the ancestor of the modern electrolytic capacitor was patented by samuel ruben in 1925, who teamed with philip mallory, the founder of the battery company that is now known as duracell international. ruben's idea adopted the stacked construction of a silver mica capacitor. he introduced a separated second foil to contact the electrolyte adjacent to the anode foil instead of using the electrolyte-filled container as the capacitor's cathode. the stacked second foil got its own terminal additional to the anode terminal and the container no longer had an electrical function. this type of electrolytic capacitor combined with a liquid or gel-like electrolyte of a non-aqueous nature, which is therefore dry in the sense of having a very low water content, became known as the "dry" type of electrolytic capacitor.