I remember it well, I agree. If there isn't any food rotting inside, then the body will not bloat, no gases forming ya see. Drowning victims surface unless they are caught by something. It just depends on how much they have eaten and the water tempurature. But they always float, because of the Gas build up in the stomach cavity.

The confederates were always hungry which meant that the stomach cavity was perpetualy empty. Acids have nothing to eat, they can't make gas.