Nitrogen (N2) constitutes 78% of air by volume. It is a ‘permanent gas’, colourless, tasteless, odourless, and non-combustible. N₂ is very inert in a free state and incapable of supporting life, is intensely cold in a liquid state reaching -196 ˚C. One volume of Liquid Nitrogen gives approximately 700 volumes of gas at ambient conditions. N₂ forms many important compounds, such as Ammonia, Nitric Acid, and the Cyanides and is a constituent of all organised living tissues, animal or vegetable.