§ 9. "The drawback payable on the exportation or shipment as stores of any chicory, coffee, or tobacco, or in respect of any molasses delivered by a refiner to a licensed distiller for use in the manufacture of spirits, and the allowance payable to a refiner in respect of any molasses used solely for the purpose of food for stock, shall be reduced by an amount not exceeding one-sixth of such drawback or allowance if the duty charged on such chicory, coffee, or tobacco, or on the sugar from which such molasses was produced, was a duty of Customs or Excise less than the existing duty."