Abstract: To provide for the rapid vaporization of a liquid, a porous body is impregnated with the liquid. Then the liquid contained in the porous body is heated, so as to cause a rapid vaporization of the liquid in the porous body which liquid continually migrates through the porous body under the effect of its pumping and suction capabilities. The whole of the mass of liquid to be vaporized is stored in the body in impregnated form, without the presence of a permanent liquid layer. The liquid is heated directly by passing an electric current through the porous body, the density of the porous body being chosen so as to provide a liquid retention capacity allowing a variation of the energy dissipated in time to be obtained in accordance with a predetermined law which is a function of the density chosen for the porous body. Thus interchangeable porous bodies can be used having different densities and allowing different curves of variation of the energy dissipated in time to be obtained, respectively.