Conjiderattons on Vegetable Extracts. 6^ 



Thefe precipitates, fome of which were thought by "Bautne 

 to be faline and others refinous, have been confidered by Pel- 

 letier as earthy fubftances, and are afcrlbed by the modern 

 cheniifts to the union which feveral of the imraedlate prin- 

 ciples of veo-etables contained in the juices have formed with 

 oxygen, which makes them lofe their foUibiHty in water. 



C. Defchamps junior, apothecary at Lyons, is of opinion 

 that thev are a mixture of Hme, extractive matter, oily or re- 

 finous fubftances in fome, and an adringent refmous fub- 

 ftance in others ; fomelimes of a little calcareous fait, and 

 fometimes of a little (ilex or alumine. 



As the obfervations and experiments on which he founds 

 his opinion may, by laying afule what he thinks unfavoura- 

 ble to oxygen, be exceedingly ufeful in the preparation of 

 extrafts, we refer to his memoir publiflied in the Jnnaies de 

 Cbimie for the vear 7. 



It refults, from the moft effential fafts announced in the 

 memoir of C. Defchamps : 



I ft. That there cxifts, in the vegetable juices or decoftions 

 which he fubjeiSted to examination, a neutral fait, the bafe 

 of w'hich has always been found to be lime, fometimes mixed 

 with a little filex and alumine, and of which the acid is oftea 

 different. 



2d. That this faline combination, not very energetic of 

 itfelf, is weakened when diluted with v/ater, and is eafilyde- 

 flroyed by ebullition, like many others, when the acid in it 

 is not in excefs, while it maintains itfelf, and is not altered 

 when the acid is fuperabundant in it. 



3d. That the dccompofition of this fait, when it takes 

 place, is only momentary, fince the dcpofits become rediffolved 

 towards the end of the evaporation by the fame acid which 

 has abandoned them ; and which then, notwithftanding the 

 lofs it has fuftained in its quantity, relumes fufficient force to 

 re-eftablifh things nearly in their firft (late. 



Hence arifes the neceffity of not Separating depofits which 

 prevent acids from being acid and deliquefcent. 



4th. Tiiat thefe depolits, the major part of which is lime, 

 which carries with it, more or lefs combined, fometimes aii 

 oily extra6live, fometimes a refino-adringent fubllancc, and 

 fometimes a little cffential fait, itfelf not being decompoied, 

 do not take place when the juices are not diluted with water, 

 when maceration and infufion are fubliituted for ebullition, 

 and when the evaporation is eirected in a genlle heal. 



liy uniting tlie fafts contained in the memoir of C. Des- 



tihanips with tlie obfervations of the chcinifts above men- 



\OL. XIV. No. 53. K tioneJ, 



