The operation of the pipelines to which this chapter applies, for the transportation of crude petroleum, coal, or gas in connection with the purchase or purchase and sale of such crude petroleum, coal, or gas, is a business in the conduct of which the public is interested, and as such is subject to regulation by law. The business of purchasing, or of purchasing and selling, crude petroleum, coal, or gas, which uses in connection with such business a pipeline of the class subject to this chapter to transport the crude petroleum, coal, or gas so bought or sold, shall not be conducted unless such pipeline so used in connection with such business is a common carrier within the purview of this chapter and subject to the jurisdiction herein conferred upon the commission. The attorney general shall enforce these provisions by injunction or other adequate remedy.