Abstract: For the chemical cleaning of cooled waveguides, in particular water-cooled waveguides of electric machines and apparatus, whose cooling cycle is maintained by a feed pump and comprises an ion exchanger in a closable bypass, alternately a complexing agent is added into the cooling cycle with the bypass closed and thereafter a purification of the cooling water via the ion exchanger is effected with the bypass open. The preferred complexing agent is a chelate former or one of the salts thereof. In addition to the complexing agent, an oxidant, in particular hydrogen peroxide or oxygen gas, may be added in at least one passage cycle.

Abstract: Apparatus for measuring dissolved gases in a fluid medium includes a tubular member which is inserted in a pipe line through which the fluid medium flows. This tubular member thus becomes a part of the pipe line and a portion of the inner wall surface thereof serves as a membrane through which the gas to be measured diffuses into a polarographic measuring cell which surrounds the tubular member and includes an annular electrolyte chamber and cathode and anode electrodes therein.