Excise duty exemption limits payable duties on specified refinery clearances by exempting amounts in excess of a capped portion. Exempts from excise duties on Fourth Schedule goods cleared from four specified refineries that portion of each listed duty in excess of an amount calculated at fifty per cent of the duty, so that fifty per cent of each listed duty remains leviable; the exemption also applies where such goods are removed under bond to a warehouse and subsequently removed from the warehouse on payment of fifty per cent of the duties.