From CubicleBot… This container of liquid nitrogen sits at a temperature somewhere below -320° F, meaning that any contact with your skin would result in instant frostbite. However, this dude was able to stick his hand in the liquid for a fraction of a second and remain unharmed due to a phenomenon known as the Leidenfrost effect.
I hadn’t realized that my hand was quite so deep into the liquid. Amazingly, I barely felt the cold at all. My skin didn’t get hurt for the same reason that water droplets dance on a hot skillet. An insulating layer of steam forms almost instantly between the water and the metal, keeping the droplets relatively cool as they float for several seconds without actually touching the hot surface. To liquid nitrogen, flesh is like that skillet—a surface hundreds of degrees above its boiling point. So the moment my hand touched the liquid, it created a protective layer of evaporated nitrogen gas, just as the skillet created a layer of steam. That gave me just enough time to put my hand in and pull it out again. Any longer than that, and frostbite would have set in.
Check out the link below to watch a video of the demonstration, and needless to say, don’t try this at home.