NITRIC ACID. 175 



nitric oxide, changed by the air into which they rise. 

 The nitric oxide is, so to speak, the fragment of nitric 

 acid, which is left after three atoms of its oxygen are 

 abstracted. Rising into the air, it combines with oxy- 

 gen enough partly to supply the place of that it has 

 just lost, and is thus converted into red fumes of per- 

 oxide of nitrogen, containing four atoms of oxygen. 

 This compound is also called hyponitric acid. Still 

 another compound of nitrogen with oxygen is de- 

 scribed in the section on nitrates. 



427. Repeat the experiment of the last 



JJeecrioe ano- . >--, 



ther method of paragraph, placing the coin and acid in a 



rld d fum/ s Ule sma11 vial or test - tube > instead of a saucer, 

 and collect the nitric oxide produced, as 

 shown in the figure. The collec- 

 tion should not be commenced 

 until a colorless gas is produced. 

 It will be best to fill the vial 

 to only two-thirds of its capa- 

 city. Then lift it from the 

 bowl, and let the remaining water run out. The air 

 will immediately rush in, and change the colorless ni- 

 tric oxide to red vapors of the peroxide of nitrogen. 



How does ni- 428. OXIDATION WITHOUT SOLUTION. 



tnc acid act Nitric acid oxidizes tin and antimony, but 



on tin { J ' 



does not dissolve them. The experiment 

 will be best made with tin-foil. After the action of 

 the acid, it will be found converted into a white pow- 

 der. Gold and platinum are neither dissolved nor ox- 

 idized by nitric acid. 



