DEUTOXIDE OF NITROGEN. 



2. HISTORY AND NAME. It appears from Dr. Hole's vegetable 

 statics, that he obtained this gas more than a century ago, hut Dr. 

 Priestley first examined its properties with attention in 1772.* He 

 called it nitrous air; it is called also nitrous gas, and nitric oxide 

 gas, and deutoxide of nitrogen. The two last names being the most 

 proper will be employed, and for brevity the term nitric oxide will 

 be commonly used. 



3. PREPARATION. 



(a.) It is best obtained by the action of nitric acid upon mercury 

 or copper: for both economy and purity the latter is preferred. 



(b.) Nitric acid, sp.gr. 1.2 or 1.3, is poured upon cuttings of 

 copper. With shears like those used by the tinmen, cut sheet copper 

 into pieces of such size that they will easily slide into a glass retort ; 

 add common aqua fortis, or any of the varieties of nitric acid of the 

 shops, till the copper is more than covered ; then add hot water, 

 by little and little, till the action comes on ; let the first red vapors es- 

 cape, and when the neck of the retort is nearly clear of the red color 

 the gas may be saved. f 



(c.) If any of the copper clippings are left, they may be rinsed 

 with water and allowed to remain in the retort for another operation. 



(d.) If a diluted acid be used, the heat of a lamp or of a few coals 

 may be employed. In general, the gas comes rather suddenly; con- 

 tinues to flow rapidly for a few minutes and then remits; it is of 

 little use to urge it with heat beyond this point ; some gas may indeed 

 be obtained, but it appears to be principally that which was dissolved 

 in the nitric acid, and, although there may be an active ebullition, 

 little is disengaged besides aqueous vapor. 



(e.) Jin economical process for obtaining nitric oxide gas is, to mix 

 sulphuric acid and nitre in the proportions to afford nitric acid, and 

 then to add to the mixture some pieces of copper. J 



(f.) THEORY of the process. The nitric acid imparts oxygen to 

 the copper and converts it into peroxide, which unites with a portion 

 of acid that has not been decomposed and forms nitrate of copper ; 

 the nitric oxide contains all the nitrogen of the acid decomposed and 

 as much of the oxygen as remains after the oxidation of the cop- 

 per. 



* Priestley on Air. 



t The contrast presented by the green solution of the copper and the red vapor 

 of nitrous acid is very striking; the solution, which will be nitrate of copper, (usu- 

 ally with excess of acid,) should be saved for future uses. 



t In some of the processes for nitric oxide, a portion of nitrous oxide, and even of 

 nitrogen, is evolved. 



