Abstract: Process for the manufacture of an aqueous solution of sodium hydroxide by electrodialysis of an aqueous solution (15) of a sodium salt derived from an acid of pK lower than the pK of carbonic acid, the solution being obtained by circulating an aqueous solution of the said acid (14) and an aqueous solution of sodium carbonate (13) on either side of a cationic membrane (12).

Abstract: Process for the manufacture of sodium hydroxide, according to which an electrodialysis cell is used, water or an aqueous sodium hydroxide solution (10, 10') is introduced into a chamber (6, 6') of the cell, defined between a cationic membrane (2, 2') and an anionic face (8, 8') of a bipolar membrane (3, 3'), an aqueous sodium carbonate solution (11, 11') is introduced into a chamber (7, 7') defined between a cationic face (9, 9') of the bipolar membrane (3, 3') and another cationic membrane (2', 2"), an alkaline pH is maintained in the chamber (7, 7') which is supplied with the sodium carbonate solution (11, 11') and an aqueous sodium hydroxide solution (12, 12') is drawn off from the chamber (6, 6') containing the anionic face (8, 8') of the bipolar membrane (3, 3').

Abstract: Forced air space heating fireplace having a metal casing defining a combustion chamber with an opening facing a room to be heated. Air flow tubes are provided beneath the floor of the combustion chamber and at the top, the air flow tubes being interconnected by lateral air flow tubes then lying outside the casing. The interconnection is such that the tubes form a continuous air flow path having an air inlet connected to a blower, which draws fresh air from outside the room to be heated, and two air outlets disposed laterally of the casing and opening into the room to be heated. In one form, the lateral flow tubes are encased in an insulating brick construction. In an other alternative, they may be contained in a jacket surrounding the casing and also including the top air flow tubes.

Abstract: The invention relates to a process for the electrolytic production of hydrogen in an alkaline medium.The process consists in using a cathode, the active surface of which essentially consists of an oxide compound of the spinel type.The process is suitable, in particular, for the electrolysis of aqueous solutions of sodium chloride in cells with a permeable diaphragm.

Abstract: An electrolytic cell having an anode compartment and a cathode compartment separated by a porous diaphragm. The cell has inlet and outlet pipes for electrolyte. A valve controls the supply of electrolyte. A gas outlet-pipe is connected to the anode compartment or to the cathode compartment. A valve is disposed in the gas outlet-pipe and is variable as to its opening. A vessel in the cell has an upper part thereof in communication with the gas outlet-pipe upstream of the valve and a lower part of the vessel is in communication with the compartment to which the gas outlet-pipe is connected. A float in the vessel is operatively connected with the valve in the gas outlet-pipe and progressively closes as it rises and opens the valve as it moves downwardly in response to electrolytic height variations. The valve is in an intermediate, partially closed position during normal operation of the cell during which the cell is partially filled with electrolyte.

Abstract: A diaphragm cell for use in the electrolysis of an aqueous solution of alkali metal chloride. The cell is provided with a chamber divided by a diaphragm into an anode compartment having at least one anode therein and a cathode compartment having at least one cathode therein. The cathode has a catalytic surface different from the active surface of the anode. The cathode surface is made of a material which catalyses the decomposition of hypochlorite ions.