But the salt circle would have to have a break in it so the
demon could enter in the first place; and it would have to be structured sort
of like a lobster trap so that the aperture is easy to spot from outside, but
hard to find again once you’re in the trap. Alternately, you could just mix
some soda and holy water and leave it out to poison the demons. It all depends
on whether you’re trying to destroy them or live-trap them.