Galvanic cell for the detection or estimation of oxygen

969, 607. Electrolytic testing apparatus. UNITED KINGDOM ATOMIC ENERGY AUTHORITY. Feb. 24, 1961 [March 4, 1960], No. 7680/60. Heading G1N. A galvanic cell for the detection or estimar tion of oxygen in other gases includes a cathode having a surface for contacting the gas, a porous member having a part of its surface contacting a part of the cathode surface, and an anode, which components are mounted together in a container such that the latter can be filled with electrolyte to a level at which the cathode is out of contact with the electrolyte, the anode enters the electrolyte, and part of the surface of the porous member contacts the electrolyte and thereby maintains electrolyte in contact with part of the cathode surface by capillary action. The gas to be tested passes down tube 9 into the space 32 enclosed by the porous P V C tube 8 and the aqueous potassium hydroxide electrolyte 34, thereafter passing up through the helical passage defined by a cathode formed by radially slotted silver annuli 10 screwed on to the silvered tube 9 such that their outer edges contact tube 8. The gas then passes via a passage in the lid 5 to a tube (Fig. 2, not shown) in the annular space 30, which dips beneath the surface of the electrolyte, through which the gas bubbles before passing up through space 30 to an outlet tube through the lid 5. Space 30 also contains a lead anode 20, and a thermistor 15 connected across the cell for temperature compensation. Alternative materials are:- Cathode-silver-plated nickel, gold, gold-plated nickel, iridium-plated nickel, orplatinum, and also nickel; anode-cadmium, antimony, arsenic, antimony amalgam, lead amalgam, or copper; electrolyte-sodium hydroxide sodium and potassium carbonates, sodium potassium bicarbonates, sulphuric acid, or an alkali metal chloride solution.