382 Analyses of Books. [Nor. 



Bi+Aa 

 •* ~ A + B 



In the present case, 



A = 1 ; a = 0-9722 



B = 0-66 ; h = 0-0694 

 Consequently, 



^ ^ 0-66 X 00694 + 0-9in ^ Q.ggiyg 

 1-66 



But this specific gravity is quite different from 0-5555, the true 

 specific gravity of carburetted hydrogen. 



A mixture of 1 volume of olefiant gas and 0-66 volume of 

 hydrogen would leave two volumes of carbonic acid gas, which 

 exceeds 1-66, the volume of the gas before combustion, by one- 

 sixth part. It is obvious that a mixture of equal volumes of 

 olefiant gas and hydrogen gas would, after combustion, leave 

 exactly its own volume of carbonic acid gas. The specific gra- 

 vity of such a mixture, determined by the preceding formula, is 

 0*5208, approaching nearer indeed to the true specific gravity of 

 carburetted hydrogen gas, but not the same with it. But such 

 a mixture would not require so much as twice its volume of 

 oxygen gas to consume it. And it may be easily demonstrated 

 that no mixture of olefiant gas and hydrogen gas can be made 

 which possesses at the same time all the three characteristic 

 properties of carburetted hydrogen gas. These three are the 

 following : 



1. A specific gravity of 0-5555. 



2. Requiring twice its volume of oxygen gas for complete 

 combustion. 



3. Leaving after combustion its own volume of carbonic acid 

 gas. 



We are absolutely certain then that carburetted hydrogen gas 

 is not a mixture of olefiant gas and hydrogen gas, but a chemical 

 compound of hydrogen and carbon. 



After this demonstration, it would be needless to examine 

 Mr. Brande's reasoning. It is founded upon loose analogies. 

 His specific gravities and his atomic weights are, without any 

 exception, inacciirate. I am surprised at the low specific gravitj 

 of coal gas which he assigns, viz. 0-443. I infer from it that the 

 London gas companies have greatly increased the volume of gas 

 obtained from a given weight of coal. Coal gas is never pure 

 carburetted hydrogen, but a mixture of three or more gases, and 

 is always or almost always contaminated with the vapour of 

 naphtha to which it owes its smell, and not a little of its lumi- 

 nous properties. Neither can pure carburetted hydrogen gas be 

 obtained by distilling acetate of potash, or any other acetate 

 which I have ever tried. Such distillations always produce 

 mixtures, and not chemical compounds. 



