Mont. Code Ann. § 70-5-201
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:
History: En. Sec. 2525, Civ. C. 1895; re-en. Sec. 5183, Rev. C. 1907; re-en. Sec. 7690, R.C.M. 1921; Cal. Civ. C. Sec. 1869; Field Civ. C. Sec. 943; re-en. Sec. 7690, R.C.M. 1935; R.C.M. 1947, 20-406.