APPARATUS FOR THE ANALYSIS OF GASSES. &5 



proportions, and of composing ternary compounds of oxi- 

 gen, hidrogen, and carbon, or varieties of oxicarburctted 

 hidrogen. 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 evi- 

 dence, I may be permitted, in explaining the following ex- 

 periments, to assume that theory, which appears to me most 

 probable; viz. that the aeriform products of the distillation Most probably 

 of vegetable substances are mixtures of carbonic acid, car- 

 bonic oxide, defiant, carburetted hidrogen, and simple 

 hidrogen gasses; or of two or more of these in various pro- 

 portions. ■■ ■ » ■ • » ■ ■■ 



The analysis of these compound gasses has hitherto been Usual mode of 

 attempted solely by their rapid combustion with oxigen gas, anal >' sls> 

 in the following manner: a mixture of the inflammable gas 

 with oxigen gas in known proportions is admitted 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 oxigen employed, as 

 well as in the residue left by potash, being determined by 

 a fit eudiometrical test, it is easy to infer what quantity of 

 oxigen has been absorbed by the detonation. And as it is 

 proved, that oxigen gas sustains no change of bulk by con- 

 version into carbonic acid, we may conclude, that, after 

 deducting from the volume of oxigen gas expended that of 

 the carbonic acid which has been formed, the remaining 

 number shows how much oxigen has been employed in the 

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

 carburetted hidrogen consume 200 of oxigen gas, and give 

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

 in combination 100 measures of the oxigen gas consumed ; 

 and that the remaining hundred have been applied to the 

 saturation of hidrogen. In this estimate it is assumed, that One source cl 

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

 oxigen necessary for its acidification, and that no part of it 

 existed previously in the state of carbonic oxide, a proposi- 

 tion, in many cases, perhaps, very far from being consistent 



with 



