HISTORY, 
67 
subject from year to year, nothing stands out promi¬ 
nently until the work of Berzelius in 1827, which ap¬ 
peared in the Jahresbericht and in his text-book. After 
remarking that every investigator offered a new method 
of preparation, he proposed two of his own, one by 
precipitating a clear infusion of nutgalls with sulphuric 
acid, and the other by a similar precipitation with po¬ 
tassium carbonate. At that time there was no distinc¬ 
tion between the tannin of the uutgall and that from 
the oak-bark, since both are described as “ Eichen- 
Gerbstoff ” and further he stated that the “ entire oak 
genus contains a tannin which appears to be identical.” 
The change of tannin into gallic acid had not been 
fully investigated at that time ; Berzelius observed that 
the question is whether gallic acid is formed by the 
destruction of tannin, or whether it results from the 
setting free of a substance with which it was in combi- 
nation. He used the classification depending on the 
color with iron salts, and described as giving a blue 
color the oak, sumac, alder, birch, and a few others, and 
as producing a green color that of cinchona, catechu, 
kino, fir, and pine. He also reported what was prob¬ 
ably the first determination of the ultimate composition 
of tannin. The lead salt was used, and his conclusion 
was that C 18 H 18 0 12 most nearly represented the formula 
of tannin. 
This work of Berzelius is full of historical data, and 
many of his results are as true to-day as at that time. 
He gave the credit of discovery to Deyeux in the fol¬ 
lowing language: “ The operation of tanning was 
known to the ancients, but the substance which com¬ 
bined with the hide was first noticed by Deyeux, and 
