skill and capital of the country1 must necessarily encounter the most strenuous opposition4 ,it is thus that some individuals have mustered all their strength against the introduction of this new art4 ,an endeavour has been made to move the public opinion by dismal forebodings of the ,greenland trade1 and the subsequent loss of a nursery of ,british seamen4 ,this objection is nothing more than the common clamour that is always set up against every new means of abridging labour1 to which had the public listened1 an interdict would have been laid upon the spinning and threshing machines1 the steam engine1 and a thousand other improvements in machinery4 ,indeed such clamour scarcely ever fails to be made when the extension of machinery and the abridgement of labour or the application of inanimate powers are considered4 ,on such occasions1 it is stated by certain humane but mistaken objectors1 that the scheme of mechanical and chemical improvement is pointed against the human species--that it tends to drive them out of the system of beneficial employment--that the introduction of machinery is injurious to the labouring class of society1 by abridging their work4 ,two creatures offer themselves for employment and support--a man and a horse4 ,i must invariably prefer the latter1 and leave the former to starve4 ,two other beings--a horse and a steam-engine1 are candidates for my favour4 ,my preference to the latter tends to exterminate the species of the former4 ,in both cases it is stated1 that the number of intelligent creatures capable of the enjoyment of happiness must be diminished for want of support2 and that1 on the whole1 the sum of the proposed improvement is not only a less proportion of good to society1 but a positive accession of misery to the unemployed poor4 ,on this wide and extended argument1 which can in fact be maintained against all improvements whatever in no other way than by insisting that the savage state of man1 with all its wants1 its ignorance1 its ferocity1 and its privations1 is preferable to the social intercourse of effort and division of labour we are habituated to prefer1 it may be sufficient to observe that it includes matter not only for reasoning and induction1 but also for experiment4 ,by reference to the matter of fact1 though it must be allowed that new improvements1 which change the habits of the poor1 must at first expose them to a temporary inconvenience and distress1 against which1 in fairness1 it is the duty of society to defend them2 yet the invariable result of such improvements is always to better the condition of mankind4 ,a temporary inconvenience to individuals must often be incurred for the sake of general national benefit4 ,it is to manufactories carried on by machinery and to the abridgment of labour1 that this country is indebted for her riches1 her independence and pre-eminent station among the nations of the world4 ,but let us return to the subject4--,the progress of the new mode of lighting with coal-gas can never wholly supersede the use of candles and moveable lights4 ,the objection with regard to the ,greenland trade is equally futile4 ,this traffic1 might with more propriety be called a drain1 than a nursery1 of the naval force4 ,the nature of the ,greenland service requires that the crew should consist chiefly of able-bodied sailors2 and being protected men1 not subject to the impress law1 they are thus rendered useless for national defence4 ,the nursery of ,british seamen is the coasting trade2 and if the gas-light illumination be put in practice to a large extent1 it will increase that trade as much as it will diminish the ,greenland fishery4 ,even on the extreme supposition that it would annihilate the ,greenland fisheries altogether1 we should have no reason to regret the event4 ,the soundest principles of political economy must condemn the practice of fitting out vessels to navigate the polar seas for oil1 if we can extract a superior material for procuring light at a cheaper rate from the produce of our own soil4 ,indeed the fisheries will find ample encouragement1 and the consequence of lighting our streets with gas can prove injurious only to our continental friends1 one of whose staple commodities1 tallow1 we shall then have less occasion to purchase4 ,there will be less waste indeed1 but a greater consumption of coal4 ,the lower classes of the community are at present very scantily supplied with firing2 and nothing but a reduction of price is necessary to increase to a very large amount the whole average quantity of fuel consumed in the country4 ,the lightness of the coke produced in the gas-light manufacture diminishing the expence of land carriage1 will facilitate its general diffusion--the comforts of the poor will be materially augmented1 and a number of useful operations in agriculture and the arts be carried on1 which are now checked and impeded by the price of fuel4 ,if any additional want were wanted for the coke it will readily be found in the continental market2 coke being much better suited than coal to the habits of most ,european nations4 ,the gas-light illumination cannot tend to diminish the coal-trade2 on the contrary it will prove beneficial to it2 it will contribute to lower the price of the superior kinds of coal1 and keep a level which cannot be shaken under any circumstances2 it will contribute to prevent combinations which do certainly operate to the prejudice of the public1 and do sometimes put this great town at the mercy of particular proprietors in the north1 who deal out coal in the way they please4 ,the competition thus produced1 it is impossible not to consider as an advantage1 which would prevent in future such combinations1 and put those in ,london out of the reach of them4 ,it is worthy observation1 that the annual importation of coal into this ,metropolis1 is above one million and eighty-eight thousand chaldrons4#ca #ca ,to give an idea how long there is a probability of ,great ,britain being applied with coal from the rivers ,tyne and ,wear only1 it must be observed1 #ast4 ,that the ,seams of coal which are now worked at ,newcastle and ,sunderland1 are equal to a seam or bed of #ae miles by #bj miles4 #b;dly4 ,that this seam1 on an average1 is at least four feet and a half thick4 #c;dly1 ,that #a-fth part of the above extent is sufficient for pillars to support the roofs of the mines1 c4 ,and1 #dthly1 ,it appears1 by experiments1 that a cubic yard of coal weighs #a ton1 or #bj cwt4 ,london ,chaldrons ,the total consumption of coal from the rivers ,tyne and ,wear known from the register to be #b1cjj1jjj ,the number of tons in the above quantity taking the ,london chaldron at #bg cwt4 is #c1ajj1jjj ,now a ton weight of coal is estimated to occupy in the earth the space of one cubic yard4 ,the number of cubic yards in the square mile is #c1jig1fjj ,the beds or seams of coal are1 on an average1 #d feet and a half in thickness1 which increases the above number of cubic yards in the square mile by half the number of square yards to #a1edh1hjj ,and hence the square mile of the beds or seams of coal we are describing contains1 of cubic yards and tons of coal #d1fde1jjj ,a deduction of #a-fth for pillars to support the mine1 c4 #hjj1jjj ,the number of tons per square mile #e1dde1jjj ,we have already mentioned the length and breadth of the seams of coal to be equal to #bj miles by #ae1 making an area of #cjj square miles1 and consequently a source of consumption for #cge years4 ,it may be objected to the universality of our conclusion1 that the price of coals1 differing very much in different places1 will occasion a variation in the expence of the new mode of illumination4 ,but there are two reasons why this should have less place1 because we find1 in ,mr4 ,murdoch's statement1 page #fi1 that of #fjjl4 the estimated yearly expence of lighting the cotton mill1 #eejl4 consist of interest of capital1 and tear and wear of apparatus1 leaving the cost of coal only #ejl4 a sum so trifling1 when we reflect that it replaces #bjjjl4 worth of candles1 that the price of coal1 even where it is highest1 can but slightly affect the general profits4#cb #cb ,see1 also1 ,mr4 ,ackermann's statement1 page #ga4 #b;dly1 ,the coal1 by yielding the gas and other products1--namely1 tar1 pitch1 ammoniacal liquor1 c4 of which we have treated already1 is converted into a substance1 increased in bulk1 and in the power of producing heat1 namely1 coke2 and as a manufactory generally requires heating as well as lighting1 there will be a gain both ways4 ,the manufacturer1 by distilling his coal1 instead of burning it as it comes from the pit1 will save his candles and improve his fuel4 ,one effort at the outset1 in erecting a proper apparatus1 will reduce his annual disbursement1 for these two articles of prime necessity1 much in the same manner1 7though in a far greater degree7 as the farmer gains by building a thrashing machine and laying aside the use of the flail4 ,the principal expence in the pursuit of this branch of civil and domestic economy is therefore the dead capital employed in erecting the machinery destined for preparing and conveying the gas2 the floating or live capital is comparatively small4 ,at the same time1 were we to offer an advice to the public on this subject1 it would be1 that no private individual resident in ,london should attempt to light his premises for the sake of economy with coal-gas by means of his own apparatus1 whose annual expence for light does not exceed #fjl4 because the expence of erecting and attending a small apparatus is almost as great as one constructed on a larger scale would be4 ,for if the quantity of gas wanted is not sufficient to keep the retorts continually in a red-hot or working state1 the cost of the gas will be considerably enhanced2 because either the empty retorts must be continued red-hot1 or the fire must be suffered to go out2 and the retorts1 when cold1 cannot be brought to a working state1 that is to say1 be made red hot again1 but at a considerable expence of fuel1 which must be wasted to no purpose4 ,whereas1 if the retorts are constantly kept red hot and in action1 one half of the coal necessary to produce a given quantity of gas will then be saved4 ,but when a street1 or a small neighbourhood is wanted to be lighted1 and the retorts can always be kept in a working state1 that is to say1 red hot1 the operation may be commenced with safety2 because the sum required for erecting the apparatus1 and the labour attending it1 together with the interest of money sunk1 will then soon be liquidated by the light which it will afford4 ,individuals1 therefore1 may engage in the distillation of coal1 and trade with advantage in the articles produced by that process1 and the lighting of cities may be accomplished without the aid of incorporated bodies2 and parishes may be lighted by almost as many individuals as there are streets in a parish4 ,from experiments1 made by ,mr4 ,,clegg1 on the effects produced by a number of gas-lights1 of a certain intensity1 there is reason to believe that the streets of small towns might be illuminated at a cheaper rate1 by means of a tower1 or pagoda1 furnished with gas-lamps1 than can be done in the ordinary way by street lamps3 the gas being conducted to the top of the building from the apparatus below1 and the light directed down again1 upon the objects to be illuminated1 by means of reflectors placed at a certain angle4 ,by this contrivance1 all the main pipes which convey the gas through the streets1 as well as those collateral ones that branch out from them to the street lamps1 would be saved1 and thus compensate for the expense of the tower4 ,the most beneficial application of gas-lights unquestionably is in all those situations where a great quantity of light is wanted in a small place3 and where light is required to be most diffused1 the advantages of this mode of illumination are the least4--,hence1 as already stated1 the lighting of the parish1 or street-lamps only1 without lighting shops or houses1 can never be accomplished with economy4 ,we have noticed before the reason why the price of coals can have little effect upon the gas-light2 because the very refuse1 or small coals1 called slack1 which pass through the screen at the pit's mouth1 and which cannot be brought into the market--nay1 even the sweepings of the pit1 which are thrown away1 may be employed for the production of coal-gas4 ,it makes no difference in what form the coal is used1 and this circumstance may contribute to enable the coal-merchant to furnish coals in larger masses1 and as they come from the mine1 instead of increasing the bulk by breaking them into a smaller size1#cc which is a practice commonly adhered to4 ,this unquestionably reduces the value of coals2 because the quantity of radiant heat generated in the combustion of a given quantity of any kind of fuel depends much upon the management of the fire1 or upon the manner in which the fuel is consumed4 ,when the fire burns bright1 much radiant heat will be sent off from it2 but when it is smothered up1 very little will be generated3 most of the heat produced will then be expended in giving elasticity to a thick dense vapour1 or smoke1 which is seen rising from the fire2 and the combustion being very incomplete1 the carburetted hidrogen gas of the coal being driven up the chimney without being inflamed1 the fuel is wasted to little purpose4 #cc ,it is not generally apprehended1 how very wasteful the use of small coals is in the ordinary open fire-grates4 ,necessity makes us use the poker very much1 particularly1 when the coals are small2 and habit prevails even when they are large4 ,by the constant stirring of the fire almost the whole of the small coal passes through the bars2 and consequently a great deal goes to the dust-hole without being burnt at all4 ,to prove this1 we need only take a shovel full of ashes and put them into a pail1 and then pouring water over them1 which being gently run off1 will carry away nearly all the light and burnt parts3 and leave an astonishing quantity of bright unburnt coal1 which has escaped from the fire-place1 in consequence of being small4 ,when the grate of the fire-place is large1 and the small coals are thrown behind2 or when we can have patience enough to bear the cold for an hour or two1 or contrive to have the fire lighted a long time before we want it1 the small coal may be of some use1 but the fire made with it is never strong1 nor so bright2 and does not burn so long as a fire made with large or round coals3 it often requires the help of the poker1 and produces a great quantity of breeze4 ,the loss in the use of small coals is more considerable to the poor1 who cannot keep large fires4 ,when they want their breakfast or dinner1 the time they can spare is limited2 and to have their water sooner boiling1 or their meals quicker ready2 they must make use of the poker1 and lose a great deal of coal4 ,this fact is so evident1 that any body who wishes to make the experiment before recommended1 will find that much more bright coal goes to the dust-hole of the poor man1 than to the dust-hole of a rich family1 where1 the fire-place being large1 the small coal has more chance of burning4 ,the loss is still greater to the poor1 in consequence of the inferior sorts of coal which are sold to them4 ,if it is the light sort1 it burns too quick1 and they consume double the quantity2 if the strong sort1 it burns too slow1 and is nearly as wasteful2 for a great quantity of it then goes to the dust-hole without having been lighted at all4 ,an incorrect opinion is often entertained1 that the real quantity of coal contained in a sack is lessened by separating or screening the small from the round coals2 but we must recollect1 that any compact body occupies less space than is required to contain the same matter1 reduced to smaller irregular pieces1 or to powder4--,now the screening only takes away the finest dusty part of the coals1 and admits more small pieces of round coals to be filled into the sack4 ,nothing can be more perfectly devoid of common sense1 and wasteful and slovenly at the same time1 than the manner in which chimney fires1 where coals are burnt1 are commonly managed by servants4 ,they throw on a load of 7perhaps all small7 coals at once1 through which the flame is hours in making its way2 and frequently it is not without much care and trouble that the fire is prevented from going quite out4 ,during this time no heat is communicated to the room2 and1 what is still worse1 the throat of the chimney being occupied merely by a heavy dense vapour1 not possessed of any heating power1 and1 consequently1 not having much elasticity1 the warm air of the room finds less difficulty in forcing its way up the chimney and escaping1 than when the fire burns bright1 and the coal-gas is ignited4 ,and it happens not unfrequently1 especially in chimnies and fire-places ill-constructed1 that this current of warm air from the room which presses into the chimney1 crossing upon the current of heavy smoke and aqueous vapour which escapes slowly from the fire1 obstructs it in its ascent1 and beats it back into the room4 ,hence it is that chimnies so often smoke when too large a quantity of fresh coals is put upon the fire4 ,so many coals should never be put on the fire at once as to prevent the free passage of the flame between them1 or to prevent them becoming quickly heated1 so as to give out the carburetted hidrogen gas which they are capable of furnishing1 and to cause it to be inflamed1 ,in short1 a fire should never be smothered3 and when attention is paid to the quantity of coals put on1 there is little use for the poker2 and this circumstance will contribute much to cleanliness1 and the preservation of furniture4 ,the author of a paper in the ,plain ,dealer asserts1 that1 of the various perversions of abilities1 there is none that makes a human being more ridiculous1 than that of attempting to stir a fire without judgment2 to prevent which he lays down the following rules3--#a4 ,stirring of a fire is of use1 because it makes a hollow where1 the air being rarefied by the adjacent heat1 the surrounding air rushes into this hollow1 and gives life and support to the fire1 and carries the flame with it4 #b4 ,never stir a fire when fresh coals are laid on1 particularly when they are very small1 because they immediately fall into the hollow place1 and therefore ruin the fire4 #c4 ,always keep the bottom bars clear4 #d4 ,never begin to stir the fire at the top1 unless when the bottom is quite clear1 and the top only wants breaking4 ,there is one subject more on which it is necessary to speak4--,in the present instance1 the public has been alarmed by representations that the general adoption of gas-lights would expose us to innumerable accidents1 from the inflammable nature of the gas1 and the explosion of the apparatus in which it is prepared1 or the bursting of the pipes by which it is conveyed4 ,but there is no ground for such fears4 ,those who are familiar with the subject will readily allow1 that there is no more risk in the action of a gas-light machinery1 properly constructed1 than there is in the action of a steam-engine1 built on just principles4 ,the manufacture of the coal-gas requires nothing more than what the most ignorant person1 with a common degree of care and attention1 is competent to perform4 ,the heating of the gas-furnace1 the charging of the retorts with coal1 the closing them up air-tight1 the keeping them red-hot1 and discharging them again1 are the only operations required in this art2 and these1 surely1 demand no more skill than a few practical lessons can teach to the meanest capacity4 ,the workman is not called upon to exercise his own judgment1 because1 when the fire is properly managed1 the evolution of the gas goes on spontaneously1 and without further care1 till all the gas is extricated from the coal4 ,no part of the machinery is liable to be out of order1--there are no cocks to be turned1 no valves to be regulated2 nor can the operator derange the apparatus but by the most violent efforts4 ,and when the stock of gas is prepared1 we may depend on its lighting power as much as we depend on the light to be obtained from a certain number of candles or oil-lamps4 ,the diversified experiments which have been made by different individuals1 unconnected with each other1 have sufficiently established the perfect safety of the new lights2 and numerous manufactories might be named in which the gas-lights have now been in use for upwards of seven years1 where nothing like an accident has occurred1 though the apparatus in all of them is entrusted to the most ignorant man4 ,it would be easy to state the causes which have given rise to some of those accidents that have spread alarm amongst the public2 but of this it is not my business to speak at length4 ,it is sufficient1 on the present occasion1 to state1 that those melancholy occurrences which have happened at some gas-light establishments which ,i have had an opportunity of examining1 were totally occasioned by egregious failures committed in the construction of the machinery4 ,thus1 an explosion very lately took place in a manufactory lighted with coal-gas1 in consequence of a large quantity of gas escaping into a building1 where it mingled with common air1 and was set on fire by the approach of a lighted candle4 ,that such an accident could happen1 is an evident proof that the machinery was erected by a bungler1 unacquainted with the most essential principles of this art2 because such an accident might have been effectually prevented1 by adapting a waste pipe to the gasometer and gasometer house4 ,by this means1 if more gas had been prepared than the gasometer would contain1 the superfluous quantity could never have accumulated1 but would have been transported out of the building into the open air1 in as an effectual manner as the waste-pipe of a water cistern conveys away the superfluous quantity of water1 when the cistern is full4 ,such an expedient did not form part of the machinery4 ,other instances might be named1 where explosions have been occasioned through egregious mistakes having been committed in the erection of the gas-light machinery1 were this a subject on which ,i meant to treat4 ,that the coal-gas1 when mixed with a certain portion of common air1 in close vessels1 may be inflamed by the contact of a lighted body1 as has been stated1 page #ih1 is a fact sufficiently known4 ,but the means of preventing such an occurrence in the common application of gas-lights1 are so simple1 easy1 and effectual1 that it would be ridiculous to dread danger where there is nothing to be apprehended4 ,in speaking thus of the safety of the gas-light illumination1 ,i do not mean to deny that no possible circumstances may occur where the coal-gas may be the cause of accident4 ,it is certain that the gas1 when suffered to accumulate in large quantities in close and confined places1 where there is no current of air1 such as in cellars1 vaults1 c4 and where it can mix with common air1 and remain undisturbed1 that it may be liable to take fire when approached by a lighted body2 but ,i do not see how it is probable that such an accumulation of gas should take place in the apartments of dwelling houses4 ,the constant current of air which passes continually through the rooms1 is sufficient to prevent the possibility of such an accumulation ever to take place4 ,and with regard to the bursting of the pipes which convey the gas1 no accident can possibly happen from that quarter2 because the gas which passes through the whole range of pipes sustains a pressure equal to the perpendicular weight of about one inch of water only1 and such a weight of course is insufficient to burst iron pipes4 ,nor could the town when illuminated by gas-lights1 be thrown suddenly into darkness1 as has been asserted might happen by the fracture of a main pipe1 supposing such an event should take place2 because the lateral branches1 which supply the street-lamps and houses1 are supplied by more than one main2 and the consequence of a fracture would be only an extinction of the few lamps in the immediate vicinity of the broken pipe1 because the rest of the pipes1 situated beyond the fracture1 would continue to be supplied with gas from the other mains1 as will become obvious from the sketch exhibited in the next page4 ,illustration3 ,main pipe1 leading from the ,gas-light station or apparatus1 situated in ,brick ,lane1 near ,old ,st4#cd ,main pipe1 leading from the gaslight apparatus1 or station1 at ,norton ,falgate4#ce ,main pipe1 leading from the gaslight apparatus1 or station1 in ,westminster4#cf #cd ,the gasometer at this place is equal in capacity to #bbjjj cubic feet4 #ce ,the capacity of the gasometer here is equal to #aeibh cubic feet4 #cf ,at this station the gasometer is equal in capacity to #adhjh cubic feet4 ,the black lines represent the gas-light mains1 or largest pipes1 from which the smaller pipes branch off3 they are connected with each other at the places marked ,a ,b ,c2 and the dotted lines represent the smaller mains1 or collateral branches before-mentioned4 ,the main pipes are all furnished with valves1 or cocks1 placed at about #ajj feet distant from each other4 ,now let us suppose that a main pipe1 in any part of the street marked in the sketch1 ,pall ,mall1 should break1 it is evident1 on mere inspection1 that the gas which is passing through the main in the ,strand1 and which is also connected with the main in the ,haymarket1 ,piccadilly1 and ,coventry ,street1 would continue to supply the broken pipe1 and the valve nearest to the fracture being shut1 would prevent the loss of any considerable quantity of gas1 and the few lamps situated between the two valves and the fracture would therefore only become extinguished4 ,further1 let us suppose a main pipe should break in ,piccadilly2 in that case1 the valve being shut on each side of the fracture1 the gas would be supplied from the mains in the ,haymarket and ,st4 ,james's ,street4 ,and the same effect would be produced in any part of the town1 supplied with gas-pipes4 ,besides all this1 in the statement thus far given1 we have assumed that all the gas-light mains are supplied with gas from one manufacturing station only1 but which in reality is not the case4 ,the range of pipes that convey the gas is connected with three gas-light establishments1 situated at different parts of the town2 and the gas which is supplied from these stations is connected with the whole system of pipes in the streets4#cg ,if1 therefore1 one of the manufactories should be annihilated1 it would make no difference1 because the lights would be amply supplied from the other two manufacturing stations4 ,hence it is obvious1 that the fracture of any of the gas-light mains1 or even the total destruction of one or more of the manufactories themselves1 would be attended with no serious consequence2 and as the system of lighting with gas becomes more extended1 the manufactories1 or stations for supplying it1 will also be multiplied1 to give effect and security to the whole4 #cg ,as shown in the sketch4 ,in fact1 no danger can arise from the application of gas-lights in any way1 but what is common to candle-light1 and lamps of all kinds1 and is the fault of none of them4 ,even in this case the gas-lights are less hazardous4 ,there is no risk of those accidents which often happen from the guttering or burning down of candles1 or from carelessly snuffing them4 ,the gas-light lamps and burners must necessarily be fixed to one place1 and therefore cannot fall1 or otherwise become deranged1 without being immediately extinguished4 ,besides1 the gas-light flames emit no sparks1 nor are any embers detached from them4 ,as a proof of the comparative safety of the gas-lights1 it need only be stated1 that the ,fire-offices engage themselves to insure cotton-mills1 and other public works1 at a less premium1 where gas-lights are used1 than in the case of any other lights4#ch ,the excessive expence of insurance arising from the numerous candles employed in most of the first rate manufactories1 and the combustible nature of the structure of the buildings2 the great difficulty of retrieving the injury resulting to a well-organised business1 from the accidental destruction of the machinery1 are objects alone sufficient to furnish the strongest economical1 as well as political recommendations1 for the adoption of the new lights in all manufactories where work is done by candle-light4 #ch ,since the preceding pages have been printed1 ,i have seen a self-extinguishing gas-lamp1 invented by ,mr4 ,,clegg4 ,this lamp is so constructed1 that the gas cannot flow to the burner1 when the flame becomes extinguished4 ,if1 therefore1 the lamp should be blown out1 and the stop-cock which supplies the gas be left open1 the extinction of the flame will effectually shut the valve4 ,the action of this lamp depends upon the expansibility of a metallic rod1 heated by the flame of the lamp1 and thus keeping open the valve1 whereas1 when the lamp is extinguished1 and the rod becomes cold1 it contracts to its natural dimensions1 and1 by that means1 effectually closes the valve4 ,the same engineer has invented a machine1 which both measures and registers1 in the absence of the observer1 the quantity of gas delivered by any pipe communicating with a gas-light main4 ,the machine occupies a space of about two feet by one foot1 and1 if put up in a room1 house1 or other place1 where gas is burnt1 will1 at any time1 by mere inspection1 give an account of the quantity of gas consumed in that place during any given time4 ,on the present occasion1 it would not become me to say more on these subjects1 which1 no doubt1 ,mr4 ,,clegg will make known to the public2 ,i shall only remark1 that these contrivances do signal honour to the talents and abilities of the inventor2 and that they will render the greatest services to those who are engaged in the gas-light illumination4 ,after considering the facts so far detailed1 many other advantages1 connected with the gas-light illumination1 will naturally suggest themselves to the reader4 ,i have endeavoured merely to point out the leading characters of the new lights1 as they are at present4 ,ingenious men may speculate from what has been done to what remains to be effected1 which1 no doubt1 will embrace objects of the greatest utility and most extended national importance4 ,the public attention is awakened to the new properties of coal1 and will not rest till they are extensively applied to economical purposes4 ,the consequence will be1 a considerable defalcation in the revenue4 ,for1 in proportion as the gas-lights are more or less generally adopted in all towns of the country1 the consumption of oil and tallow will be diminished1 and the impost on those articles become less productive2 and when this takes place1 ,government1 no doubt1 will share in the profits1 by levying a tax on the new lights4 ,the ,exchequer will thus have nothing to fear2 as one branch of the revenue fails1 another1 and a more productive one1 will supply its place4 ,upon the whole1 when we reflect that the object of the gas-light illumination is to open a source of national wealth1 of which nothing can deprive us1 to create1 we may almost say1 new articles of value1 its friends cannot be thought guilty of great presumption1 if they look forward with confidence to the successful extension of this new art of civil economy2 and if1 contrary to all expectations1 the effects of jealousy and prejudice should1 in some respect or other1 continue here and there its influence against this new art of procuring light1 a firm perseverance of its application must at length remove that ignorance which alone can give them birth4 ,,tabular ,,view1 ,,exhibiting ,the quantity of ,,gas1 ,,coke1 ,,tar1 ,,pitch1 ,,essential ,,oil1 and ,,ammoniacal ,,liquor1 obtainable from a given quantity of ,,coal2 together with an ,estimate of the quantity of ,coal necessary to produce a quantity of ,gas1 capable of yielding a ,light equal in duration of time and intensity to that produced by ,tallow ,candles of different kinds4 ---------------------------------------- ------------- ,cost of ,coal4 ,minimum4 ,maximum4 ,average4 ---------------------------------------- ------------- ,one ,chal4 of ,coal1 #djs to #fjs -- #ejs from #be to #bh cwt4 ,one ,ton #cjs to #dhs -- #chs #f;d ,one ,sack #cs #d;d to #es -- #ds #b;d ,one ,bushel #as #b;d to #as #h;d -- #as #e;d ,one ,peck #c to #e;d -- #d ,one ,pound ---------------------------------------- ------------- ---------------------------------------- ------ ,weight of ,coal4 ,min4 ,max4 ,aver4 ---------------------------------------- ------ ,one ,chal4 of ,coal1 #b1hjj to #c1acf -- #b1ifh from #be to #bh cwt4 ,one ,ton #b1bdj ,one ,sack #bcc to #bfa -- #bdg ,one ,bushel #gh to #hg -- #hb ,one ,peck #ai to #ba -- #bj ,one ,pound #a ---------------------------------------- ------ ---------------------------------------- --- ,produce of ,gas1 in cubic feet4 ,min4 ,max4 ,aver4 ---------------------------------------- --- ,one ,chal4 of ,coal1 #h1ijf to #aa1hgb #aj1chhci from #be to #bh cwt4 ,one ,ton #f1gbj to #h1ifj -- #g1hdj ,one ,sack #gda to #ihh -- #had ,one ,bushel #bdg to #ccj -- #bij ,one ,peck #fa to #hb -- #ga ,one ,pound #c to #d -- #c ---------------------------------------- --- ---------------------------------------- ------------ ,candles4 #i1eaf #aa to the pound4 ,one ,chal4 #ci;,equal to #h1fea #aj do4 of ,coal1 as many tallow #g1ghf #i do4 from #be to candles1 #ab in #f1iba #h do4 #bh cwt4 the pound1 #f1eef #g do4 burning two #e1aid #f do4 ,one ,ton hours2 or to #d1cbe #e do4 ,one ,sack #c1dfc #d do4 ,one ,bushel #b1eie #c do4 ,one ,peck #a1gcj #b do4 ,one ,pound #hff #a do4 ---------------------------------------- ------------ ,,coke4--,one chaldron of coal1 from #be to #bh cwt4 gives #a to #a chaldron of ,coke4 ,,tar4--,one chaldron of coal1 from #be to #bh cwt4 gives from #aej to #ahjlb4 of ,tar1#ci or #ae to #ah ale gallons1 #ajlb4 each4 ,,ammoniacal ,,liquor4--,one chaldron of coal1 gives from #bbj to #bdjlb4 of ,ammoniacal ,liquor1 or #bb to #bd ale gallons4 #ci #ajjjlb4 of ,coal-,tar afford by distillation1 from #bfj to #bfelb4 of ,essential ,oil1 or ,naphtha4 #ajjjlb4 of ,coal-,tar produce by mere evaporation1 from #dfj to #dhjlb4 of ,pitch4 ,tabular ,view1 exhibiting the illuminating power of ,coal-,gas1 compared with the illuminating power of ,tallow ,candles of different sizes4 ,one chaldron of ,coal produces1 according to weight and quality1 ,cubic feet of ,gas4 ,average4 ,burning4 ,candles4 #ab to #alb4 #f to #alb4 ,from #i1jjj to #ab1jjj #aj1ejj #a hour #ba1jjj #aj1ejj ----- ------ ------ #b hours #aj1ejj #e1bej #f1jjj #h1jjj #g1jjj #c ditto #g1jjj #c1ejj #d1ejj #f1jjj #e1bej #d ditto #e1bej #b1fbe #c1fjj #d1hjj #d1djj #e ditto #d1djj #b1bjj #c1jjj #d1jjj #c1ejj #f ditto #c1ejj #a1gej #b1ega #c1dbh #c1jje #g ditto #c1jje #a1ejb #b1bej #c1jjj #b1fbe #h ditto #b1fbe #a1cab #b1jjj #b1fff #b1ccc #i ditto #b1ccc #a1aff #a1hjj #b1ajj #b1ajj #aj ditto #b1ajj #a1jej #a1fcf #b1aia #a1iac #aa ditto #a1iac #ief #a1ejj #b1jjj #a1gej #ab ditto #a1gej #hge #a1chd #a1hdf #a1fae #ac ditto #a1fae #hjg #a1bhe #a1gad #a1dii #ad ditto #a1dii #gdi #a1bjj #a1fjj #a1djj #ae ditto #a1djj #gjj #a1abe #a1ejj #a1cab #af ditto #a1cab #fef #a1jeh #a1aaa #a1bcd #ag ditto #a1bcd #fag #a1jjj #a1ccc #a1aff #ah ditto #a1aff #ehc #idg #a1bfc #a1aje #ai ditto #a1aje #eeb #ijj #a1bjj #a1jej #bj ditto #a1jej #ebe #heg #a1adc #a1jjj #ba ditto #a1jjj #ejj #hah #a1jie #ief #bb ditto #ief #dgh #ghc #a1jdd #iac #bc ditto #iac #def #gej #a1jjj #hge #ba ditto #hge #dcg ,n4 ,b4 ,if it be required to know1 for how many hours one pound1 or one peck1 or one bushel1 or one sack1 of coal will produce ,gas ,light equal to that of a certain number of well-snuffed ,tallow ,candles1 the proportion of each of the average weights of a pound1 peck1 bushel1 or sack1 to that of the average weight of a chaldron of coal1 is as follows3 #a lb4 #bifhth part of a chaldron4 ,one peck #bj #adhth ditto4 ,one bushel #hb #cfth ditto4 ,one sack #bdh #abth ditto4 ,,rule4--,divide with either of the above parts of weight1 the number of lights opposite to their hours1 and the product will be the number of lights burning for the same number of hours4 ,,example4--,to know how many lights one peck of coal will give for six hours1 divide the #adhth part in #c1ejj1 opposite to the number of six hours1 the product is almost #bd lights4 ,the same rule holds good for any given quantity or number of pounds of coal1 in a chaldron1 to find how many lights1 or candles1 #ab to the lb4 or #f to the lb4 they will give for a given number of hours4 ,,description ,,of ,,the ,,gas-,,light ,,apparatus4 ,,plate ,i4 ,exhibits a perspective view of a gas-light apparatus1#dj for lighting factories1 or small districts of houses4 ,it consists of the following parts3 which may be considered separately4 #dj ,this apparatus was erected by ,mr4 ,,clegg1 and is now in action at ,mr4 ,,ackerman's establishment1 in this metropolis4 ,,fig4 #a4 ,the ,retort ,furnace1 for distilling the coals4 ,it is built of brick-work4 ,the bricks which are exposed to the immediate action of the fire1 are ,welch tumps1 or fire-bricks2 they are bedded in clay1 or ,windsor loam4 ,,fig4 #b4 ,the ,tar ,cistern1 to collect the coal-tar1 and other condensible products obtained during the distillation of the coals4 ,it is a cast-iron hollow cylinder1 closed at the top with a cast-iron cover1 which has a very small hole to allow the air to escape as the liquid enters into the vessel4 ,,fig4 #c4 ,the ,lime ,machine1 for purifying the crude coal-gas1 and to render it fit for use4 ,the construction of this machine will be explained in plate ,,vii4 ,it is put together of cast-iron plates4 ,,fig4 #d4 ,the ,gasometer1 for collecting and preserving the purified gas1 and for distributing and applying it as occasion may require4 ,it consists of two principal parts--namely1 a large interior vessel closed at the top and open at the bottom1 made of sheet iron1 designed to contain the gas1 and an outer cistern or vessel1 of rather greater capacity1 constructed of cast-iron plates1 in which the former vessel is suspended4 ,the latter contains the water by which the gas is confined4 ,the interior vessel which contains the gas is suspended by chains hung over wheels or pullies1 to which weights are attached1 so as to be just sufficient to balance the weight of the gasometer1 all but a small difference1 and allowing its slow descent in the manner which is found as nearly adapted as can be to the proper supply of the lamps4 ,the weight of the chains must be equal to the specific gravity of the material of which the gasometer is composed1 so as to compensate accurately for the quantity of water which the gasometer displaces1 or what is the same1 it must be equal to the loss of weight which the gasometer sustains1 when immersed in the water2 and the counterpoise weight must be equal 7or nearly so7 to the absolute weight of the gasometer4 ,the action of these different parts of the apparatus will be obvious from the following explanation3 ,a1 ,a1 are two iron retorts1 placed horizontally1 and side by side1 in the furnace2 the mouth of the retorts where the coals are introduced1 projects into an arched chamber1 situated in front of the furnace1 as shewn in the drawing by the broken down brick-work4 ,the object of suffering the mouth of the retorts to project into a separate chamber1 is merely to discharge with convenience the red hot coke from the retorts when the process is at an end2 the coke being suffered to fall to the bottom of the chamber1 where it cools1 without becoming troublesome to the operator4 ,it may be removed from this fire-safe chamber by the door represented at the end view of the furnace4 ,when the operation commences1 the inner vessel of the gasometer1 fig4 #d is sunk down1 to expel the air which it contains to a level with the exterior vessel1 or outer cistern1 of the gasometer2 and1 consequently1 becomes filled with water4 ,as the distillation of the coal in the retorts proceeds1 the liquid and gazeous products evolved from the coals are transmitted by means of the perpendicular syphon pipes ,b1 ,b1 into the horizontal pipe or main condenser ,c1 with which they are connected4 ,the liquid which is distilled1 collects in the pipe1 or main condenser1 ,c1 where it is retained until its quantity has risen so high as to discharge itself into the pipe ,d1 which is connected with the upper part of one of the extremities of the condenser1 ,c4 ,one of the extremities of the pipes1 ,b1 ,b1 therefore become immersed into the liquid contained in the main condenser or pipe ,c1 whilst the vaporous or condensible fluid1 after having overcome the pressure there opposed to it1 is transported into the pipe ,e1 which1 after passing in a serpentine direction1 ,e1 ,e1 c4 through the exterior vessel or cistern of the gasometer1 terminates in the tar-vessel1 fig4 #b4 ,thus the vaporous fluids are condensed by passing through the serpentine pipe1 ,e1 ,e1 c4 and become deposited in the tar-cistern1 fig4 #b2 whilst the non-condensible or gazeous products are made to proceed by the pipe ,f1 which branches off from the pipe ,e1 into the lime machine1 fig4 #c4 ,in this apparatus the gas1 as it is evolved from the coals1 comes into contact with slaked lime and water2 the object of which is1 to strip it of its sulphuretted hydrogen and carbonic acid gas with which it always abounds1 and to render it fit for illumination4 ,this being accomplished1 the purified gas is conducted away out of the lime machine by means of the pipe ,g1 into the perpendicular pipe ,h1 which branches up through the bottom of the gasometer cistern4 ,the upper extremity of this pipe is covered1 in the manner of a hood1 by a cylindrical vessel ,i1 open at bottom1 but partially immersed beneath the surface of the water contained in the outer cistern of the gasometer1 it is also perforated round near the lower edge with a number of small holes4 ,the gas1 as it passes out of the pipe ,h1 displaces the water from the receiver ,i1 and escapes through the small holes1 and is thus made to pass through the water in the cistern1 in which the hood of the pipe ,i1 is partly immersed1 so as to expose a large surface to its action1 that it may once more be washed1 and deprived of all the foreign gazeous products which might have escaped the action of the lime1 whilst it was agitated with this substance in the lime machine1 fig4 #c4 ,after rising through the water in the gasometer cistern1 it enters into the gasometer1 which then ascends as the gas accumulates in it4 ,in this manner the process proceeds1 until the whole of the volatile products of the coal in the retort are disengaged4 ,the use of the gasometer is1 partly to equalize the evolution of the gas which comes from the retort more quickly at some time than others4 ,when this happens1 the vessel rises up to receive it1 and when the stream from the retort diminishes1 the weight of the gasometer expels its contents1 provided the main-cock be open4 ,when the process is finished1 the retort is suffered to cool1 and its lid is then removed to replenish it with coal4 ,when the main stop-cock is then opened1 the gasometer descends1 and the gas passes from the gasometer through the pipe ,k1 to the burners1 or main pipe1 which communicates with the gas burners or lamps4 ,l1 is a wooden tub or barrel1 containing the mixture of lime and water1 for charging the lime machine2 and into which the contents of the barrel1 ,l1 may be conveyed by the curved pipe ,m1 without admitting common air4 ,n1 ,n1 is a water-pipe1 to convey fresh water into the gasometer cistern occasionally2 because it is essential that the water used for washing and purifying the gas should be changed for fresh as soon as it becomes dirty2 and unless this is done1 the gas will not be perfectly purified by washing1 but produce a disagreeable odour when burnt2 the same holds good with regard to the lime machine1 the contents of which should be renewed occasionally4 ,this pipe also conveys the necessary water into the barrel1 ,l4 ,o1 is a waste-pipe1 to convey the water as it becomes impregnated with the impurities of the gas1 out of the gasometer cistern4 ,p1 is an agitator1 to stir up the contents of the lime machine occasionally1 ,q1 ,q1 are two iron rods1 which serve as stays to guide the motion of the gasometer4 ,r1 is an index1 connected by means of a shaft and pulley with the axis of one of the gasometer wheels4 ,this index is graduated to the capacity of the cubical contents of the gasometer1 so as to indicate1 by the rising and falling of the gasometer1 its relative contents of gas expressed in cubic feet4 ,s1 is the waste pipe of the lime machine1 to remove the insoluble parts of the lime4 ,t1 represents the iron cover1 or lid1 which is turned on the lathe1 and ground air-tight1 to close up the mouth of the retort1 so as to make readily an air-tight fitting4 ,u is an iron wedge to secure the cover of the retort4 ,the left-hand retort in the design shows the retort closed up1 and the cover1 or lid of the mouth of it secured by means of the wedge1 in its place1 so as to render the mouth of the retort perfectly air tight4 ,there is a safety valve attached to this gasometer which could not be represented in the drawing2 and the object of which is1 to convey away any portion of gas that might happen to be produced by a careless operator1 when the gasometer is full1 and which is thus prevented from accumulating in the place where the gasometer is erected4 ,it is represented in the right-hand corner of plate ,,vii4 where fig4 #a shows the edge of the gasometer2 #b1 the surface of the water in the inside of the gasometer2 #c1 the surface of the water in the outside of the gasometer1 or in the cistern2 #d1 a pipe issuing from the lower edge of the gasometer1 and surrounded at its upper extremity with a cup marked #e2 #f1 the waste pipe1 the mouth of which is immersed in water4 ,it is obvious that1 when the gasometer is full1 if an additional quantity of gas should be attempted to be put into it1 it will be transported by means of the pipe #d1 into the waste-pipe #f2 the upper extremity of which reaches out of the building1 and there communicates with the open air4 ,,plate ,,ii4 ,represents a ,portable experimental ,gas ,apparatus for exhibiting1 in the small way1 the general nature of the gas-light illumination4--,it is described page #gi4 ,,plates ,,iii4 ,,iv4 ,v4 ,show designs of various kinds of ,gas ,lamps1 ,chandeliers1 ,candelabras1 c4--,see pages #aad1 #aah1 #adj4 ,,plate ,,vi4 ,,fig4 #a4 ,exhibits a design of the gasometer framing1 or skeleton1 which serves to give stability and strength to the gasometer4 ,it consists of wooden frame work1 marked ,a1 ,a1 ,a1 interlaced with iron rods1 ,b1 ,b1 ,b1 c4 ,the whole framing is so disposed that it will float in the cistern horizontally1 and therefore keep the gasometer perfectly steady and level with the surface of the water4 ,the rest of the sketches represent various kinds of gas pipes employed as mains for conveying the gas1 and the methods of connecting them4 ,,fig4 #b4 ,represents a longitudinal section of a ,spigot and ,faucet ,pipe4 ,these kinds of pipes are applicable in most cases as mains for conveying gas4 ,a1 is called the spigot1 and ,b1 the faucet4 ,they are joined together1 and made air tight1 by iron cement1 the composition of which is as follows3 ,take two ounces of sal ammoniac1 one ounce of flowers of sulphur1 and sixteen ounces of cast iron filings or borings4 ,mix all well together1 by rubbing them in a mortar1 and keep the powder dry4 ,when the cement is wanted for use1 take one part of the above powder1 and twenty parts of clean iron borings or filings1 and blend them intimately by grinding them in a mortar4 ,wet the compound with water1 and when brought to a convenient consistence1 apply it to the joints with a wooden or blunt iron spatula4 ,by a play of affinities1 which those who are at all acquainted with chemistry will be at no loss to comprehend1 a degree of action and re-action takes place among the ingredients1 and between them and the iron surfaces1 which at last causes the whole to unite as one mass4 ,in fact1 after a time1 the mixture and the surfaces of the flanches become a species of pyrites 7holding a very large proportion of iron17 all the parts of which cohere strongly together4 ,the inner parts of the faucet ought to be no larger in diameter than just to fit the spigot4 ,this supports the pipe1 independently of the cement1 and prevents the risk of hurting the joint from any external stress4 ,the inner faucet is commonly made about #b inches deep1 and has the spigot inserted #a inch into it4 ,the practice of some workmen1 is to make the outer faucet1 or that which contains the cement1 six inches deep1 for all pipes above six inches diameter2 and to make the faucets of all pipes below six inches1 the same depth as the diameter of the pipes4 ,it is usual to make the space for the cement1 all round the spigot1 from #a to #a inch2 that width is required1 in order that the cement may be firmly driven into the joint4 ,when the space is very narrow1 this cannot be done4 ,on the other hand1 when too wide1 there is a waste of cement1 and a risk of injury from unequal expansion4 ,,fig4 #c4 ,exhibits a profile view of these kinds of pipes when joined together4 ,the spigot and faucet pipes are liable to burst from the great expansion of the spigot1 and the risk of this accident is increased by increasing the space between the spigot and faucet1 which requires to be filled with cement4 ,,fig4 #d4 ,represents a longitudinal section of two flanch pipes1 and the modes of connecting them4 ,a and ,b1 show the parts of the pipes2 and ,c and ,d1 the flanches4 ,these pipes are also joined together1 and rendered air-tight1 by interposing between the flanches rope-yarn1 hemp1 or some other pliable material1 and iron cement1 and then screwing up the faces of them by means of the bolts and screw nuts4 ,,fig4 #e4 ,profile view of the same kind of pipes connected together1 ,a and ,b1 the pipes2 ,c and ,d1 the flanches2 ,e and ,f1 the bolts4 ,,fig4 #f4 ,represents the method of joining spigot and faucet pipes when they are to have a turn or angle4 ,this method is convenient when the place where the turn required to be made is previously known1 and the pipes cast accordingly4 ,,fig4 #g4 ,exhibits the method of connecting spigot and faucet pipes when they have a round turn4 ,a and ,b1 the junctures of the pipes4 ,,fig4 #h4 ,represents a longitudinal section of the mode of joining pipes by means of what is called a thimble joint4 ,the junctures of the pipes to be connected1 are made air tight1 as mentioned already1 by iron cement4 ,a1 the thimble or small cylinder1 with projecting edges1 which unites the pipes ,b1 ,c4 ,,fig4 #i4 ,a thimble joint made in two parts1 which is sometimes convenient to join pipes4 ,the parts are joined together by screw bolts1 and nuts1 in the usual manner4 ,,fig4 #aj4 ,section of the same4 ,,fig4 #aa4 ,represents a profile view of what is called the saddle joint4 ,it is employed for taking off a branch-pipe4 ,the branch has a piece ,a ,b1 formed on its end1 and fits round one-half of the outside of the pipe from which it is to proceed4 ,c1 is called the saddle1 which fits round the other half of the pipe4 ,the parts are secured together by screw bolts1 and iron cement4 ,by this method a branch may be formed on any part of a gas-pipe1 by cutting a hole there1 and applying the branch to that place4 ,where there is much risk of the inequality of expansion1 the joints at certain places1 should be secured by a soft stuffing of hemp and tallow2 but in most cases the joints may be made with iron cement4 ,lead is frequently used for making the joints of gas pipes instead of iron cement1 though cheaper and more easy of repair4 ,the galvanic action which takes place between the lead and iron1 soon renders the joints leaky1 and the danger is increased by the unequal expansion of the two metals4 ,,fig4 #ab4 ,section of the saddle-joint4 ,before the gas is suffered to enter into the pipe1 they should be proved to be sound1 by the usual process of forcing water into them3 ,the pipes serving as mains1 are placed perfectly solid1 so that they cannot give way2 their course should be rectilinear1 having a descent of about #a inch in #i or #aj feet1 to allow the water of condensation which may be deposited from the gas by a change of temperature to collect readily at the lowermost part4 ,,fig4 #ac4 ,shows a reservoir for collecting the water of condensation which might accumulate in the pipes4 ,it consists of a receptacle1 ,a1 in which the water may pass2 ,b1 a branch-pipe closed at the top1 by means of which the water may be removed1 by drawing it out with a syringe4 ,this receptacle is placed in those situations where pipes incline towards each other4 ,,plate ,,vii4 ,exhibits a perpendicular section of a gas-light apparatus1 calculated for lighting towns1 or large districts of streets and houses4 ,,fig4 #a4 ,the ,retort ,furnace4 ,the retorts are placed over each other in one or more rows2 so that a certain number of them may be heated by separate fire-places4 ,a1 ,a1 shows two of the retorts placed horizontally above each other2 ,b1 the fire-place2 ,c1 the flue which causes the fire to circulate round the retorts so as to heat them equally in every part2 ,d1 the opening of the flue where the fire passes into the chimney2 ,e1 the ash-pit2 ,f1 a chamber in front of the retort furnace1 into which the orifice or mouth of the retorts project2 ,g1 ,g1 the doors of the chamber1 to enable the workmen to charge and discharge the retorts2 ,h1 a funnel shaped hole at the floor of the chamber ,f1 through which the red hot coke as it is discharged from the retorts passes into the arched vault ,i2 ,k1 the syphon tube2 ,l1 the horizontal condenser#da--the action of both of these pipes have been already explained1 p4 #afh2 ,m1 main pipe1 which conveys the liquid substances from the condenser1 to the tar cistern1 fig4 #c1 and which conducts also the gazeous products into the lime machine1 fig4 #b2 ,n ,n1 shows that part of the pipe which is interposed between the tar cistern1 fig4 #c1 and the condensing pipe ,m1--it passes in a serpentine direction along the inner sides of the gasometer cistern1 and1 like the so-called worm in a distillatory apparatus1 condenses the products which escape in a vaporous state from the condenser ,l2 ,o1 shows the place where the serpentine pipe ,n ,n1 passes again out of the gasometer cistern1 and its communication with the lime machine1 fig4 #b1 and tar chamber1 fig4 #c4 ,the action of the lime machine is as follows3 ,the liquid products evolved from the coal1 having been deposited in the tar cistern1 fig4 #c1 by means of the serpentine pipe ,n1 ,n1 the gazeous products which accompany it1 are conveyed by means of the pipe ,p1 which branches out from the pipe ,o1 into the interior receptacle of the lime machine marked ,q1 which consists of a vessel open at the bottom1 and closed at the top1 where it communicates with the pipe ,o4 ,as the gas accumulates in the interior part ,q1 of the lime machine1 it is made to pass through the liquid which it contains1 namely1 slaked lime and water2 and escapes through appertures made in the horizontal partitions ,r1 ,r1 ,r1 ,r1 into the outer vessel1 ,s1 of the lime machine and from thence it is conducted away by the pipe ,t1 ,t1 ,t1 into the additional washing apparatus1 of the gasometer2 fig4 #d1 the construction of this apparatus1 greatly resembles the lime machine1 fig4 #b1 namely1 ,v1 is a water pipe1 proceeding from a cistern ,u1 placed #c or #d feet above the orifice of the pipe ,v2 ,t1 ,t1 is the gas-pipe1 covered with a hood1 marked ,w1 and immersed in a small cistern1 having horizontal perforated shelves1 like those in the lime machine--they fit close to the hood4 ,the gas which enters the hood ,w1 meets with a shower of water delivered by the pipe ,v4 ,the gas1 as it passes through the holes in the horizontal partitions1 is1 therefore1 again washed and thoroughly purified from foreign gases which may have escaped the action of the lime machine2 ,y1 is a waste pipe1 the lower extremity of which is sealed by being immersed in water1--it serves to carry away the water delivered by the pipe ,v1 as it has been acted on by the gas4 ,the summary action of this gas apparatus is1 therefore1 as follows3 ,the liquid products obtained from the coal during the distillation are first deposited in the main condenser ,l1 by means of the pipe ,k1 and from whence they cannot escape until a quantity of tar has accumulated in it to a certain height1 and by this means1 one of the extremities of the pipes ,k1 ,k1 becomes immersed and hermetically sealed by the liquid which the condenser ,l1 contains4 ,the liquid products1 after having accumulated to a certain height in the condenser1 overflow the perpendicular portion which it contains1 and discharge themselves into the pipe ,m1 from whence they are transported into the tar cistern1 fig4 #c1 by means of the system of pipes ,n1 ,n1 ,o1 whilst the gazeous products are made to pass by means of the branch pipe ,p1 into the lime machine1 fig4 #b4 ,from this part of the apparatus the gas passes through the pipe ,t1 ,t1 ,t1 into the additional or smaller washing apparatus placed upon a tressel in the cistern of the gasometer1 where it is again exposed a second time to the action of a current of fresh water2 and from this vessel the gas ascends into the gasometer4 ,the gasometer is furnished with a pipe ,a1 closed at the top1 and fixed in one corner of the gasometer1 but open at the bottom2 it includes another pipe marked ,b1 which communicates with the main pipe leading to the burners1 or place where the gas is wanted4 ,the pipe ,a1 which slides over the pipe ,b1 is perforated at the top1 the gas passes through these perforations and is thus made to enter into the pipe ,b1 and disposed of as mentioned4 ,c1 ,c1 is a tube of safety adapted to the gasometer2 its lower extremity remains sealed by the water in the cistern so long as the gasometer is not overcharged with gas2 but1 if more gas should be made to enter the gasometer than it is destined to receive1 this pipe then delivers the gas into the funnel-shaped tube ,d1 which reaches through the roof of the gasometer house1 and thus the superfluous quantity of gas is conveyed away into the open air4 #da ,the condenser in this apparatus is placed at right angles to the row1 or rows of retorts4 ,it is furnished at one extremity with a partition placed perpendicularly1 and of a height equal to about one-half of the diameter of the condenser4 ,the object of this partition is to prevent the tar1 c4 deposited in it1 to seal the pipes ,k1 ,k1 and not to discharge itself into the pipe ,m1 till this has been effected4 ,the partition is seen in the drawing4 ,the cylindrical vessel ,p1 of fig4 #c1 surrounding the orifice of the pipe ,o1 which delivers the tar into the tar cistern1 fig4 #c1 serves to keep this pipe constantly immersed into a portion of tar1 so that the contents of the cistern may be drawn off by the cock without admitting air into any part of the apparatus4 ,the tar cistern has a small hole at the top1 to allow the air which it encloses to escape1 as it becomes filled with tar and ammoniacal liquor4 ,the main condenser ,l1 is placed1 as shown in the drawing1 higher than the level of the water in the gasometer cistern1 to allow a free descent of the distillatory liquids as they pass from this vessel along into the pipes ,m1 ,n1 ,o1 c4 ,the cistern of the gasometer1 as well as the lime machine1 and tar cistern1 are constructed of cast iron plates1 bolted and cemented together with iron cement4 ,the gasometer is made of sheet iron plates rivetted together--,e1 ,e1 are two iron stays--,g1 ,g1 are friction wheels4 ,,method of correcting the relative pressure of the ,gasometer1 so as to cause the gas which it contains to be uniformly of an equal density4#db #db ,for this elegant contrivance we are also indebted to ,mr4 ,,clegg4 ,we have mentioned already that the pressure of the gas in the gasometer should be invariable1 for it is obvious that the weight of the gasometer is constantly increasing in proportion as it fills with gas1 and rises out of the water--see p4 #hh1 and #afg4 ,to render its pressure uniform1 we first take the absolute weight of that part of the gasometer which becomes immersed in the water1 and knowing the specific weight of the substance of which it is composed1 we divide its absolute weight by the specific weight of the substance of which it is composed2 and this being done1 we make part of the chain1 7measured at right angles from the axis of the wheels over which it passes downwards towards the top of the gasometer17 which is equal to the length of that part of the gasometer which becomes immersed in water1 equal in weight to the specific gravity of the substance of which the gasometer is composed4 ,for example1 let us suppose that the part of the gasometer which becomes immersed in water weighs #hfa lb4 and that it is composed of sheet iron1 the specific gravity of which1 in round numbers1 we will take to be #g4 ,it is then evident1 that the part of the chain of the gasometer measured downward from the axis of the wheel over which it passes1 and which is equal in length to the height of the gasometer1 must be loaded with a weight of1 or must itself weigh1 #abclb4 for this would be the weight of the water displaced by the gasometer2 or let us suppose the gasometer to be made of sheet copper1 the specific weight of which 7omitting decimals7 is #h2 and that the absolute weight of the gasometer is #agiblbs4 then the chain of the gasometer equal in length to the height of the gasometer1 immersed into the water must weigh #bbdlb4 for this would be the weight of the quantity of water which the gasometer displaces4 ,this being accomplished by then adding or diminishing the absolute or balance weight of the gasometer1 any desired uniform pressure may be effected1 and the same bulk of gas will always be of the same specific gravity4 ,,directions ,,to ,,workmen ,,attending ,,the ,,gas-,,light ,,apparatus#dc4 #dc ,copied from a printed direction drawn up by ,mr4 ,clegg1 for the use of workmen4 ,particular care must be taken to make the joints of the mouth-pieces of the retorts perfectly air tight1 which may be done in the following manner3--,take some common clay1 dry1 pulverize1 and sift it1 then add as much water as will make it into the consistency of treacle2 make the mouth-piece and the lid of the retort clean1 lay this luting thinly over the turned part of the lid1 press the lid so luted gently to the mouth-piece1 and then secure it moderately1 by means of the iron wedge3 if the workman observes this rule1 he will never fail to make good joints2 but if1 on the other hand1 the operator is careless and neglects to remove the old luting1 c4 from the turned or smooth part of the mouth of the retort1 and thereby cause a bad joint1 the consequence will be the loss of a considerable quantity of gas1 and a very disagreeable smell and smoke4 ,the bridge or row of bricks of the flue ,c1 of the retorts1 should never be made hotter than a bright red1 which may be regulated by the door of the ash-pit being kept close shut when the fire is getting too hot4 ,if the operator neglects this1 and suffers the fire-bricks to arrive at a bright white heat the retorts will soon be destroyed1 and bad gas be produced4 ,the gasometer should be well examined1 at least once a week1 to see if it leaks1 by the following method1 viz4 ,let the main stop-cock be shut1 then make a mark on the gasometer at the water's edge when it is full or nearly of gas1 there being no gas coming from the retorts at the time1 and if the mark sinks in the water1 the gasometer leaks2 to find out the place1 walk slowly round it1 and you may perceive the leak by the smell1 apply a lighted candle to the part suspected1 and if there be gas issuing from it1 it will take fire1 and perhaps appear like a small blue flame--blow it out1 and mark the place3 thus proceed round the gasometer till you have found all the places2 if you perceive a smell1 and yet cannot produce a flame in the part suspected1 take a brush with a little thin white-lead paint1 and lay it on the part where you think the leak is1 and1 if it be there1 the gas which escapes from the leak1 will immediately turn the paint brown4 ,after the sides of the gasometer have been well examined1 and secured by dipping a piece of cloth about the size of a shilling1 into some melted pitch1 tempered with a little bees-wax and tar1 apply the cloth whilst hot to the place with the end of your finger1 rubbing it till it is quite cold2 next examine the top of the gasometer in the same manner1--when it is about two feet high in the cistern1 it will then be better to get at4 ,the water in the cistern should always be kept within #c or four inches of the top1 if suffered to sink much lower without replenishing1 the gas will not pass through a sufficient quantity of water1 and oily particles will be apt to condense in the pipes1 to their great detriment4 ,the only thing to be observed in the place lighted is1 that the lamps and pipes are not suffered to be touched on any pretence whatever1 but by the person entrusted with their care4 ,when a lamp is not wanted1 it must be completely shut off from the pipe which supplies it1 by a stop-cock provided for the purpose1 and not opened again but when a flame is held over it2 not a lighted candle1 as the tallow is liable to drop into the lamps2 lighted paper is better4 ,,estimate ,,of ,,the ,,price ,,of ,a ,,gas-,,light ,,apparatus1 ,,if ,,erected ,,in ,,london1 ,capable of affording1 every #bd hours1 ,light equal to #dj1jjj ,tallow ,candles1 six in the pound1 burning one hour4 4 s4 ,gasometer1 to contain #aj1jjj cubic feet of gas #bcf #j ,wheel-work1 regulating chain1 ballance-weight for #afj #aa ditto1 with wooden framing ,wrought iron cistern for gasometer--#cf feet wide1 #ejj #j #bd feet long and #af feet deep 7,it would weigh about #af tons47 ,wooden framing built around it1 to secure ditto #aej #j ,condenser1 cistern and communicating pipes #abf #j ,lime machine1 made of cast iron plates #hb #j ,gasometer-house1 built of frame-work and weather-boarded #bej #j ,twenty-four retorts set in brick-work1 with furnaces #ccf #j for ditto1 compleat ,sundries #ajj #j --------- #aidj #aa 99 99 99 99 99 ,a gas-light apparatus complete for work1 capable of affording every twenty-four hours a quantity of light equal to #a1djj ,argand's ,lamps1 each lamp equal in intensity to six candles1 six in the pound1 burning for five hours1 will cost #c1ejjl4 if erected in this metropolis4 ,,london ,price ,list of the most essential articles#dd employed in the erection of a ,gas-,light apparatus4 #dd ,all the articles are warranted to be perfect and of the best kind4 ,they are delivered free of expence at any wharf between ,london and ,westminster-bridge4 ,sheet-iron pipes brazed4 s4 d4 inch in diameter #j #d a foot ditto #j #d ditto ditto #j #e ditto ditto #j #f ditto ditto #j #f ditto in ditto #g ditto #ae #a inch1 ditto #j #g ditto to #a ditto #j #i ditto #ah #a ditto #j #aj ditto feet #a ditto #j #aa ditto lengths4 #b inch1 ditto #a #a ditto #b ditto #a #d ditto #b ditto #a #e ditto #c inch1 ditto #a #f ditto ,copper pipes brazed inch #j #d per foot ,ditto1 ditto1 ditto inch #j #e ditto ,gas-light cockspur burners with stop-cock #bs #f;d to #cs #f;d ,argand's lamps1 with glass-holders1 from #cs to #ds #f;d ,cast-iron retorts1 weighing #g cwt4 at #aes #f;d per cwt #e #h #f ,mouth-piece for ditto1 compleat #a #ad #h ,cast-iron door frames for retort furnace #a #j #j ,furnace bars #ajs4 per cwt4 ,sheet iron for gazometer 7,no4 #bc7 #bds4 per cwt4 ,gazometer chains1 #e;d per lb4 ,ballance weights ,plates for gazometer1 #il #ajs per ton4 ,cast-iron cistern plates ------------------------ smaller size for lime machine1 #ahl per ton4 ------------------------ middling size for tar cistern1 #afl ditto ------------------------ largest size for gazometer cistern #adl ditto ,cast-iron flanch pipes #b-;inch diameter1 at #es per yd4 in #f feet lengths ditto #c ditto #fs ditto #f ditto ditto #d ditto #hs #f;d ditto #i ditto ditto #e ditto #ajs ditto #i ditto ditto #f ditto #abs ditto #i ditto ditto #g ditto #acs #f;d ditto #i ditto ditto #h ditto #i #aal4 #es4 per ton #i ditto ditto #aj ditto #aa inch nuts1 screws and washers to put iron pipes together #g;d4 per lb ditto #g;d4 ditto ditto #f;d4 ditto ,english bar-iron #acl4 per ton ,best1 ditto #ahl4 ditto ,,finis4 ,illustration3 ,fig4 #a ,london ,pub4 ,april #a-ahae1 at ,r,ackermann's1 #aja ,strand4 ,illustration ,transcriber's notes ,the entries in the ,table of ,contents do not always conform to the chapter and section headings in the text4 ,both have been retained as in the original work4 ,the errata have already been incorporated in the text2 the error mentioned as occurring on page #bd actually occurs on page #bb4 ,the original language1 including inconsistencies in spelling1 hyphenation1 punctuation1 formatting1 etc4 has been retained1 except as mentioned below4 ,unclear parts of the text have been checked against the on-line copy of this book of the ,eidgenssische ,technische ,hochschule ,zrich4 ,fractions like and #a-ajth have both been retained4 ,page #ij1 ,van ,dieman1 ,troostwyck3 ,jan ,rudolph ,deiman and ,adriaan ,paets van ,troostwijk4 ,changes made to the text3 ,obvious punctuation and typographical errors have been corrected silently4 ,some footnotes1 tables and illustrations have been moved2 some tables have been re-arranged4 ,other changes3 ,page #bc3 any surfaces changed to any surface ,page #bf3 opening or shuting changed to opening or shutting ,page #dg3 ,a ,new changed to ,a new ,page #dh3 trafic changed to traffic2 footnote #aj3 corporated changed to incorporated 7cf4 errata7 ,page #ec3 ,this combustion changed to ,the combustion 7cf4 errata7 ,page #fd3 ,cleg changed to ,clegg 7cf4 errata72 footnote anchor #ad moved from next page 7cf4 errata1 footnote anchor 9972 communicates changed to communicated 7cf4 errata7 ,page #fg3 #abej #b #bejj changed to #abej #b #bejj ,page #fi3 ,mr4 ,,lee changed to 8,mr4 ,,lee for consistency ,page #gb3 closing quote mark added to letter ,page #if3 pure coal- changed to pure coal-gas ,page #ajb3 sub acetate changed to sub-acetate ,page #aah3 ball #f changed to ball b ,page #aai3 e1 are changed to e e1 are ,page #abe3 #ahj degree changed to #ahj degrees 7cf4 errata72 footnote #bh3 may he compleatly changed to may be compleatly ,page #aca3 and make changed to and makes ,page #acb3 coal changed to coal-tar 7cf4 errata7 ,page #aeh3 ,nortou ,falgate changed to ,norton ,falgate2 a about changed to about ,page #afe1 table3 #aj1eji changed to #aj1ejj4