64 Royal Socicfij : — 



the constitution of the alkaloid originally employed, if we take 

 the formula C^"H-^N-0-, as given by Gerhardt, for that of cin- 

 chonine. 



The cinchonine and quinidine salts further agree in containing 

 only 1 atom sulphuric acid, whereas the quinine and cinchonidine 

 salts contain 2 atoms. 



These investigations appear to show that the alkaloids in each 

 instance undergo some modification, but not analogous to substitu- 

 tion ; it appears more like a sjjlitting-up into different molecular 

 groups, and a rearrangement of these amongst themselves, as the 

 formulae of the organic bases differ much from those of the original 

 alkaloids. 



All these iodo-salts possess double refractive properties. 



When the acid sulphates of the mixed alkaloids, quinine, quinidine, 

 cinchonine and cinchonidine, are dissolved in dilute spirit, and the 

 temperature increased to 80" or 120°, treatment with tincture of 

 iodine readily separates the quinine salt first. 



Subsequent further treatment in the same manner produces the 

 cinchonidine salt, more or less mixed with the quinine salt. 



On still further treatment, the quinidine salt is formed with its 

 well-marked characters. 



The cinchonine salt is by far the most soluble in spirit ; and 

 when a large quantity of cinchonine exists, this compound will also 

 appear along with the quinidine salt. 



This test is a beaiitiful and ready method of proving the presence 

 of cinchonidine in cinchonine, which would otherwise be considered 

 pure, Brandes' test having shown the absence of quinine and quini- 

 dine. In the same way, this test is an easy method of detecting 

 mixtures of quinine and quinidine, the optical characters of the two 

 salts being so well marked, that no difficulties can exist in their 

 discrimination. 



It does not offer such facilities for the separation of quinine from 

 cinchonidine ; the two salts go down together, especially if large 

 quantities of cinchonidine exist with mere traces of quinine. 



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

 vnth quinine and quinidine j-s^o^h W^^ ^^ ^ 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 

 quinidine, was really the cinchonidine of Pasteur, and the details of 

 his cures of fever, therefore, bj^ quinidine are rather to be ascribed to 

 cinchonidine. 



The cinchonidine 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 



