Memoir upon Coffee. 23 
short, it will be recollected that the decoction, when pro- 
Jonged, dissipates, in a great measure, the aromatic smell, 
and is highly charged wai gum and gallic acid. If there is 
any resin in it, it 1s only i in suspension ; shit injures the trans- 
parency of the liquor, and it is precipitated by repose. 
Ashes of Coffee.—Although it is almost indifferent to 
know what coffee contains when reduced to ashes, I inci- 
nerated about half a pound of it: the ashes were light; 
washed in distilled water, they only presented a little lime 
to my analysis, and but very little potash. I sharpened 
this ley with a little nitric acid, and the filtered solution 
precipitated in a fine blue prussiate of potash, and was 
abundantly precipitated by the oxalic acid. Barytes did not 
alter it; it beeame white with the nitrate of silver. Thus 
the ashes of coffee. are composed of charcoal, lime, and 
muriate of potash. I did not think it w ort sani to esti- 
mate the proportions. 
I thought I had here terminated my ed i but M. Par- 
mentier has lately read in the Pharmaceutic Society a long 
essay upon coffee by M. Payssé, who has already published 
some very interesting works. It is said in this essay, Ist, 
That the precipitate formed by the mixture of the decoction 
of coffee with the sulphate of iron, is only soluble in the ni- 
tric, sulphuric, phosphoric, or oxalic acids: 2d, That coffee 
contains no gallic acid: 3d, That it contains a particular 
acid, sui generis, which the author calls coffic acid, and 
which he obtained by following the process of M. drsnead: 
‘consisting in making a detoction of raw coffee, filtering it, 
precipitating it by the muriate of tin, and decomposing the 
precipitate by sulphuretted hydrogen gas. 
The authority of the name of Chenevix, and the exacti- 
tude with which M. Payssé makes his observations, induced 
me to make several experiments to confirm the new facts 
they had announced. 
I boiled, for two hours, two ounces of Bourbon coffee in 
half a pound of water ; this decoction presented me with the 
same phenomena J had already seen; it assumed a yellowish 
green tint, which became more lively by the separation of a 
little albumen, and oxygenated extractive was precipitated. 
This 
