Section 1. From and after the passage of this Act, the salary of the County Superintendent of Public Instruction of each county in Texas having a population of not less than twenty-two thousand, one hundred (22,100) and not more than twenty-two thousand, five hundred (22,500), according to the last preceding Federal Census, shall be Thirty-six Hundred Dollars ($3600) per annum, to be paid in equal monthly payments out of the county's available per capita apportionment coming to such counties, upon the order of the County School Trustees.