which possesses the characteristic Properties of Tannin. 125 
was subsequently poured into it, by which it was rendered 
turbid, and a small portion of a dark brown precipitate was 
produced, resembling that which is commonly afforded by the 
artificial tanning substance. 
3 - 
The remainder of the above mentioned liquor, with the 
residuum of the roasted galls, were digested with a quarter 
of an ounce of nitric acid until the whole had become dry. 
Water was then poured upon it, and formed a dark brown 
solution, which yielded a copious brown precipitate by the 
addition of dissolved isinglass. 
From these experiments on galls it appears, that the natural 
tannin contained in them is destroyed by nitric acid ; that the 
tannin is also diminished, (and I may add,) is ultimately 
destroyed by the process of roasting ; that when galls have 
not been so far roasted as to destroy the whole of the tannin, 
then the remainder of this seems to be destroyed by the ad- 
dition of nitric acid, whilst at the same time a small portion 
of the artificial tanning substance is produced ; and that this 
last is always plentifully afforded by roasted galls when 
digested with nitric acid, similar to other vegetable bodies 
when thus treated. 
These remarks are also partly confirmed by the following 
experiments upon oak bark. 
1. 
200 grains of oak bark, reduced into very small fragments, 
were infused in about four ounces of water, after which the 
infusion was examined by dissolved isinglass, and yielded a 
considerable precipitate. 
R 2 
