The company shall have the power to contract with the holders of any of its bonds as to the custody, collection, securing, investment and payment of any money of the company, and of any money held in trust or otherwise for the payment of bonds, and to carry out such contract. Money held in trust or otherwise for the payment of bonds or in any way to secure bonds and deposits of money may be secured in the same manner as money of the company, and all banks and trust companies are authorized to give security for the deposits.