taste, and a deep brown colour. By long boiling, the virtues of the bark are nearly destroyed, owing to the 
chemical change and precipitation of its active matter. 
From the experiments of Yauquelin, Fabroni, and others, it appears that the active principles of cin- 
chonine, resin, extractive, gluten, a very small portion of volatile oil, and tannin. Vauquelin has determined 
the presence of a peculiar acid, to which he gives the name of kinic acid, in some varieties of the bark. The 
following are the most important results that have been obtained by MM. Pelletier and Caventou, respect- 
ing the composition of the three officinal species : — 1 . In pale bark, they found acidulous kinate of cincho- 
nine, a green fatty matter which they term red cinchonine, tannin, a yellow colouring matter, kinate of lime, 
gum, starch, and woody fibre. 2. In yellow bark they found that the alkaline base differs from cinchonine, 
in being uncrystallizable, very soluble in ether, and forming salts with the acids different from those formed 
by cinchonine. The chemical constituents of yellow bark are, an acidulous kinate of this salt, which thev 
have named quinine, a deep yellow, fatty matter, red cinchonine, tannin, yellow colouring’ matter, kinate of 
lime, starch, and woody fibre. 3. Red bark contains acidulous kinate of cinchonine, kinate of quinine, red- 
dish fatty matter, red cinchonine, tannin, kinate of lime, yellow colouring matter, starch, and woody fibre. 
The difference between the pale, the red, and the yellow barks, depends principally on the quantity of the 
two alkaline bodies, cinchonine and quinine, found in them. The pale bark contains cinchonine, but a very 
small portion of quinine ; the alkali, again, which predominates in the yellow bark, is quinine, while in the 
red bark, and some spurious kinds, there is a combination of both these substances. The presence of cin- 
chonine, as a distinct vegetable principle, was first discovered in Peruvian bark by Dr. Duncan of Edinburgh. 
The separation of the cinchonine from the pale bark, and of the quinine from the yellow, is a very simple 
operation. It consists in digesting the bark, coarsely powdered in weak sulphuric acid, and then to repeat 
this digestion with about half the quantity of liquid, till all the soluble matter is extracted. To this decoc- 
tion a small quantity of powdered slacked lime is added, somewhat greater than is necessary to saturate the 
acid ; the precipitate that ensues (a mixture of cinchonine and the sulphate of lime) is collected, dried, and 
boiled for a few minutes in alcohol, which takes up the cinchonine, but will not dissolve the sulphate of 
lime ; the solution is decanted off while still hot, and fresh portions successively added for the repetition of 
the same operation, until it ceases to act on the residuum, which is then merely sulphate of lime. The dif- 
ferent alcoholic solutions are then put into a retort, and considerably evaporated, during which, and on 
cooling, acicular crystals of cinchonine are deposited. By repeating the solution once or twice in boiling 
alcohol, and again crystallizing, the cinchonine will be obtained in a perfectly pure state. It has an in- 
tensely bitter taste, and exerts the same action on the animal economy as the bark itself, but it is less 
generally used in medicine than the other active principle of bark, quinine, because the yellow bark from 
which it is procured is more plentiful ; the quinine, therefore, is cheaper than cinchonine, and equally effica- 
cious. 
Quinine may be obtained from the yellow bark in the same manner as cinchonine is prepared from the 
pale bark, or by adding an alkali to a solution of the sulphate of quinine. Quinine is not crystallizable like 
cinchonine, but on the application of heat it melts into a kind of paste. It has a much more bitter taste 
than the other, and is very sparingly soluble in water. 
The sulphate of quinine is frequently adulterated with starch, pipe-clay, and various other substances. 
To determine its purity, the simple process of heating it is sufficient ; if it evaporate entirely, without 
charring and melting, it is pure ; but if it should turn black, or smell sweetish, it is probable that sugar or 
starch is present. 
Pure quinine is seldom used in medicine, but the sulphate possesses, in a very eminent degree, the 
medicinal properties of Peruvian bark, one grain or one grain and a half, being equivalent to a drachm of the 
bark in substance. It has superseded in a great measure the Peruvian bark, and is now extensively used 
in all cases where that valuable medicine is indicated, in doses of from two to five grains. 
Medical Properties and Uses. — Peruvian bark has been long known as one of the most powerful 
and valuable tonics we possess, and may be administered with great freedom in §ill cases where that class of 
remedies is indicated. The only effects of an overdose, are headaeh and nausea. It also possesses antiseptic 
and astringent powers in a very eminent degree, and is universally employed as a febrifuge in the cure of 
intermittent and remittent fever, in diseases of debility, such as typhus, cynanche maligna, in passive 
haemorrhagies, confluent small-pox, in dysentery, in some cutaneous diseases, as lichen agrius and lividus, in 
purpura, in some varieties of erysipelas, in gangrene, in dyspepsia, and even in acute rheumatism and gout. 
The decoction of yellow cinchona bark given in large quantities, is the best antidote to the poison of tartar 
emetic. 
Its usual dose is half a drachm. The only inconvenience of a larger dose is its sitting uneasy on the 
stomach. It may, therefore, if necessary, be frequently repeated, and in urgent cases may be taken to the 
extent of an ounce or even two ounces in twenty-four hours, though from such large doses probably no 
adequate advantage is derived. If it excite nausea, smaller doses may be taken and repeated more frequently, 
and may be reconciled to the stomach by the addition of any grateful aromatic. 
Off. Prep. — Decoctum Cinchonae, L. E. D. 
Infusum Cinchonae, L. E. D. 
Extractum Cinchonae, L. E. D. 
Ext. Cinchonae resinosum, L. D. 
Tinctura Cinchonae, L. E. D. 
Tinctura Cinchonae, Comp. L. D. 
Vinum Gentianae, Comp. E. 
