If any warrant presented to the city controller contains an item for which no appropriation has been made, or there shall not be a sufficient balance of the proper fund for the payment thereof, or which for any other cause should not be approved, he shall notify the proper department of the fact, and if the city controller shall approve any warrant contrary to the provisions hereof, he and his sureties shall be individually liable for the amount of the same to the holder thereof.
53 P.S. § 12428