5-5 On the various Species of Cinchona. 



the yellow cinchona, the principle which precipitates glae 

 along with that which precipitates emetic ; and in this re- 

 spect these two substances resemble each other : but they 

 clitier in respect of the bodies which act upon tan and upon 

 iron, since this metal is precipitated green by cinchona, and 

 blue by gall-nuts; they also differ in another respect, as 

 they mutually precipitate each other. 



Tan Bark. — The infusion of this substance, made as care- 

 fully and with the same quantity of water as cinchona, givesi 

 in the solution of glue a yellow precipitate ; with iron, a 

 blue ; with copper, a brown precipitate : but it did not cause 

 any change in the solution of Santa-F^ cinchona, nor in the 

 emetic solution: it reddens the tincture of turnsole, and is 

 precipitated by the oxalate of anunonia. 



We see by this that oak bark does not contain, like gall- 

 nuts, yellow cinchona, and some others, that substance 

 which precipitates emetic; and that, although both of them 

 precipitate glue, yet they differ in this respect. 



Bark of the Cherry Tree. — This bark, which has been 

 sometimes fraudulently substituted for cinchona, has no- 

 thing in conmnon with the latter, except the property of 

 giving a green precipitate with a solution of f^ulphate of iron. 

 It produces no change upon glue, emetic, nor decoction of 

 tan. It is therefore very doubtful if ,the cherry tree bark 

 possesses any febrifuge property. 



Centawium a.ni.\ CkamcEdrTjs. — These two plants furnished 

 the same results as the cherry tree bark, and it is equally 

 doubtful if they can cure fevers. 



Bark of the IVhitc IVillotv. — This bark, to which febri- 

 fuge virtues were formerly attributed, certainly possesses 

 some of the chemical properties of some species of cin- 

 chonas; it precipitates glue, sulphate of iron green, and the 

 acetate of copper brovvu. Thus, as it unites bitterness and 

 astringeney, it may be a febrifuge. 



Angustnra. — The infusion of this bark does not precipi- 

 tate glue; but it precipitates alumdantly the infusion of gall- 

 nuts and infusion of yellow cinchona, but not at all that 

 (jf Santa-iV: cinchon-.i; it only produces a slight turbidness 

 in it. 



It 



