The bark of Quercus alba.

Characters. - In nearly flat pieces, deprived of the corky layer, about a quarter of an inch thick, pale brown, inner surface with short sharp longitudinal ridges, tough, of a coarse, fibrous fracture, a faint, tan-like odour, and a strongly astringent taste.

Composition. - Querci-tannic acid and quercin, a bitter crystalline substance.



Decoctum Quercus

(1 1/2 oz. to 1 pint).



Action and Use. - Chiefly used externally as a local astringent, e.g. as a gargle in relaxed sore-throat or as an injection in gonorrhoea and leucorrhoea.