Memoir upon Coffee. ei 



Mixed with a solution of gUic, there results from it no 

 precipitate nor change of colour different from that which is 

 natural to the mixture of the two liquors. 



A quantity of cofl'ee equal to that above eiYiployed was 

 pulverized, and boiled repeatedly like the foreg-oing in three 

 times its weight of pore water, in order to convince myself 

 that the husks were completely exhausted : the second and 

 third decoctions gave a greenish appearance deeper than the 

 first, without my being able to ascertain positively the cause 

 of this slight difference. I merely presumed that, the latter 

 decoctions being made in the open air, the extractive matter 

 had been able to oxvgenate^ itself sutKciently, and to pro- 

 duce this effect without precipitating it. These decoctions 

 always maintain a muddy appearance, in spite of repeated • 

 filtrations. 



All these liquors united were submitted t6 evaporation in 

 a glass retort so managed as to avoid the contact of the 

 air, and consequently the oxygenation of the extract. Con- 

 densed to the consistence of a syrup slightly boiled,.! finished 

 their evaporation in a glass capsule. This production be- 

 came transparent in proportion as it acquired consistence, 

 and viscous like an extract : its colour was that of horn, of 

 a bitter acid taste mixed with a degree of roughness which 

 I do not know how to describe, and it reddened the blue 

 colours: its weight was 15-216 (4 drachms), wiiich I put 

 aside for the purpose of being examined, as we shall see 

 hereafter. 



Sixty-one grammes 143 milligrammes (2 ounces) of cof- 

 fee in powder were digested in a glass vessel with 122 gram- 

 mes 286 milligramnjes (4 ounces) of alcohol, giving 34 de- 

 grees at Baume's areometer : 1 filtered, after two hours' ma- 

 ceration at a temperature of 13° {Gb'^ of Fahr.) ; the alcohol 

 vras highly coloured ; when evaporated it gave a product of 

 7 grannnes 643 miiligrammes (2 drachms) of a hyacinth-co- 

 loured matter, slightly viscous, bitter, acid, partly soluble 

 in water, and precipitating, when diluted in this liquid, 

 grayish fiakis, burning, like the resins, with a thick smoke, 

 and which I considered as a resinous substance. The por- 

 tion dissolved, treated with the re-agents already mentioned, 

 l'> 3 presented 



