690 QUININE 



The powdered bark is boiled in solution of caustic alkali (soda preferred), which 

 removes the useless extractive, gummy matters, and colouring-matter. After being 

 well boiled, the bark is washed and pressed. This process of boiling with alkali, 

 &c., may be repeated, if necessary, and the bark, after being well washed and pressed, 

 having become decolourised, is boiled with dilute sulphnric acid, being kept con- 

 stantly stirred whilst boiling. After the separation of the liquid, the bark is boiled 

 with a second portion of dilute acid, and sometimes with a third ; but the liquid from 

 the last boiling is kept to be used for a fresh portion of bark. The first and second 

 portions are mixed, strained, and treated with soda, which precipitates the alkaloids ; 

 the precipitate is washed and pressed, and then digested with dilute sulphuric acid, 

 which dissolves the alkaloids ; this solution is evaporated and allowed to cool, when 

 the sulphate of quinine crystallises out, accompanied with some sulphates of quinidine 

 and cinchonine, if the bark employed contained these latter alkaloids in any quantity. 

 The sulphate of quinine thus obtained is dried, and forms the unbleached or hospital 

 quinine. When the sulphate of quinine is required quite pure, this is treated with 

 pure animal-charcoal, and subjected to two or three further crystallisations. 



It will be seen that the principal points in this process are the extraction of the 

 colouring-matter by the caustic alkali and the use of pure animal-charcoal in 

 producing the perfectly white sulphate, which prevents completely the admixture of 

 sulphate of lime with the sulphate of quinine. 



This process yields from 80 to 90 per cent, of the quinine contained in the bark 

 employed ; and to obtain the remaining 10 or 20 per cent, the blood-red solutions 

 formed by boiling the bark with the caustic alkali are treated with dilute hydrochloric 

 acid in excess, which retains in solution any alkaloids that are present. This solution 

 is strained and mixed with lime. The precipitate thus formed is collected, pressed, 

 dried, and powdered. 



It is then digested with benzol, or any solvent which is not a solvent of lime. These 

 various tinctures or preparations are well agitated with dilute sulphuric acid, which 

 extracts the quinine, &c. ; when allowed to settle, the benzol, oil of turpentine, or lard, 

 whichever has been used, rises to the surface. The acid liquid is then syphoned off 

 and evaporated, and the sulphate of quinine obtained from it is purified by two or 

 three crystallisations, when it yields a salt equal to that obtained by the first process, 

 viz. the unbleached or hospital sulphate of quinine. 



The sulphate of quinine of commerce is the neutral sulphate, and has the following 

 composition: 2C 40 H 24 N 2 4 ,2HS0 4 + 14 aq. (2C 20 H 24 W 2 O 2 ,H 2 SO 4 + 7H 2 O). 



When pure it occurs as white spangles, or slender needles, which are slightly flexible, 

 and possess a pearly lustre and an intensely bitter taste. It effloresces in the air, and 

 loses about 12 atoms of water (Saup). It requires for solution, 740 parts of cold 

 water and 30 parts of boiling water, 60 parts of alcohol at ordinary temperatures, and 

 much less of boiling alcohol. 



Its solution in acidulated water turns the plane of polarisation strongly to the left, 

 and presents a blue tint, which is due to a peculiar refraction of the rays of light on 

 the first surface of the solution, and is termed fluorescence by Professor Stokes, who, 

 as well as Sir John Herschel, has examined the cause of it, the latter referring it 

 to epipolic dispersion. 



Heated to 212 F., sulphate of quinine becomes luminous, which is augmented by 

 friction, and the rubbed body is found to be charged with a vitreous electricity, 

 sensible to the electroscope. It fuses easily, and in that state resembles fused wax ; 

 at a higher temperature it assumes a red colour, and at length becomes charred. 

 When a solution of quinine is treated with chlorine and ammonia, it yields a bright 

 green solution, very characteristic of quinine. 



Besides the neutral sulphate, there exists an acid sulphate, or bisulphate, of the 

 following composition :C 40 H 24 N 2 4 ,2HS0 4 + 16HO. (C 20 H 24 M >2 O 2 ,H 2 SO 4 + 8H 2 O). 



It is formed by dissolving the neutral sulphate in dilute sulphuric acid, evaporating 

 and crystallising. It crystallises in rectangular prisms, or silky needles. It is much 

 more soluble in water than the neutral sulphate, requiring only 1 1 parts of water at 

 ordinary temperatures to dissolve it. The solution reddens blue litmus-paper. 



It fuses in its water of crystallisation, and at 212 F. loses 24'6 per cent, of water 

 (Liebig and Baup). With sulphate of sesquioxide of iron, it forms a double salt, 

 which crystallises in octahedra resembling those of alum. 



Adulteration of sulphate of quinine. Owing to the high price of sulphate of quinine, 

 it is often adulterated with various substances, as alkaline and earthy salts, boracic 

 acid, sugar, starch, manite, margaric acid, salicine, sulphates of cinchonine and 

 quinidine ; the two latter substances will be found in most of the commercial sulphate 

 of quinine, and are not looked upon as fraudulent mixtures when present only in 

 small quantities, arising then from the imperfect purification of the sulphate of 

 quinine. Sometimes, however, sulphate of cinchonine is present in largo quantities, 



