Nitrogen
N., at. wt. 14.01, colorless, odorless, tasteless gas, forming, approximately, four-fifths of the atmosphere. Slightly lighter than the air. Discovered in 1772 by Rutherford, in the University of Edinburgh. It can be prepared by passing air over some reagent which will readily react with and absorb oxygen, such as reduced iron, alkaline, pyrogallol, or phosphorus; or by liquefying air and distilling, when the more volatile nitrogen is vaporized. Nitrogen is found in all vegetable and animal life, usually in organic combination, and in varying quantities in the earth's crust in both organic and inorganic combination. It is a necessary constituent of plant and animal food. Certain legumes have the power of fixing the nitrogen of the air by means of root nodules, and obtain their supply in this way, while electric discharges in the atmosphere cause the union of nitrogen and oxygen, the resulting oxides of nitrogen being washed into the soil by rain.
These sources are not sufficient, however, to enrich the soil to the extent needed for intensive cultivation, and by added, either in the form of decomposguano, etc.) or inorganic salts (nitrates, ammonium sulphate, etc.). The most fertilizer is sodium nitrate or Chili salt- commonly used inorganic nitrogenous petre, NaNO3, but it is believed that the supply of this material will become exhausted in less than forty years. Moreover, nitrogen in the form of nitric acid, nitrates, or ammonia is an important raw material in the manufacture of ex-