The salaries fixed by the commission for its officers, experts, engineers, statisticians, accountants, inspectors, clerks, and other employees, and fixed by Code Section 45-7-4 for Commissioners, shall be paid monthly from the funds provided for the use of the commission after being approved by the commission. All expenses incurred by the commission, including the actual and necessary traveling and other expenses and disbursements of the Commissioners, and of officers and employees, incurred while on business of the commission, shall be paid from the funds provided for the use of the commission after being approved by the commission. The necessary expenses of conducting the business of the commission and the salaries of the Commissioners shall be provided for by appropriations made for such purposes. The funds assessed and collected as provided in Code Section 46-2-10 shall be specially designated as the Public Service Commission Fund and shall be expended only as provided and directed in this title.