In the electrical industry nitrogen is used to prevent oxidation and other chemical reactions, to pressurize cable jackets, and to shield motors. In the food industry nitrogen gas is employed to prevent spoilage through oxidation, mold, or insects, and liquid nitrogen is used for freeze drying and for refrigeration systems. In the chemical industry, nitrogen is used as a preventive of oxidation or other deterioration of a product, as an inert diluent of a reactive gas, as a carrier to remove heat or chemicals and as an inhibitor of fire or explosions. The inability of nitrogen to support life (Greek: zoe) led Lavoisier to name it azote, still the French equivalent of nitrogen.

Nitrogen first was considered a chemical element by Antoine-Laurent Lavoisier, whose explanation of the role of oxygen in combustion eventually overthrew the phlogiston theory, an erroneous view of combustion that became popular in the early 18th century. Later work showed the new gas to be a constituent of nitre, a common name for potassiumnitrate (KNO3), and, accordingly, it was named nitrogen by the French chemist Jean-Antoine-Claude Chaptal in 1790. At about the same time, nitrogen also was recognized by a Scottish botanist, Daniel Rutherford (who was the first to publish his findings), by the British chemist Henry Cavendish, and by the British clergyman and scientist Joseph Priestley, who, with Scheele, is given credit for the discovery of oxygen. The “fire air” was, of course, oxygen and the “foul air” nitrogen. Carl Wilhelm Scheele, a Swedish chemist, showed in 1772 that air is a mixture of two gases, one of which he called “fire air,” because it supported combustion, and the other “foul air,” because it was left after the “fire air” had been used up. About four-fifths of Earth’s atmosphere is nitrogen, which was isolated and recognized as a specific substance during early investigations of the air.

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