Abstract: In the pH glass electrode comprising a double-walled glass tube in which an electrical screen is provided between the walls, the inner glass tube is sealed at one end with a glass lid and at the other end with a pH-sensitive glass membrane which forms, with the glass tube, a cavity which is filled with internal reference solution and into which the reference electrode extends. A feed tube (10) and a drain tube (11) which are passed through the lid (5) and intended for the internal reference solution (8) are disposed in the internal glass tube (3), the drain tube (11) extending down to the lowest point in the cavity (7).

Abstract: In the pH glass electrode comprising a double-walled glass tube in which an electrical screen is provided between the walls, the inner glass tube is sealed at one end with a glass lid and at the other end with a pH-sensitive glass membrane which forms, with the glass tube, a cavity which is filled with internal reference solution and into which the reference electrode extends. A feed tube (10) and a drain tube (11) which are passed through the lid (5) and intended for the internal reference solution (8) are disposed in the internal glass tube (3), the drain tube (11) extending down to the lowest point in the cavity (7).

Abstract: In the process for monitoring water, in particular boiler feed water, for organic impurities by measuring the conductivity, a part stream is diverted from a sample water stream and its conductivity is measured. The other part stream evaporated at 300.degree.-500.degree. C.; the vapor is thermally treated at temperatures of 800.degree.-1000.degree. C.; the treated vapor is condensed and the conductivity of the condensate is measured. Subsequently the difference between the measured conductivities is taken.

Abstract: In the method of measuring the pH value of a test solution with glass-electrode measuring cells and of simultaneously calibrating the measuring cells, the potentials occurring at the pH glass electrode and the reference electrode are processed in a pH meter with temperature compensation and measuring-cell slope derivation. The potentials from a reference electrode (4) and two pH glass electrodes (2, 3) having different internal reference solutions (6, 7) are processed in a first (8) and a second pH meter (9). The measuring-cell slope is derived from the processed potential and, together with the slope, the measured value is derived simultaneously.

Abstract: For the quantitative determination of the total oxygen demand of water containing oxidizable matter, the water is continuously evaporated at about 900.degree. C. in the presence of varying amounts l.sub.1, . . . , l.sub.n of oxygen-containing gas added per unit of steam at continuously repeated intervals. The oxygen-containing gas should not exceed 1 to 5% by volume, calculated on the amount of steam produced during each interval. The residual oxygen concentrations S.sub.1, . . . , S.sub.n in the steam gas/mixture are measured for the different amounts of oxygen-containing gas added and the oxygen demand is calculated from the residual concentrations and the added amounts of the oxygen-containing gas.

Abstract: In the determination of the quantity of carbon present in water in the form of organic compounds the carbon-containing water is first evaporated in the presence of oxygen at a temperature of about 900.degree. C. Care must be taken that the oxygen does not exceed 1 to 5 volume %, calculated on the quantity of steam. Then the CO.sub.2 content is measured with a CO.sub.2 analyzer. In a second step the carbon-containing water is measured without oxygen under identical conditions. The quantity of carbon present in water in the form of organic compounds is determined from the measured CO.sub.2 concentrations.