The finder of a thing may sell it, if it is a thing which is commonly the subject of sale, when the owner cannot with reasonable diligence 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 losing the greater part of its value; or, 2. When the lawful charges of the finder amount to two-thirds of its value.