Hc7h5o5+H2O=187.55. An organic acid, usually prepared from Tannic Acid.

Source

By exposing a mixture of Nutgall and distilled water in the form of a thin paste, to the air for a month, expressing and rejecting the liquor, boiling the residue with distilled water and filtering, when hot, through purified Animal Charcoal. Hc14h9o9+H2O=2Hc7h5o5.

Characters

White, or pale fawn-colored, silky, interlaced needles, or triclinic prisms; odorless; having an astringent or slightly acidulous taste; permanent in the air.

Solubility

In 100 parts of water, and in 5 parts of Alcohol; also soluble in 40 parts of Ether, and in 12 parts of Glycerin. Very slightly soluble in Chloroform, Benzol, or Benzin.

Incompatibles. - Ferric and metallic salts generally, and Spiritus AEtheris Nitrosi.

Dose, 5 to 20 gr.; .30 to 1.20 gm.

Action And Uses Of Gallic Acid

Gallic acid has no power to coagulate albumin, and therefore possesses none of the local properties of tannic acid. If it is wished to produce the supposed remote astringent effects of tannic acid, gallic acid may be administered, for tannic acid is in the intestine converted into it.