

21 



For the success of this test, a small portion only is necessary : 

 with quinine and quinidin -^th part of a grain has furnished evi- 

 dence of the two alkaloids ; one grain would be abundant to detect 

 all the alkaloids. 



The foregoing method of examination has enabled the author to 

 prove that the substance which Rosengarten, of Philadelphia, called 

 quinidin, was really the cinchonidin of Pasteur, and the details of 

 his cures of fever, therefore, by quinidin are rather to be ascribed to 

 cinchonidin. 



The cinchonidin of Wittstein, of Munich, is a totally different 

 alkaloid, giving, with sulphuric acid and iodine, a salt at once to 

 be distinguished by the eye from either of the two iodo-sulphates 

 described, but yet possessing optically doubly absorbent powers. 

 This salt has a deep orange-yellow colour by transmitted light, 

 merging into sienna-brown in thicker plates, which are generally 

 flat and much imbricated in the method of crystallization, and also 

 derived from a rhombic prism. The reflected tints are brownish- 

 olive, not unlike dead leaves, or brown beech-leaves. These crystals 

 are more doubly absorbent than either the quinidin or cinchonine 

 salt, but less powerfully optical as tourmalines than the quinine or 

 cinchonidin compounds. When polarized, they transmit a sienna- 

 brown body-colour if moderately thick, and thicker plates are bistre- 

 brown, but when sufficiently thick, they are wholly impervious to 

 plane-polarized light. The substance was not in sufficient quantity 

 to admit of any analysis. 



All the alkaloids were furnished in a most obliging manner by 

 Mr. John Elliott Howard, to whom the author is deeply indebted 

 for them, and thus publicly desires to express his acknowledgments ; 

 many of these various alkaloids having taken more than ordinary 

 trouble in the preparation and purification. 



It is well known that quinine and quinidin, under the continued 

 effect of heat and dilute sulphuric acid, undergo a molecular change 

 into quinicine, which M. Pasteur has asserted to be isomeric with 

 the original alkaloids, but hitherto no complete analysis has been 

 made of the metamorphosed alkaloids. 



The author has produced an iodo-sulphate of quinicine, but it is 

 no longer a crystalline compound ; it presents itself as a deep blood- 

 coloured resin, very soluble in spirit and readily precipitated by water 



