*nitrogen*

n. [ L. nitrum natron + -gen: cf. F. nitrogène. See Niter. ] (Chem.) A colorless nonmetallic element of atomic number 7, tasteless and odorless, comprising four fifths of the atmosphere by volume in the form of molecular nitrogen (N2). It is chemically very inert in the free state, and as such is incapable of supporting life (hence the name azote still used by French chemists); but it forms many important compounds, such as ammonia, nitric acid, the cyanides, etc, and is a constituent of all organized living tissues, animal or vegetable. Symbol N. Atomic weight 14.007. It was formerly regarded as a permanent noncondensible gas, but was liquefied in 1877 by Cailletet of Paris, and Pictet of Geneva, and boils at -195.8 ° C at atmospheric pressure. Liquid nitrogen is used as a refrigerant to store delicate materials, such as bacteria, cells, and other biological materials. [ 1913 Webster +PJC ]