Salicin, , is a crystalline glucoside obtained from the bark of the Salix alba and other species of Salix (Willows), and also from the bark of several species of Populus (Poplars). It occurs in small white crystals, without smell, but having a very bitter taste; is soluble in 28 parts of cold water, in 1 part of boiling water, and in 60 parts of rectified spirit. When treated with strong sulphuric acid it dissolves with a bright red colour; being a glucoside it is readily decomposed by suitable chemical agencies into glucose (grape-sugar) and saligenin. Saligenin can be easily oxidised to form salicylic acid. It is used to a considerable extent in medicine. Its action and uses when given internally are much the same as those of Salicylic Acid (q.v.), but it is less powerful, is not so depressant, and does not disturb digestion so much.
Being a bitter, it promotes appetite and digestion, and therefore has a certain amount of tonic effect. Its dose is 5 to 30 grains.