Abstract: For the production of a gaseous mixture contains chlorine dioxide and chlorine, alkali chlorate in an aqueous solution with acid is reacted in a reactor. The reactor comprises a plurality of superimposed reaction levels which are traversed by the solution from top to bottom. In the lower portion of the reactor the solution in which chlorate and acid have been depleted is reboiled in a reboiling chamber by an indirect heating at a temperature in the range from 100.degree. to 110.degree. C. The depleted solution is conducted from the reboiling chamber to a pressure chamber, in which a pressure of at least 1.2 bar is maintained. In the pressure chamber the solution is reboiled at temperatures from 110.degree. to 150.degree. C. and the vapors formed by the reboiling in the pressure chamber are conducted through the reboiling chamber for an indirect heating therein.

Abstract: In an electrode assembly for gas-forming electrolyzers, particularly for monopolar membrane electrolyzers comprising vertical plate electrodes and opposite electrodes and a membrane between the plate electrode and the opposite electrode, the distribution of current in the membrane is improved and the voltage drop is decreased in that the plate electrodes are provided on that surface which faces the membrane with ante-electrodes, which consist of apertured, electrically conducting surface structures, which are electrically conductively connected to the plate electrodes and extend in planes which are parallel to the plate electrodes.

Abstract: In an electrolytic cell having a membrane and vertical electrodes composed of a plurality of units,a. the electrode having one polarity is horizontally divided into a plurality of units,b. the electrode having the opposite polarity is vertically divided into a plurality of units, andc. the units of at least one of the two electrodes are adapted to be displaced by spring elements. Spacers are suitably provided between the units of that electrode which is not contacted by the membrane.