Principle of Lighting by Gas illustrated. 489 



1 821.] 



paiid into the greatest possible volume, 

 and picfercncc siiuiilc) lio given fo that, 

 the vapour of wiiich only burns l)y the 

 aid of heat still more intense. Should 

 this heat be diminished, the combustion 

 of the vapour ceases. Lamps of a small 

 size consume the most oil, in proportion 

 to the light they emit; and the old noc- 

 turnal lamps are at least ten times more 

 expensi^e than those invented by 

 Quinquet. 



The combustion of gas disengages 

 iniich more caloric thati is wauled lo 

 raise the burner and the combustible to 

 the due degree of ignition. The combi- 

 nation of pure hydrogen with oxygen 

 equally pure, in the proportions neces- 

 sary for the formation of water, pro- 

 duces a temperature strong enough to 

 melt platinum and several other sub- 

 stances that resist the most violent fire of 

 forges and reverberating furnaces. Oils, 

 greasy substances, and wax, may be re- 

 duced to a temperature low enough to 

 cease burning, while a lamp, fed by the 

 coldest gas, will not go out, or its light 

 experience any sensible diminution. 



Alcans have already been perfected, 

 •of converting vegetable and animal oils 

 into gas with very little loss. By this 

 Iransforinaliou, a measure of oil, which 

 for twenty-four hours would have given 

 but a glimmering light, w ith an unplea- 

 sant smell, will supply, through seventy- 

 five hours, a lively, ardent Hume, free 

 from any scent. 



Gas, extracted from oils, has the pro- 

 perty of illuminating in tlie highest 

 degree. I'wo measures of gas fiom oil 

 enlighten as much as seven measures of 

 gas from pit-coal. By comparing equal 

 weights of these two fluids, two parts of 

 gas from oil, spread somewhat more 

 Jiglit than three par(s of gas from pi(- 

 coal, antl the specific weight of llie 

 latter is nearly four-ninths of that of the 

 former. From these and other obser- 

 vations, the enlightening power of gas 

 seems to augment, with its specific 

 weight, to a term not hitherto ascer- 

 tained. This may become a source of 

 valuable discoveries ; and, for this pur- 

 pose, experimentalists would do well to 

 try improvements in pheonietry, or the 

 measuring of light, photomclrical inslru- 

 menls being far from that perfection 

 which thermometers have risen to. 



Gas from oil is, doubtless, of the most 

 solid value and real use, as it may be 

 fabricated on a small as well as a large 

 jcale, and it has no tendency to allect 

 the eiiltine of oleaginous |)lants. It 

 tnay be taken for a term of comparison, 



in researclies relative to the creating cf 

 artificial light. 



The apjjaratus for converting oil info 

 gas is olllie simplest nature. The liquid 

 must be raised to the tem[ierature of 

 red-hot iron, and so remain for sonve 

 seconds. The oil is introduced, by 

 drops, into cast pipes placed in a fur- 

 nace, and heated red hot. Il vapourises, 

 runs along the pipes, undergoes decom- 

 position, fakes the gaseous state, and 

 passes into the gazometer. This process 

 resembles that of Conte, in filling 

 air-balloons. 



In the preparation of oily gas, the 

 I)ipes are only opened to admit the oil 

 and let out the gas; the fire of the fur- 

 nace may be kept on witiiout interrup- 

 tion, the oil and the gas co-operate with 

 regularity, the furnace and [lipes remain 

 invariable, and the manual labour is in- 

 considerable. The hazard of losses is 

 also counteracted, and there is a combi- 

 nation of all the means of economy. 

 The interest of tlie consumers, and 

 of those employed in the labricalion, is 

 alike consulted. 



The (>|)erations for extracting gas 

 from pit-coal, wood, lignites, and ollrcr 

 carbonaceous substances, are not so 

 simple as those for turning oil into gas ; 

 and selection is required in the materi- 

 als, or the gas will be extremely fetid. 

 Certain lignites, and pit ccal of calcare- 

 ous soils, are remarkable for tliis quality. 

 The bark of the birch-tree furnishes not 

 only oil for tanning ; but is, also, cou- 

 vcitible into gas !'or lighting. Hitherto, 

 it has proved lasier to derive advantage 

 from pit-coal in distillation, than from 

 wood. I'it-eoal takes up less room in 

 the apparatus; of course, the furnaces 

 are smaller, and less luel is wanted. 



As lo tiie giis now in use in France 

 il would have been serving an appren- 

 ticeship to follow up the ideas of Lebon ; 

 and the process has been put at once 

 under the direction of English artists. 

 In their practice, pit-coal is employed, 

 and not wood. Should the new mode 

 of lighting find its way into liie north, 

 wood will form the malejials; it is then, 

 only, that comparisons, on a large scale, 

 will decide whichof these substances is 

 preferable. 



The intensity of the light that gas, 

 extracted IVoni wood, produces, l)a.s 

 not been subjeetcd to rigorous calcula- 

 tion. In specific weight, it is inferior to 

 that of gas from oil, but superior to that 

 of hydrogen obtained by the process 

 of Conte, Annexed are the sj)tcifio 

 weights of the fluids followin,^: aimo- 

 spliciio 



