OS VARIOUS SPECIES OF CINCHONA. 209 



poured on the residuums of" these cinchonas, dissolve the re- 

 siniform substance, and saturate themselves with it like the 

 nitric acid. The colour they thus acquire inclines less to 

 yellow than that of the nitric acid: it is always of a more de- 

 cided red. 



The precipitates formed in these solutions by alkaline car- Action of car- 

 bonutes are likewise of a purer red ; and an excess of these al- bonates on 

 iv . • i •• i * li these solu- 



xaline sails gives the precipitate a more evident blue. tions. 



The residuums of the cinchonas appear to contain a large Lime in the 

 quantity of lime : at least a great deal of sulphate of lime is re:>lduums - 

 produced by spontaneous evaporation in the sulphuric acid in 

 which they have been macerated. 



From the action of acids on the resiniform matter of these Remarks on 



c •" i •/ > f J i l i . c'-i i i tr »e action of 



species of cinchona, if it snould at any future time be demon- acid3< 



strated, that this substance is the only febrifuge principle in 

 them, it is evident, that the art of physic may derive from 

 these barks much more advantage in the cure of intermittent 

 and low fevers, by adding to them acids or wine. In fact, as 

 has been seen above, water extracts from cinchona, particu- 

 larly when it is merely bruised, but a very small quantity of 

 resiniform matter, and even the greater part of this is precipi- 

 tated by cooling. Now by this means it is certain, that from 

 a large quantity of cinchona we extract but a very small part 

 of the febrifuge principle*; which too, being diffused through 

 a large body of water, unquestionably cannot produce ail the 

 effect, of which it would be capable in a more concentrated 

 state. 



It has long been known, that the effect of the essential salt II * €ssentl£ d 



suit, 

 of cinchona in fever is by no means proportional to that of 



the quantity of bark from which it has been extracted : which 

 proves, that something useful in the cure of this disease is 

 left in the magma. 



According to my way of thinking, the method hitherto pur- Hith^ta ex- 

 sued for preparing the essential salt of bark is the reverse of ^d process- 

 what it ought to be. When an infusion of cinchona is made, 



* Mr. Vauquelin has forgotten hi-; if, in the first sentence of this pa- 

 ragraph. U has not yet been proved, that this is the febrifuge principle : 

 and indeed he himself had before ranked the principle soluble In water 

 ■with it in this respect. Tr. 



Vol. XIX— March, 1803. P it 



