Abstract: A sensor such as for sensing dissolved oxygen in plural cells spaced apart from each other by a predetermined distance includes projection sections provided at intervals spaced according to the predetermined distance on an edge section of a plate shape base body. At least an active electrode and a counter-electrode are at predetermined positions on each projection section, and lead-out terminals are provided at predetermined positions on the substrate facing the substrate portion where the projection sections are formed. The substrate has wiring electrically connecting both the active electrodes and the counter-electrode to the lead-out terminals. This arrangement greatly reduces measurement labor and variance in measurement data results. In addition, it increases the number of objects that can be measured during a measurement operation.

Abstract: A halogenated hydrocarbon is effectively fluorinated by reacting the halogenated hydrocarbon with hydrogen fluoride in the presence of a fluorination catalyst which comprises a partially fluorinated chromium oxide containing at least one metal selected from the group consisting of ruthenium and platinum.

Abstract: A vulcanizable rubber composition which contains an iodine- or bromine-containing rubber and an organic peroxide of the formula. ##STR1## wherein R.sup.1 is a hydrogen atom, a chlorine atom or methyl group, R.sup.2 is a linear or branched alkyl group having 2 to 5 carbon atoms, and n is an integer of 1 to 3, generates only a small amount of methyl iodide or methyl bromide during the vulcanization.

Abstract: Hydrogen fluoride and 1,1,1-trifluoro-2-chloroethane forms an azeotropic mixture. A mixture comprising hydrogen fluoride and 1,1,1-trifluoro-2-chloroethane is phase separated when it is cooled to a temperature below 7.degree. C. 1,1,1-Trifluoro-2-chloroethane is purified effectively from the mixture by cooling the mixture to form an upper liquid phase and a lower liquid phase and distilling the lower liquid phase so that the hydrogen fluoride is removed as an azeotropic distillate and 1,1,1-trifluoro-2-chloroethane substantially free from hydrogen fluoride is obtained as a bottom product.

Abstract: Chlorotrifluoroethylene is prepared in high yield by reacting tetrafluoroethylene with hydrogen chloride in the presence of a metallic catalyst without using 1,1,2-trichlorotrifluoroethylene, which destroys the ozone layer.