When so requested by any party interested, the commission shall rule upon any question of substantive law properly arising in the course of any proceeding before the commission or any member or members thereof, and any party interested aggrieved by such ruling may object thereto, and may secure a review as hereinafter provided. Any failure or refusal of the commission to rule upon such question at or prior to the entry of a final order or decision shall be taken and recorded as a ruling adverse to