i$6 Mr. Chenevix’s Observations on the 
water, leaving some carbon in the retort. But, destructive dis- 
tillation, although it has given us much knowledge as to animal 
matter in general, is too vague a method for investigating par- 
ticular animal substances. 
I shall now proceed to mention the experiments I have made 
upon all the humours. I shall first relate those which were made 
upon the eyes of sheep, (they being the most easily procured,) 
and shall afterwards speak of those of the human body, and 
other eyes. I think it right to observe, that all these eyes were 
as fresh as they could be obtained, 
sheeps' eyes. 
Aqueous Humour . 
The aqueous humour is a clear transparent liquid, of the 
specific gravity of 10090,* at 6o° of Fahrenheit. When fresh, 
it has very little smell, or taste. 
It causes very little change in the vegetable reactive colours ; 
and this little would not, I believe, be produced immediately 
after death. I imagine it to be owing to a generation of am- 
monia, some traces of which I discovered. 
When exposed to the air, at a moderate temperature, it eva- 
porates slowly, and becomes slightly putrid. 
When made to boil, a coagulum is formed, but so small as 
hardly to be perceptible. Evaporated to dryness, a residuum 
remains, weighing not more than 8 per cent, of the original 
liquor. 
Tannin causes a precipitate in the fresh aqueous humour, 
* Ail these specific gravities are mean proportionals of several experiments. The 
eyes of the same species of animal, do not differ much in the specific gravity of their 
humours. 
