gallic acid

noun

, Chemistry.

a white or yellowish, crystalline, sparingly water-soluble solid, C 7 H 6 O 5 , obtained from nutgalls, used chiefly in tanning and in ink dyes.

gallic acid

a colourless crystalline compound obtained from tannin: used as a tanning agent and in making inks, paper, and pyrogallol; 3,4,5-trihydroxybenzoic acid. Formula: C 6 H 2 (OH) 3 COOH

First recorded in 1785–95, gallic acid is from French acide gallique

C18: from French gallique; see gall ³

A mixture of the two esters melted within the limits given for the ester of gallic acid.

The melting point behavior of the acid corresponds with that of gallic acid; it melted with decomposition at about 230°.

While the tests leading to the identification of gallic acid were being made, another series of experiments was in progress.

For the sake of comparison, an ester was made from gallic acid obtained from another source and the two agreed in properties.

All appeared to be impure gallic acid which had become brown by absorption of oxygen.

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