14 
THE TANNINS. 
Seguin’s conclusions were strengthened by the fact 
that, when he boiled hide with water and added to the 
clear cold liquid an infusion of oak-bark, he obtained 
a light-colored precipitate, which was insoluble in hot 
or cold water and became dark on exposure to light. 
We derive our knowledge of Seguin’s experiments 
from the report of a committee appointed to examine 
his process; after some months’ investigation, during 
which time a hundred or more hides were tanned and 
the committee wore shoes made of the leather, a satis¬ 
factory report was made and published. The commit¬ 
tee consisted of the citizens Lelievre and Pelletier. 
Seguin’s method of preparing the liquor was some¬ 
what ditferent from that of Fay. The latter, it will be 
remembered, boiled together the bark and water, while 
the former poured the liquor from one lot of ground 
bark to another until it reached a strength of from 10° 
to 12°. The advantage claimed for this form of the 
tanning material was that it could be transported, and, 
as the committee feared the early extinction of forests 
in France, they suggested that such an extract could be 
made in America. 
The first separation of tannin in a pure condition 
was accomplished by Proust in 1798. He added a so¬ 
lution of stannous chloride to a decoction of galls, and 
produced an abundant yellow precipitate, which he 
stated to be a combination of the tanning principle 
with tin and free from gallic acid. The precipitate 
mixed with water and treated with hydrogen sulphide 
was decomposed, forming a sulphide of the metal, 
which precipitated, while the astringent principle re¬ 
mained in solution. After removing the sulphide by 
