What is Leyden jar?
{{multiple image |image1 = Early Layden jar.png |width1 = 207 |caption1 = Early water-filled Leyden jar |image2 = Leyden jar engraving.png |width2 = 120 |caption2 = Later more common type using metal foil, 1919}} The '''Leyden jar'''<ref>Named after [[Leiden University]] where the device was created.</ref> (or Leiden jar) is a device for storing [[static electricity]]. It is large glass bottle, usually lined on both the inside and the outside with some type of metal foil. Some of the early ones had water inside. They allow the experimenter to collect a large amount of [[Electric charge|charge]]. They are the first form of electrical storage. These methods are known today as 'condensers' or '[[capacitor|capacitors]]'. The first electrical storage jar was created by [[Ewald Georg von Kleist]] on 11 October 1745.<ref>[https://web.archive.org/web/20090326073456/http://chem.ch.huji.ac.il/history/musschenbroek.htm Biography, Pieter (Petrus) van Musschenbroek]</ref> He was the [[dean]] of the cathedral of Cammin in [[Pomerania]], on the north coast of Germany (at that time a separate country). He was interested to find whether static electricity could be stored in a bottle, because he knew that electricity could not pass through glass. He thought he might be able to capture and hold a small amount. He only had a small experimental friction [[generator]]. He underestimated how much electricity a small medicine bottle could hold by thousands of times. A peculiarity of electricity allows it to continue flowing into the bottle provided the outside of the bottle has an electrically conductive surface connected to the earth. This neutralises the pressure from the charge trying to flow back out. In von Kleist's case, this electrically conductive surface was just his hand, but it was enough to allow a very substantial charge to enter and remain in the jar through a nail he had driven through the cork. When he accidentally touched the nail, he received such a shock that it threw him across the room. He had made a conne