S62 



DJstilletL 



■Retains nitric 

 acid in combi- 

 nation. 



Impure part 

 soluble in 



«atei. 



Tlie resin treat- 

 ed with nitric 



Amer thus 

 formed from it. 



'ACTION OF NITTlie ACID ON INDIGO, 



It (lid not redden litmus paper, till it was concentrated by 

 boiling. 



When the resin was thrown on a red hot iron, it emittecj 

 a fragrant smell, and left a tumid coal. 



On distilling it in a small glass retort, I obtained, among: 

 other products, a liquid, that had a strong smell of pru-ssic 

 acid, and of oily ammonia. 



The resin is soluble in solution of potash, nitric add, and 

 alcohol. I believe, that, even after it has been well washed, 

 it contains nitric acid in real combination, and a little vola- 

 tile acid and amer. It is probable, that all the resinous 

 matters, which are formed in treating animal or vegetable 

 compounds with nitric acid, retain a portion oti this acid ia 

 combination. 



34. The waters in which the resin was washed (32) were 

 reddish, grew turbid on cooling, and lei fall a resinous 

 matter, which was a little viscous, bitter to the taste, and 

 appeared to differ from the washed resin only in containing 

 a larger quantity of nitric acid, volatile acid, and amer. I 

 imagine it was by,means of these on!'y, that it dissolved in. 

 the water. 



On treating this resinous matter with one fourth its 

 •weight of carbonate of lead, I obtained a solution of amcr^ 

 Tolatile acid, and lead. The resin was not dissolved, but 

 retained a little oxide of lead in combination with it. 



If the resin be boiled with an excess of carbonate of lead, 

 it is still acid, and still yields ammonia by distillation. This 

 confirms me in the opinion, that it retains nitric acid. 



35. The resin, when treated repeatedly with nitric acid 

 at 45* [sp. gr. 1*455], was dissolved into a reddish browra 

 liquor. From this water separated a substance of the yel- 

 low colour of shamoy leather, which appeared to me to be 

 resin combined with amer and nitric acid. Some amer, mat- 

 ter of an oily appearance, and a little resin, remained la 

 solution. 



Though the resin, that had been employed in my experi- 

 ments, contained a little amer, I have no doubt, that » 

 certain portion was formed by the action of the nitric acid, 

 as Messrs. Fourcroy and Vauquelin have said. What ap- 

 peared to me, to iirevent the total conversion of the resin 



into 





