Wherever a city of the second class in a county under township organization forms a part of one or more townships in any county, the county board of said county is empowered to create a new township out of said city, whenever requested so to do by a petition or petitions signed by sixty percent of the electors of said city, and also by sixty percent of the electors of the outlying part of the township or townships, of which said city forms a part; Provided, however, that before final action is taken in such matter by said board, two weeks’ notice of the filing of such petition, or petitions, and of the time when and place where a hearing thereon will be had, shall be given by publication in some newspaper published in said city, if any such there be.