Liquid Nigrogen

Liquid nitrogen is nothing short of its name; the liquid state of the element nitrogen. The coumpound can be found in the atmosphere under temperatures of 63 K and 77.2 K (-346 F and 320.44 F). Below 63 K, nitrogen freezes into a solid; under 77.2 K, nitrogen becomes a gas.

It is normally obtained from the attmosphere thus making it inexpensive and therefore is rarely refrigerated. Liquid nitrogen is stored in containers known as Dewars and is left to boil away. Since it boils, Laboratories have liquid nitrogen that has been shown to have temperatures of 77.2 K. Liquid nitrogen looks like boiling water, but it is extremely cold; it can be very dangerous to a human when in direct contact but it can be very usefull in science.

Reference: http://education.jlab.org/qa/liquidnitrogen_01.html