Salicine, a crystallizable bitter substance contained in the leaves and young bark of the willow (salix), poplar, and several other trees, discovered by Leroux in 1830. It was investigated by Piria, who discovered many of its derivatives, among them salicylic acid. It is prepared by boiling the bark in water, concentrating the decoction, digesting with oxide of lead, and precipitating the lead by sulphuretted hydrogen, when salicine crystallizes out on evaporating and cooling. By treatment with animal charcoal and recrystallizing it may be obtained pure in small white silky needles, having an intensely bitter taste, but no alkaline reaction. Its formula is C13H18O7. It is soluble in 5.6 parts of cold, and in much less boiling water. The addition of sulphuric acid produces a deep red color. Distilled with a mixture of bichromate of potash and sulphuric acid, among other products there is a yellow, sweet-scented oil, called salicylol, having the composition C7H6O2, identical with the volatile oil which was obtained from the flowers of spiroea ulmaria or common meadow-sweet by Löwig and Weidmann.