I ^5 ON COrFEE. 



9. The moment you are going to drink the coffee, heat 

 it over a brisk fire, but do not let it boil. 



10. The infusions should be made in a china, earthen- 

 ware, or silver pot. 



Such is the process pointed out by theory, and I can re- 

 commend it from experience. 



Paysse's analy - To give the whole of Mr. Paysse's memoir, alluded to 

 ' above, would occupy too mueh room ; but we apprehend 

 it will be acceptable to the reader, to have subjoined the 

 conclusions which that gentleman draws from his chemical 

 investigation of raw coffee; particularly as he differs, in 

 some respects, both from Mr. Cadet, and from Mr. 

 Chenevix. 



It contains a j. jt results from all these experiments*, that coffee 



' contains a peculiar acid sufficiently characterised : that it is 



in some respects free, since the powder of the berry speedily 



reddens blue vegetable tinctures: and that cold water, or 



even alcohol, can separate it in a state more or less pure. 



which decom- 2. That the acid decoction of coffee easily decomposes 



fa^lksolu^io^s 6 " mos * °*" * nc metallic solutions, as those of tin, lead, 

 iron, &c. 



Precipitates of 3. That the precipitates obtained by a mixture of this 



these by the d ecoc tion w i tn * nc metallic solutions are more copious 

 decoction more r 



copious, be- than those formed by the pure acid, because the decoction 

 cause less pure. con t a ; ns extractive matter, colouring matter, albumen, &c. 

 beside the acid. For the colouring matter is partly preci- 

 pitated by the affinity it has for the compound, formed of 

 the come acid with the metallic base; and on the other 

 hand the albumen, being separated from the acid which 

 promoted its solution in the liquid, falls down and in- 

 creases the bulk of the precipitate. To be convinced of 

 the truth of this, nothing more is necessary, than to boil 

 a coffat of tin, lead, or alumine, in a coloured vegetable 

 decoction, to obtain the result in question. 

 Methods of ob- 4. That the acid of coffee may be obtained sufficiently 

 acid!" 8 ' l 1ure ky mixing a decoction of coffee in water, or a tinc- 



ture of it in alcohol, with the muriate of tin or of lead, 

 and afterward decomposing this combination by sulphuretted 



* Annates dr. Chimie, Vol. LIX. p. 196. August, 1806, 



hidrogen, 



