£14 ON VARIOUS SPECIES OF CINCHONA. 



evaporate spontaneously ; and it was thus reduced to the 

 The acid erys- s f a t e f a very thick sirup, without affording anv sian of 

 talhzed sud- ,,••',- • i i i i i " •• , • 



denly on agi- crystallization, atter it had stood above a week. Having 



tation. stirred it however with a piece of glass, in order to take out a 



portion which I intended for another experiment, I was sur- 

 prised to find the fluid crystallized a few instants after into 

 a hard mass, formed of a great quantity of lamina*, diverg- 

 ing from several very distinct centres of crystallization. 



It was slightly tinged of a brown colour: its taste was ex- 

 tremely acid and a little bitter, because the salt of cinchona 

 I had employed had not been perfectly purified. 



I shall now proceed to the properties I ohserved in this 

 acid, on which however I cannot enlarge very minutely, as 

 I had but a moderate quantity of the salt at my disposal. I 

 believe however, that I have examined it sufficiently, to be 

 convinced of its being a peculiar acid hitherto unknown. 



Its properties. In its state of crystallization it has a very acid taste, and is 

 a little bitter*, as I have said above. 



It keeps perfectly well in the open air, being neither deli- 

 quescent nor efflorescent* 



On burning coals it melts very quickly, boils, grows black, 

 emits pungent white vapours, and leaves but a very light 

 coally residuum. 



With the earths and alkalis it forms soluble and crystal- 

 lizable salts. 



It does not precipitate nitrate of silver, mercury, or lead, 

 as most other vegetable acids do. 



It is s new ve- There appears no doubt, that this acid is new to us; for, 



differing from on reviewin°' the characters, of all the other vegetable acids 

 known, neither of them unites in it all the properties of this. 



the oxalic, Jn fact oxalic acid forms an insoluble salt with lime, and 



besides decomposes the compound formed of this earth and 

 acid of cinchona. 



citric, and tar- The citric and tartarous acids form likewise insoluble salts 

 with lime, and decompose acetate of lead. 



malic, The malic acid- does not crystallize, and precipitates ace- 



tate of lead. 



* Mr. Vauquelin has just beon ascribing this bitterness to the im- 

 purity of the salt he employed, consequently iti> not a character of Lhe 

 afcid. Tr.' 



The 



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