Provided that the Collector may at any time invest the whole or any portion of the amount payable as compensation under this Act in any Government securities, and such securities shall be held by the Collector for the benefit of the persons interested, and the persons interested shall be bound to receive such securities with any interest which may have accrued upon them as full payment of the sum which the Collector paid for such securities, and of any sum which he may have paid as expenses incurred in purchasing the same, and of any interest which might otherwise have accrued on such sums.