If prior to the date when an ordinance of a general nature passed by the council shall take effect, or within thirty (30) days after the passage of same, a referendum vote should be demanded on same, as hereafter provided, such ordinance shall be submitted to the legal voters of the City of Fort Worth, and the same shall not be effective and valid until the said ordinance shall have been approved by a majority of those voting thereon; provided, that this section shall not apply to mere matters of routine, or emergency measures passed on the ground of urgent public need for the preservation of peace, health, safety or property, by a vote of not less than three-fourths of the City Council, nor to the general appropriation ordinance or bond ordinances.