The revision of boundary lines provided for in this chapter shall be made only at a meeting of the board of port commissioners with attendance of all of the members of the commission, which meeting shall be public, following notice of said meeting, and the purpose thereof published in a newspaper of general circulation within the port district, or, if there be no such newspaper published within the district, in a newspaper published at the county seat of the county in which such port district is located. Such notice shall be published not less than twice, the date of the first publication to be not less than fifteen nor more than twenty days prior to the date fixed for said hearing, and shall state the time, place and purpose of the hearing.