Abstract: A method and device for automatic surveillance of electrochemical protection on submersible metal structures. The difference in electric potential between the steel structure and at least one electrode, in contact with the ambient water, is detected with a supply of electric alternating current, via the steel structure and a parallel, insulated conductor. The detected values are transmitted to a central monitoring unit recording said values, via said steel structure and said conductor, as a pulse coded signal, superposed upon the supply current, which acts as a system clock.

Abstract: The invention relates to an electrodeposition method for forming a film of an electrochemically synthesizable and functional substance, e.g. Prussian blue useful as an electrochromic material, on an electrode plate having a conductive coating film relatively high in surface resistivity such as a tin dioxide or indium trioxide film. A desired film of uniform thickness can be formed even when the electrode plate is as large as 40 cm square or is still larger by providing the electrode plate with an elongate auxiliary electrode element formed of, for example, a metal wire or foil, which is attached to the outer surface of the conductive coating film so as to extend at least along the whole periphery of the electrode plate.