new Polarising Crystals produced from Quinine. 189 



ration finished, the excess of sulphuretted hydrogen was expelled 

 by boiling, testing with acetate of lead paper occasionally, the 

 precipitated sulphur removed by filtering, washed well with di- 

 stilled water, and to the filtrate ammonia added, nearly to neu- 

 trahzation, but short of precipitating the quinine ; then the so- 

 lution boiled and the iodine precipitated by nitrate of silver, 

 collected on a filter, washed with distilled water, then with 

 diluted nitric acid to remove any quinine (which falls with iodide 

 of silver even from an acid solution), and lastly dried and fused 

 by Ignition in a platina capsule ; 25 grs. of crystals gave by this 

 method 15-14 grs. of iodide of silver = 8-1523 ^rs. of iodine 

 = 32-6092 per cent. 



The solution after the separation of iodine was then, together 

 with the washings, treated with acetate of baryta until no further 

 deposition of sulphate occurred ; it was boiled to hasten the sepa- 

 ration, filtered, washed, dried, ignited and weighed ; it gave 7-76 

 grs. BaO + 803 = 2-653 80^ = sulphuric acid per cent. 10-612. 



The hquid after the separation of iodine and sulphui-ic acid 

 was then acted on, first by sulphate of ammonia to remove ex- 

 cess of baryta, then with hydrochlorate of ammonia to remove 

 the excess of silver. 



To this fluid, concentrated by evaporation to about 3 fluid 

 ounces, was added ammonia in excess ; an immediate deposition 

 of alkaloid was the consequence, ^ther was now added in suf- 

 ficient quantity to dissolve the alkaloid, the supernatant sethe- 

 rial fluid was decanted into a counterpoised flask, the operation 

 being repeated as often as necessary; the retherial fluids mixed 

 were then distilled; the residue, dried at 212° Fahr., weighed 

 7-533 grs. ' ° 



The aqueous and ammoniacal solution, upon evaporation to 

 dryness in a water-bath, again treating with jether as long as 

 necessai-j', and distiUing as before, furnished a second quantity 

 of alkaloid, weighing, after drying as before, 3-14 grs. 



Then 7-533 + 3-14= 10-673 alkaloid equal to 42-692 per cent. 



This analysis, therefore, accounts for — 



Per cent. 



lodme 32-6092 



Sulphuric acid .... 10-612 



Alkaloid 42-692 



85-9132 



The loss of 14-0868 was probably water of ciystallization, 

 but It now became necessary to perform an analysis to make 

 this point certain ; after several attempts, the following process 

 was adopted, and furnished correct results. 



Having arranged an apparatus for preparing a current of dry 

 hydrogen gas, the stream was passed through a flask containing 



