Every corporation, joint stock company, limited copartnership, partnership or other person, now or hereafter engaged in the business of carrying or transporting natural gas for hire, for compensation or otherwise, by pipeline, or pipelines within this state, and by virtue of and in conformity to, any valid law incapable of revocation by any law of this state or of the United States, or by virtue of and in conformity to the provisions of this act,¹ shall be a common carrier thereof as at common law, and no such common carrier shall allow or be guilty of any unjust or any unlawful discrimination, directly or indirectly, in favor of the carriage, transportation or delivery of any natural gas, offered to it, in its possession or control, or in which it may be interested, directly or indirectly, and provided further, that any person, firm or corporation owning or operating a natural gas pipeline within the limits of any incorporated city or town in this state shall be exempted from the provisions of this section only as to its distributing lines located wholly within the corporate limits of said city or town; and provided further, that any person, firm or corporation engaged in gathering natural gas in this state shall be exempted from the provisions of this section as to such gathering activities and instead shall be subject to the provisions of Sections 2 and 3 of this act.²