from
The Collaborative International Dictionary of English v.0.48
Gallic \Gal"lic\ (277), a. [From {Gall} the excrescence.]
Pertaining to, or derived from, galls, nutgalls, and the
like.
[1913 Webster]
{Gallic acid} (Chem.), an organic acid, very widely
distributed in the vegetable kingdom, being found in the
free state in galls, tea, etc., and produced artificially.
It is a white, crystalline substance, {C6H2(HO)3.CO2H},
with an astringent taste, and is a strong reducing agent,
as employed in photography. It is usually prepared from
tannin, and both give a dark color with iron salts,
forming tannate and gallate of iron, which are the
essential ingredients of common black ink.
[1913 Webster]