 Liquid nitrogen can be used to condense the oxygen from the air. Liquid nitrogen boils at minus 196 degrees Celsius, which is a lower temperature than the boiling point of liquid oxygen, which is minus 183 degrees Celsius. We add liquid nitrogen to the metal cup. The cup cools down to minus 196 degrees Celsius. The oxygen condenses from the air and drips off the bottom of the metal cup. We collect that in the styrofoam cup.