HISTORY. 
69 
far is this artificially prepared tannin distinguishable 
from the natural? Are not the two identical sub¬ 
stances ? 
“ In case of arriving at a fuller knowledge of the 
different tanning substances, to what use are the various 
ones best adapted in tanning and manufacturing as well 
as in medicine?” 
While the answers to these questions are full of in¬ 
terest, it is impossible to see that the knowledge of the 
subject was very materially advanced by the writer. 
Some of the questions are still unsolved. 
The next important work was in 1834, when a me¬ 
moir was presented to the Institute of France by Pe- 
louze, which memoir was widely copied and appears to 
have caused a general awakening among the scientists 
of that day to a closer investigation of this almost 
dormant subject. 
Probably the most important part of Pelouze’s me¬ 
moir was the new method proposed for preparing tan¬ 
nin. This process is the one usually quoted in the text¬ 
books at the present day, and is well adapted for the 
extraction of the tannin from a substance as rich in it 
as nutgalls. 
Briefly, it consists in extracting galls with ether con¬ 
taining some alcohol and water. The solution separates 
in^.o two layers, the upper an ethereal one of gallic acid 
with some tannin, the lower an aqueous solution of 
tannin containing some ether. This aqueous solution 
on evaporation leaves a porous mass of tannin, which 
Pelouze claimed was quite pure. 
This substance gave on drying at 120° the following 
percentage composition : 
