476 
The aqueous infusion is of a pale ruby colour; its action on the 
solutions of galls and of isinglass is nearly the same as those 
of the two former species, but it is not altered by tartarised anti- 
mony, nor by the superacetate of lead; and the solution of iron 
occasions a dirty yellow colour only, little being precipitated. 
The alcoholic tincture is of a deep brownish red colour, and 
precipitates the solution of the sulphates of iron and of tartarised 
antimony; the former of a black colour, and the latter red. 
From the experiments of Vauquelin, Fabroni, and others, it ap- 
pears that the active principles of Cinchonas consist chiefly of 
cinchonine, resin, extractive gluten, a very small portion of vola- 
tile 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 im- 
portant results that have been obtained by MM. Pelletier and 
Caventou, respecting the composition of the three officinal 
species.—Ist, 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. 2nd, In yellow bark they found that the alka- 
line base differs from cinchonine in being uncrystallizable, very 
soluble in ether, and forming salts with the acids very different 
from those of cinchonine. The chemical constituents of the yel- 
‘ low bark are an acidulous kinate of this salt, which they have 
named quinine, a deep yellow fatty matter, red cinchonine, 
tannin, yellow colouring matter, kinate of lime, starch, and 
woody fibre. 3rd, Red bark contains acidulous kinate of cin- 
chonine, kinate of quinine, reddish fatty matter, red cincho- 
nine, 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 qui- 
nine ; 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 cinchonine, as a distinct vegetable principle, was first dis- 
covered in Peruvian bark by Dr. Duncan, of Edinburgh. 
The separation of cinchonine from the pale bark, and of qui- 
nine from the yellow bark, is a very simple operation. It con- 
sists in digesting the bark, coarsely powdered, in weak sulphuric 
acid, and then to repeat this digestion with about half the quan- 
tity of liquid, till all the soluble matter is extracted. To this 
decoction 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 different 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 per- 
fectly pure state. Its crystals are semi-transparent, have a 
pearly lustre, and are usually obtained in the form of small 
needles. It has but little taste, and requires 700 parts of water 
for its solution, but boiling alcohol dissolves it much more abun- 
dantly ; it is sparingly soluble in oils and sulphuric ether. Ata 
moderate heat it is partly volatilized, and partly decomposed. 
It combines with different acids, forming neutral salts. Mr. 
Brande found that it contained no oxygen, 100 parts consisting of 
about 80 parts of carbon, 13 of nitrogen, and 7 hydrogen. It has 
an intensely bitter taste, and exerts the same action on the animal 
RUBIACEÆ. X. Cincnona. 
economy as the bark itself, but it is less generally used in medi- 
cine than the other active principle of the bark, quinine, because 
the yellow bark from which it is procured is more plentiful; the 
quinine, therefore, is cheaper than cinchonine, and equally effi- 
cacious. 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 the solution of the sulphate of quinine. 
Quinine is not crystallizable like cinchonine, but on the applica- 
tion 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. 
They differ also remarkably in their chemical composition, cin- 
chonine containing no oxygen, while in quinine there is a notable 
proportion of this element. According to Mr. Brande, it con- 
sists of about 5.55 parts of oxygen, 7.65 hydrogen, 13 nitrogen, 
73.80 carbon. By digesting quinine in a weak solution of sul- 
phuric acid, the sulphate of quinine is obtained, which is the 
salt now generally used for medicinal purposes. The most ap- 
proved process for preparing this salt was pointed out by Mr. 
Henry. A kilogramme of bark (2 Ibs. 3 oz. 5 dr.) is reduced 
to a coarse powder, and boiled twice for about a quarter of an 
hour in 14 or 15 pints of water, 2 ounces of sulphuric acid being 
added to it each time. The decoctions containing the sulphate 
of quinine are of a reddish colour, which gradually acquire a 
yellow tint, and have a very strong bitter taste. They are to 
filtered through a linen cloth, and about half a pound of powderet 
quicklime added to the solution. The sulphate of quinine 1$ 
decomposed in this manner, the alkali being precipitated along 
with the sulphate of lime. This is digested repeatedly in we 
hol, till it no longer imparts any bitter taste to this fluid ; a 
alcoholic solutions are then evaporated till a very bitter visci 
substance is obtained, which becomes brittle as it cools. ThA 
is the quinine separated from almost all the other ingredients 0 
the bark, and by digesting it in dilute sulphuric acid a solution 
of sulphate of quinine is obtained, which crystallizes on evapo- 
ration. It is a white pulverulent substance; 1t crystallizes t 
small white 4-sided prisms, which are distinguished by their pearly 
lustre. It is not very soluble, therefore not affording a ee 
bitter taste; but by adding a drop or two of acid to the Bh 
tion, its solubility is increased, and then it becomes m it- 
ter. It is decomposed by the alkalies and earths ; 1t volatilizes 
at a moderate heat, and it can unite with an excess of acid, gs 
ing a bisulphate of quinine. The sulphate of quinine 1S jg 
quently adulterated with starch, pipe-clay, and various other su 
stances. To determine its purity, the simple process of age 
it is sufficient ; if it evaporate entirely without charring and ee 3 
ing, it is pure; but if it should turn black or smell sweetis a 
is probable that sugar or starch is present. Pure quinine 1s $ z 
dom used in medicine, but the sulphate possesses in a very PE 
nent degree the medicinal properties of Peruvian pat oe a 
grain, or one grain and a half, being equivalent to a drac m ; 
the bark in substance. In Paris it has superseded, in eee 
measure, the Peruvian bark, and is now extensively used E = 
country in all cases where that valuable medicine 1s indicated, 
doses of from 2 to 5 grains. ; lea 
Medical properties and uses.—Peruvian bark has been g 
known as one of the most powerful and valuable tonics T P 
sess, and may be administered with great freedom in al’ ea ef 
where that class of remedies are indicated. The only effects i 
an overdose are headache and nausea. It also possesses e = 
septic and astringent powers in a very eminent degree, seo 
universally employed as a febrifuge in the cure of interm i 
and remittent fever, in diseases of debility, such as typ (oi 
cynanche maligna, in passive hæmorrhages, confluent sma p $ 
in dysentery, in some cutaneous diseases, as lichen ane wn 
livida, in purpurea, in some varieties of erysipelas, in 8408 The 
in dyspepsia, and even in acute rheumatism and gout. 
