of Charcoal and Hydrogen. 93 
distillation. of camphor, from which it differs essentially in com- 
position, it is plain that he was not correctly acquainted with the 
properties of pure carburetted hydrogen. “Previously to the se- 
cond set of experiments, I satisfied myself by the careful a analysis 
of a specimen of the gas from stagnant water, for which I was 
indebted to Mr. Dalton, that it really has the properties which 
have been ascribed to it by him as characteristic; and in 
1807 I found precisely the same characters in the fire-damp of 
coal-mines *. Dr. Thomson, also, from experiments in 1811+, 
on the gas from stagnant water, and Sir Humphry Davy f, from 
the analysis of the fire-damp in 1815, drew the same conclusions. 
It is in the power, indeed, of every chemist to investigate for 
himself the properties and composition of carburetted hydrogen 
gas, since it may easily be procured in considerable quantity, by 
stirring the bottom of almost any stagnant pool, especially if 
composed of clay. During the last summer, I obtained it from 
a source of this kind, which afforded it in such abundance, that 
several gallons might have been collected in a few minutes. This 
gas I submitted to repeated and most careful examination. It 
contained ',th its volume of carbonic acid, but no sulphuretted 
hydrogen whatever, and no proportion of oxygen gas that could 
be discovered by attentively testing it with nitrous gas. ‘I'he re- 
sults of its combustion with oxygen gas, effected in a Volta’s 
eudiometer in the usual manner, showed that it was contaminated 
with 54th its volume of azotic gas. Apart, however, from this, 
the pure portion, in a great number of trials, required, as nearly 
as can be expected in experiments of this sort, two volumes of 
oxygen for combustion, and gave one volume of carbonic acid. 
Its specific gravity, taken on quantities procured at three several 
times, varied only from *582 to °586, the mean of which is °584 ; 
and this, allowing for ;4th of azotic gas of specific gravity 972, 
gives °556 for the specific gravity of pure carburetted hydrogen 
gas, a number which coincides alinost exactly with that found by 
Dr. Thomson §. Since, therefore, the came results have been 
obtained from the examination of gases similarly collected at di- 
stant times and places, there appears to me no reason for refus- 
ing to consider carburetted hydrogen gas as a true chemical com- 
pound, characterized by perfect uniformity of properties and com- 
position. At the temperature of 60° Fahrenheit, and under 30 
inches pressure, 1OU cubical inches must weigh 16 95 grains, aud 
be composed (taking the weight of 100 cubic inches of carbonic 
* Nicholson's Journal, 8vo. xix. 149. 
+ Mem. of the Wernerian Society, i. 506. 
f Phil. Trans. 1816, p.5 
§ Annals of Philosophy, vol. xyi. p. 252. 
acid 
