Nitrogen Compounds. 199 



We have here all the advantage of the strong 

 affinity of oxygen in producing light and heat, and 

 in supporting life, while its action is beautifully 

 regulated by the nitrogen with which it is diluted. 

 We see, then, its frness for a constituent of the 

 atmosphere, by Itfl very negative properties. It has 

 no taste, nor color, nor odor ; and its affinity is so 

 sluggish, that though mingled with oxygen in an 

 aerial ocean more than fifty miles deep, rolling on 

 the whole earth, only the minutest portions of it 

 ever combine with that oxygen. \Ve cannot con- 

 ceive of any change that could be made to compen- 

 sate for the loss of nitrogen in the atmosphere, 

 unless oxygen were t increased in quantity, and 

 .kencd in its chemical affinity. And there is no 

 end to the confusion that change would introduce 

 into the relation of the chemical elements most use- 

 ful to man. To meet his wants, oxygen must have 

 the power it now has to combine, and it must be 

 mingled with just such a body as nitrogen to control 

 its combination. 



Nitrogen is confined mainly to the air, to organic 

 beings, and to those compounds that, small in quan- 

 tity, but widely distributed, seem like a special pro- 

 vision for the food of plants and for the use of man. 

 Most of its compounds are soluble or easily decom- 

 posed. They cannot therefore make up any portion 

 of the permanent crust of the earth. In fact, it is 

 chiefly in those countries where rain seldom falls, 

 or in places entirely protected from rain and run- 

 ning water, that they can accumulate. It is on the 



