ACTION OF NITRIC ACID ON INDIGO. OCK 



were mixed directly with the liquid saturated with potash, 

 no Prussian blue was obtained). 



The residuum of the distillation was reddish, and gelati- Residuum. 

 nized. Sulphuric acid evolved from it a smell of prussic 

 acid, mixed with that of nitrous acid. 



The water therefore had dissolved, beside the undecom- Nitric acid and 

 posed amer, carbonic acid, prussic acid, and nitric aczc/:*^'".'*^*'"- 

 and I have every reason to think, that it contained a little 

 ammonia. 



18. The gaseous residuum insoluble in water was placed The gaseous' 



in contact with a solution of potash for twenty-four hours, P'^,°^"^^ "'^' 



t^ J i soluble m water 



m order to abstract from it the carbonic and prussic acid, were 



that it might still retain. After this it was carefully wash- 

 ed. In this state it did not redden infusion of litmus; but 

 as soon as it was exposed to the air, it reddened it, and 

 produced a pretty strong smell of nitrous acid; so that it 

 must have contained nitrous gas. It burned in the same 

 manner as oily hidrogen. I had observed several times, 

 that this residuum extinguished burning substances, because 

 then it contained a great deal of nitrogen gas; and at other 

 times, that it burned like carbonic oxide gas. It appeared, 

 that these differences were owing to the degree of rapidity, 

 with which the amer was decomposed. 



The gaseous residuum insoluble by water or potash, there, nitric oxide, 



fore, consisted of nitrous gas. inflammable gas, and mVro-^!^'^*'^'^"' ^'^^ 

 ' & 7 ./ o 7 nitrogen. 



gen. As I was not able to make an accurate analysis of 

 -this residuum, I cannot say whether the whole of the ni- 

 trogen came from the air in the apparatus, the oxigen of 

 •which was converted into nitric acid by the nitrous gas; or 

 whether part of it arose from the decomposition of the 

 amer. 



19. From these facts it appears to me, that amer is a Composition of 

 -compound of nitric acid, and a. vegetable matter, probably*"^"- 

 of an oily or resinous nature. Perhaps it may be objected, 

 that the nitrous gas obtained may be formed during the 

 'process, by the compression the gasses undergo : as is the 

 •case when hidrogen is detonated with oxigen containing ni- 

 trogen in Volta's eudiometer, or in a glass globe for the re., 

 composition of water: but the compression of the gasses in 

 4hese apparatuses appears to me to be much greater, than 

 A a 2 *^^y 



