general it may be stated that the synthetic fibers made in accordance with the present invention have a cross sectional dimension on the order of 0 05 to 10 microns various alternatives suggest themselves to those skilled in the art in regard to the forming of the composition used to make the diaphragm other surfactants than the 34 fluorad fc 170 34 mentioned above may of course be used a principal consideration being the desirability of reducing the surface tension of the medium to below 30 dynes per centimeter means other than air sparging can of course be used to ensure the agitation of the composition during the vacuum deposition of the diaphragm and in the case of diaphragms of relatively small dimension such agitation may be omitted entirely after the initial dispersion of the fibers to form a slurry because the diaphragm may be formed before the composition has an adequate opportunity to separate to an appreciable extent those skilled in the art will vary the schedule of the degree of vacuum and the time used therefore in accordance with the permeability requirements of the diaphragm when the fibers are of different dimensions or where blends of different sized fibers are used either the deposition time or the degree of vacuum drawn on the interior of the cathode member may be changed from that specified above in order to produce a diaphragm having given permeability characteristics in regard to how the diaphragm is to be used after it has been installed those skilled in the art will again find modifications or variations to make but these will in most cases be dependent upon the degree of permeability which has been achieved although there has been described above the process of making a diaphragm containing the particular kinds of surface.