A DEVICE FOR DETECTING A COMPONENT IN A GAS MIXTURE CONSISTS OF A STRIP OF TWO LAYERS LAMINATED TOGETHER, ONE LAYER BEING A BETTER SOLVENT FOR THE GAS COMPONENT THAN THE OTHER AND EACH BEING EFFECTIVELY A NON-SOLVENT FOR THE OTHER COMPONENTS IN THE MIXTURE, A SUPPORT MEANS FOR SECURING ONE END OF THE STRIP AND A RECORDING MEANS AT THE FREE END OF THE STRIP FOR RECORDING A DEFLECTION IN THE STRIP DUE TO THE LATERAL EXPANSION OF THE SOLVENT LAYER WITH

RESPECT TO THE NON-SOLVENT LAYER. ALSO DESCRIBED IN THE EMBODIMENT WHEREIN THE RATIO FO TWO COMPONENTS IN THE GAS MIXTURE MAY BE DETERMINED BY MEANS OF A DEVICE WHEREIN THE STRIP CONSISTS OF TWO LAYERS ONE OF WHICH IS A SOLVENT FOR ONE COMPONENT AND THE OTHER LAYER IS A SOLVENT FOR THE SECOND COMPONENT.