47 fast. 
acid. Method: of detecting this principle in 
plants: by application to mouth, and by effects 
on living animal body, by solution of copperas, 
- &e. Cullen’s opinion relative to the degree of 
corrugation induced in the mouth, asa criterion of 
the intensity of the astringent power in the sub- 
stance used. 
The astringent principle resides in cortex and 
liber of most oaks and peruvian barks: in the liber of 
many trees and shrubs, the cortex of which possessee 
little or none of it’s in the roots of numerous plants, 
85 the ratanhy root, alum root, tormentil;- rose. 
tree, geranium maculatum, | the we 
_ Many trees, as logwood; in the leaves of many _ 
plants, as shumach, common green tea, &e.; in 
the excressences which form the nidus of insects, 
as oak-apple, aleppo-galls, &c. in the latter it ex- 
ists united with a peculiar acid which has received 
the name of gallic acid. This was once supposed 
to be the astringent principle ; not correct ; galls 
do not contain more of this acid principle than other 
astringent vegetables: Higgins’ experiments shew. 
ome species of shumach contain more than. 
vegetabies, yet analised. Chemical proper- 
s of gallic acid. : ; 
<8 + eo 
MEDICAL USE OF ASTRINGENTS. 
_ Of the use of astringents in diseases:—best given — 
in substance, when the stomach will bear that form 
—otherwise, should be given in the pharmaceutical — 
liquid preparations. Astringency is fixed in sub- 
stances containing it; of course the absence of | 
volatility in this property, renders it nugatory to 
employ the distilled waters of astringent medicines, 
Watery and spirituous menstrua take up the 
astringency of substances, subjected to their action: 
<3) 2 : 
the wood of — - 
