Origin. - The dried bark of Cinchona succirubra Pavon, and of its hybrids containing not less than 5 per cent. of its anhydrous cinchona alkaloids.

Description and Properties. - In quills or in curved pieces, varying in length, and from 1/12 to 1/6 or 1/5 inch (2 to 4 or 5 Mm.) thick; the outer surface covered with a grayish-brown cork, more or less rough from warts and longitudinal warty ridges, and few, mostly short, transverse fissures; inner surface more or less deep reddish-brown and distinctly striate; fracture short-fibrous in the inner layer; powder reddish-brown; odor slight; taste bitter and astringent.

Among the various alkaloids found in cinchona the following are the most important: Quinine, quinidine, cinchonine, and cinchonidine, the medicinal value of the bark depending almost exclusively upon the alkaloid quinine.

Other less important ingredients are kinic and kinovic acids, kinovin, cinchotannic acid, cinchona-red, and a minute quantity of a butyraceous, volatile oil. The ash amounts to between 1 and 2 per cent., consisting chiefly of the carbonates of calcium and potassium.

Dose of powdered cinchona, 15-60 grains (1.0-4.0 Gm.) [15 grains (1 Gm.) U. S. P.].