1820.] Dr. Henty's Experiments on the Gas from Coal. 37 



In gases free from all admixture with carbonic oxide, it is 

 easy to know how much of the oxygen consumed has been spent 

 in saturating the charcoal ; for as oxygen gas by conversion into 

 carbonic acid suffers no change of volume, the quantity which 

 has combined with the charcoal is exactly represented by the 

 volume of carbonic acid produced by the combustion. For 

 example, as lUO measures of olefiant gas afford by detonation 

 200 of carbonic acid, 200 measures of oxygen must have united 

 with the charcoal of the olefiant gas. But beside these 200 

 measures, an additional 100 measures of oxygen are found to be 

 consumed, and these must have combined with hydrogen, the 

 other ingredient of the gas, the volume of which in its full state 

 of expansion would be 200 measures, as determined by the fact, 

 that oxygen gas uniformly takes for saturation double its volume 

 of hydrogen gas, and no other proportion. 



Nature of the Gas from Coal. 



The opinion which I formerly advanced on this subject,'}' 

 though opposed by writers of so much authority as M. Berthollet 

 and Dr. Murray, still appears to me to be much more probable, 

 than that the varieties of gas from inflammable substances, 

 which may be almost infinitely- diversified by modifications of 

 temperature, are, as those philosophers suppose, so many dis- 

 tinct compounds of hydrogen and charcoal, or of hydrogen and 

 charcoal in combination with oxygen. The reasons that induce 

 me to abide by my original view of the subject are the following: 



1. We are acquainted with two distinct and well characterized, 

 compounds of hydrogen and charcoal, in one of which a given 

 weight of charcoal is united with a certain qunntity of hydrogen, 

 and in the other with double that quantity. Besides these two, 

 no other compound of those two elements has been hitherto 

 proved to exist. 



2. It is inconsistent with experience that two bodies which, 

 like hydrogen and charcoal, unite by an energetic affinity, should 

 combine in all possible proportions. On the contrary, it is to be 

 expected from analogy in general, and from that of the com- 

 pounds of charcoal and oxygen in particular, that hydrogen and 

 charcoal unite in few proportions only, and in such a manner 

 that these proportions are multiples or divisors of each other by 

 some entire number. 



3. All the phenomena may be satisfactorily explained by 

 supposing the gas from coal, and from other inflammable sub- 

 stances, to be mixtures of this kind. For example, referring to 

 the one hour's gas in the first table, we shall find that it contains, 

 in 100 measures, 18 of olefiant gas, which require for combus- 

 tion 54 measures of oxygen, and afford 36 of carbonic acid. The 

 same gas contains also 774- measures of another inflammable gas, 



• Nicholson's Journal, 8vo. xi. 68. 



