The eudiometer was used in the last quarter of the 18^th century to study the properties of air and gases in general. Alessandro Volta made extensive use of it, starting in 1777, to measure the amount of oxygen present in the air and thus deduce its ‘healthiness’. The device on display is a model modified by Volta in 1783 to obtain more accurate measurements.
It consists of a glass cylinder enclosed in a brass frame; a funnel-shaped base equipped with a tap would have been screwed onto the lower end. A thin conductor was inserted into the upper end of the vase, terminating on the outside with a brass ball, which served to produce a spark by means of the small Leyden jar supplied. A cup equipped with a tap is screwed onto the top of the vessel and a long glass barrel enclosed by a metal frame inserted.
A graduated scale is engraved on the frames of both cylinders.
Device on display.