Gas Chambers

[Vengeance]

I was thinking about how to setup a gas chamber for when I start breeding my Feeder rats. I would much rather prefer to use co2 over whacking. But because I won't be having a huge production line of rats to euthanize, using co2 canisters could get expensive. So I was trying to brainstorm some other ideas on how to setup a gas chamber and was wondering what you guys would think of the following idea, would it be considered humane or not?

Basically my idea is to use a large air tight jar or container and instead of introducing co2 into the environment and pushing the o2 out. What about burning the o2 out of the air and replacing it with co2? Basically I'd want to secure an area that the mouse/rat would not be able to access by suspension or other means (I haven't figured this part out yet) and use a clean burning substance such as isopropyl alcohol and basically light the fuel, close the lid and allow the flame to burn off all the o2 in the container and replace it with co2. Now because I would use a clean burning fuel I wouldn't have to worry about smoke inhalation being the cause of death. But I was wondering if anyone had any thoughts on if the o2 would be burned from the air too quickly thus causing the burning sensation on the eyes and lungs or would the heat produced by the flame heat up the air to a point that it would cause allot of discomfort to the mouse/rat?

Any opinions on this matter would be great, also keep in mind I'm currently not using this method, only brain storming ideas for cheap ways to euthanize mouse/rats using a co2 method.