The difference between the current that is actually obtained, at any particular value of the potential of the @[email protected] or @[email protected], for the reduction or @[email protected] of an ionic @[email protected] and the current that would be obtained, at the same potential, if there were no transport of that substance due to the electric field between the electrodes. The sign convention regarding current is such that the @[email protected] current is negative for the reduction of a @[email protected] or for the @[email protected] of an @[email protected], and positive for the @[email protected] of a @[email protected] or the reduction of an @[email protected] Hence the @[email protected] current may tend to either increase or decrease the total current observed. In any event the @[email protected] current approaches zero as the @[email protected] of the @[email protected] is decreased by increasing the concentration of the @[email protected], and hence the @[email protected]