This happens because the temperature at which oxygen changes from a gas to a liquid is about 13 degrees Celsius above that of nitrogen. The oxygen can be seen dripping from the can just as on a humid day you can see drops of water condense and drip from a can you take from the refrigerator.
Though you technically can join the military up to age 42, if you're 35 or over you'll need an age waiver if you've never been in the military before.
Quick Answer. The cutoff age to join the military differs in each branch. As of January 2015, it is 34 for the Army and Navy. It is 29 for the Marines, 39 for the Coast Guard and 27 for the Air Force. The limits may change based on prior or reserve service.