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ON POPULUS TREMULOIDES. 
most of the activity resides. It does not yield readily under 
the pestle, the fibres being very tenacious ; but is more easily 
ground, in which form it is most generally found in our 
shops. 
MEDICAL HISTORT. 
The Populus Tremuloides is noticed in the United States 
Dispensatory, last edition, Appendix, as a tonic. It has 
been very little used by medical practitioners, except the 
Thomsonians. It has been used by them for a number of 
years, and it enters into several of their preparations. Sa- 
muel Thomson, the founder of the system, remarks in his 
work, that the bark, given in the form of a tea, is one of the 
best articles to remove bile, and restore the digestive organs, 
of anything he ever used. He prescribed an ounce of the 
bruised bark to a pint of boiling water ; the dose of which is 
to be from one to two ounces. It is also used by them as a 
diuretic with much success. 
CHEMICAL HISTORY. 
No chemical analysis has been made of this plant, as far as 
I have been able to learn, although the Populus Tremula or 
European Aspen has been thoroughly analyzed by Bracconnot 
and other eminent chemists, who obtained salicin and popu- 
lin; salicin having been previously obtained by M. Leroux, 
in 1S30, from the Salix Helix, from which it obtained its 
name. Its powers as a remedy have caused it to be substi- 
tuted for quinine, in the cure of intermittents, as has been 
confirmed by Majendie and other medical writers. 
The following experiments will show what the bark con- 
tains: 
Experiment 1. — Starch, Gum, Tannic Acid. 
An infusion of the bark was made by displacement with 
boiling water, which, with tincture of iodine, formed a bluish 
