T w e n t y S i d e d
Here is a YouTube video where a guy brings a big bowl of liquid nitrogen to a swimming pool and throws it in, thus forming a cool mist and maybe a very temporary layer of thin ice on the surface. Then a girl jumps in. Can you spot the dangerous part of this stunt?
No, it’s not the girl jumping in, which is what everyone around the pool was worried about. In that much (probably warm) water, the temp would have been back to safe levels after just a few seconds. Sure, the water was cold, but (crazy) people jump into freezing water all the time. The REAL daredevil in this thing is the guy who brought in the open bowl of nitrogen. It will freeze your skin on contact, and he’s carrying it around in a salad-bowl sized container which is filled to the brim. He’s wearing sandals, a t-shirt, his arms are bare and he has nothing really protective on anywhere. If he’d tripped it could have disfigured him, although his glasses would have saved him from eye damage.
Who has the capacity to obtain liquid nitrogen but can’t be bothered to get a practical container? Nobody would behave this way with corrosive acid, even though both can be equally dangerous to unprotected skin.
UPDATE: My questions about the sandals are answered below, where I also learn that this movie was filmed at Penguicon.
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I’ve been told (though have no interest in trying it myself) that liquid nitrogen splashed on skin is not so much of a problem because it will evaporate so quickly from your body heat and the vapor barrier will prevent a significant transmission of heat. The problem is more touching things (metal etc) that conduct the cold rapidly from the liquid nitrogen to you.
See e.g. http://www.biotech.ufl.edu/EM/data/ln2.html recommending sandals and recommending against non-sandal footwear when dealing with liquid nitrogen.
BTW, I have handled liquid nitrogen in salad bowls: a fun way to make ice cream is to start with a standard ice cream mix in a bowl, pour in liquid nitrogen, and stir. But when I’ve done it we haven’t been carrying the bowl around and it wasn’t filled brim-full.
I saw a recent Iron Chef (the American version) where a chef used liquid nitrogen to make a quick batch of ice cream. Very theatrical. Now I want some.
as has already been stated, the nitrogen evaporates the instant it touches you. I’ve seen people gargle the stuff (seriously) without any ill effects.
Here’s another example for you. I grew up on a dairy farm and my folks frequently used AI to breed the animals. The straws are kept in big tanks of liquid nitrogen until they are ready to use. A guy came every couple of months and topped off the tank. One time he knocked over a container and a bunch of straws fell to the bottom of the tank. He just shrugged and thrust his bare arm in the tank and pulled them out. I was amazed – I figured it must have caused permanent damage (or at least a lot of pain). He said it didn’t bother him, he did it all the time. I was never brave enough to try it myself.
I thought there would be a danger in the lack of breathable air hanging over the surface of the water. It’s pure nitrogen, right? When the swimmer jumped in, the cloud moved away, so I thought: no problem. Then he swam casually into the vapor and still seemed to suffer no ill-effects.
How come?
Wow. Learn something new every day.
Okay, so sandal-bot wasn’t risking his skin. Still, I wouldn’t try it myself. Yikes.
Carl the Bold – that mist isn’t “pure” nitrogen, it’s little droplets of evaporating liquid nitrogen. And while the nitrogen content of the surrounding air *might* increase slightly, the effects would probably be negligable – remember air is already 70% nitrogen.
Actually, in this case (nice warm pool, lots of water vapour) the fog you see is probably just that – fog. As in water vapour lowered to the dew point in temperature. It was clearly a warm night and the liquid nitrogen would have cooled the air immediately above the pool by quite a bit as soon as it hit the water – almost certainly reaching dew point in just a few moments.
As for a danger from the nitrogen… in open air like that it would mix with the surrounding air so rapidly that you’d never even notice the difference. Now, do that with a big bowl of Halon and you might have yourself a problem since it is heavier than air! Luckily Halon is a bit hard to come by these days (it’s outlawed).
I find dipping your hand into molten lead is more impressive. ^_^
The time I was involved in liquid-nitrogen-ice-cream-making, the person pouring the liquid nitrogen had her hands in oven mitts as she carried the container of liquid nitrogen over to the table where the mixing would take place. I helped mix a fair bit, but let someone else add the liquid nitrogen as needed.
Aside from the oven mitts, she wasn’t wearing much. Loincloth and sandals was about it. Oh, and a bit of body paint.
There is at least one account of someone swallowing a decent quantity of liquid nitrogen, doing serious harm to his upper digestive tract in the process, whilst attempting to do the old smoke-from-the-nostrils trick.
I can’t find it at the moment, alas (it got written up in a medical journal afterwards as I recall), but the site I’ve linked to above is pretty nifty.
I would probably need a dewar before I did this, but those suckers are expensive. A 4-L dewar is $500 or so.
Now you want to have fun, use liquid helium. I still remember the day our OrgChem prof was talking about our NMR machine. He said if you ever heard it’s dewar going “spit-spit”, leave the room quickly. The NMR was in a (positive pressure) room about 15′ by 20′ or so, and it doesn’t take too much liquid helium to displace all that oxygen really fast. Sure, it probably wouldn’t kill you since the helium would be displaced quickly, but I still wouldn’t want to be in there.
As others have said, handling liquid nitrogen is not actually that dangerous, at least spilling it on you isn’t. What was a bit daft was using a metal bowl and a towel to handle it. That metal bowl would quickly get to 77 Kelvin and any contact with it would cause damage.
I love seeing all the places where this video pops up! I was standing right behind the cameraman when this was filmed. It took place at Penguicon 4.0 in Novi, MI last year (a linux/sci-fi convention … where else would someone be carrying around a salad bowl of liquid nitrogen?) They were making ice-cream with it, and had a bunch left over.
Darn, the rally cool stuff has already been pointed out (even the dipping-bare-hand-in-molten-lead thing).
OK, 2 little tidbits: the guy I saw doing those tricks (I didn’t watch the linked videos, so it might be a different guy) did the hand-in-lead thing, and end up with a few nasty scars… elsewhere on his body, where the liquid lead splashed on him. His hand was fine. Also, he quit doing the “blow ligsuid nitrogen” thing… after having done it many times with no problems, he once screwd up and let the stuff hit his teeth… “spiderweb cracking” probably isn’t a direct quote, but it gets the point across. Ouch.
So, yeah, doing that stuff is “safe”… it’s the possibl side-effects that are dangerous. (Oddly enough.)
A big “thank you” to commenter Kevin for pointing out that this video took place at Penguicon. Failing to put our URL of penguicon.org as a caption on this video is one of the biggest promotional mistakes we’ve ever made.
Anyway, I’ve put liquid nitrogen on my bare skin without much ill effect. It forms a surface of gaseous nitrogen between the liquid and your skin. In fact, clothing holds it to your body, making it much more dangerous that way.
I read the account of someone tswallowing liquid nitrogen that Jorpho mentioned. It was in a Darwin award book (although the guy didn’t die).
I’m the one who was holding the bowl. LN2 is about as dangerous as boiling water: it’s something to respect but not the huge danger movies make it out to be.
Here’s a brief analysis I did of the various dangers for the penguicon concom:
http://www.penguicon.org/pipermail/concom/2006-April/001044.html
Cool. As you said in the linked article, “We tend to fear the new and unknown.”
Thanks for the little LN2 lesson.