Subject to the Provisions of this Act, the Feu Duties which shall become payable under any Contracts, Dispositions, or Charters of Feu, or Writs by Progress, and the Rents under any Building Leases, to be granted in virtue of this Act, shall in all Time thereafter belong to the Minister, and shall be held and enjoyed by him in lieu and place of the natural Possession of such Glebe, or the Rents, Mails, Duties, and Profits of the same, and subject always to the Burden of Payment of Interest on the permanent Burden after referred to, so long as it subsists : Provided that after feuing out or letting on Building Lease or selling the said Subjects or any Part thereof, in virtue of this Act, it shall not be competent for the Minister or his Successors in Office, to make any Demand upon the Heritors, for providing him in a Glebe or in any Portion of Land in lieu of the Glebe Land so feued, leased, or sold : Provided always, that nothing herein contained shall preclude or prejudice any Claim which the Minister may have to any additional Glebe that might have been competent to him if this Act had not passed.