Abstract: The present invention relates to a new type of diaphragm for use in electrolytic cells for the production of hydrogen and oxygen, which diaphragm consists essentially of fluorocarbon polymers which have been oxidized to improve its wettability. According to the present invention the improved diaphragm is characterized in that the fluorocarbon polymers are present in the form of monofilaments, that only the surface of the monofilaments is oxidized, and that the monofilaments are woven into a fabric. In a preferred embodiment the monofilaments have a diameter of less than 0.25 mm in the weft and less than 0.15 mm in the warp. The permeability of gas in the dry state is from 50 to 1000 l.dm.sup.-2.min.sup.-1 when the difference in pressure is 200 Pa. Preferably the monofilaments are evenly spaced to effect even size of the pores between the monofilaments.

Abstract: Magnesium is electrolytically produced from a salt melt comprising magnesium chloride by the use of an electrolyzer having at least one electrolysis compartment and at least one metal separating compartment separated from the electrolysis compartment by a partition wall. Magnesium chloride is fed in solid form in a direction counter current to the flow of chlorine gas liberated during electrolysis to a melting room or chamber in the electrolysis compartment arranged such that contact between the magnesium chloride and the anodes of the electrolyzer is avoided. Flow patterns are produced in the melt to ensure that sludge forming impurities in the fed magnesium chloride are continuously removed from the electrolysis compartment to the metal separating compartment.

Abstract: A replaceable cathode unit, suitable as a module for the building up of stable, non-deformable cathode systems in electrolyzers for the production of magnesium by melted salt electrolysis, is the form of a straight, longitudinal main cathode with active cathode side surfaces and two shorter transverse cathodes arranged approximately at right angles in relation to the main cathode. One transverse cathode is at the front end of the main cathode, and the other transverse cathode is at the back end of the main cathode.

Abstract: Improved active cathodes, prepared by cleaning and etching with nitric acid and activated by a galvanic coating in a bath containing a nickel salt and sulphur liberating component, are provided. The improvement resides in controlled etching and activation conditions.