140 Experiments upon the 



For a long time it has been known that the essent'ial salt 

 of cinchona has not in fevers an action proportioned to 

 that of the quantity of cinchona in powder from which it 

 has been extracted ; which proves that there remains in the 

 refuse something useful in the cure of fevers. 



lii my opinion I think that, to the present moment, a 

 method has been pursued for the preparation of the essential 

 salt of cinchona, quite t!ic reverse of the proper process. 

 When an infusion of cinchona is made, it is evaporated to 

 a certain degree and cooled, in order to deposit a precipi- 

 tate ; the resinous deposit, u^hich had been formed while 

 cooling, is then separated : this is repeated until the liquor 

 is no longer turbid, and has only a pale yellow colour : it is 

 then dried upon pktes placed in ovens. By performing the 

 operation in this manner, a very small quantity of resinous 

 matter only remains in the water, with a gum and a salt with 

 a base of lime, the efficacy of which in the cure of fevers is 

 very doubtful. 



Comparative Examination of the Resin of these Cinchonas 

 ivitk the other known Vegetable Substances, 



Does there exist in the vegetable kinadom any immediate 

 principle to which we may refer the latter r Should we class 

 it among the resins, as hitherto done? It is true, that for- 

 merly chemists and apothecaries united together under this 

 genus so many species of substances, that we might still class 

 the one in question among them, if we did not narrowly re- 

 flect upon some of its peculiar properties ; but upon apply- 

 ing the name of resin to such substances as truly deserve it, 

 those of cinchona and of many other vegetables ought to 

 be separated from the resins properly so called. 



Tf the resinous matter of these cinchonas resembles the 

 resins bv its solubility in alcohol, it is different from it by 

 its solubility in water, in the acids, the alkalis, and parti- 

 cularly by its property of precipitating the metallic salts, 

 and of attaching itself firmly to cloths. I think, therefore, 

 that we ought to regard this substance as a particular vege- 

 ta!)le principle, of which chemists have not yet known the 



properties. 



