This study was undertaken to develop a more practical mercury cathode for use in analytical separations. A new mercury cathode has been designed which employs a magnetic circuit.The cathode removes metals rapidly and completely, is rugged and convenient to operate, and contains no mechanical moving parts. The novel magnetic circuit provides rapid countercurrent stirring at the mercury electrolyte interface, continuously cleans mercury surface (ferromagnetic element), and requires a minimum amount of mercury per analysis. Electrolysis with the mercury cathode is often used as a means of separation of certain elements in analytical techniques. It is particularly useful where large amounts of interfering metals must be separated from small quantities of other elements to be assayed. The new cathode provides the analytical chemist with a practical, rapid tool for quantitative analytical separations.