Section 31. The treasurer, at least three weeks before the time of the sale of a pew for taxes, shall post a notice of the intended sale on the principal outer door of the meeting house, stating the number of the pew, if any; the name of the owner or occupant, if known; and the amount of the tax due thereon; and if any part of said tax remains unpaid at the time of sale, he shall sell the pew by public auction to the highest bidder and shall execute and deliver to the purchaser a bill of sale thereof. The money arising from the sale, in excess of the taxes and reasonable incidental charges, shall be paid by the treasurer to the former owner of the pew.