370 i ON ARTIFICIAL TANNIN. 



gas; 7th, nitrogen gas * ; 8th, prussicacid, sensible to the 

 smell, but in too small quantity to afford prussian blue; 

 9th, charcoal. 



9. The matter A digested with a small quantity of water 

 coloured it red, and gave it the property of precipitating 

 gelatine. The residuum boiled with fresh water was in part 

 dissolved; and ultimately left a blackish substance, heavier 

 than the matter A, and very slightly colouring water with 

 which it was boiled. I believe it was nothing but the oxide 

 of carbon described by Proust. To this I shall presently 

 return. 



10. The washings of the matter A were concentrated by 

 a gentle heat. A substance was deposited, apparently very 

 similar to A, and a very astringent matter remained in the 

 concentrated liquor. 



Separated into Hence it follows, that water separated the matter A into 



three sub- three different substances: 1st, a black substance, nearly 



stances. . - ' ' J 



insoluble in water, which I shall call A 1 : 2d, a substance 



soluble in water, but precipitable from it by evaporation, 

 which J shall denote by A*: 3d, a substance very soluble 

 in water, A 3 . 

 The insoluble 11. A 1 was a little acid. 5 dec. [7*7 grs], heated in the 

 substance ex- gj ass bulb, melted, diffusing a red light, and giving out, 1st, 

 water; 2d, carbonic acid; 3d, inflammable gas, burning 

 white; 4th, nitrous gas; 5th, nitrogen gas; 6th, a little 

 ammonia; 7th, a coal, that emitted a strong smell of prus- 

 sic acid. 

 A compound of Hence it is evident, that this substance, which possesses 

 nitric acid and ^ p r0 p ert i es ascribed by Proust to the oxide of carbon, is 

 a compound of nitric acid and carbon : it differs from A 2 

 and A 3 only by containing less acid: and what appears to 

 confirm this is, by boiling it in concentrated nitric acid it is 

 totally dissolved ; and, when water is poured into this so- 

 lution, it throws down a yellow flocculent precipitate, ex- 

 hibiting all the properties of the unwashed matter A. Hence 

 I imagine, that, when the matter A is boiled in water, the 



* With respect to this product see what I have said in the arti- 

 cle of the decomposition of Welther's amer by heat in my paper 

 on the amers from indigo. See Journ. vol. XXX, p. 351. 



portion 



