Student drinks liquid nitrogen...and survives

Putting a small amount of liquid nitrogen on your tongue does not cause any trouble, as long as you don't swallow it. I have a friend who used to do this frequently. See a comment I made elsewhere on this story for more details

That was his point -- having liquid nitrogen in your mouth is safer than it sounds, since you get a gas layer insulating the liquid from the rest of your mouth.

But in addition to the danger of accidentally swallowing, I've also heard stories of people having teeth crack by doing this; so I'd say that "safer than it sounds" is still far from "safe".

From what I could gather, it's a common parlour trick in his circles to pour liquid nitrogen into your mouth, at which point it will sort of stay on your tongue (above an air cushion that protects the tissue) until it's evaporated. But this time he swallowed, and once it's inside your body the vapour cannot escape into the room as it expands, creating horrific amounts of pressure on your insides.

> "Michael performed a stunt he and other students and teachers have been doing for years," says Thomas Keil, professor and head of WPI's Physics Department. "Only this time, for some reason, he swallowed the liquid nitrogen. That turned a trick into a life-threatening medical emergency."

The evaporating liquid nitrogen creates a buffer of nitrogen gas between the liquid nitrogen and your mouth. Nitrogen gas conducts heat very poorly, so you won't get burned, as long as you're careful.

Swallowing the liquid nitrogen is different, because the nitrogen gas is trapped inside your body. According to the article, they estimate that the liquid nitrogen he swallowed expanded to "3 or 4 liters" of nitrogen gas. That won't fit in your stomach, so it will go to other parts of the body, rupturing tissue as it goes. That's what hurt him -- 3-4 liters of nitrogen gas gave him ruptured organs.