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ORIGINAL COMMUNICATIONS. 
upon the diseased part, and of course is more rapid in its effects 
than when compelled to travel the whole circuit of the circu- 
lation before reaching that part which requires its aid. 
One of the chief advantages which attends our knowledge 
of the presence of these active principles in vegetable remedies, 
and of the means by which they may be separated, is, that we 
are at once furnished with a prompt and certain mode of 
ascertaining the qualities of vegetable medicines. For since 
it has been proved that all owe their efficacy to the presence 
of some one of these, it is evident that their powers are in 
direct proportion to the amount of the active principle which 
they are found capable of furnishing. Hence, in making 
choice from different portions of opium, in order to select 
that which is best, we naturally prefer that which produces 
the largest amount of morphia; the same reasoning will apply 
to bark from which the separation of quinia forms the 
criterion by which the judgment is formed; and the quan- 
tity of atropine, or hyoscyamine, obtained from the plants in 
which these principles exist, enables us to decide whether 
the leaves which furnish them, are entitled or not to our 
confidence. 
In a word. Pharmacy has applied to vegetable substances 
the same unerring test for estimating their value to which 
general chemistry had already subjected mineral bodies. The 
amount per cent, which may be yielded, in both cases, being the 
direct measure of their value. This object is, alone, one of 
primary importance, and cannot too often be made available 
in the successful prosecution of the duties of a pharmaceutist 
and physician. 
But Pharmacy has by no means limited her investigations 
to those which have been announced; she has directed her 
attention to the improvement of the processes by which the 
extractive matter of plants is removed from them and con- 
verted into a form, by which its efficacy is preserved 
unimpaired, and may be employed long after the plant which 
furnished it has mingled with the dust. She has discovered 
and invented hundreds of modes by which the form of medi- 
