My buddy yoyojedi got quite the score at the last U.W. public auction: a 35 liter dewar, for only $150! The folks at Central Welding (our preferred purveyors of liquid nitrogen) had never seen one so big. But that didn’t stop them from filling it for us. Just halfway, thanks.
Handling LN2 is a somewhat tricky business. First there is the obvious threat of burns and frostbite when handling a substance at -321 °F. Since it has an expansion ratio of nearly 1:700, there’s also the possibility of explosion if it is stored improperly (hence the use of a proper dewar rather than, say, a thermos). Then there’s the threat of asphyxiation, should enough of the liquid turn to gas in a closed space (for example, an automobile). But none of this deterred us as we happily purchased about 12 liters of the stuff.
(Yes, we rode just a short distance with the windows down.) Fortunately, all went well and many fun freezing adventures were had by all. I was so happy with the day that I got myself a pony keg of argon to celebrate. I gotta say it was a GOOD DAY.