The bark of the Quercus alba Linne (nat. ord. Cupuliferae).

Habitat

North America, westward to Minnesota, Kansas, and Mississippi; in woods.

Characters

In nearly flat pieces, deprived of the corky layer, about 5 mm. thick; pale brown; inner surface with short, sharp, longitudinal ridges; tough; of a coarse, fibrous fracture, a faint, tan-like odor, and a strongly astringent taste. As met with in the shops it is usually an irregularly coarse, fibrous powder, which does not tinge the saliva yellow.

Composition

The chief constituents are - (1) Quercitannic acid, C28H24 O12, 6 to II per cent., a variety of Tannic Acid. (2) Quercin, a bitter principle. (3) Quercite, a sugar. (4) Resin.

Incompatibles. - See Tannic Acid, p. 593.