All contracts, bonds, and other instruments of writing in which the city is concerned shall be prepared in the office of the city solicitor, and he shall receive for the city a reasonable fee from the persons for whom such contracts, bonds, or instruments may be drawn, to be fixed by ordinance, and he shall approve all security required to be given for the protection of the city, and a proper registry shall be kept by him of all such contracts, bonds, and instruments.
53 P.S. § 12464