76 
THE TANNINS. 
dissolving in water and precipitating with ether, and in 
another case by dissolving in ether and precipitating 
with water. By these operations different layers were 
obtained, the heaviest of which he considered the purest 
and separated. These were then evaporated in vacuo 
and heated to 125°. Seven different preparations gave, 
when burned with copper oxide, closely agreeing results. 
He offered, as further evidence of the glucosidal nature 
of the acid, the fact that WetheriU obtained 87 per cent, 
of gallic acid and he found 22 per cent, of glucose. 
Robiquet in 1852 arrived at somewhat different con¬ 
clusions, but these were not backed by such a mass of 
experimental data as characterized Strecker’s. 
The work of Strecker might be a fitting close to the 
historical consideration, since the next important work 
brings us to such a modern period that it may be more 
properly studied under the properties and constitution 
of the acid. 
The authors, however, should be mentioned in this 
connection ; therefore we must give to Julius Lowe and 
Hugo Scliiff the credit of independently establishing 
by careful research our present knowledge of tannic 
acid. The former in 1867 first succeeded in reconvert¬ 
ing gallic into tannic acid by treating barium gallate 
with silver nitrate and obtaining a substance which 
he described as precipitating gelatin and the alkaloids. 
His work was taken up by Schiff in 1871 and carried 
on for several years, and to this latter scientist we owe 
our present knowledge of digallic acid. It is worthy 
of note, however, as has been already stated, that most 
discoveries are in a certain degree anticipated, and this 
one of digallic acid was no exception, for Illasiwetz in 
