Nitrogen (N) is a gas that makes up 64% of the air that we breathe! Liquid Nitrogen is the Nitrogen gas that has been supercooled. That means that the gas got cold and turned into a liquid. When that happens, we get a boiling liquid that is – 196 °C (- 320 °F)! That is Liquid Nitrogen. It boils because the outside air around it is hotter than the liquid, itself. When the Liquid Nitrogen touches something hotter than itself, the liquid vaporizes into a gas. That creates a smoky effect. Liquid Nitrogen is mostly used for keeping things refrigerated or cold. When people are shipping food or other things that need to be kept cold around the world, they use Liquid Nitrogen to keep it cool. Liquid Nitrogen is also used in movies because it gives a foggy, smoky effect in the movie.