Compensated gas-analyisis bridges

Claim 1

A GAS-ANALYSIS BRIDGE INCLUDING A REFERENCE CELL AND AN ANALYTICAL CELL TRAVERSED BY THE GAS MIXTURE TO BE ANALYZED AND HAVING TEMPERATURE-SENITIVE RESISTORS RESPECTIVELY IN ADJACENT BRIDGE ARMS AND HEATED FROM A COMMON SOURCE OF CURRENT, SAID CELLS AND THEIR RESISTORS BEING SIMILAR WITHIN PRACTICAL TOLERANCES OF MANUFACTURE AND ASSEMBLY, SENSITIZING MEANS COOPERATIVE WITH SAID ANALYTICAL CELL TO RENDER SAID ANALYTICAL CELL RESISTOR RESPONSIVE TO A CHARACTERISTIC OF A SELECTED COMPONENT OF SAID GAS MIXTURE, AND MEANS FOR INSURING ACCURATE MEASUREMENT OF SMALL CHANGES IN CONCENTRATION OF SAID SELECTED COMPONENT DESPITE THE DIFFERENCE WITHIN SAID TOLERANCES OF MANUFACTURE AND ASSEMBLY BETWEEN THE SENSITIVITIES OF SAID SIMILAR REFERENCE AND ANALYTICAL CELLS TO BACKGROUND CHARACTERISTICS OF THE GAS MIXTURE COMPRISING A COMPENSATING RESISTOR IN CIRCUIT WITH AND IN THE SAME BRIDGE ARM AS ONE OF SAID CELLS AND HAVING SUCH VALUE OF RESISTANCE THAT THE RATIO OF ONE FACTOR OF THE VOLT/AMPERE CHARACTERISTIC OF THE ARM INCLUDING SAID COMPENSATING RESISTOR TO THE SAME FACTOR OF THE SAME CHARACTERISTIC OF SAID ADJACENT ARM REMAINS CONSTANT FOR VARYING BACKGROUND COMPOSITION OF THE GAS MIXTURE TRAVERSING BOTH CELLS, THE VARIATION IN RATIO OF THE OTHER FACTOR OF SAID CHARACTERISTICS THEN BEING REPRESENTATIVE SOLELY OF THE VARIATION OF SAID SELECTED COMPONENT OF THE GAS MIXTURE.