56 Transactions. 



precipitates 0294 gram cinchoniue or cinchonidine .'. 1 c.c. N 

 sulphocyanide precipitates 0098 gram cinchonine or cinchoni- 

 dine. 



This volumetric method of analysis was then compared 

 with the official B.P. methods for estimating quinine in the 

 drug " ferri et quininae citras," and the total alkaloids in the 

 crude cinchona-bark. Whilst losing nothing in accuracy, the 

 new method effects a considerable reduction in the time and 

 trouble which is expended in the performance of the analysis 

 according to the British Pharmacopoeia. 



"Fern et Quinina Citras." — About 1-5 grams of the 

 substance was dissolved in water, and the quinine was pre- 

 cipitated by ammonia, and extracted with chloroform. The 

 quinine was removed from the chloroform by shaking with 

 5 per cent, nitric acid, and this solution was titrated as 

 described above. The method of the British Pharmacopoeia 

 is to evaporate the chloroform-solution to dryness, and to 

 heat to 100° till the weight is constant. The results obtained 

 by the different methods are as follows : — 



B.P. method (time, an hour and a quarter) : 1 654 grams 

 gave 0-246 gram quinine = 14-8 per cent. 



Titration method (time, half an hour) : (a) 1-659 grams 

 required 2-6 c.c. NH 4 CNS = 14-6 per cent. ; (b) 1-551 

 grams required 2-4 c.c. NH 4 CNS = 14-4 per cent. 



The Cinchona Bark (an epitome of the process is given 

 in the adjoining table). — Fifteen grains of the finely powdered 

 material were treated with lime and a small quantity of water. 

 The alkaloids were then extracted with a boiling solution of 

 benzine, containing 20 per cent, of amyl alcohol. This was 

 shaken several times with dilute sulphuric acid, and the solu- 

 tion made up to 100 c.c. So far the method is identical with 

 that of the B.P. Fifty c.c. were diluted to about 200 c.c, 

 heated to boiling and neutralised with ammonia. On cooling 

 the insoluble quinine-sulphate crystallizes out. The usual 

 method of analysis is to collect this on a tared filter, and to 

 heat to 100° till its weight is constant. This operation, how- 

 ever, takes a considerable time, and several weighings are 

 necessary. Further, it often happens that the precipitate of 

 quinine-sulphate separates in such a form that it cannot be 

 conveniently placed on a filter. 



In order to estimate the quinine by titration the solution 

 is filtered without troubling to remove the precipitate which 

 adheres to the beaker. After washing with a small quantity 

 of ammonium-sulphate the precipitate on the filter and that 

 left in the beaker is dissolved in a little dilute nitric acid. The 

 amount of quinine in solution is then determined by adding 

 sulphocyanide and titrating as described above. 



