CORTEX CINCHONiE. 365 



But to ascertain the real value of a cinchona bai-k, a quantitative 

 estimation of the alkaloids is necessary. A good process for this opera- 

 tion has been given by De Vry.' It is as follows : — Mix 20 grammes of 

 powdered bark, dried at 100° C, with milk of lime (5 grm. slaked lime 

 to 50 grm. -water), dry the mixture slowly ; by stirring it frequently, 

 the cincho-tannic acid loses its solubility, being gradually transformed 

 into cinchona-red. Then boil the dry powder with 200 cubic centimetres 



of alcohol 0"830 sp. gr. Pour the liquid on to a small filter, and after- 



wards the residual bark and lime mixed with 100 cub. cent, more 

 alcohol. Wash the powder on the filter with 100 cub. cent, of spirit. 

 From the mixed liquids, about 870 cub. cent., separate the cal- 

 cium by a few drops of weak sulphuric acid. Filter, distill off the 

 spirit and pour into a capsule the residual liquid, — to which add a 

 small quantity of spirit and water with which the distilling apparatus 

 has been rinsed out. Let the capsule be now heated on a water-bath 

 until all the spirit shall have been expelled; and let the remaining 

 liquor which contains all the alkaloids in the form of acid sulphates be 

 filtered. There will remain on the filter quinovic acid and fatty sub- 

 stances, w^hich must be washed with slightly acidulated water. The 

 filtrate and washings reduced to about 50 cub. cent., should be treated 



precipitate 



After ^ww...>^ 



o 



to a filter. It is then to be washed with the smallest quantity of water 

 pressed between folds of blotting paper, removed therefrom and dried. 

 The weight multiplied by 5 will indicate the percentage of mixed 

 alkaloids in the bark. 



_ To separate the alkaloids from each other, treat the powdered mass 

 vyith ten times its weight of ether. This will resolve it into two por- 

 tions— (a) insoluble in ether, (b) soluble in ether. 



(a.) This should be converted into neutral acetates, and to 

 the solution there should be added iodide of potassium, which 

 J^U possibly separate a little quinidine. After removal of the 

 latter (if present), add solution of tartrate of potassium and sodium, _ 

 jmch will throw down in a crystalline form tartrate of cinchoni- 

 a^iie; from the mother-liquor, cinchonine may be precipitated by 

 caustic soda. 



(b.) The ether having been evaporated, the residue is to be dried at 

 100" C. and weighed. It may in many cases practically be considered 

 as consisting of quinine only. If however the estimation of quinidine 

 (conquinine) and quinamine is required, the residue, or a determined 

 portion of it, should be dissolved in acetic acid just as much as will bo 

 necessary for affording a neutral solution. From this the hydroiodate 

 pi qumidine is precipitated by means of an alcoholic solution of 

 iodide of potassium. In the filtrate quinine may be precipitated 

 oy adding a few drops of dilute sulphuric acid and an alcoholic 

 tincture of iodine. The herapathite thus formed (see p. 3G0) is col- 

 lected after a day, dried at 100" and weighed; it then contams 55 per 

 cent, of quinine. 



After adding a few drops of sulphurous acid, the alcohol should now 

 oe evaporated from the fluid from which the crystals of herapathite have 



^^ J'^'f^i- Joiim. iv. (1873) 241, and Dr. the present article, p. 3G9 ; also private 

 'ya papers mentioned at the end of commTinications. 



