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PREFACE, Vil 
bark. The powers of digitalis in certain diseas- 
es are of very recent observation, At the pres- 
ent day, we are speculating on the probable com- 
position of a vegetable medicine, which cures the 
gout, 
Medicinal substances frequently owe their first 
introduction to aceident. Many have been at first 
brought up as antidotes for the poison of serpents, 
as remedies for syphilis, or as specifics against 
imaginary diseases. Previously to this, they were 
neglected as useless, or avoided as dangerous. 
It is a subject of some curiosity to consider, if the 
knowledge of the present Materia Medica were 
by any means to be lost, how many of the same 
articles would again rise into notice and use. 
Doubtless a variety of new substances would de- 
velop unexpected powers, while perhaps the pop- 
py would be shunned as a deleterious plant, and 
ihe cinchona might grow unmolested upon the 
mountains of Quito. 
It is the policy of every country to convert as 
far as possible its own productions to use, as a 
mean of multiplying its resources, and diminish- 
ing its tribute to foreigners. The plants of the 
United States are various in their character in 
proprotion to the extent of latitudes and climates, 
which our country embraces. Among those which 
