20 Memoir upon Coffee. 



The solution of green sulphate of iron acquired, on a si- 

 milar mixture, a very slight green tint, which became deeper 

 on being exposed to the air. 



The coffee powder remaining was put into a glass retort 

 with thrice its weight of distilled water : having joined a re- 

 ceiver to th.e head and luted it, I heated it sufficiently to 

 bring the liquor to the boiling point: having kept it six 

 hours in this state, I unluted the apparatus and filtered the 

 liquid, which I submitted to some experiments. 



The liquor which came over duHng thfe distillation was 



charged with the aroma of coffee in a very sensible degree; 



it was of a sweetish taste; not altering the blue vegetable 



colours^ nor the different re-agents with which it was put in 



'contact. 



The filtered water of the decoction had a greenish appear- 

 ance J was of a slightly viscous consistence ; had a bitter taste 

 mixed with roughness : discolouring and changing into red 

 the turnsole and violet tinctures ; communicating suddenly 

 a very fine green colour to the solution of oxygenated 

 iron; a very clear green to the green sulphate; a sombre 

 gray precipitate to the nitrate of mercury; a greenish gray 

 to the precipitate of nitrate of silver; a yellowish white to 

 the precipitate of nitrate of bismuth ; a light and grayish 

 green precipitate to the sulphate of copper; a green inclining 

 to violet to the precipitate of sulphate of manganese; a 

 sombre gray to that of the sulphate of zinc; a dirty white 

 to that of the sulphate of alumine, with a discolouring of 

 the liqiior; a whitish gray to a very voluminous and very 

 sudden precipitate of the muriate of tin; a more decided 

 gray than the preceding to that of the muriate of lead, which 

 is also very abundant; a white inclining to yellow to the 

 acetite of the rame metal ; a white to a slight precipitate of 

 muriate, nitrate, and acetite of barytes. 



The sulphuric acid produces a yellow colour with a flaky 

 precipitate, light and grav ; the nitric and muriatic acids 

 produce a yellow colour. 



Potash, soda, ammonia, pure barvtes and lime, give this 

 decoction a saff'ron yellow colour; the hydrosulphurets give 

 it the same colour, with a light precipitate. 



Mixed 



