All lots in such townsite which were unoccupied within the meaning of the said acts of congress at the time of the entry of said townsite in the United States land office shall be sold by such judge or under his or her direction, at public auction to the highest bidder for cash, each lot to be sold separately, and notice of such sale, or sales, shall be given by posting five written or printed notices in public places within said townsite, giving the time and particular place of sale, which notices must be posted at least thirty days prior to the date of any such sale, and by publishing a like notice for four consecutive weeks prior to any such sale in a newspaper published in such town, or if no newspaper be published in such town, then in some newspaper having general circulation in such town. And deed shall be given therefor to the several purchasers: PROVIDED, That no such unoccupied lot shall be sold for less than five dollars in addition to an assessment equivalent to assessment provided for in RCW 58.28.300, and all moneys arising from such sale or sales after deducting the cost and expenses of such sale or sales shall be placed in the fund hereinbefore mentioned.