The common school fund of the state shall consist of any sums accredited thereto in pursuance of law, of the interest on the school fund proper, which fund is 3% upon the proceeds of the sales of public lands in the State, 1/6 part excepted; and the interest on the surplus revenue distributed by Act of Congress and made part of the common school fund by Act of the legislature, March 4, 1837. The interest on the school fund proper and the surplus revenue shall be paid by the State annually at the rate of 6%, and shall be distributed as provided by law.