On Oil and Gil-gas. 71 
is merely to increase the heated surface, in or- 
der to accelerate the decomposition. In my 
experiments on a small scale I have put the 
whole quantity of oil into the retort at first, 
not amounting to more than 4 or 3 of an 
ounce, and without any of the materials 
above-mentioned. The retort being compa- 
ratively large and only one end of it heated 
red, I found no inconvenience from any sud- 
den rush of the gas, nor from any quantity 
of oil that might escape decomposition. 
I have made three experiments at different 
times on the decomposition of oil. The first, 
I think was on spermaceti oil, and the other 
two on common whale oil of the same parcel. 
The first gas was exceedingly good, being of 
better quality than any I have seen an account 
of; but I regret that the quantity was too 
small to admit its specific gravity to be taken. 
The second was comparatively good, and its 
specific gravity was nearly the same as that 
of common air. ‘The third was somewhat 
inferior in quality, but more so in its specific 
gravity, it being only .7 of commonair, I 
have little doubt but the first was heavier 
considerably than common air. All the three 
contained undetermined proportions of car- 
bonic acid, but amounting to 10 or 20 per 
cent., which were taken out previously to their 
being weighed. 
