120 ON VARIOUS SPFCIES OF CINCHONA. 



it except the property of forming a green precipitate with 

 solution of sulphate of iron. It occasions no change in isin- 

 glass, tartarised antimony, or decoction of oak bark. It£ 

 possessing any febrifuge property therefore is very question- 

 able. 



Centaury and Germander. 



Centaurea and These two plants afforded me the same results as cherry- 

 chamicdrys. tree bark: their efficacy in fever therefore is equally doubt- 

 ful. 



White willow bark. 



Bark of the This bark, to which febrifuge virtues have formerly been 



white willow, ascribed, possesses in fact some of the chemical properties 

 of certain species of cinchona, namely those of precipitating 

 isinglass, and throwing down sulphate of iron green, and 

 acetate of copper brownish. The white willow bark, there- 

 fore, as it unites the bitter' and astringent tastes, may possi- 

 bly be a febrifuge. 



Angustura 

 bark. 



Angustura bark. 



The infusion of this bark does not precipitate isinglass: 

 but it forms a copious precipitate with infusion of nutgalls, 

 and with that of yellow bark, though it merely renders in* 

 fusion of Santa Fe bark slightly turbid. 



It precipitates iron, tartarised antimony, copper, lead, and 

 infusion of tan, all yellow. 



This bark, we see, differs from several of the species of 

 cinchona, and from the other substances submitted to the 

 comparative examination, in not precipitating animal gela- 

 tine. It wants too the astringent taste, but on the other 

 hand is extremely bitter. There is reason to believe too, 

 that the principle, which in this precipitates the metallic so- 

 lutions, is not altogether the same with that in the cincho- 

 nas; at least the colour of the precipitates it gives is very 

 different. From these properties however the Angustura 

 bark may possibly be a febrifuge. 



(To be concluded in the next number.) 



Experiments 



