\\£ 0N COFFEE. 



ized muriatic acid deprives the decoction of its colour but in 

 part; and, if an alkali be added to this mixture, it becomes 

 red. 



Distillation. 



Dialled yield- I distilled eight pounds of water with a pound of raw 



«d a volatile oil coffee, and obtained an aromatic water, on the surface of 



which were a few drops of a concrete oil, similar to that of 



the-m$r4ca cerifera, or candleberry myrtle. The decoction 



remaining in the still was viscous. This I diluted with a 



The decoction little water, and poured into it alcohol. A copious preci- 



gummy. pitate was thrown down, which, collected on a filter, was 



soluble in water, and had all the characters of mucilage. 



Resin left in The coffee from which the water had been distilled, being 



the coffee. dried in a stove, and digested in alcohol, afforded a tincture, 



which gave a precipitate on adding water. 

 The decoction The aqueous decoction of raw coffee does not redden ve- 

 turned litmus getable blues. With litmus it even produces a green. All 

 the chemists who had analysed coffee before me have said, 

 that the decoction .held in suspension a free acid, which red- 

 dened blue vegetable colours. Geoffroy even went so far as 

 to assert, that water distilled from coffee by the heat of a 

 and contained water bath was rendered very sour. I have tried five differ- 

 no acid. en t sor ts of coffee, and repeated the experiment more than 

 twenty times, but the decoction never appeared sour to me. 

 Xfecoraposed It decomposes sulphate of alumine, and precipitates its 

 »!um. earth, which it colours slightly. 



Raw Coffee treated with Alcohol. 



Alcohol ex- Alcohol becomes slightly tinged by standing on dry coffee, 



tracts its resin, gygu without heat, and holds in solution a considerable 



quantity of extracto-resinous matter. If water be added to 



this tincture, it turns milky, and the resin falls down of a 



dirty white colour. With a solution of sulphate of iron 



the precipitate is green; with muriatic acid it is fawn- 



kavinj; extract coloured. The coffee exhausted by alcohol, and afterward 



and mucihge. treated with water, still furnishes extractive matter and 



mucilage. 

 Immrdiatc From these preliminary experiments we may conclude, 



principles of that raw coffee contains, 1. an aromatic principle soluble in 



water ; 



