(FR2729306-A1)      A method for the sepn. of an acidic gas from a gaseous mixt. contg. this gas and at least one non-acidic gas-comprises contact of the gaseous mixt. with a multi-layer composite membrane consisting of a first polymer carrier layer and a sepn. layer comprising a mixt. of water-soluble polymer and a salt of formula AxBy.nH2O (I) contg. at least one semi-equiv. of the repeat units in this polymer which is reactive towards the acidic gas. The membrane separates the acidic gas from the mixt. by selective permeation. A, B = ionic species with opposite charges; and n = moles water per mol. (I).    USE -   Useful for the sepn. of CO2 from H2 in synthesis plants for H2 and the removal of H2S and CO2 from natural gas.    ADVANTAGE -   The membrane has an increased permeability to the acidic gas without a redn. in selectivity.    (JP8229367-A)      A method for the sepn. of an acidic gas from a gaseous mixt. contg. this gas and at least one non-acidic gas-comprises contact of the gaseous mixt. with a multi-layer composite membrane consisting of a first polymer carrier layer and a sepn. layer comprising a mixt. of water-soluble polymer and a salt of formula AxBy.nH2O (I) contg. at least one semi-equiv. of the repeat units in this polymer which is reactive towards the acidic gas. The membrane separates the acidic gas from the mixt. by selective permeation. A, B = ionic species with opposite charges; and n = moles water per mol. (I).    USE -   Useful for the sepn. of CO2 from H2 in synthesis plants for H2 and the removal of H2S and CO2 from natural gas.    ADVANTAGE -   The membrane has an increased permeability to the acidic gas without a redn. in selectivity.    (DE19600954-C2)      A method for the sepn. of an acidic gas from a gaseous mixt. contg. this gas and at least one non-acidic gas-comprises contact of the gaseous mixt. with a multi-layer composite membrane consisting of a first polymer carrier layer and a sepn. layer comprising a mixt. of water-soluble polymer and a salt of formula AxBy.nH2O (I) contg. at least one semi-equiv. of the repeat units in this polymer which is reactive towards the acidic gas. The membrane separates the acidic gas from the mixt. by selective permeation. A, B = ionic species with opposite charges; and n = moles water per mol. (I).    USE -   Useful for the sepn. of CO2 from H2 in synthesis plants for H2 and the removal of H2S and CO2 from natural gas.    ADVANTAGE -   The membrane has an increased permeability to the acidic gas without a redn. in selectivity.    (JP2829268-B2)      A method for the sepn. of an acidic gas from a gaseous mixt. contg. this gas and at least one non-acidic gas-comprises contact of the gaseous mixt. with a multi-layer composite membrane consisting of a first polymer carrier layer and a sepn. layer comprising a mixt. of water-soluble polymer and a salt of formula AxBy.nH2O (I) contg. at least one semi-equiv. of the repeat units in this polymer which is reactive towards the acidic gas. The membrane separates the acidic gas from the mixt. by selective permeation. A, B = ionic species with opposite charges; and n = moles water per mol. (I).    USE -   Useful for the sepn. of CO2 from H2 in synthesis plants for H2 and the removal of H2S and CO2 from natural gas.    ADVANTAGE -   The membrane has an increased permeability to the acidic gas without a redn. in selectivity.