of Cancer , and on Animal Hepatic Air . 40,7 
that the former was to the latter in bulk as 1 to 4. One-fourth 
therefore of the volume of the foluble part of animal air con- 
fills of fixed air, and the remaining three-fourths of hepatic, 
mixed with a very fmali proportion of alkaline air 
It appeared from the experiment, that animal hepatic air, 
when it was abforbed by water, was not capable of being again, 
difen gaged by a heat which raifed the water to the boiling 
temperature ; for, after the fixed air was expelled, the liquor in 
the proof was made to boil nearly half an hour, but no perma- 
nently elaflic fluid could be difengaged. The portion of the 
liquor which now remained had a faint yellow colour ; it 
fmelled ftrongly of animal hepatic air, and depofited a brown 
precipitate upon the addition of nitrated filver. 
It appears, therefore, that the foluble part of the air which 
is difengaged from the lean of animal fubflances by heat,, con- 
fills of three diftindl fluids; of alkaline air, fixed air, and ani- 
mal hepatic air. It fee me d extremely probable, that thefe 
three aerial fluids, flowly combining together, formed the oily 
empyreumatic fubftance which was colledled at the bottom of 
the jar, while the air was undergoing the diminution defcribed 
above. In this conclufion I was confirmed by trials that were 
made with the empyreumatic oil that came over during the 
latter part of th6 dlflillation : for when it was examined by 
chemical tells, foon after it was obtained, it was found to 
contain fixed air, volatile alkali, and animal hepatic air. 
* It is proper to remark, that, in fome experiments, the relative quantity of 
animal hepatic air was found to be lefs than that which has been hated above. 
I do not as yet know, with certainty, the caufes to which this difference is to be 
attributed ; but I believe it principally depends upon the period of the diftillation 
in which the air is received, the degree of heat applied to the bottom of the retort,, 
and the nature of the animal fubftance employed in the experiment* 
I next 
