J22 ON COFPEE. 



with sulphate of iron, is soluble only in the nitric, sul- 

 phuric, phosphoric, and oxalic acids : 2d. that coffee con- 

 Contains a pe- ta j ns no g a uj c ac jri : 3^. that it contains a peculiar acid, 

 sui generis , which the author calls coffic acid, and which 

 he obtained by following the process of Mr. Chenevix, that 

 is, making a decoction of raw coffee, filtering, precipitat- 

 ing by muriate of tin, and decomposing this precipitate by 

 sulphuretted hidrogen gas*. 



The authority of the name of Chenevix, and the ac- 

 curacy with which the processes of Mr. Paysse are 

 generally conducted, induced me to make several ex- 

 periments, in order to confirm the new facts that were 

 announced. 

 Decoction. I boiled two ounces of Bourbon coffee in a pint of water, 



for two hours. The decoction exhibited the same pheno- 

 mena as I had already observed. It assumed a yellowish 

 green colour, which became more bright by the separation 

 of the little albumen, and let fall a precipitate of oxige- 

 nized extractive matter. This decoction, when filtered, 

 turned the aqueous tincture of litmus green. 

 Precipitated by I mixed a portion of this decoction with a solution of 

 iron atC ° sulphate of iron, and obtained a precipitate of a very 

 deep blue, inclining to black. This precipitate I redis- 

 solved in oxigenized muriatic acid, strong and weak acetic 

 acid, tartarous, citric, and even benzoic acid. 

 and by muriatic Muriatic acid rendered the liquor yellow ; but it resumed 

 its transparency, after letting fall a tolerably heavy pre- 

 cipitate of oxigenized extractive matter. This precipitate, 

 being rcdissolved by ammonia, gave a fine brown red 

 colour to the liquor. 

 Precipitate by The immediate precipitate of the sulphate of iron dis- 

 sulphate of solved by acetic acid, comported itself nearly in the same 

 manner, except with regard to the colour, which was of a 

 violet blue. It was likewise redissolved by ammonia. The 

 and by acids, other acids afforded nearly the same precipitate as the mu- 



* Mr. Chenevix does not say, that the substance he obtained 

 by this process was an acid, but a new product, the nature 

 of which he does not determine. [See Journal, Vol. II. 

 p. 114.) 



riatic ' 



