The Encyclopedia Americana (1920)/Cinchona Bark

CINCHONA, sĭn-kō′nạ, BARK, the bark of several species of Cinchona, a genus of trees and shrubs of the family Rubiaceæ. The following are the most important: Cinchona flava cortex, yellow cinchona bark, which occurs as quills covered with a brown epidermis, mottled with whitish yellow lichens, and also in flat cinnamon-colored pieces. They break with a fibrous fracture and the escape of a powder. Yellow bark is rich in quinine, and 100 grains should yield not less than two grains of alkaloid. It is derived from C. calisaya, which grows in the peculiar cloudy regions of the Andes. C. pallida cortex, pale cinchona bark, from C. officinalis. It occurs always in quills covered with crustaceous lichens. Its fracture is short and not fibrous. It contains chiefly cinchonine. Two hundred grains of the bark yield about one grain of alkaloid. C. succirubra, a native of Peru, appears to thrive in India. The bark occurs in flattened rough-fibrous, dark-brown red pieces, which are covered with a brown-red epidermis. It breaks with a red fibrous fracture. It contains about equal quantities of cinchonine and quinine, and 100 grains of the powdered bark should yield not less than one and one-half grains of alkaloid. The yellow bark is used in the form of decoction, extract, infusion and tincture. The pale bark is contained in tincture cinchonæ composita and in mixtura ferri aromatica. The cinchona barks contain, besides the alkaloids, certain acids having astringent properties, and are valuable as tonics in cases of great debility. Cinchona barks rich in quinine generally contain much lime, and their solutions are precipitated by sodium sulphate. See Quinine.