ON POPULUS TREMULOIDES. 
279 
other processes were tried, but without success, until the pro- 
cess of Messrs. Tyson and Fisher (Journ. Philada. College of 
Pharmacy, Vol. 3, page 213,) was adopted with the following 
results: 
A portion of the bark was boiled with water and caustic 
lime, filtered, and sulphate of zinc added to the solution until 
the lime was precipitated and again filtered. This liquid was 
then carefully evaporated to dryness, and the extract treated 
with boiling alcohol, and again evaporated. Spontaneously, 
a brown coloured matter was obtained, which possessed much 
bitterness, but was not crystalline. This substance was re- 
dissolved in alcohol, and a portion of pure animal charcoal 
added, and the mixture boiled for ten minutes and filtered; 
the filtered liquid was then suffered to evaporate spon- 
taneously, numerous flocculi being suspended in it and 
on the sides of the vessel. The whole was then thrown 
on bibulous paper and subjected to strong pressure, until 
all the fluid part was absorbed, leaving a light brown 
matter on the surface of the paper. This was collected and 
redissolved in alcohol, and allowed to evaporate sponta- 
neously, when numerous prismatic, acicular crystals were ob- 
tained, which possessed the following characters. They were 
soluble in alcohol, sparingly soluble in cold water, very solu- 
ble in boiling water, and very slightly soluble in ether. The 
taste is bitter, followed by the after taste of the bark, which 
is so peculiar in salicin. When added to sulphuric acid it in- 
stantly becomes purple, and communicates the color to the 
acid. When added to concentrated hydrochloric acid, and 
slowly heated, it was dissolved; but on increasing the heat, a 
white, insoluble compound was separated. From these, and 
other characteristics, there can be no doubt of the identity of 
this principle with salicin, thus adding another instance of a 
species of poplar yielding this principle. 
From the foregoing experiments it may be inferred, that 
the bark of the Populus Tremuloides contains the following 
principles: Gum, Starch, Extractive Matter, Tannic Acid 
Gallic Acid, Chlorophylle, Fixed Oil, Salicin, Salts of Lime, 
and Potassa. 
