!42 Expcrhneuts upon the 



7. It seems that it is to the tannin of oak bark and of 

 gall-nuts that this principle joins, in order to form the pre- 

 cipitates which it occasions in the infusion of these sub- 

 stances : nevertheless, this principle existing in some species 

 of cinchonas which precipitate glue at the same time, it re- 

 mains doubtful if it truly unites to the tannin of the infusion 

 of oak bark, or that the principle of the other kinds of cin- 

 chona which precipitate glue is true tannin. 



8. But it must necessarily happen that the one or other of 

 these suppositions is true, since the iniusions of these two 

 kinds of cinchonas mutually precipitate each other. 



9. The principle which in some kinds of cinchonas pre- 

 cipitates glue, has a bitter and astringent taste: it is more 

 sohible in water than that which in other kinds precipitates 

 the infusion of tan : it is also soluble in alcohol, and does 

 HOt precipitate emetic. 



10. It woidd seem that the substance which precipitates 

 infus-ion of tan is the same wjjich decomposes emetic. 



Th'is from all these doubts there remains much more to 

 do before we can exactly ascertain the effective principle or 

 principles of cinchonas in the cure of fevers. It is to be 

 hoped, that throuo;li time, and in consequence of assiduous 

 labour, we shall he able to resolve this importaiit question. 



jlnahjih of the Salt of Clndiona. 



M. Deschamps junior, apothecary at Lyons, is the first 

 who, to my knowledge, announced the presence of a par- 

 ticular salt in cinchona, which ought not to be confounded 

 with the essential salt of cinchona, v/hich contains at the 

 same time both resin and mucilage; but M. Deschamps 

 havino" only described some physical properties of this salt, 

 I thouglit it right to analvse it, in order to ascertain the na- 

 ture and proportions of its principles. In another place I 

 have. «x,'j>laincd how this salt of cinchona may be obtained, 

 and what processes ought to be employed in order to purify 

 it: i shall therefore now confine myself to a simple detail of 

 its properties. 



1. This salt is white; it crystallizes in square laminae, 



sometimes 



