A master forfeits the dominion over his slaves whom he hath abandoned.
Gist of Idea
A master forfeits ownership of slaves he abandons
John Locke (Second Treatise of Government , 237)
How often did slave owners take a day off, I wonder? Presumably slaves will take back their freedom, even if the masters haven't 'forfeited' their ownership, so Locke's point is fairly academic.
Locke,John: 'Two Treatises of Government' [Everyman 1988], p.239