The county commission shall reserve from sale lots and squares of ground, wherever it may be necessary to erect county buildings, and shall, from time to time, order the sale of the residue, prescribing the terms of such sale, and the commissioner shall make such sales accordingly; and when the purchase money shall be paid in full, the commissioner shall execute a deed to the purchaser, as commissioner, for and on behalf of the county, conveying to the purchaser all the right, title and interest of the county to the premises so conveyed, and such deed shall be acknowledged and recorded as other deeds.