For some reactions, two platinum wires (chosen for their non-reactivity) are placed in the sealed end so an electric spark can be created between them.

The use of the device is quite similar to the original barometer, except that the gas inside displaces some of the liquid that is used.

From these experiments Priestley is credited with discovering many new gases such as oxygen, hydrogen chloride, and ammonia.

[2] Marsilio Landriani was studying pneumatic chemistry with Pietro Moscati when they attempted to quantify Priestley's nitric acid test for air quality.

His description of photosynthesis was published in 1779, and in 1785 he wrote about eudiometers in Journal de Physique (v 26, p 339).

[6] Volta invented this instrument in 1777 for the purpose of testing the "goodness" of air, analyzing the flammability of gases, or to demonstrate the chemical effects of electricity.

A spark could be introduced into the gas chamber by electrodes, and possibly catalyze a reaction by static electricity, using Volta's electrophorus.

[8] Because the eudiometer was originally used to measure the amount of oxygen in the air, which was thought to be greater in "nice" weather,[9] the root eudio- appropriately describes the apparatus.

Applications of a eudiometer include the analysis of gases and the determination of volume differences in chemical reactions.