When a municipal corporation is the owner of a natural gas plant for the purpose of supplying the citizens thereof with natural gas for fuel, the legislative authority thereof may provide for supplying natural gas, at rates to be determined by it, to persons living outside of and in the vicinity of such municipal corporation, and to county homes, children's homes, and other public institutions within or without such municipal corporation.
To encourage the location or establishment of manufacturing industries within such municipal corporation, the legislative authority may reduce the price of gas to be used to operate such manufacturing, or may donate it for a term of years for such purpose. This section shall be inoperative if the municipal corporation or the citizens thereof are thereby deprived of a full supply of such gas.