LN2, im not sure cos normally its not accesible to consumers..
Its just like all those acids and chemical stuffs..
If u happen to know somebody working at science lab, i think this might come handy..
Hmm, maybe i jus give my buddy a call and try asking if he could get his hands on LN2..

some funny thoughts to share..

Dry Ice Obligatory Warning
Madshrimps ©

Carbon dioxide is heavier than air and it can concentrate in low areas or in enclosed spaces (like a car or a room where dry ice is sublimating). Normal air is 78% Nitrogen, 21% Oxygen and only 0.035% Carbon Dioxide. If the concentration of carbon dioxide in the air rises above 5%, carbon dioxide can become toxic.

Arj, u sure u r not toxicated 
Any clue where did u get those big blocks of DI..