Analysis of the compound inflammable Gases. 279 



of composing ternary compounds of oxygen, hydrogen, and 

 carbon, or varieties of oxy~ carbureted hydrogen. It would 

 encroach too much on the time of the Royal Society, to enter 

 upon this controversy. And, as neither opinion admits, at 

 present, of demonstrative evidence, I may be permitted, in 

 explaining the following experiments, to assume that theory 

 which appears to me most probable ; viz. that the aeriform 

 products of the distillation of vegetable substances, are mix* 

 tures of carbonic acid, carbonic oxide, olefiant, carbureted 

 hydrogen, and simple hydrogen gases ; or of two or more of 

 these in various proportions. 



The analysis of these compound gases has hitherto been 

 attempted solely by their rapid combustion with oxygen 

 gas, in the following manner : a mixture of the inflam- 

 mable gas with oxygen gas in known proportions, is ad- 

 mitted into a Volta's eudiometer, inflamed over mercury by 

 the electric spark ; and the diminution ascertained. To the, 

 remainder caustic potash or lime-water is added, by which it 

 sustains a second diminution of bulk \ and the amount of 

 this denotes the quantity of carbonic acid formed by the 

 combustion. The quantity of nitrogen gas, in the oxygen 

 employed, as well as in the residue left by potash, being de- 

 termined by a fit eudiometrical test, it is easy to infer what 

 quantity of oxygen has been absorbed bv the detonation. And 

 as it is proved that nxvgen gas sustains no change of bulk by 

 conversion into carbonic acid, we may conclude that, after 

 deducting from the volume of oxygen gas expended, that of 

 the carbonic acid which has been formed, the remaining 

 number shows how much oxygen has been employed in the 

 saturation of hydrogen. If, for example, 100 measures of 

 carbureted hv-drovren consume 200 of oxygen gas, and give 

 100 of carbonic acid, 'it follows, that the carbonic acid holds 

 in' combination 100 measures of the oxygen gas consumed ; 

 and that the remaining hundred have been applied to the sa- 

 turation of hydrogen. In this estimate it is assumed, that the 

 carbon has acquired, by combustion, the whole of the oxygen 

 tiecessaryfor its acidification, and that no part of it existed pre- 

 viously in the state of carbonic oxide; a proposition, in many 

 cases, perhaps, very far from being consistent with the truth. 



S 4 This 



