NOVELTY - The gas generator useful in provision device for the generation of electricity and heat, fuel cells and in soldering or welding device, comprises a reaction chamber (2) with a casing (3), which has a membrane (4) with an outer surface, which faces away from the reaction chamber. The reaction chamber contains a first reactant (5) or is filled with the reactant, which does not alter a permeability of the membrane (4). The permeability of the membrane is continuously changed to higher values by contact with a second reactant (12) for which the membrane is permeable.    USE - Gas generator useful in provision device for the generation of electricity and heat, fuel cells and in soldering or welding device.    ADVANTAGE - The gas producer ensures to produce gas with high quality and quantity.    DETAILED DESCRIPTION - The gas generator useful in provision device for the generation of electricity and heat, fuel cells and in soldering or welding device, comprises a reaction chamber (2) with a casing (3), which has a membrane (4) with an outer surface, which faces away from the reaction chamber. The reaction chamber contains a first reactant (5) or is filled with the reactant, which does not alter a permeability of the membrane (4). The permeability of the membrane is continuously changed to higher values by contact with a second reactant (12) for which the membrane is permeable and which reacts with the first reactant for reaction gas. The membrane is also permeable for the reaction gas and is degradable with the second reactant through contact. Within the reaction area, a further membrane is arranged, whose permeability is also continuously changed to higher values by contact with the second reactant. The first reactant is a water-reactive material and the second reactant is water or acid or a mixture of water and acid. The membrane has component parts. The casing is formed by a capsule and has a metal foil. A separation layer is formed, which is impermeable for the second reactant and separates the outer surface of the membrane and the second reactant. The separation layer surrounds the outer surface of the membrane. A device is available for pointed destruction of the separation layer and works mechanically, chemically and/or electrically. The gas producer is arranged within the reaction area, which has a volume of 0.1-2 cm3. A pre-chamber is connectable with the reaction areas and is fillable with the second reactant. The pre-chamber partially or completely surrounds the outer surface of the membrane and is filled with the second reactant, which is surrounded with the separation layer impermeable for the second reactant. The pre-chamber has a filler tube and is formed as housing. A discharge area is connected with a gas pipeline in gas tight manner and is permeable for the reaction gas. An INDEPENDENT CLAIM is included for a procedure for the production of reaction gases from reactants.    DESCRIPTION OF DRAWING(S) - The figure shows a cartridge like gas producer with pre-chamber.    Reaction chamber (2)    Casing (3)    Membrane (4)    First reactant (5)    Second reactant. (12)