In the Thirty-ninth Judicial Circuit, each circuit judge is hereby authorized to receive as a supplemental salary to that paid by the state a sum equal to 30 percent of the salary paid the judges by the state. The County Commission of Limestone County is hereby directed to pay the supplemental salaries provided herein out of the county general fund. The supplemental salaries shall be in addition to any other salary, compensation, allowance, or expenses provided by law but shall be in lieu of any other supplemental salary paid by the county.