Cinchona flava. Yellow Bark. From Cinchona calisaya.

Cinchona pallida. Pale or Brown Bark. From Cinchona con-daminea.

Cinchona rubra. Red Bark. From Cinchona succirubra. [The bark of an undetermined species of Cinchona called in commerce Red Bark, and yielding not less than two per cent. of alkaloids containing crystallizable salts. U. S.]

Quiniae Sulphas. Sulphate of Quina. A crystalline salt, prepared from the bark of Cinchona flava (calisaya), and from the bark of Cinchona lancifolia. Mutis.

All the different species of Cinchona belong, in the Linnaean system, to Pentandria monogynia, and inhabit the Andes, chiefly on the eastern face of the Cordilleras, from 4,000 to 12,000 feet above the sea, and extending from 10° of North latitude to 20° of South latitude, growing therefore in Peru, Bolivia, and Columbia. Dr. Karsten gives the following description of the locality favourable to the growth of Cinchona:- "The cinchonae which are rich in alkaloids inhabit the peculiar cloudy region of the Andes, in which, during the rainy season, which continues for nine months in the year, a steady rain is only interrupted during the day by short gleams of sunshine, interchanging with clouds and mist; whilst in that part of the year which answers to our winter, cold nights, in which the temperature of the air descends to freezing point, are followed by days in which the rays of the sun, piercing here and there, through the thick clouds, raise the temperature to 77° Fah.; whilst the leaves are kept almost continually bedewed by the continual mists. Ravines stretching upwards into the grass-covered region, and filled with forest vegetation, are the channels by which the streams of air ascend, when the mid-day sun warms the leafy covering of the mountain side. Here the mist first begins to form, when the strata of warm air, containing much aqueous vapour, mix with the colder atmospheric currents descending from the icy summits, and there ensues a frequently-repeated alternation of thick mist, which entirely bedews the surface of plants, and of warm sunbeams, which dry and warm the moistened leaves. This lasts till late in afternoon, when misty clouds overspread the whole district, until they are condensed by the cold of the night, to be again raised into vapour by the morning sun. This is the peculiar climate of those Cinchonas which are rich in organic bases." Endeavours are now being made to cultivate the more important species of cinchona plants in India (Neilgherries), Ceylon, Java, Jamaica, and Trinidad.

Description. Until recently great doubt existed as to the origin of the different kinds of cinchona barks, but the recent researches of Weddel have thrown much light upon the subject; still the tree or trees from which red bark is obtained is involved in mystery.

Cinchona flava, or true yellow bark, which has been shown by Weddel to be obtained from Cinchona calisaya (of which there are at least two varieties, vera and Josephiana, the latter a shrub), occurs in two forms, in quills or flat pieces; the former, the quills, are from 6 to 18 inches in length, and from 1 to 3 inches in diameter, with a thickness varying from 1/5 to 1/8 of an inch. The quills are generally single, and the bark is covered with a brown epidermis, mottled with white or yellowish lichens, and marked with longitudinal wrinkles and transverse or circular fissures. The latter, or flat pieces, are more fibrous, denuded of the epidermis, and of a cinnamon colour. Both varieties are very bitter in taste, and break with a fibrous fracture and the escape of a powder.

Cinchona calisaya inhabits the forests of southern Peru. Yellow bark is rich in quinine; and 100 grains should yield not less than 2 grains of quinia.

Cinchona pallida, pale Brown or Loxa bark, is the produce of Cinchona condaminea; always occurs in quills, which are single or double, from 6 to 15 inches in length, from 1/6 to 3/4 inch in diameter, and from 1/20 to 1/10 inch in thickness: it is marked with longitudinal wrinkles, and tranverse or circular cracks; the epidermis brown or grey, and frequently covered with crustaceous and stringy lichens; the inner surface cinnamon-brown in colour, and smooth: the taste is bitter and astringent; the fracture short and not fibrous, except in the larger pieces; the medium-sized quills are most esteemed.

Cinchona condaminea is found in the forests of Loxa, in the Republic of Equador.

Pale bark yields cinchonia chiefly; and 200 grains of the bark treated in the manner directed in the test for yellow cinchona bark, with the substitution of chloroform for ether, should yield not less than 2 grains of alkaloids.

Cinchona rubra, red bark, from Cinchona succiruba, occurs in quills or flattened pieces, more frequently the latter; covered with a brownish-red epidermis, rarely white from adherent lichens; occasionally strongly tuberculated on the surface, and then termed warty; internally rough, fibrous, and of a dark red chestnut colour; the taste is very bitter, the fracture finely fibrous and red; the bark varies from about 6 to 24 inches in length, and the flattened pieces are sometimes 4 or 5 inches broad, and 1/2 inch or more in thickness.

Cinchona succiruba grows in the forests at the foot of the great mountain of Chimborazo.

Red bark yields quinia and cinchonia in about equal quantities; and 100 grains of the bark, treated in the manner directed in the test for Cinchona pallida, should yield not less than 2 grains of alkaloids.

Besides the above-described officinal barks, from which alone the pharmaceutic preparations should be made, there are others which are at the present day extensively employed for the extraction of the alkaloids; among these the most important are the orange Carthagena bark and the grey bark.

Fibrous Carthagena Bark, called also Spongy or Orange Carthagena Bark, Bogota, and Coquetta Bark, the produce of Cinchona lancifolia (Mutis,) is referred to in the Pharmacopoeia as one of the sources of quinine. It occurs in quills or flattened pieces, according to the age of the stems from which it is peeled; the surface is often covered with crustaceous lichens, giving it a silvery appearance. The bark is characterized by its extremely fibrous texture, often breaking with long stringy splinters; the texture is loose and spongy; the colour, especially of the larger pieces, is strongly yellow or sometimes orange; hence the name. The powder is also yellow, with an orange tint.