Oil of Wintergreen (Oleum Gaultheriæ).
This product is obtained by distillation from the leaves and twigs of Gaultheria procumbens or else by distilling the bark or leaves of Betula lenta with water, in which case the oil is generated by the action of the water, as it does not pre-exist in the birch, and, moreover, in this case the oil consists of nothing but methyl salicylate. It differs, like oil of meadowsweet, very markedly from the other aromatic substances and mainly consists of a so-called compound ether. It is a salicylate of methyl, boils at 220° C. (428° F.), is much heavier than water (specific gravity 1·173 to 1·184), and dissolves readily in alcohol and other solvents. It is used chiefly for scenting soap; the perfumes sold as wintergreen are usually mixtures of different substances which contain no oil of wintergreen.