17 



which, with 2 atoms water, constitute the optical salt dried over 

 sulphuric acid at 62 Fahr., thus : 



1 atom dry residue .................... 822 



2 atoms water ..................... . . . 18 



840 



and these results may be expressed by the following formula : 

 C 57 H 33 N 2 O 5 





which appears to be the constitution of the optical salt dried at 

 62 Fahr. over sulphuric acid. 



From this it appears that the optical salt of quinine differs in 

 chemical atomic numbers merely in the possession of 1 atom less 

 iodine, the cinchonidin salt having 3, the quinine salt 2 atoms iodine ; 

 but in each case 2 atoms of sulphuric acid, and 5 water, with an 

 organic base of C 57 H 33 N 2 O 5 common to both. How this is derived 

 from C 40 H 24 N 2 O 4 in the one case, or C 40 H 24 N 2 O 2 in the otheis it 

 is difficult to point out in the present state of the question. 



Were these views correct, it might naturally be imagined that the 

 two salts may be mutually convertible. The author has undertaken 

 numerous experiments with this object in view ; and whilst he has 

 proved that it is possible (by boiling the quinine salt in spirit sur- 

 charged with iodine) to communicate the golden tint of the reflected 

 ray and the blue tint of the body-colour to the crystals on their 

 re-formation, yet this modified salt retains the crystallographic forms 

 of the true quinine salt ; whilst, by treating the cinchonidin salt by 

 spirit and aqueous sulphurous acid, that salt is modified also, 

 becomes fibrous in character, and assumes the red body-colour of 

 quinine salt, yet is at once to be distinguished from the true quinine 

 salt even by the naked eye alone ; and on redissolving these in 

 spirit, the blue body-coloured salt again recrystallizes with its ordi- 

 nary golden reflected tint. The effect of diluted sulphuric acid in 

 converting the cinchonidin salt into the golden silky fibrous variety, 

 is a striking distinguishing characteristic between the two alkaloids. 



These facts lead to the conclusion, that the grouping of the con- 

 stituent molecules in the two salts differs materially ; that closely as 

 the quinine and cinchonidin salts agree amongst themselves, they 

 differ widely from the quinidin and cinchonine compounds. 



The quinidin salt, after recrystallization, presents itself as long 



VOL. IX. C 



