Each of said commissioners shall hold office for a term of four years, and until their successors are duly appointed, but nothing herein contained shall be construed to render a commissioner who has faithfully performed his duties ineligible for reappointment. No member of said commission shall receive any compensation for his services as commissioner, but each commissioner shall be entitled to receive his actual disbursements for expenses in performing the duties of his office, and an account of which expenses, shall be approved by the chairman and paid by the State Auditor as other claims authorized by law.