1825.] finely divided Platinum on Gaseous Mixtures. 429 



of carburetted hydrogen were consumed by this rapid combus- 

 tion. But of the loss of volume first observed (viz. 86 — 43*5 

 = 42"5) 2-25 are due to the carbonic acid formed ; and deduct- 

 ino- this from 42-5, we have 40-25, which are due to the oxygen 

 and hydrogen converted into water ; and 40*25 x •§- = 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 frac- 

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

 of the mixture will stand in volumes as follows : 



Hydrogen 26-8 62-32 



Carbonic oxide 4-5 10-50 



Carburetted hydrogen . . 11-0 25-56 



Nitrogen 0-7 1-62 



43-0 100-00 



On calculating what should be the specific gravity of a mix- 

 ture of gases in the above proportions, it was found to be "303,* 

 which coincides, as nearly as can be expected, with the actual 

 specific gravity of the gas submitted to analysis, viz. -308. To 

 place the correctness of the results beyond question, I mingled 

 the gases in the above proportions, and acted on the artificial 

 mixture in the same manner as on the original gas, when I had 

 the satisfaction to find that the analytical process again gave 

 the true volumes with the most perfect correctness for the hydro- 

 gen and carbonic oxide, and within the fraction of a measure for 

 the carburetted hydrogen. Notwithstanding this successful 

 result, which was twice obtained, 1 should still prefer, for the 

 reason which has been stated, having recourse to a temperature 

 carefully regulated, for the analysis of similar mixtures, in all 

 cases where the hydrogen is in moderate proportion, and where 

 great accuracy is desirable. Whenever (it may again be 

 remarked) defiant gas is present in a mixture, it should always 

 be removed by chlorine, before proceeding to expose the mixture 

 to the agency of the spongy metal. 



It can scarcely be necessary to enter into further details 

 respecting methods of analysis, the appUcation of which to par- 

 ticular cases must be sufficiently obvious, from the experiments 

 which have been described on artificial mixtures. The apparatus 

 required is extremely simple, consisting, when the balls are 

 employed, of graduated tubes of a diameter between 0-3 and 0*6 

 of -an inch ; or, when an increased temperature is used, of tubes 

 bent into the shape of retorts, of a diameter varying with the 

 quantity of gas to be submitted to experiment, which may be 



• In this estimate, the specific gravity of hydrogen is taken at -Oeoi ; tliat of car. 

 bonic oxiUe at -672'^ ; of carburetted hydrogen at -5555 ; and of nitrogen at '9788. 



