jellyroll 34 fashion from which a circular electrode which could then be cut as shown in fig7 along line b b while various techniques such as spraying electrocoating or screen printing for example are known to the art for depositing alternate layers of hydrophobic materials and hydrophilic and catalyst containing materials which may be used to practice this invention the following examples will describe the preferred filtration techniques employed by the applicants it should be noted that while the following specific examples provide the details used by the applicants in the preparation of certain embodiments of their invention certain general criteria should be followed in conducting the filtration processes i in order to obtain uniform thin in the order of magnitude of microns layers by filtration the suspended solids should be in a submicron state of subdivision this is no particular problem since the basic particles in commercially available metal blacks carbon blacks and teflon dispersions are of this order of magnitude ii the dispersions which are to be filtered should be very dilute to inhibit agglomeration of the particles iii the dispersing medium should be capable of wetting the hydrophobic materials for otherwise it will be impossible to filter through the previously deposited hydrophobic layers water containing wetting agents such as triton x 100 trademark of rohm and haas co philadelphia pa 19105 u s a or alcohol water mixtures which wet the otherwise hydrophobic materials are preferred because of their commercial availability and relatively low cost iv the filter medium employed should be smooth flat and highly porous with pores in the magnitude of less than 5 microns stretched sintered teflon tape or commercial grades of millipore.