Three electrode system: drop mercury electrode as the working electrode, saturated calomel electrode as the reference electrode, platinum electrode as the auxiliary electrode. What do you mean by the reference electrode being large and small? Saturated calomel electrode was better than dropping mercury electricity greatly greatly ah, you can refer to the volt ampere and polarographic analysis including the particularity of the particularity of electrode electrode performance in polarographic analysis is to use a is usually a dropping mercury electrode area is small, another is often a very large area of the saturated calomel electrode (and generally use two large area of the electrode electrochemical analysis).