British Interactive Group - Newsletter Spring 1998

Nitrogen story - urban myth?

From our Internet Correspondent ...

The society of physics students held a roughly annual welcome back party, and, as tradition dictates, we made our own ice cream with liquid nitrogen (77 K) as a refrigerant and aerator. Things were going fine for a while. We spilled a little of the nitrogen onto a table, and watched tiny little drops of it dance around. Then someone asked, “Why does it do that?”

That may have been the point of no return. I, as is traditionally my role, answered that the nitrogen evaporates at the surface of the table, which provides a cushion of air for the drop to sit on, and thermally insulates the drop to minimise further evaporation. So you see a drop dance around without boiling away and without interacting with the table and getting slowed down or smeared out.

Then, I continued ... I mentioned that the same principle makes it possible to dip a wet hand into molten lead, or to drink liquid nitrogen without injury. I had done the latter several years earlier in a cryogenics lab, and remembered the physics behind how it worked. Naturally, people around me were sceptical. But I was sure of myself. I had done it before, and I believed in the physics behind it. So, naturally, I poured myself a glass and took a shot. Simple. Swallow. Blow smoke out nose and mouth and impress everyone at the party.

Within about two seconds, I had collapsed to the floor, unable to breathe or feel anything other than intense pain. Ambulance arrives. Police arrive. Trip to hospital. Try to explain to ER staff exactly how something like this happens. Then I pass out. Wake up next morning connected to many machines, some beeping, others performing more important functions like digesting my food and breathing for me. Turns out that, in accordance with popular belief, you really should not drink the stuff.

I eventually learned a few things about liquid nitrogen. Like ... while you can safely (not true - Ed.) put it in your mouth and blow neat smoke patterns, you should never ever swallow. First off, the closing of the epiglottis prevents the nitrogen gas from escaping, so it is forced into your body instead. Second, your oesophagus naturally constricts around anything inside it, so, even if there is a thin protective gas layer, the oesophagus will find a way to make contact with the liquid nitrogen. Also turns out that my memory was flawed. When I had done it six years ago, I put it into my mouth and didn’t swallow.

The consequences ... my entire upper GI tract, from epiglottis to the bottom of the stomach was badly burned, scarred, and perforated. The gas also expanded quite a bit while inside my body. It filled my chest cavity with several litres of nitrogen gas, which was under enough pressure to collapse a lung. So after what I’m told was a gruelling all-night surgery, they removed part of my stomach, and had my entire digestive system, top to bottom, running on machine power for a while. I also had a breather for the first day or so, until my lung was restored. There are a few details that are considerably uglier which I will spare you. The recovery ... they were impressed with my recuperative skills. After four weeks, I was up and about again. Now, after something like eight weeks, I’m virtually healed, with the exception of a number of unsightly scars. I am the first documented medical case of a cryogenic ingestion. Read the New England Journal of Medicine. Three articles are in review now, and will be published soon, I’m told.

I don’t like letting the above go without a warning - you never know where BIG Newsletters end up! Tricks with liquid nitrogen are not a joke. Skin and very cold temperatures don’t mix. Before you demonstrate, know what to do and what not to do. Practice safe science. Ed.

Newsletter Spring 1998 Contents



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