Sir H. Davy's Experiments on the 
experiment on the charcoal of oak, and the least in that on 
the charcoal procured from oil of turpentine. The charcoal 
from oak left a residuum of white ashes, which was princi- 
pally carbonate of lime ; that from oil of turpentine produced 
no residuum ; that from alcohol, which was formed in a com- 
mon process of the manufacture of ether, left a minute quan- 
tity of ashes, probably owing to the impurity of the sulphuric 
acid employed. 
The quantity of mercury which entered the apparatus indi- 
cating the change of volume of the gas, was in the experiment 
on the charcoal of oil of turpentine - io7*5 grains 
In that on the charcoal of alcohol - 194-5 
In that on the charcoal of oak - 513-3 
From the results of these different experiments, it appears 
evident, that the diamond affords no other substance by its 
combustion than pure carbonic acid gas ; and that the process 
is merely a solution of diamond in oxygene, without any change 
in the volume of the gas ; for the slight absorption in the se- 
cond experiment is scarcely more than a compensation for the 
volume occupied by the diamonds consumed. 
It is likewise evident that in the combustion of the different 
kinds of charcoal, water is produced ; and from the diminu- 
tion of the volume of the gas, there is every reason to believe, 
that the water is formed by the combustion of hydrogene ex- 
isting in the charcoal, and experiments which I have referred 
to, or detailed in my third Bakerian Lecture, prove the pre- 
sence of hydrogene in common charcoal, and as the charcoal 
from the oil of turpentine left no residuum, no other cause but 
the presence of hydrogene can be assigned for the diminution 
occasioned in the volume of the gas during its combustion. 
