ON VARIOUS SPECIES OF CINCHONA. 1 ]0, 



To gain some additional light respecting the nature of the Other sub- 

 principles contained in cinchona, I instituted a comparative parg^withdn- 

 examination of several other vegetable substances, that ap- chona. 

 pear to have some analog}' with it, and the composition of 

 which is a little better known ; such as galls, oak, bark, 

 Angustura bark, and some others. 



Natgalls. 



The infusion of this substance copiously precipitated i sin- Galls, 

 glass white; iron, blue; tartarised antimony, yellowish 

 white; infusion of yellow bark, in dirty white flocks; cop- 

 per, brown yellow ; and lead, yellowish white. 



It did not precipitate infusion of Santa Fe bark, or of 

 tan. 



The infusion of nutgalls therefore, like that of yellow 

 bark, contains the principle that precipitates isinglass with 

 that which precipitates tartarised antimony; and in this re- 

 spect they resemble each other. But they differ with regard 

 to the principle that acts on tan and on iron, since their me- 

 tal is precipitated green by cinchona, and blue by galls. 

 They differ too in another point, since they mutually preci- 

 pitate each other. 



Tan. 



The infusion of this substance, made with the same care Oak bark. 

 and in the same proportions as those of the cinchona bark, 

 precipitated solution of isinglass yellowish; iron blue; cop- 

 per, brown : but it occasioned no change in solution of Santa 

 Fe bark, or solution of tartarised antimony. It reddened 

 infusion of litmus, and was precipitated by oxalate of am- 

 monia. 



Hence we see, that oak bark, does not contain the sub- 

 stance that precipitates tartarised antimony, as nutgalls, yel- 

 low bark, and some other barks do; and in this respect it 

 differs from them, though they agree in precipitating isin- 

 glass. 



Cherry-tree bark. 



This bark, which has sometimes been fraudulently sub- Bark of the 

 stituted for that of cinchona, has nothing in common with c h " rr y- tlf '« 



» it 



