The trees frequently die after the operation.

The bark arrives in Europe packed in chests made of slips of wood roughly fastened together, and covered with skins : each chest contains about 200 lbs. weight, well packed, but generally mixed with a quantity of dust and other heterogeneous matter. The pieces are eight or ten inches in length, some of them scarcely one tenth of an inch, others a line in thickness; singly and doubly quilled, or rolled inward, the quills, generally, being in size from a swan's quill to an inch in diameter1; and others of a coarser texture, thicker and nearly flat.

1 Estan raro, que apenas corresponde a uno par mil de las ostras especies juntas-Ann. de Hist. Nat. torn. ii. p. 210.

2 This term, orange-coloured bark, might imply a difference from pale bark, but the internal surface is orange-coloured in both varieties.

3 The following are also synonymes of this kind of bark :-

Cascarilla amanlla.

-------------de miina.

-------------boba amarilla.

-------------callisalla.

------------crespilla.

------------ ahumada de Loxa.

-----------angustas. ------------- poco velludas.

Cascarilla rugosas.

-------------lampina.

-----------negra.

----------- palo bianco.

------ Cortezon. Quina con hojas un poco velludas.

--------negra de Loxa.

--------tunita.

4 A pale bark is also known by the name Silver Huanuco, the Quina Huanuco of the Spaniards, which M. Virey refers to the Cinchona glandulifera: but there is reason for doubting the accuracy of this opinion.

It has a chopped, grayish, or dull brown or black, or cineritious epidermis, often much covered with lichens2, chiefly species of Lecanorae, Parmeliae, Sticta, and Collemata; the latter indicates that the bark is bad. This bark is internally of a pallid fawn or cinnamon hue, sometimes of a dull red tint. This colour is brightened when the bark is moistened, approximating to pale orange. The fracture of the pieces is usually clear, and slightly fibrous within, but in the larger quills it is fibrous. The colour of the powder is a pale fawn. Both the quilled and the flat varieties are evidently the bark of the same tree; the quilled sort being that of the smaller branches, and the flat that of the larger and of the trunk. But the chests probably contain barks obtained from different species of Cinchona. The pale barks are known in commerce under the names Lima bark, Loxa or Crown bark, Jaen bark, and Huanidies bark.3

Qualities. - Good bark of this description has scarcely any odour when in substance, but during decoction the odour is sensible, and agreeably aromatic. The taste is bitter, but not unpleasant, slightly acidulous and austere, moderately astringent, resembling in some degree that of a dried rose. It is light, and breaks with a close fracture, with the internal fibres somewhat drawn out. If it separates into fibres when chewed, it is considered to be of an inferior quality. The powder of the quilled kind is paler than the bark, being of an uniform pale cinnamon hue; but the flat kind yields a deeper-coloured and browner powder. The best specimen of this bark which could be procured by me, and subjected to experiment, gave the following results:-Water at 212° degrees extracted all its active principles; affording an infusion, which, when filtered, was of a pale yellow or straw colour, and had the odour and taste of the bark. The infusion reddened litmus paper; was instantly and copiously precipitated by solution of galls; and, in a smaller degree, and more slowly, in yellowish flocculent flakes, by solution of isinglass, gelatine.

A solution of tartar emetic was rendered turbid, and slowly precipitated by it;-this effect was quickly and copiously produced on a solution of acetate of lead. Sulphate of iron changes its colour to bright olive-green, but was scarcely precipitated. Decoction afforded a more saturated solution, with a colour resembling the cold infusion of the yellow bark; and a yellowish precipitate was deposited. The powder macerated in sulphuric ether afforded a golden yellow tincture, which reddened litmus paper, and left a pellicle of bitter resin, when it was evaporated, on the surface of water, to which it gave the colour of the tincture. This coloured water had the flavour of the watery infusion; but differed from it, in not precipitating the solution of galls nor that of tartar emetic, and in throwing down a copious precipitate from the solution of sulphate of iron. With alcohol the powder afforded a tincture of a deep orange hue, which precipitated sulphate of iron, tartarized antimony, and infusion of galls; became turbid when added to water, and let fall a light reddish precipitate.

From the effects of these re-agents on the aqueous infusion of this bark, it appears to be the same as the 3d and 15th species examined by Vauquelin; which he names superior gray Cinchona, and common Cinchona of Peru.1 But these experiments throw no light on the nature of the active principle of this species of cinchona; and it was not until the subject was investigated by MM. Pel-letier and Caventou, in 1818, that that principle was ascertained to be an alkaline substance, which has been named Cinchonia, combined with a peculiar acid, the Kinic, and a small quantity of Kinate of Quina.2 It is obtained by boiling a pound of bruised pale bark in a gallon of water, previously mixed with six fluid drachms of sulphuric acid. On completing this decoction, the residue should be again boiled with half the quantity of water and acid, and so on until all the soluble matter be extracted. To these decoctions mixed together, slacked quicklime is to be added to saturate fully the acid, and the precipitate, which is a mixture of sulphate of lime and cinchonia, being dried and pulverized, is boiled for some minutes in strong alcohol, which is decanted off whilst it is hot. The residue is again to be boiled in fresh alcohol, and these boilings repeated until the alcohol ceases to act on it.