|physics an early type of capacitor consisting of a glass jar with the lower part of the inside and outside coated with tin foil|
|[C18: first made in Leiden]|
|Leyden jar (līd'n) Pronunciation Key
An early device for storing electric charge that uses the same principle as a modern capacitor. It consists of a glass jar with conductive metal foil covering its inner and outer surfaces, with the glass insulating these surfaces from each other. The inner surface is charged (by an external source) through an electrode penetrating the top of the jar; the inner and outer foil layers can then hold an equal and opposite charge.