Every contract involving an appropriation shall designate the item on which it is founded, and shall be numbered by the city controller in the order of its date, and charged as numbered against such item, and so certified by him, before it shall take effect as a contract, and shall not be payable out of any other fund, and if he shall certify any contract in excess of the appropriation properly applicable thereto, the city shall not be liable for such excess, but the city controller and his sureties shall be liable in damages for an amount, not exceeding such excess, which may be recovered by the contracting party aggrieved.