A neutral principle (glucoside) obtained from several species of the willow and poplar tree.

Habitat.—Europe, but cultivated in North America.

Derivation.—Obtained from a decoction of willow bark. Salicin crystallizes on evaporation, after removal of tannin by agitation with lead oxide. It is purified by repeated solution and crystallization.

Properties.—A white, silky, shining crystalline needle, or colorless crystalline powder; odorless, and having a very bitter taste. Permanent in air. Soluble in 28 parts of water and 30 parts of alcohol.

Dose.—Horses and cattle, 2 dr. to 1 oz.; sheep, 1 to 4 dr.; pigs, ¹/₂ to 1 dr.; dogs, 5 to 30 gr.

Actions.—Bitter tonic, antipyretic, antiferment and antiseptic, somewhat antiperiodic resembling quinine in its actions, but not as powerful.

Uses.—Used in febrile conditions about the same as quinine, its chief use is in acute rheumatism, for which it is a very good remedy; as a diaphoretic is used in large doses.