“…They determined an exchange current density in 0.1 AT lithium perchlorate of 20 µ cm-*, which means that an electrode area of greater than 10 cm* is required for twoelectrode polarography. Finally, Fried and Barak (119) have compared all six of the propylene carbonate electrodes suggested to date. They conclude that the best system is a calomel-tetraethylammonium chloride couple.…”