Before any such bonds shall be issued the mayor and council shall, by ordinance, provide that said bonds shall be issued, which said ordinance shall fix the maximum amount of said bonds and in a general way the purposes for which said money shall be expended and shall submit the question to issue bonds to the voters of the city. The ballots shall state the maximum amount of bonds proposed to be issued and the fact that such bonds are not to be payable from taxation and will not be a debt of said city and the general purpose for which they are to be issued. If the majority of voters voting on the question assent, the mayor and city council may, by ordinance, cause such bonds of such municipality not exceeding the maximum amount submitted to the voters to be issued for the purpose set out in said ordinance and secure the same as herein provided.