413. Gaultheria.—Wintergreen. Checkerberry. Partridge Berry.
413. GAULTHERIA.—WINTERGREEN. CHECKERBERRY. PARTRIDGE BERRY. The leaves of Gaulthe'ria procum'bens Linné. Habitat: Northern Hemisphere. This is a small evergreen shrub, consisting of slender, erect, reddish stems, bare below, leafy at top, rising at intervals from a creeping root to the height of eight or ten inches. Fruit a scarlet-red, berry-like, fleshy capsule. Leaves roundish, oval or obovate, about 37 mm. (1 ½ in.) long, on a short pedicel; coriaceous; margin serrate, with a few appressed teeth; somewhat revolute at the edges; odor fragrant, especially when chewed; taste aromatic, astringent. The fragrance is due to a volatile oil (413a). Stimulant, astringent, and diuretic. Dose: 15 to 60 gr. (1 to 4 Gm.).
413a. OLEUM GAULTHERIAE.—OIL OF WINTERGREEN. A nearly colorless volatile oil, distilled from the fresh leaves, "consisting almost entirely of methyl salicylate, CH3C7H5O3, and nearly identical with volatile oil of betula." The latter, according to Power, is composed entirely of methyl salicylate and is optically inactive, while the former is laevogyrate. As it comes into market it is of a brownish-yellow or reddish color and has a very agreeable, characteristic odor and taste. Specific gravity of 1.172 - 1.182. An aqueous solution gives, with ferric salts, a purplish color. It yields, with 6 parts of 70 per cent. alcohol at 20°C., a perfectly clear solution—a property serving to detect adulterations. (Official as Methyl Salicylas, 413 b).
413b. METHYL SALICYLAS.—A product yielding not less than 98 per cent. of methyl salicylate (CH3C7H5O3). It is produced synthetically or obtained by distillation from Betula lenta Linné, or from Gaultheria procumbens Linné, and the source from which it is derived must be stated on the label.
Specific gravity at 25°C.: Synthetic 1.18 to 1.185; when from Sweet Birch or Gaultheria 1.172 to 1.182.
Most of the so-called "true" oil of wintergreen is made by distilling a mixture of wintergreen leaves and the bark of the sweet birch.
Dose of Methyl Salicylas: 12 minims (0.75 mils), U.S.P. IX.