§ 17. Heirs of patriotic Indian. The heirs of an Indian to whom real property was granted for military services rendered during the war of the Revolution may take and hold such real property by descent as if they were citizens of the state at the time of the death of their ancestors. A conveyance of such real property to a citizen of this state, executed by such Indian or his heirs after March seventh, eighteen hundred and nine, is valid, if executed with the approval of the surveyor-general or state engineer and surveyor prior to January first, nineteen hundred and twenty-seven, and thereafter with the approval of the commissioner of transportation indorsed thereon.