317 



and crystallized at 02 F., the concentrated solution decanted gave 

 the following elements for Blot's formula : 



Arc 

 e. d. I. blue violet. 



02728 -85172 315-8 l8-5/ = 251 '?/ 



II. Its sulphate, perfectly neutral, and concentrated at 61 F.: 



e. d. I. Arc. 



0088441 1-00406 315*8 7/ = 249 ' 55 / 



These observations were all made with the naked eye, and the 

 tint of passage was that of the blue-violet petal. When the pink 

 violet, or lilac tint was employed, the arc observed was 20' 25 for 

 No. I. experiment, which with the same elements of calculation gave 

 274'093^; and with No. II., the arc 25'75, which, as before, gave 

 279 C '7*/ The slightly dextro-gyrate alkaloid existing as a contami- 

 nation was quinicine ; and upon its removal, the /3-quinidin had the 

 same solubility in ether as the quinidin of Pasteur. One very pecu- 

 liar circumstance elicited during this examination, was the fact that 

 the perfectly pure recrystallized quinidin, if made into the neutral 

 sulphate and crystallized by cooling, produces, if made with distilled 

 water at 212 F., a slightly greenish solution, however great the care 

 which might have been taken to remove all the mother-water by 

 washing the crystal on the filter. This green tint deepens consider- 

 ably during concentration, or by boiling, and at length gives rise 

 to the erroneous impression that some salt of copper is present : 

 in this condition, a tube having a length of 315*8 millims., when 

 filled with the solution, is absolutely impervious to light. It is pro- 

 bable that some molecular change is produced by the action of boil- 

 ing, even if only for a short time ; therefore it was necessary to make 

 a concentrated solution at 1 20 F., and set in repose for some days 

 at 62 F., by which precaution the solution experienced only a very 

 slight discoloration. When formerly experimenting on /3-quinidin, 

 the author obtained an iodo-sulphate very different from that which 

 he has described as indicative of the quinidin of Pasteur : having 

 pursued this inquiry, he is now enabled to state that his former dis- 

 crepancies arose from the fact that quinidin forms two iodo-sulphates, 

 according to the manner in which it is treated. 



1st. When- a dilute solution of the acid sulphate of quinidin is 



