There is established a revolving fund for the purpose of administering the funds appropriated for stationery allowances to each Representative, Delegate, the Resident Commissioner from Puerto Rico; and stationery for use of the committees, departments, and officers of the House. All moneys hereafter received by the stationery room of the House of Representatives from the sale of stationery supplies and other equipment shall be deposited in the revolving fund and shall be available for disbursement from the fund in the same manner as other sums that may be appropriated by the Congress for this purpose. The unexpended balance of all moneys heretofore received by the stationery room of the House of Representatives from the sale of stationery supplies and equipment shall be deposited in the Treasury of the United States to the credit of the fund: Provided, That the unexpended balances in the appropriations "Contingent expenses, House of Representatives, stationery, 1945–1946"; "Contingent expenses, House of Representatives, stationery, 1946"; "Contingent expenses, House of Representatives, stationery, 1947–48", as of June 30, 1947, shall be transferred to and made available for expenditure out of the fund, together with appropriations herein or hereafter made therefor, to remain available until expended.