Electro capillarity

Phenomenon observed in two conducting fluids in contact; e.g., if water and mercury be brought in contact, the surface of separation has three properties; surface tension, a difference of potential on the two sides of it (the water and mercury being two heterogeneous bodies in contact), and electrostatic capacity, as the surfaces are really separated by ab. 20000000 of a centimeter. These properties are found to depend upon one another, so that if any one be varied the others will change also. Lippman has utilized this action in the construction of a capillary electrometer and an electro capillary engine.