The Secretary of the Treasury is authorized and directed to pay, out of the moneys heretofore or hereafter covered into the Treasury from deposits made by individuals to cover cost of work performed and to be performed in the offices of such agency as the Secretary of the Interior may designate in connection with the survey of mineral lands, any excess in the amount deposited over and above the actual cost of the work performed, including all expenses incident thereto for which the deposits were severally made or the whole of any unused deposit; and such sums, as the several cases may be, shall be deemed to be annually and permanently appropriated for that purpose. Such repayments shall be made to the person or persons who made the several deposits, or to his or their legal representatives, after the completion or abandonment of the work for which the deposits were made, and upon an account certified by the office of such agency of the district in which the mineral land surveyed, or sought to be surveyed, is situated and approved by the Secretary of the Interior or such officer as he may designate.