There is established a working capital fund, to be available without fiscal year limitation, for expenses necessary for the maintenance and operation of (1) a central reproduction service; (2) a central visual exhibit service; (3) a central supply service for supplies and equipment for which adequate stocks may be maintained to meet in whole or in part the requirements of the Department; (4) a central tabulating service; (5) telephone, mail, and messenger services; (6) a central accounting and payroll service; and (7) a central laborers’ service: Provided, That any stocks of supplies and equipment on hand or on order shall be used to capitalize such fund: Provided further