No president, director, officer, agent or employee of any railroad or canal company, shall be interested, directly or indirectly, in the furnishing of material or supplies to such company, or in the business of transportation as a common carrier of freight or passengers over the works owned, leased, controlled or worked by such company. Nor in any arrangement which shall afford more advantageous terms, or greater facilities than are offered or accorded to the public. And all contracts and arrangements in violation of this section shall be void.