The finder of a thing may sell it, if it is a thing which is commonly the subject of sale, when the owner, with reasonable diligence, cannot be found, or, being found, refuses upon demand to pay the lawful charges of the finder in the following cases:
1. When the thing is in danger of perishing or of losing the greater part of its value; or 2. When the lawful charges of the finder amount to two-thirds of its value.