SOURCE.—The preputial follicles of both sexes of Cas'tor fiber Linné. These follicles are not perceptible until the outer skin is removed, when they are seen to lie between the cloaca and pubic arch of the animal. This species of animals is commonly known as the beaver, and is found more or less throughout the Temperate and North Temperate Zones.
DESCRIPTION.—The dry, resinous, brownish contents of the fig-shaped sacs or follicles have a strong and peculiar odor, an acrid, nauseous taste, and are soluble in alcohol and ether. An aqueous decoction of castor is of a light yellowish-brown color which becomes turbid on cooling, and changes to a dark color when ferric chloride is added.
VARIETIES.—American or Canadian, and Russian or Siberian Castor. The Russian variety differs from the American in the size of the inclosing follicles; in the former the size varies from 2 ½ oz. to 8 oz. (75 to 240 Gm.) in weight, and in the latter from 1 to 4 oz. (30 to 120 Gm.). There is also a difference in the composition of the product from the different varieties, the American probably containing a larger percentage of resin.
ADULTERATIONS.—Earthy matters, as well as resin and blood, are sometimes used for this purpose, but not frequently. The product from diseased animals is also met with; this often contains as much as 50 per cent. of inert material and is of a brownish-gray color.
CONSTITUENTS.—A bitter resinous substance 14 to 58 per cent., 1 to 2 per cent. of volatile oil containing carbolic acid, a small quantity of castorin (a colorless, odorless and tasteless, crystalline, non-saponifiable fat, soluble in ether and boiling alcohol), together with salicin, cholesterin, and about 3.5 per cent. ash. The resin is dark brown, slightly acid, soluble in alcohol but not in ether. The volatile oil contains the odoriferous principle and is generally colorless, having an acrid, bitter taste.
ACTION AND USES.—Castor enjoys some reputation as a stimulant, antispasmodic, and emmenagogue, and is employed in cases of hysteria, chorea, and epilepsy, associated with sexual disorders. On account of its disagreeable taste it is best administered in the form of a pill.
DOSE.—5 to 10 gr. (0.3 to 0.6 Gm.) in the form of a pill; 1 to 4 fl. dr. (4 to 15 mils) of the tincture.