When the board of supervisors shall offer for sale the sixteenth section or lands selected in lieu thereof, or any portion of the same, or any part of the five-hundred-thousand-acre grant, the county auditor shall give at least forty days’ notice, by written or printed notices posted in five public places in the county, two of which shall be in the township in which the land to be sold is situated, and also publish a notice of said sale once each week for two weeks preceding the same in a newspaper published in the county, describing the land to be sold and the time and place of such sale. At such time and place, or at such other time and place as the sale may be adjourned to, the county auditor shall offer to the highest bidder, subject to the provisions of this chapter, and sell, either for cash or one-third cash and the balance on a credit not exceeding ten years, with interest on the same at the rate of not less than three and one-half percent per annum, to be paid at the office of the county treasurer of said county on the first day of January in each year, delinquent interest to bear the same rate as the principal. Such county treasurer shall pay to the state treasurer on the first day of February all interest collected.