THE DISCOVERY OF THE TANNINS. 15 
filtration, the solution was evaporated in a silver basin, 
yielding a deep-brown, friable residue, which possessed 
the characteristic odor of the astringent principle. It 
had a vitreous fracture and did not attract moisture 
from the air. The taste was strongly astringent, and 
it completely dissolved in water and alcohol. The so¬ 
lution of this extract added to a solution of glue formed 
a magma which possessed the elastic properties of the 
gluten of flour, was perfectly insoluble in hot water, 
and was not susceptible of putrefaction. This the 
author believed to be the secret of Seguin’s preser¬ 
vation of leather. The remainder of his interesting 
memoir was devoted to the effects of tannin and gallic 
acid on ferrous and ferric salts. He also pointed out 
the fact that the juice of sumac gave the same reaction 
as this compound from galls. 
By these four investigators the existence of tannin 
was completely established, and gallic acid became of 
secondary importance as a constituent of galls and in 
tanning. It may be briefly stated that Dize first indi¬ 
cated the existence of tannin and prepared it in an im¬ 
pure state, Deyeux prepared it in considerable quantity 
and recognized it as one of the important constituents 
of galls, Seguin considered it the tanning principle and 
put the knowledge of its existence to practical appli¬ 
cation, and Proust first prepared it in an almost pure 
state. 
In 1801, Karsten reviewed the history of tannin, and 
attributed the discovery wholly to Seguin, although he 
spoke highly of Proust’s work. It is very probable 
that his credit to Seguin was on account of the great 
practical importance of the latter’s invention, which 
