A depositary, who believes that a thing deposited with him is wrongfully detained from its true owner, may give him notice of the deposit; and if within a reasonable time afterwards he does not claim it, and sufficiently establish his right thereto, and indemnify the depositary against the claim of the depositor, the depositary is exonerated from liability to the person to whom he gave the notice, upon returning the thing to the depositor, or assuming, in good faith, a new obligation changing his position in respect to the thing, to his prejudice.