Whenever there remains in the treasury of any county an unexpended balance of any special fund, and all claims against such funds have been fully paid, and the purpose for which it was created has been fully observed, and there remains no further use for such balance for the purpose for which it was created, it shall be lawful for the board of county commissioners of such county to transfer such balance to any other fund of the county or subdivision to which such balance belonged.
R.L. 1910, § 1614.