102 Analysis of Scientific Books. 



In the third section, he applies the facts detailed in the former 

 two, to the analysis of mixtures of combustible gases in unknown 

 proportions. For this purpose, he caused a quantity of gas to be 

 collected from coal, by continuing the application of heat to the 

 retorts two hours beyond the usual period, and receiving the gas 

 into a separate vessel. Gas of this quality was purposely chosen, 

 because, from former experience, it was expected to contain free 

 hydrogen, carbonic oxide, and carburetted hydrogen, but no 

 olefiant gas, the production of which is confined to the early 

 stages of the progress. After washing it, therefore, with liquid 

 potash, to remove a little carbonic acid, and ascertaining its spe- 

 cific gravity when thus washed to be .308, he proceeded at once 

 to subject it to the following method of analysis. 



Having ascertained, by a previous experiment with Volta's 

 eudiometer, that ten volumes of the gas required for saturation 

 9 volumes of oxygen, he mixed 43 measures with 43 of oxygen 

 (= 41 pure) and passed a platinum ball, which had been re- 

 cently heated, into the mixture.. An immediate diminution of 

 volume took place, attended with a production of heat, and for- 

 mation of moisture. The residuary gas, cooled to the tempera- 

 ture of the atmosphere, measured 43.5 volumes. Of these, 4.5 

 were absorbed by liquid potash, indicating 4.5 carbonic acid, 

 equivalent to 4.5 carbonic oxide ; the rest, being fired in a 

 Volta's eudiometer with an additional quantity of oxygen, gave 

 1 1 volumes of carbonic acid ; the diminution being 22 volumes, 

 and the oxygen consumed 22 also, circumstances which prove 

 that 1 1 volumes of carburetted hydrogen were consumed by this 

 rapid combustion. But of the loss of volume first observed, 

 (viz. 86 — 43.5=42.5) 2.25 are due to the carbonic acid formed ; 

 and deducting this from 42.5, we have 40.25, which are due to 

 the oxygen and hydrogen converted into water ; and 40.25 x f := 

 26.8 shows the hydrogen in the original gas. But the sum of 

 these numbers (26.8 + 4.5 + 11) being less by 0.7 than the volume 

 of gas submitted to analysis, we may safely consider that fraction 

 of a measure to have been nitrogen. The composition then of 

 the mixture will stand in volumes as follows : 



Hydrogen .... 



Carbonic oxide . . 



-Carburetted hydrogen 



Nitrogen .... 



43.0 100. 



On calculating what should be the specific gravity of a mixture 

 of gases in the above proportions, it was found to be .303*, which 



« In this estimate, the specific gravity of hydrogen is taken at .0694 ; that 

 of carbonic oxide at ,6722 j of caiburetted hydrogen at .5555; and of nitro- 

 gen at .9728. 



