In addition to the income of the investments of the Public School Fund, the General Assembly shall make provision for the annual payment of not less than one hundred thousand dollars for the benefit of the free public schools which, with the income of the investments of the Public School Fund, shall be equitably apportioned among the school districts of the State as the General Assembly shall provide; and the money so apportioned shall be used exclusively for the payment of teachers' salaries and for furnishing free text books; provided, however, that in such apportionment, no distinction shall be made on account of race or color. All other expenses connected with the maintenance of free public schools, and all expenses connected with the erection or repair of free public school buildings shall be defrayed in such manner as shall be provided by law.