Abstract: In a solid electrolyte electrochemical cell device for generating an EMF signal based on the Nernst equation which is indicative of the SO.sub.2 content of a monitored gas environment, the oxygen content of the reference environment of the cell is adjusted to maintain it equal with the oxygen content of the monitored gas environment to eliminate the effect of oxygen on the EMF signal measurement of SO.sub.2.

Abstract: An alkali ion conductive solid electrolyte electrochemical concentration cell assembly for measuring gases containing anhydrides or related compounds in air or in oxygen-bearing gases is divided into two identical alkali ion conductive half cycles. Each half cell is secured to opposite surfaces of the closed end of a solid membrane exhibiting alkali ion conductivity corresponding to the alkali ion conductivity of the half cells. The membrane effectively isolates a monitored gas environment contacting one half cell from a reference gas environment contacting the other half cell while supporting the equilibrium mode of operation of the concentration cell assembly to generate an electrical signal indicative of a gas species of interest in the monitored gas environment.

Abstract: A circuit means in combination with a conventional oxygen ion conductive solid electrolyte cell establishes the cell in a voltage mode for the purposes of measuring excess oxygen and developing a voltage signal indicative thereof, and switching the cell to a current mode of operation in response to an excess combustible environment wherein current drawn by the cell to pump oxygen for combustible reaction with the excess combustibles environment is measured as an indication of the combustibles content of the gas.