284 



NITROGEN. 



filled with white fumes, which have an irritating odour; 

 and the gas which then comes off is little more than nitrogen. 

 Nitrous oxide should be collected in a gasometer or in a 

 gas-holder filled with water of a temperature about 90, as 

 cold water absorbs much of this gas. The whole salt undergoes 

 the same decomposition, and nothing whatever is left in the 

 retort.* 



Nitrous oxide is likewise produced when the salt called nitro- 

 sulphate of ammonia is thrown into an acid ; and also when 

 zinc and tin are dissolved in dilute nitric acid, but the latter 

 processes do not afford the gas in a state of purity. 



The nature of the decomposition of the nitrate of ammonia 

 will be best explained by the following diagram, in which an 

 equivalent of the salt, or 1004 parts, is supposed to be used. 

 It will be observed that the three equivalents of hydrogen in the 

 ammonia are burned, or combine with three equivalents of 

 the oxygen of the nitric acid, and form water, while the two 

 equivalents of nitrogen in the ammonia and nitric acid com- 

 bine with the two remaining equivalents of the oxygen of the 

 latter : 



Before decomposition. 



After decomposition. 



277 nitrous oxide. 

 277 nitrous oxide. 



1004 nitrate of ammonia. 



1004 



Or in symbols : 

 NH, 



677 Nitnc acid, 



214.5 Ammonia. 



.112.5 Water. 

 1004 



Oxygen 100 

 Oxygen 100 

 ,00 



1004 



HO + N(X=2NO and 4HO. 



From the diagram it appears that 1004 grs. of the salt yield 

 554 grains of nitrous oxide and 450 grains of water. One grain 

 of salt yields rather more than one cubic inch of gas. 



Properties. Nitrous oxide possesses the usual mechanical 

 properties of gases, and has a faint agreeable smell. It has been 

 liquefied by evolving it from the decomposition of the nitrate 

 of ammonia in a sealed tube, and possessed in the liquid state 



* For the preparation and properties of this and other gases, the Elements of 

 Chemistry (1829) of the late Dr. Henry may be consulted with advantage. 



