Council may set aside in a separate fund any money received out of or from the sale, lease or other disposition of any borough property or received from any source unless the money was received or acquired for a particular purpose. The fund must be controlled, invested and administered, and the income arising from the fund expended, in the manner as may be determined by action of the council under the ordinance creating the fund. The ordinance may provide that only the income from the fund may be used or expended and that neither principal nor any part of the principal may be used or expended unless upon authorization of a majority vote of the qualified electors of the borough. The ordinances previously enacted by a borough creating and establishing a separate fund as authorized by this section must be deemed and taken as valid and effectual for all purposes if the other requirements of law concerning the enactment of the separate fund have been complied with.