ON COFFEE. J21 



I took this same coffee, already washed with cold wafer, and lastly boil- 

 and infused in hot, and boiled it in six ounces of water, ed - 

 till they were reduced to four. This decoction contained a 

 great deal of gum and gallic acid, but little aroma, and af- 

 forded no trace of tannin or resin with reagents. 



Observations. 

 These experiments prove, that cold water divests roasted Effects of 

 coffee of the little tannin it contains, of part of its extrac- cold water ' 

 tive matter, and of great part of its aroma; but that it 

 takes up only a small portion of its, gallic acid, and of its 

 gum. We perceive, that the hot infusion is more loaded f hot, 

 with both of the latter principles; but that its aroma is 

 weaker. Lastly we find, that long boiling dissipates in a of boiling. 

 great degree its odour, but is highly loaded with gum and 

 gallic acid. If it be found to contain resin, this is only 

 suspended in it, disturbs the transparency of the liquor, 

 and is deposited by standing. 



Ashes of Coffee. 

 Though it is of little importance to know what coffee Incinerated, 

 reduced to ashes contains, I incinerated about half a pound, and the ashes 

 The ashes were pretty light. Lixiviated with distilled water, 

 their analysis afforded nothing but a little lime, and a very 

 little potash. I acidulated the lixivium with a small quan- 

 tity of nitric acid, and the filtered solution precipitated 

 prussiate of potash of a fine blue. Oxalic acid gave with 

 it a copious precipitate. It was not altered by barytes. 

 Nitrate of silver turned it white. Coffee ashes then are contain carbon 



composed of carbon, iron, lime, and muriate of potash. iron > lime > and 

 L '■ ,. , , ' L < .. .,. . muriate of 



1 did not think it necessary to ascertain their proportions. pc tash. 



I had intended here to have concluded my analysis, when Coffee analysed 

 Mr. Parmentier read at the Society of Pharmacy a very b y Mr - ?*Y^- 

 copious memoir on coffee, written by Mr. Paysse, an 

 apothecary, who has already published several very inte- 

 resting works. It is said in this memoir, 1st. that the pre- 

 cipitate formed by the mixture of the decoction of cofiee* 



* This is a mistake. It was the precipitate formed by the acid 

 of coffee, as Mr. Paysse calls it, obtained in the way in which 

 Mr. Chenevix found what he considers as a distinct principle, by 

 precipitating the decoction with muriate of tin, and separating 

 the tin by sulphuretted hidrogen. T. 



Vol. X VII.— July, 1807. K with 



