ON VARIOUS SPECIES OF CINCHONA. 205 



another remaining in a flocculent form and of a reddish co- 

 lour : but if the mixture be heated, this dissolves too, and the 

 result is a clear liquor, of a very deep red, which grows turbid 

 on cooling, but lets fall very little sediment. 



What is remarkable in the manner in which this substance Singular effect 

 comports itself with water is, that, if we employ but a small of wateronit ' 

 quantity of this fluid, it dissolves entirely, and produces a 

 clear liquor : if after this more water be added, it grows tur- 

 bid; and again it becomes clear on the addition of a still 

 greater quantity of this fluid. 



It would seem from this, that there is spme other sub- Apparently 



stance present with it, which promotes its solution when con- °^ m & to some 



- ' ' *•■'*. • other pnnci- 



centrated, and loses this property by being diluted in water, pie. 



This is the matter, that renders the decoction or infusion of Erroneously 

 cinchona turbid, by separating as it cools ; as it does the ca U ed resin.' 

 water in which it is macerated, if this be evaporated to a cer- 

 tain point. It is the same as has been called in pharmacy 

 resin of bark : but its solution in water grows mouldy in a few 

 days, and produces fungi, like a solution of gum ; which 

 proves it not to be a true resin, for it is well known, that 

 resins never grow mouldy. 



The aqueous solution of this substance, recently prepared, Its aqueous so- 



and in a somewhat concentrated state, produced the follow- milie & 



ing effects with the different reagents I shall mention. 1. 



With ammonia it coagulated into a whitish, thick matter, with ammonia, 



which grew brown in the open air, and hardened considerably 



a little while after: but it softens by heat, and assumes the 



ductility and silky lustre of turpentine when kneaded between 



the hands. 



'*Z. It produced nearly the same appearances with the alka- alkaline car- 

 ... bonates. 



line carbonates. 



3. The common acids produced no sensible change in it. acids > 

 Oxigenized muriatic acid turned it yellow, without pro- 

 ducing any precipitation; but if ammonia were then added, 



a light, flocculent, grayish white precipitate was formed.- 



4. The solution of animal gelatine does not precipitate it: g elatme > 

 yet the infusion of these species of cinchona precipitates the 

 solution of animal &l tie; the principle that produces this ef- 

 fect therefore must be altered during the evaporation. s 



5. The 



