Menioir upon Coff'ee. 23 



was manifested in the form of a white precipitate, which I 

 had the precaution to shake freqiientlv with a glass tube, in 

 order to make it present a greater surface and more points 

 of contact to the hydrogen gas saturated with sulphur. The 

 operation beino; finished, I unluted the apparatus and filtered 

 the liquor of the flask, which passed very limpid, preserv- 

 ing, however, a slight smell of sulphuretted hydrogen. I 

 proceeded to evaporate it in a glass capsule, with a mode- 

 rate heat : the liquor, when reduced to one third of its vo- 

 lume, no longer retained the hvdiosulphuretted smell. I 

 continued the evaporation in order to give to the liquid a 

 pretty strona; syrupy consistence : when brought to this point 

 it was v-ery transparent and of the colour of horn, as ob- 

 served by Mr. Chencvix. In this state it was submitted to 

 the followins: experiments : 



Applied to the tongue, its bitter taste was mixed with an 

 acidity and a roughness of which we have already spoken ; 

 mixing itself with water and even alcohol in any propor- 

 tions; presenting no crvstalli/ation in snite of the care 

 taken in its evaporation ; liquefying in the fire, and afier- 

 v-ards swelling very lightly ; spreading a sharp and pungent 

 whitish 3moke ; leaving as a residue a charry matter, not 

 voluminous, and very slightly salt. 



I afterwards submitted the acid tjius collected to an ana- 

 lysis by fire in close vessels. For this purpose I introduced 

 100 parts of it into a glass retort, to which I adapted the 

 hydro pneumatic tub. and an ' intermediate flask with two 

 necks: the first product which appeared was only water ; 

 this was coloured in proportion as I augmented the fire 

 under the distillatory vessel, and during this time there 

 })as<5ed into the flask a little oil highly coloured and very 

 Iftid : upon raising the temperature still higher, I succeeded 

 in liberating son)C cubic inches of carbonic acid gas and car- 

 bonated hydrogen gas. When there was no more disengaged, 

 I put out the fire and unluted the apparatus: when the re- 

 tort was broken 1 found a charcoal wcig-hing 0-36: made 

 red-hot in a platina crucible for an hour, it was impossible 

 to incinerate it; heated with the blow-pip'e it lost in weight, 

 and a very small portion of it was incinerated; yet it was 

 Ij 4 impossible. 



