SECTION II. 
GENERAL CHARACTERS. 
The terms “ tannin” and “ tannic acid” are used 
indiscriminately by many writers, while others employ 
the term “ tannic acid” to indicate the whole series and 
“ tannin” to denote the product from oak-galls. It, 
however, appears more rational to apply the term 
u tannic acid” to the product from galls, since it is an 
acid when pure, and to use the term “ tannin” to desig¬ 
nate the whole class of astringent substances, many of 
which are glucosides, and many more hold an un¬ 
known position among the chemical compounds. Thus 
u tannic acid” will agree with the German gerbs&ure 
and the French acide tannique, and “tannin” with the 
German gerbstoff and the French tannin, although many 
writers in those languages have also confused the respec¬ 
tive terms. There is no objection to the use of a more 
exact designation by prefixing the source of the com¬ 
pound, as gallotannic acid to the product from galls, 
sumaetannic acid to that from sumac, catechutannin to 
that from catechu, etc. In the following pages, there¬ 
fore, the term “tannin” will be applied to the whole class 
of astringents, while the compound from galls, as well as 
those from other sources where they have been shown 
to be chemically and physically identical with it, will 
be designated by “ tannic acid.” In both cases a prefix 
indicating the source will be applied when necessary. 
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