On the new Polarizing Crystals produced from Quinine. 187 



times with acetic acid at 40° Fahr., which had been previously 

 found to have httle solvent power on this compound at that 

 temperature. The crystals having been well washed^ were dis- 

 solved in boiling alcohol, spec. grav. "838, and on cooling they 

 recrystallized ; this operation having been repeated, they were at 

 length obtained pure from any admixture of disulphate of quinine. 

 Ha^dng been drained on a filter and washed with cold spirit, 

 they were dried at 90° Fahr., then over sulphuric acid, and 

 weighed : 66'6 grs. were obtained by this operation. 



The acid mother-liquid, together with the first washings, were 

 then examined for iodine ; upon allowing a few drops to evapo- 

 rate spontaneously on a slip of glass, polarizing crystals formed 

 around the edge of the liquid ; consequently the compound is 

 slightly soluble in cold acid. The acetic acid having been nearly 

 neutralized by ammonia, nitrate of silver was dropped into the 

 solution as long as any iodide of silver was deposited ; this was 

 then carefully collected on a filter, washed repeatedly with di- 

 stilled water, then with ammonia to remove any chloride, again 

 with distilled water, dried and ignited; it weighed 2'00 grs.= 

 iodine 1-08. 



The alcoholic mother-liquids and washings were then examined 

 for iodine, and crystals were similarly obtained upon sponta- 

 neous evaporation. In order to precipitate the iodine, a silver 

 salt was used, and dropped into the solution as long as any 

 cloudiness was produced ; the whole thrown on a filter, and the 

 precipitated iodide of silver, washed with diluted nitric acid to 

 remove any quinine, and subsequently with ammonia to take 

 up any chloride, and then with distilled water ; dried and ignited, 

 it weighed 3"63 grs. = iodine i"951. 



It now remained to examine the distilled liquids for iodine, 

 as it existed in these in the free state dissolved in alcohol ; they 

 were mixed together, and placed in a counterpoised matrass 

 with metallic zinc. After prolonged digestion, a little water 

 added to facilitate the operation, the iodine was converted into 

 iodide of zinc ; the fluids were then distilled off, the iodide of 

 zinc dried at 212° and weighed; 3-35 grs. = iodine 2-6715 grs. 

 were obtained. 



Now, if any substitution compound had been formed by the 

 action of the iodir.'! on the quinine, it was probable that hydriodic 

 aether would be produced; if so, it wouldbe found in the distilled 

 fluid ; this was carefully examined for this substance, but none 

 detected. Subsequent experiments showed that none could have 

 been produced, or if any, so small a quantity, that its presence 

 would be immaterial, for all the iodine used, with the exception 

 of 2-56 grs., can be accounted for thus : — 



