: 37& ON ARTIFICIAL TANNIN. 



5 dec. [7*7 grs] of A 1 , which had been dissolved by the 

 carbonate, and afterward precipitated by sulphuric acid, 

 melted with heat, and afterward gave out carbonic acid gas, 

 nitrous gas, &c, leaving a coal, that emitted a smell of 

 prussic acid, and contained an atom of potash. 

 Examination 12. A 2 , which dissolved in the water of elutriation of 



pfedpiS^y A > and afterward fell down during its evaporation (10), 

 concentration, was of a blackish brown colour. Treated wiih boiling 

 water part was dissolved, and imparted to the wate* the 

 property of coagulating gelatine. The solution yielded by 

 evaporation a residuum, that melted, and evolved nitrous 

 gas. The part but little soluble in water greatly resembled 

 A 1 . It melted, and gave out nitrous gas, but in smaller 

 quantity than the portion that had dissolved in the water. 

 This indicates, that acid was transferred from the portion 

 but little soluble to the other. 

 Examination of 13. A 3 , which remained in solution after the concentra- 

 lT v ^ solu " tion of the washings of A, and had been obtained by eva- 

 poratiug them, was fawn-coloured. Heated in the glass 

 bulb it melted ; yielded water, carbonic acid, nitrous gas, 

 &c. ; and left a coal, that emitted a very strong smell of 

 carbonate of ammonia. 

 Its difference This substance, which precipitated gelatine very well, 

 from artificial differed from Hatchett's tannin (Art. I) in its alkaline so- 

 lution being precipitable by acids, in its being consequently 

 less soluble in water, and in its not melting by heat. 

 The three differ 39. The matter A therefore is divisible by water into 

 vr d "t-oof *h ree portions, which differ from each other only by the 

 nitric acid. quantity of nitric acid they contain, since by taking a por- 

 tion of this acid from those that contain the most they are 

 converted into those that contain the least; and by adding 

 acid to those that have lost it, they are brought back to their 

 former state, 



I 



4 II. Tanning mq,tter formed with fir \- charcoal. 



Artificial tan- 40. A hundred parts of fir charcoal, which had been cal- 



nm from char- c j nec j j a a p] a tina crucible, in a red heat, required for their 



solution iu nitric acid more time and more acid than 100 



parts of pitcoal. The solution of the charcoal was brown, 



and thick like a sirup. When .water was added, a brown 



matter 



