Pouring liquid nitrogen into a dirty container - GIF

[wesser1]

Grew up near a helium mine ("well", maybe?) and they used to come to my middle school and do demonstrations. The man doing the demonstrations was the father of a classmate and he would bring him up on stage to assist. Witnessed a frozen banana drive a nail into a board, a frozen inflated balloon shrivel up into a raisin and then come back to life, a sponge ball bounce and then shatter when thrown down after a liquid nitrogen bath. But the most impressive feat of all was after all this he would pour the liquid nitrogen over his son's outstretched palm without causing harm. Explained that the nitrogen evaporating from the heat of his hand formed a vapor barrier that the liquid flowed over as they both fell to the floor. Also explained that if the hand was stuck into the liquid nitrogen then the hand would be frozen instantaneously. I wouldn't advise doing either and have probably forgotten some trick to the hand pouring trick in the 50 years since this demo, so DO NOT TRY THIS AT HOME!!!