Yeah, you're right - it works if you dip them in it for ages
it doesn't if you pour it on, because the constant vapourisation at the surface means a layer of gas between the tube and the liquid for the duration and vapour is a rubbish conductor. I've poured the stuff onto my bare hand before for the same reason. Although I wouldn't recommend it, kids.
( the mighty badger Aphrodite, on a bar stool, by your side, Wed 21 Sep 2011, 13:58, 1 reply)

Good tricks with LN2
#341: Fill a foam polystyrene bucket with the stuff, drop a rubber bung in and then reach in and pick it out with your bare hand. Note: long arm hairs can penetrate the vapour barrier, let the liquid through and sting like hell.
(ubergeekian, Wed 21 Sep 2011, 16:38, closed)

Since my research group is more biology than anything else these days
it's the dry ice for the pranks. You'd have thought, with my supposed maturity and seniority, I'd have stopped putting dry ice in other people's tea, wouldn't you?
( the mighty badger Aphrodite, on a bar stool, by your side, Wed 21 Sep 2011, 17:26, closed)