All ordinances shall be presented in writing, and no ordinance shall be so amended in its passage as to change its general purpose. No ordinance shall be considered for final passage at the meeting at which it is introduced, unless by unanimous consent entered of record. No ordinance shall contain more than one subject, which shall be clearly expressed in its title; nor shall any ordinance be passed by the council unless a majority of all the members elected to the council shall concur therein by yeas and nays when the question is put upon its passage.