various Species of Cinchona. 139 



chona ; but with the assistance of a little alkali, alumine car- 

 ries off with it the colouring part, and the liquor loses its 

 colour. 



In the countries which produce these cinchonas a very- 

 fine and durable chestnut red colour may be extracted from 

 their barks for dyeing cotton and wool : this colour changes 

 to pink with soap and water. 



Acllon of the Sulphuric and Muriatic Acids upon the 

 Rtsidues of Cinchona. 



These acids diluted in water dissolve the resin-formed 

 matter of these cinchonas, and saturate themselves with it, 

 like the nitric acid. The colour they acquire by this com- 

 bination inclines less to the yellow than that of the nitric 

 acid ; it is always of a more decided red. 



The precipitates which the alkaline carbonates form in 

 these solutions are also of a pure red ; and an excess of these 

 alkaline salts causes the precipitate to pass to a more decided 



blue .'our. 



The residues of cinchona seem to contain a great quantity 

 of lime; at least, the sulphuric acid in which they are in- 

 fused furnishes, upon spontaneous cvapcraliofi, plenty of 

 sulphate of lime. 



According to the action of the acids upon the resinous 

 matter of these species of cinchona, if we could one day 

 demonstrate that this substance is the only one in cinchona 

 which has a febrifuge property, it will be evident that the 

 medicine might derive from this bark many more advan- 

 tas:es in the cure of intermittent and ataxic fevers, by uniting 

 wi^th it the acids or wine. In fact, as we have seen above, 

 water only extracts from cinchona, particularly when it is 

 not bruised, a very small quantity of re;;inous matter, of 

 which even the greatest part is precipitated upon cooling. 

 But bv this method it is certain, that from a great quanthy 

 of cinchona we can extract but a very small part of the fe- 

 brifugc principle, which, being divided among a great quan- 

 tity o7 water, does not, of course, produce the same effect 

 it would do if more concentrated. 



For 



