

ON COFFEfc. l\$ 



plant, and the place in which It flourishes, will, I am per- 

 suaded, be acceptable information to the Society. 



I am, Dear Sir, 



Your most obedient humble Servant, 



W. ROXBURGH. 



III. 



Extract from a Dissertatio?i on Coffee, its History, Pro- 

 perties, and the Mode of obtaining from it the most plea- 

 sant, wholesome, and economical Beverage : by Antony 

 Alexis Cadet deVaux, Member of various Academies: 

 with its Analysis, by Charles Lewis Cadet, Apothecary 

 in ordinary to his Majesty the Emperor, Professor of 

 Chemistry, fyc* 



X ASSING over the historical part, which is sufficiently 

 known, we shall confine ourselves to the chemical and eco- 

 nomical. 



Raw Coffee treated with Water. 



When boiling water is poured on coffee as we find it in Decoction of 



the shops, it acquires a yellowish green colour. + If the raw c ° ffee J 



n . , .,'*■» . , treated with re- 



action of heat be continued, the decoction grows brown, a geuts T 



and a light scum rises, which remains insoluble. The de- 

 coction passes clear through the filter, but becomes turbid 

 on cooling. A little caustic potash poured into this decoc- 

 tion gives it a deeper brown, and ammonia produces a simi- 

 lar effect. Lime water forms in it a copious flocculent pre- 

 cipitate. Sulphate of iron converts it into a black ink. 

 Solution of gelatine is not rendered turbid by it. Oxigen- 



* Journal de Physique, Vol. LXIII. p. 216, Sept. 1806. 



+ When coffee is fresh gathered, its decoction is of a fine emerald Lake from 

 green. A lake might be made of it, and Mr. Dupont de Nemours coffee. 

 informs me, that in the West Indies it is used for washing and co- 

 louring maps. 



ized 



