18 



CONSTITUENTS OF CHINCHONA BAEKS. 



Chap. I. 



most barks chinchonine exists in tlie cellular layer, and 

 quinine iu the liber, or fibrous layer ; but IMr. Howard has 

 since shown that this view is quite incorrect.^ In 1829 

 Pelletier discovered a third alkaloid, which he called aricine, 

 of no use in medicine, and derived from a worthless species 

 of chinchona, growing in most of the forests of Peru, called 

 C. puhescens}^ 

 The organic constituents of chinchona barks are — 



These materials are in different proportions according to 

 the barks. Grey bark chiefly contains chinchonine and 

 tannin ; Calisaya, or yellow bark, much quinine, and a 

 little chinchonine ; red bark holds quinine and cliinchonine 

 in nearly equal proportions ; while the barks of New Granada 

 cliiefly contain chinchonidine and quinidine. The two latter 

 alkaloids were definitively discovered in 1852 by M, Pasteur ; 

 although the Dutch chemist Heijningen had, in 1848, found 

 what he called /3 quinine or quinidine. Chinchonidine is 

 only second to quinine itself in importance as a febrifugal 

 principle. 



Quinine is a white substance, without smell, bitter, fusible, 

 crystallized, with the property of left-handed rotatory polari- 

 zation. The salts of quinine are soluble in water, alcohol, and 

 ether. Of all the salts the bisulphate of quinine is preferred, 

 because it constitutes a stable salt, easy to prepare, and con- 

 taining a strong proportion of the alkaloid. It is veiy bitter 



' Nueva Quinologia de Pavon, No. 

 10. 



'" Aricine, as a sulphate, does not 

 crystallize, but forius a peculiar trem- 



bling jelly. It was so named from the 

 port of Arica, whence the bark of C. 

 pubesceiis is exported. 



