Leydenfles

Leydenfles, or Leyden jar, is an early electrical capacitor named after Leiden, Netherlands. It stores static electricity by establishing opposite charges on two conductive coatings separated by a glass dielectric. A typical device consists of a glass jar or bottle coated inside with a conducting foil and coated on the outside with another foil. A metal rod or wire passes through a stopper to connect to the inner foil, while the outer foil is connected to a separate terminal. When the inner conductor is charged by an electrostatic generator, the outer coating acquires the opposite charge, and the glass between them acts as the dielectric, allowing the assembly to store energy. Discharging is achieved by touching the inner and outer conductors, often across a spark gap, or by shorting the terminals. Capacities of Leyden jars are small, usually tens to a few hundred nanofarads, but voltages could reach thousands of volts, enabling static electricity experiments and demonstrations.

History and significance: The Leyden jar was independently developed in 1745 by Dutch scientist Pieter van Musschenbroek in Leiden and by German inventor Ewald Georg von Kleist in Germany. The famous experiment associated with Musschenbroek’s laboratory helped establish the concept of electrical storage and sparked wide interest in electrostatics across Europe. The device became a standard laboratory tool in the 18th and early 19th centuries and laid foundational concepts for the development of modern capacitors and the study of dielectrics. The term Leydenfles remains the Dutch name for this historic apparatus.