114 DESCRIPTION AND ANALYSIS OP A MINERAL, ETC. 
By adding a solution of gelatin to the decoction, a precipi- 
tate was obtained, having the characters of tanno-gelatin. 
Persulphate of iron causes a dark greenish blue precipitate 
with the decoction. 
Tincture of iodine has no effect on the decoction. 
A portion of the bark was macerated in alcohol 36°, for 
three days. The tincture thus formed, when added to water, 
caused no precipitate or cloudiness. 
To the bark remaining after the alcoholic maceration, ether 
was added, and permitted to stand two days. The ethereal li- 
quor, when evaporated, yielded a small portion of fixed oil of 
a deep yellow color. When the alcoholic extract is treated 
with ether, and the ether evaporated, a small quantity of the 
same fixed oil is obtained, proving the solubility of this oil in 
alcohol. From the foregoing observations we may infer that 
this bark contains salicin, tannin, gum, and fixed oil. Its 
power as a febrifuge is undoubtedly due to salicin, of which 
it contains about two per cent. 
