Sec. 5. COUNTIES OF 23,000 TO 23,400; 17,600 TO 17,650; 15,700 TO 15,730. That the salary of the county superintendent of public instruction in all counties in Texas having not less than twenty-three thousand, three hundred (23,300) nor more than twenty-three thousand, four hundred (23,400) population, according to the last preceding Federal Census, and in all counties having not less than seventeen thousand, six hundred (17,600) nor more than seventeen thousand, six hundred and fifty (17,650) population, according to the last preceding Federal Census; in all counties having not less than fifteen thousand, seven hundred (15,700) nor more than fifteen thousand, seven hundred and thirty (15,730) population, according to the last preceding Federal Census, shall be, from and after the effective date of this Act, Two Thousand, Six Hundred Dollars ($2,600) per year to be paid in twelve equal payments out of the State and county available school fund of such counties.