which possesses the characteristic Properties of Tannin. 119 
5 > 
200 grains of the same horse chesnuts were moderately 
roasted, and being treated as above described with water, 
yielded a dark brown decoction which was not rendered turbid 
by isinglass. 
6. 
The horse chesnuts, which had been employed in the pre- 
ceding experiment with the remaining liquor, were digested 
with a quarter of an ounce of nitric acid until the whole was 
become dry. Water was then poured upon it, was digested, 
and a dark brown liquid was formed, which afforded a consi- 
derable precipitate by the addition of solution of isinglass. 
From these experiments it appears, that the small portion 
of tannin which the horse chesnut peels originally contained, 
was destroyed by the process of roasting ; that the brown 
decoction subsequently obtained from the roasted peels and 
from the horse chesnuts, did not act upon gelatine ; but that 
these were speedily converted into the artificial tanning sub- 
stance, by the addition of a small portion of nitric acid and sub- 
sequent evaporation. 
The first preparations of the artificial tanning substance 
which have been mentioned in the former Papers, were made 
from coal of different descriptions digested with nitric acid, 
and as similar products have been obtained by the same acid 
from various decoctions of roasted vegetable substances, there 
cannot be any doubt, that vegetable bodies when roasted, 
yield solutions by digestion in water, which essentially consist 
of carbon approaching to the state of coal, although not abso- 
lutely converted into it, for if so, all solubility in water would 
cease. 
But coal is apparently nothing more than carbon oxidized 
