Atmospheric Nitrogen

Atmospheric Nitrogen and the Inert Gases function mainly as diluents in the atmosphere, exerting a restraining influence upon the chemical activity of the oxygen. They exist in approximately the following proportions by volume:

Nitrogen	78.06 per cent
Argon	0.941 per cent
Helium	1 part in 185,000
Neon	1 part in 55,000
Krypton	1 part in 20,000,000
Xenon	1 part in 170,000,000

The nitrogen is not entirely inert, however. During thunderstorms it can unite with the oxygen yielding, in the presence of the moisture, both nitrous and nitric acids. Again, certain plants, such as the leguminosce, owing to the presence of bacteria in their root-tubercles, are liable to assimilate nitrogen direct from the atmosphere, and certain bacteria in the soil act similarly. These reactions, however, are relatively of minor importance. The inert gases, on the other hand, appear to be absolutely inert and to enter into no atmospheric chemical reactions whatever.

To the presence of krypton in the atmosphere is due the phenomenon known as the aurora borealis or northern lights. The inert gases find their way into the atmosphere through escape from mineral springs, and, in the case of helium, through the disintegration of radium.