476 NITROUS OXIDE. 



NITROUS OXIDE PROTOXIDE OF NITROGEN. 



Remarks. It has already been stated that this oxide has been re- 

 served for the present place, because it will be best understood in con- 

 nexion with the salt from ivhich it is always obtained. Otherwise it 

 would naturally have been introduced after nitrogen and before its 

 deutoxide, the nitric oxide gas. 



1. HISTORY. Discovered by Dr. Priestley, in 1772, by whom it 

 was called dephlogisticated nitrous air ; Mr. Davy examined it with 

 more particular care, and called it nitrous oxide. 



2. PREPARATION. 



(a.) The nitric oxide can be converted into the nitrous oxide, by 

 the action of various substances which will abstract half the oxygen ; 

 they will be mentioned in an appendix to this article. 



(b.) But the only eligible method is by the decomposition of the 

 nitrate of ammonia by heat.* 



(c.) The solid nitrate, which should be as dry as possible, should 

 not Jill more than one quarter the body of the retort a good Ar- 

 gand's lamp or a few live coals are sufficient for the decomposition, 

 which is known to be proceeding well, when the melted materials boil 

 quietly and emit small bubbles ; a thin snowy vapor revolving in the 

 retort, and no red fumes appearing. If the heat is raised too high, 

 the bubbles will be very large, and a reddish tinge in the retort will 

 indicate the formation of nitrous acid vapor. 



3. THEORY OF THE DECOMPOSITION AND EQUIVALENT NUMBER. 



(.) The nitrate of ammonia is composed entirely of the pondera- 

 ble part of gases, and the effect of the heat is so to rearrange them, 

 by the exertion of new affinities, that the solid is converted, wholly, 

 into aerial products ; steam, and nitrous oxide. 



(b.) The nitrate of ammonia is composed of one proportion of ni- 

 tric acid 54, and one of ammonia 17=71. 



The acid is composed of nitrogen, 1 proportion, 14, and oxygen, 5 

 proportions, 8x5=40=54. 



The alkali consists of nitrogen, 1 proportion, 14, and hydrogen, 3 

 proportions, 1x3=3=17. 



(c.) The representative or equivalent number of nitrous oxide is 22, 

 made up of I proportion of nitrogen 14, and 1 of oxygen, 8=22. 



(of.) During the decomposition, 71 grains of the salt afford 27 of 

 water, consisting of 3 proportions, viz. 9x3, and water is composed 

 of I proportion of hydrogen I, and 1 of oxygen, 8=9; there are 

 produced also, 44 grains of nitrous oxide, consisting of two propor- 

 tions, or 22x2. 



* In addition to what has been already said under the nitrate of ammonia, we will 

 observe that, notwithstanding the statements under 2, (c, d, and e,) it is not necessa- 

 ry to use a thermometer to regulate the decomposition of this salt. 



