Origin. - A glycosid obtained from several species of Salix (willow) and Populus (poplar).

Description and Properties. - Colorless or white, silky, shining, crystalline needles, or a crystalline powder, odorless and having a very bitter taste. Permanent in the air. Soluble in 21 parts of water, 71 parts of alcohol at 250 C. (770 F.), 0.7 part of boiling water, and in 2 parts of boiling alcohol.

Dose. - 10 grains-2 drams (0.6-8.0 Gm.) [15 grains (1 Gm.), U. S. P.].

Physiological Action. - Its physiological effect is analogous to that of salicylic acid, but is much less active than the latter. It does not disturb digestion, but in moderate doses promotes appetite and acts like other bitters. It is more rapidly absorbed than salicylic acid, is partly decomposed, and is found in the urine, as salicin and salicylic acid, in from fifteen to thirty minutes after the ingestion of a single dose.

Therapeutics. - While inferior to salicylic acid in most respects, salicin is frequently used for the same purposes.

Administration. - Salicin may be administered in powders, capsules, or solution. Owing, however, to its bulk and intensely bitter taste, it is perhaps best given in suspension in the aromatic elixir of licorice or in syrup of yerba santa.