DESCRIPTION AND ANALYSIS OP A MINERAL, ETC. 113 
Analysis. — An ounce of the bark was boiled in half a pint 
of water for an hour. To the decoction thus formed, sub- 
acetate of lead was added, until it ceased to cause a precipitate, 
and the liquor separated by a filter. This was then boiled 
with an excess of chalk, to precipitate the oxide of lead, and 
the liquor again separated by filtration. It was then evaporat- 
ed to one-tenth and allowed to remain at rest. Numerous 
crystals were gradually deposited as the liquor concentrated 
by spontaneous evaporation. These were redissolved in wa- 
ter and boiled with purified animal charcoal, the solution fil- 
tered, and again evaporated and crystallized. The substance 
thus obtained was white, had a very bitter and peculiar taste, 
crystallized in flattened rectangular prisms, soluble in water 
and alcohol, much more so by heat, but insoluble in ether. 
When put in contact with concentrated sulphuric acid, it is im- 
mediately turned red, which color it communicates to the acid. 
It is neutral to litmus paper. 
The mother water was treated with carbonate of potassa, 
and the precipitate thus formed, by boiling water, and the wa- 
ter partially evaporated, suffered to cool, but no evidence of 
populin was obtained. The precipitate was carbonate of lime, 
resulting from the decomposition of the acetate of lime, by the 
carbonate of potassa. 
When the crystalline matter above mentioned was treated 
with oxalate of ammonia, no evidence of lime was manifested. 
These properties are evidently those of salicin, as mentioned 
by Leroux, its discoverer ; and this principle has already 
been found in the bark of the Populus tremulus, of Europe, by 
Braconnot. Captain Bonneville says the bitter cottonwood 
and willow grow promiscuously on the Rocky Mountains. 
(Irving's Rocky Mountains.) May not the bark under con- 
sideration be the product of a species of salix? It has been 
ascertained that the bark of several species of that genus con- 
tain salicin, but no populin, which is the case with that which 
forms the subject of these remarks. 
As has been said, subacetate of lead causes a copious preci- 
pitate. 
VOL, VI. — NO. U. 15 
