Every certificate of sale and instrument of conveyance issued under sections 282.221 to 282.226 shall state that the sale or conveyance does not include any right, title, or interest in or to any iron, coal, copper, gold, or other valuable minerals which may be upon the land therein described, and that these minerals are reserved by the state for its own use; but no instrument shall be effective to transfer any right, title, or interest in or to any such minerals, notwithstanding the failure of the proper officer to insert this statement.