And be it further enacted That no Retailer or Shopkeeper shall be permitted to ship any Salt to be sent to any Port or Places within this Kingdom of England Dominion of Wales and Town of Berwick upon Tweed before he hath made it appear by Oath or otherwise before the Commissioners for collecting of the said Duties granted by this Act or their Officers or some or one of them (which Oath they have hereby Power to administer) that the Duty of such Salt is paid or secured to be paid or that it was bought of some other Retailer or Shop-keeper that hath paid the Duty.