All necessary preliminary expenses actually incurred by the governing body in the making of surveys, estimates of costs and revenues, employment of engineers or other employees, the giving of notices, taking of options and all other expenses of whatsoever nature, necessary to be paid prior to the issue and delivery of the revenue bonds pursuant to the provisions of sections 91.620 to 91.770, may be met and paid in the following manner: Said board or governing body may from time to time certify such items of expense to the governing body, directing the payments of the several amounts thereof, and thereupon the proper officer shall at once draw a warrant or warrants upon the governing body, which warrant or warrants shall be paid out of the general funds of said governing body not theretofore appropriated, without a special appropriation being made therefor; or, in case there are no general funds of such city not otherwise appropriated, the governing body may temporarily transfer from other funds of such governing body a sufficient amount to meet such items of expense, or the making of a temporary loan for such purpose, and such governing body shall thereupon at once make such transfer of funds, or authorize such temporary loan in the same manner that other temporary loans are made by the governing body; provided, however, that the fund or funds of such governing body from which such payments are made shall be fully reimbursed and repaid by said board out of the first proceeds of the sale of revenue bonds herein provided for, and before any other disbursements are made therefrom, and the amount so advanced to pay such preliminary expenses shall be a first charge against the proceeds resulting from the sale of such revenue bonds until the same has been repaid as herein provided.