ON VARIOUS SPECIES OF CINCHONA. J 07 



nally of a pale red; thin, and convoluted from the contrac- 

 tion of the inner surface; smooth and us it were resinous in 

 its fracture, but sometimes slightly iibrous; and of an as- 

 tringeut and bitter taste. Its powder is fawn coloured, 

 mingled with a tinge of gray. 



The second, known by the name of red bark, and some- the red» 

 times erroneously called in France quinquina pitton, is of 

 a much deeper coiour ; commonly very thick; little if at all 

 convoluted; fibrous, and not at all resinous in its fracture; 

 with an astringent and very slightly bitter taste. 



The third, or yellow bark, which is of most recent date, the yellow. 



must not be confounded with the Angustura bark, as is 



sometimes done by the French druggists. This is of a pale 



yellow colour ; of a more bitter but less astringent taste than 



either of the preceding; partly woody, partly resinous in its 



fracture; and a little convoluted, according as it is more or 



less thick. 



It would be of important service to the physician, as well No ready me- 

 , i ■/» i i i thod of <lis- 



as to the merchant, it there were any sure and simple me- tinguishine 

 thods of distinguishing the good kinds of cinchona from, their goodness, 

 such as are bad or damaged : but hitherto we have nothing 

 to guide us except their appearance, which may be fallaci- 

 ous, and our judgment from which must depend on our in- 

 dividual skill and practice. Mr. Seguin indeed has said, Seguin mis- 

 that the aqueous infusion of the good kinds possesses ex- la ken. 

 clusively the property of precipitating infusion of tan, and 

 that of the bad of precipitating animal gelatine; but this is 

 an errour, for there are several species of true cinchona, that 

 do not precipitate tannin, and yet cure fever*. 



I have compared the physical and chemical properties of 

 the infusions of every kind of cinchona to be found in the 

 shops, to which I have added that of some other vegetable 

 substances, apparently analogous with cinchona, and which 

 are said to have cured fever. The infusions were prepared 

 with the same quantity of water, the same quantity of bark, 

 at an equal temperature, and for an equal time, so that no 

 difference could arise from the mode of preparation. 



* Our readers will recollect, that Seguin fancied he had discovered the 

 febrifuge principle in cinchona to be nothing more or less than gelatine. 

 See Journal, Vol. VI, p. 13G. 



Spec* 



