A simple equation for ohmic solution resistance in cells with mercury drop electrodes

A simple analytical expression for the ohmic solution resistance in cells with mercury drop electrodes is presented. This expression is derived using a geometric model in which the bottom of the glass capillary is treated as an infinite insulating plane and equipotentials in solution are considered to be spheres centered about the drop electrode and truncated by the insulating plane. A simple modification of the expression makes it possible to treat the hanging merecury drop electrode as well as the dropping mercury electrode. It is shown that the resistance predicted by the equation derived in the present work closely approximates that obtained from a rigorous solution of the primary potential and current distribution.