Liquid nitrogen is nitrogen that has been cooled to a temperature in the range of -321 degrees to -346 degrees Fahrenheit, which is approximately 77 to 63 degrees Kelvin. Higher temperatures cause nitrogen to boil into a gas and lower temperatures turn it into a solid.
Liquid nitrogen is made of pure nitrogen. It must be kept in specially insulated containers in freezing units to prevent damage to anything nearby and to maintain the liquid's temperature. Vacuum-sealed containers can more easily maintain the temperature of liquid nitrogen. Liquid nitrogen was first discovered in 1883 by a pair of Polish scientists at Jagiellonian University.