|The LEYDEN jar is, without doubt, the first known apparatus
for storing electricity.
Generally it consists of a glass jar, within which is enclosed a sheet of tin or silver foil linked to an external rod.
A second sheet of foil is attached to the outside of the jar.
There are also models which have a double brass flask, separated by either air or glass to serve as an insulator. An example of such a model is shown in the image opposite.
This apparatus, the original capacitor, was unable to provide current during a sustained period and was discharged almost instantaneously.
From VOLTA's time, many researchers became motivated to find a source of electricity which was readily available, easily transportable and capable of delivering a constant current over long periods of time.
The earliest generators capable of storing a substantial quantity of electrical energy were based on the electro-chemical exchanges between metals.
They fell into two categories:
- Batteries or (Primary)
- Rechargeable Batteries (Secondary)
Other types of battery exist, of course, such as thermo-electric or fuel cells which are recent concepts and out of scope of this site.