20 Memoir upon: Coffee. 
matic qualities; its taste resembled that of almond cake z 
it was not bitter, and was not so green as the former. 
No.2. was more easily ground. .A-cold infusion of it 
furnished Jess tannin, ‘its aromatic flavour was weaker, its 
taste more sugary ; it was neither bitter nor green. A warm 
infusion neither yielded more taste nor more aroma. 
No. 3. was very easily powdered. A cold infusion was 
almost free from aroma}; its taste was empyreumatic, anda 
little bitter ; it formed a precipitate scarcely perceptible with 
solution of gelatine: the warm infusion was more bitter, more 
empyreumatic, and the aroma was more distinct. 
. All these infusions contained mucilage and galli¢ acid, 
but in an inverse progression to the tannin; because the 
proportions of gum and acid increased with the roasting, 
whereas ihe tannin diminished. 
M. Bouillon-Lagrange, in a very excellent paper upon 
gall-nuts, has already considered the gallic acid as a modi- 
fication of tannin: these experiments support his opinion. 
Roasted Coffee.—As the immediate principles of coffee 
are not equally soluble or volatile, it was necessary to exar » 
mine comparatively the cold and warm infusions of the 
three kinds of coffee, as well as their decoctions. 
Infusion in cold Water.—i poured eight ounces of distilled 
water upon one ounce of roasted and ground coffee; I al- 
lowed it to infuse two hours, and I filtered it. The infu- 
sion was of avery clear brown; did not redden paper; be- 
came black by the sulphate of iron ; and slightly precipitated 
the solution of gelatine. Alcohol separated from it a little 
mucilage, and gave the infusion the smell of juniper.. Moka, 
Bourbon, and Martinique coffee, presented the same cha- 
racters. 
- Infusion in warm Water.—t infused, for a quarter of an 
-hour, one ouince of roasted and ground coffee in eight ounces 
of water at 70° (158° Fahr.). This infusion did not redden 
turnsole paper; did not precipitate solution of gelatine; and 
formed ink with sulphate of iron. Alcohol separated more 
gum from it than from the cold infusion. The three kinds 
of coffee acted in the same manner in these experiments. 
Decoction. 
