10 



XIV. Leers' combination of the ether test with that of Brandes 

 can readily detect small portions of quinine, quinidin, or quinicine 

 in cinchonine or cinchonidin, especially when used in the manner as 

 modified by the author. 



PART II. On the Optical and Chemical Characters of the 

 lodo- Sulphates of the Cinchona Alkaloids, Quinine, 

 Quinidin and Quinicin, and Cinchonine, Cinchonidin 

 and Cinchonicine ; together with the Chemical Ana- 

 lysis of many of the Salts, and new methods of discri- 

 minating those Alkaloids, founded upon the production 

 of these remarkable compounds, and the recognition of 

 their optical characters. 



In the former part of his paper, the author examined the existing 

 tests for discriminating between the various cinchona alkaloids, and 

 pointed out their insufficiency. In the present part, he shows that 

 the optical characteristics of the iodo-sulphates of the alkaloids 

 quinine and quinidin are sufficiently well marked to render the ex- 

 istence of either one of these alkaloids certain, and that although 

 the iodo-sulphate of cinchonidin is very closely related optically and 

 chemically to the homologous salt of quinine, yet there are sufficient 

 points of dissimilarity to enable us to diagnose between the two ; 

 and, moreover, that the production of this salt is a beautiful means 

 of deciding readily whether cinchonidin is present in specimens of 

 cinchonine or cinchonicine; all evidence of quinine or its allies 

 having been decided in the negative by the results of the previous 

 tests, as proposed by Brandes, Vogel, Pelletier, Leers, or the author. 



The cinchonidin of Wittstein has also, by the same method, been 

 proved by the author to be totally different from the cinchonidin of 

 Pasteur. 



Acetic acid and chloroform may also be employed for discriminating 

 between cinchonine and cinchonidin. 



The chemical characters of all these iodo-salts furnish no means of 

 discrimination, for as a class they all agree in being more or less 

 soluble in spirit, giving a deep sherry-brown solution, from which 

 water precipitates them in an amorphous form, as dark brown, cin- 

 namon-brown or purplish-brown coloured precipitates ; they are 



