For the purpose of meeting disbursements for annuities and other payments in excess of the receipts, there shall be kept available by the treasurer of state an amount not exceeding ten per cent of the total amount in the funds provided for by this chapter on deposit in any bank or banks in this state, organized under the laws thereof, or under the laws of the United States, or with any trust company or trust companies incorporated by the law of this state. Said banks or trust companies shall furnish adequate security for said deposit. The sum so deposited in any one bank or trust company shall not exceed twenty-five per cent of the paid-up capital and surplus of said bank or trust company.