A relatively fast and rapidly recurrent voltage sweep has been applied to the dropping mercury cathode in a solution. A preliminary apparatus using 30 voltage sweeps per second from zero to 2.5 volts and one mercury drop per voltage sweep gave good polarographic curves on the cathode ray oscillograph. It has been possible almost to attain the sensitivity of the slower Heyrovsky polarograph. The increase in the charging current, due to the electrostatic capacity of the mercury solution interface, is a major disadvantage relative to the slower polarograph. The advantages over the Heyrovsky polarograph are : 1. Rapidity of indication. 2. Ability to give a practically continuous polarographic record through rapidly or slowly changing conditions. 3. Absence of polarographic maxima.