Liquid nitrogen, liquid nitrogen! It is inert, colorless, odorless, non-corrosive, non-flammable, and extremely low temperature. Nitrogen constitutes most of the atmosphere (78.03% by volume, 75.5% by weight). Nitrogen is inactive and does not support combustion. A large amount of endothermic contact during vaporization causes frostbite; nitrogen accounts for 78% of air. Under normal pressure, the temperature of liquid nitrogen is -196°C; 1 cubic meter of liquid nitrogen can expand to 696 cubic meters of pure gaseous nitrogen at 21°C.

Liquid nitrogen is a colorless, odorless, liquid and gas at low temperature under high pressure. Liquid nitrogen (often written as LN2) is a liquid form of nitrogen formed at low temperatures. Nitrogen has a boiling point of -196°C, and liquid nitrogen will form if the temperature is below this under normal atmospheric pressure; if it is pressurized, liquid nitrogen can be obtained at a higher temperature. In industry, liquid nitrogen is obtained by fractional distillation of air. After the air is purified, it is liquefied in a pressurized and cooled environment, and separated by the different boiling points of the components in the air. There is no problem when the human skin is directly exposed to liquid nitrogen. It takes more than 2 seconds to get frostbite and it is irreversible.