The county board of the several counties of the state may appropriate to the county general fund any county sinking fund in the county treasury not levied for the payment of any bonded indebtedness; also any county money from whatever source, excepting the money levied for school purposes, that remain on hand in the county treasury and are no longer required for the purposes for which same were levied; Provided, the county commissioners of the several counties of the state, not under township organization, may appropriate any unexpended balance remaining in the county treasury to the credit of any such precinct (such balance having accrued by reason of taxes collected from a precinct levy for the payment of bonds, after such bonds are paid), to the school districts within such precinct, apportioning such unexpended balance to the several school districts in the said precinct according to the property valuation of the several school districts, as found by the assessor for the year next preceding such appropriation. Where such unexpended balance accrued by reason of taxes collected from a precinct levy for the payment of bridge or irrigation bonds, the county boards of the several counties of the state, not under township organization, may appropriate such unexpended balance remaining in the county treasury to the credit of the road fund of the commissioner district of which such precinct forms a part, to be expended for the improvement of roads, within the limits of such original precinct wherein such taxes were collected.