Nitrogen is named from the Greek nitron, native soda, and genes, forming, and was discovered in 1772. Nitrogen makes up 78% of the earth's atmosphere, by volume. The estimated amount of this element in our atmosphere is more than 4000 billion tons. From this source it can be obtained by liquefaction and fractional distillation. Nitrogen as a gas is colorless, odorless and a generally inert element. As a liquid it is also colorless and odorless and is similar in appearance to water. When nitrogen is heated it combines directly with magnesium, lihtium or calcium; when mixed with oxygen and subjected to electric sparks it forms first nitric oxide and then the dioxide; when heated under pressure with a catalyst with hydrogen, ammonia is formed (Haber process). The ammonia formed is used to produce fertilizers and it can be oxidized to nitric acid. The ammonia industry is the largest consumer of nitrogen. Nitrogen as a gas is also used in large quantities by the electronics industry as a blanket medium during production of transistors, diodes, etc. The steel industry uses nitrogen for annealing stainless steel and other steel products. Liquid nitrogen is used in missiles as a purge for components, as an insulator for space chambers, and also by the oil industry to build up pressure in wells to force crude oil to the surface.