Sirius is very close to right. What happens is that you
end up with a very small,
dim, round
flame on a
wick. It sometimes gets just enough
oxygen through the
methods mentionned by Lockheart, but often it just
chokes out.
Interestingly enough, though
diffusion does eventually move all the air around, it's slow enough that
shuttles have
fans to prevent
carbon-dioxide pockets from forming around
astronauts.