CO2 canisters

[macandchz]

well, i bought 1 of those CO2 canister set-ups to do away with mice for mac. i have a few questions before i give it a try. how long do i have to keep the gas going to kill the mouse? if i don't do it long enough can the mouse resusitate itself if mac's slow about eating it? how many uses do you get out of those little re-fill cans? any easy tricks on how to use it? thanks!