Breathing the nitrogen of the air is like talking prose: People do it all their lives without giving it thought. Man has been accustomed, through ages past, to breathe nitrogen in certain proportions to oxygen and other atmospheric gases. But let the proportions vary, and the gas formerly ignored assumes vital importance. In modern life, such abnormal circumstances arise more and more frequently and so call attention to things normally taken for granted. The result is that atmospheric nitrogen, generally thought of as a rather inert gas with the simple formula N2, turns out to have peculiarities of serious import.
One of these peculiarities is the fact that nitrogen has definite and significant solubilities in water, fat, and fat-solvents. Since man is constantly immersed in an atmosphere containing 78% nitrogen, his body is completely in equilibrium with it. A measurable amount of free nitrogen, physically dissolved, is constantly present