If the owner of any such land shall not redeem the same within the period aforesaid, it shall thereafter be lawful for the commissioners to sell any such land, by public sale, and make a deed therefor to the purchaser, which shall be available in law, as well against the county as against the person or persons as whose estate the same had been sold, but no tract shall be sold for a sum less than the amount of taxes, costs and interest which shall be due at the time of such sale by the commissioners, and such land shall thereafter be charged by the township assessors in the name of such last purchaser or redeemer, as other lands of equal value may be charged, and shall again be liable to be assessed and sold for taxes, agreeably to this act and the act¹ to which this is a supplement.