Not Me wrote:
"Tom Quackenbush"

| I should also mention that CO is heavier than O2 so the atmosphere
| at the bottom of the rat hole will be have increasingly concentrated CO
| levels. If all else fails the critter will have one h*ll of a head ache.
|
| C = 12, O = 16, N = 14
|
| CO = 28, O2 = 32, N2 = 28

The real world physics/dynamics is not quite that simple but sufficient to
say CO is heavier than air and will settle to the lowest level i.e. the
bottom of the rat hole.

Are you sure you're not thinking of CO2?

Carbon monoxide is obviously lighter than air (but not by much). If
you don't believe me, Google for "carbon monoxide lighter air".

R,
Tom Q.