Hydrogen and Carbon. 261 
gravity of the gas obtained by distilling pit-coal, as shown 
by the experiments of Dr. Henry. 
_ When water and carbon are present together, as is ‘he 
case in most animal and vegetable substances, they act on 
each other, and give origin to variable quantities of car- 
bonic oxide, which must also very much alter the pro- 
perties of the gas evolved. To these two causes, namely, 
the oil dissolved, and the carbonic oxide formed, most if 
not al] the varieties in the combustible gases, obtained 
from animal and vegetable substances, are owing. 
Berthollet, in a dissertation which he lately published in 
the second volume of the Mémoires d’Arcueil, has endea- 
youred to prove that all the heavy inflammable gases con- 
tain oxygen as a constituent. He has examined a number 
of gases obtained by distilling charcoal, and has shown 
that each of them contained a considerable proportion of 
oxygen. This opinion has likewise been maintained by 
Mr. Murray, in bis System of Chemistry.. _ 
If any confidence can be put in the preceding observa- 
tions, it is clear that this obscure subject can never be elu- 
cidated by examining gases from charcoal, or from animal 
and vegetable substances. The first will always yield car- 
bonic oxide as well as carbureted hydrogen, and the gas 
from the other bodies will be disguised by the oil held by 
jt in solution. 
Analogy is strongly in favour of the common opinion, 
that there exists a gas composed simply of hydrogen and 
carbon. Hydrogen, we know, is capable of dissolying every 
other simple combustible, sulphur, phosphorus, and bora- 
cium. It dissolves likewise several of the metals; as arsenic, 
zinc, tellurium, and potassium. Why then may it not be 
capable of dissolving carbon? 
There is a gas which rises in considerable quantity from 
stagnant waters during the summer season. Jt was ex- 
amined by Cruickshanks and Daltou; and both of them 
concluded it to be a compound of carbon and hydrogen, 
without any sensible quantity of oxygen. But as neither 
of these gentlemen has published a detailed account of their 
experiments, I thought it worth while to examine the gas 
anew, in order, if possible, to determine the point in a sa- 
tisfactory manner. I accordingly collected considerable 
quantities of it at different times in the neighbourhood of 
Restalrig, where ponds of muddy water are left stagnant 
in order to collect manure. This gas I found to have the 
following properties : 
1, It is colourless, and transparent like air. 
R3 2. It 
