The Structure of the Collodion Membrane and Its Electrical Behavior X. an Expe~t~..ntal Test of Some Aspects of the Teorell and Meyer-sievep.s Theories of Electrical Membrane

In several recent publications 1-6 we have shown experimentally that the acidic groups present in collodion are the primary cause of its electrochemical activity in solutions of strong inorganic electrolytes. The surface concentration of these acidic dissociable groups is assumed to determine the degree of electrochemical activity of any given collodion sample. The abundance of these groups varies with the past history of the collodion from which the membranes are prepared. This concept of the cause of the electrochemical membrane activity is in general agreement with some newer theories of electrochemical membrane activity, outlined independently by TeorelV and by Meyer and Sievers. 8 On the basis of these theories it can be concluded that the base exchange capacity of the pore surfaces of a given membrane and its porosity are the factors determining its electrochemical activity. The theory also allows quantitative predictions by which one can llnk in a definite way base exchange capacity and electromotive behavior. The empirical correlation between the base exchange capacity of various collodion preparations and their electrochemical activity has been described previously 4 in connection with studies of the base exchange properties of precipitated fibrous collodion. Such preparations have a very large specific surface and are suitable objects from which to obtain basic information. Our experimental results can be summarized by stating that there is no necessary