476 



RUBIACE.E. X. CINCHONA. 



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. 1st, 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 

 tor its solution, but boiling alcohol dissolves it much more abun- 

 dantly ; it is sparingly soluble in oils and sulphuric ether. At a 

 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, 1 3 of nitrogen, and 7 hydrogen. It has 

 an intensely bitter taste, and exerts the same action on the animal 



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 be 

 filtered through a linen cloth, and about half a pound of powdered 

 quicklime added to the solution. The sulphate of quinine is 

 decomposed in this manner, the alkali being precipitated along 

 with the sulphate of lime. This is digested repeatedly in alco- 

 hol, till it no longer imparts any bitter taste to this fluid ; the 

 alcoholic solutions are then evaporated till a very bitter viscid 

 substance is obtained, which becomes brittle as it cools. This 

 is the quinine separated from almost all the other ingredients of 

 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; it crystallizes in 

 small white 4-sided prisms, which are di ,tinguished by their pearly 

 lustre. It is not very soluble, therefore not affording a very 

 bitter taste ; but by adding a drop or two of acid to the solu- 

 tion, its solubility is increased, and then it becomes intensely bit- 

 ter. It is decomposed by the alkalies and earths ; it volatilizes 

 at a moderate heat, and it can unite with an excess of acid, form- 

 ing a bisulphate of quinine. The sulphate of quinine is fre- 

 quently adulterated with starch, pipe-clay, and various other sub- 

 stances. To determine its purity, the simple process of heating 

 it is sufficient ; if it evaporate entirely without charring and melt- 

 ing, it is pure ; but if it should turn black or smell sweetish, it 

 is probable that sugar or starch is present. Pure quinine is sel- 

 dom used in medicine, but the sulphate possesses in a very emi- 

 nent 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. In Paris it has superseded, in a great 

 measure, the Peruvian bark, and is new extensively used in this 

 country in all cases where that valuable medicine is indicated, in 

 doses of from 2 to 5 grains. 



Medical properties and uses. Peruvian bark has been long 

 known as one of the most powerful and valuable tonics we pos- 

 sess, and may be administered with great freedom in all cases 

 where that class of remedies are indicated. The only effects of 

 an overdose are headache and nausea. It also possesses anti- 

 septic 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 haemorrhages, confluent small pox, 

 in dysentery, in some cutaneous diseases, as lichen agrius, and 

 livida, in purpurea, in some varieties of erysipelas, in gangrene, 

 in dyspepsia, and even in acute rheumatism and gout. The 



