218 Royal Society :— 



The author is at present engaged on this branch of the inquiry, 

 a detailed account of which he hopes to embody in a communication 

 to the Royal Society, the present paper being intended only as an 

 outline to be hereafter filled in. 



In conclusion, the author would remark that a rich harvest can 

 scarcely fail to be reaped, from submitting to the action of zinc-ethyle 

 the metallic compounds of other groups, such as arsenic, bismuth, 

 and antimony. 



" Preliminary Notice of Additional Researches on the Cinchona 

 Alkaloids."— Part III. By W. Bird Herapath, M.D. 



Having had occasion to make some experiments upon the rotatory 

 power of the /3-quinidine mentioned in the first part of his paper*, he 

 arrived at the conclusion that some other feebly dextro- gyrate alka- 

 loid accompanied it, and of a more soluble and less crystallizable 

 character. Consequently, on its further purification by frequent re- 

 crystallization from alcohol, the quinidine was obtained perfectly pure ; 

 it "then had the molecular rotation assigned to it by Pasteur, namely 

 250°- 75 J^. Two examinations have given the following elements : — 



I. Its solution having been made in rectified spirit of -836 by boihng, 

 and crystallized at 62° F., the concentrated solution decanted gave 

 the following elements for Biot's formula : — 



Are 

 e. d. I. blue violet. 



•02728 -85172 315-8 l8°-5/= 251°-7/ 



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



6. S. 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°- 2.4 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°- 7 /' . The slightly dextro-gyrate alkaloid existing as a contami- 

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

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

 liar circumstance ehcited during this examination, was the fact that 

 the perfectly pure recrystallized quinidine, 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 boihng, 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 



* Phil. Mag. vol. xvi. p. 55. 



