196 ALKALOIDS. 



after three or foiu" days. In this case a different correction must 

 be made from that above mentioned, viz. 1 in 465, as determined 

 by Hielbig, instead of 1 in 600. It is more advantageous to sepa- 

 rate the quinine from the greater part of the cinchonidine by 

 ether, then precipitate in the cold and filter off at once} 



III. The amount of quinine thus found is calculated into 

 tartrate, and deducted from the weight of the mixed tartrates 

 determined in I. ; from the difference the amount of cinchonidine 

 present can be calculated. 



IV. The filtrate and washings from the tartrate-precipitate are 

 mixed with iodide of sodium (in the proportion of 0-5 gram for 

 each gram of mixed alkaloids), evaporated to 20 cc. cooled, and then 

 vigorously stirred. After standing twenty-four hours, the iodide of 

 quinidine, etc., that has separated, is collected on a small tared 

 filter, transferred to a small beaker, and triturated with 10 cc. of 

 95 per cent, spirit, returned to the same filter, and again treated 

 ■svith the same quantity of spirit. The residue is finally washed 

 "with 20 cc. of water,2 dried and weighed. 100 parts of precipi- 

 tate correspond to 71*68 parts of anhydrous quinidine, to which 

 a correction of "002481 gram has to be added for each cc. of 

 filtrate and washings. 



V. To the filtrate and washings from the last operation hydro- 

 chloric acid is added until perfectly clear, then considerable excess 

 (2 to 3 grams) of carbonate of soda, and the mixture evaporated to 

 dryness on the water-bath. The residue is reduced to the finest 

 possible powder, transferred to a small dry flask, and extracted by 

 maceration with ])ure ether, in successive portions of 10 to 20 cc. 

 each, as long as any colour is removed. The ethereal filtrates 

 are evaporated, the residue dried and weighed as amorphous 

 alkaloid after deducting the quinine that has escaped precipitation 

 as tartrate. 



VI. The portion insoluble in ether is freed from that liquid by 

 warming, and treated with water to remove soda, etc. ; the cin- 

 chonine is then filtered off, washed, dried at 110°, and weighed. 

 Traces of that alkaloid adhering to the filter used in filtering the 

 ethereal solution and to the sides of the fiask, may be dissolved 



^ Compare Christensen, Pharm. Zeitschr. f. Russland, 1881 (Pharm. Journ. 

 und Trans. [3], xii. 441 ; de Vrij, ibid. 601). 



- The object of washing with .spirit is to redissolve any iodide of cinchonine 

 or amorphous alkaloid that may have separated out. It is important that the 

 relative proportions of li'iuid, wash-spirit, and wash-water should be observed. 



