Gallo-tannic acid

SYNS d ACIDETANNTQUE (FRENCH) GALLO-TANNIC ACID GALLOTANNIN GLYCERITE TANNIN... 

Gallo-tannic Acid.—One of these is gallo-tannic acid, also known as simply tannic acid, or tannin, also as di-gallic acid. It is found in gall-nuts and in tea and yields gallic acid on hydrolysis. 

Synonyms Digallic acid Chinese tannin Gallo-tannic acid Galloylglucose Glycerite Digalloyl glucose Tannin Tannins... 

Gallo-tannic acid—Acidum tannicum (H. S., Br.)—is the best known of the tannins, and is obtained from nut-galls, galla (tf. S., Br.), which are excrescences produced upon oak trees by the puncture of minute insects. It appears as a yellowish, amorphous, odorless, friable mass has an astringent taste very soluble in water, less so in alcohol, almost insoluble in ether its solutions are acid in reaction, and on contact with animal tissues give up the dissolved tannin, which becomes fixed by the tissue to form a tough, insoluble, and non-putrescible material (leather). 

A freshly prepared solution of pure gallo-tannic acid gives a dark blue precipitate with ferric salts, but not with ferrous salts. If, however, the solution have been exposed to the air, it is altered by oxidation, and gives, with ferrous salts, a black color (in w hose production gallic acid probably plays an important part), which is the coloring material of ordinary writing-ink. 

Joslyn, M.A., and Click, Z. 1969, Comparative effects of gallo-tannic acid and related phenolics on the growth of rats,... 

Common/vernacular names. Tannin, gallo-tannic acid, and gallotannin. 

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