When a dealer or dealers in coal in cities or towns where public sales are kept may be requested by a person or persons buying as much as 500 pounds of coal at any one time to weigh such coal upon the public scales, such dealer or dealers shall do so. The person or persons buying the coal shall pay the fee for weighing the same if such is of proper weight; otherwise, such fee shall be paid by the dealer. Any dealer refusing to weigh or to have weighed such coal as required in this section or to pay such fee for weighing the same as required by this section shall be guilty of a misdemeanor.