Eudiometer truly pioneered by Count Alessandro Volta (1745–1827), an Italian physicist who is well known for his contributions to the electric battery and electricity. Aside from its laboratory function, the eudiometer is also known for its part in the "Volta pistol". 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. Volta's Pistol had a long glass tube that was closed at the top, like a eudiometer. Two electrodes were fed through the tube and produced a spark gap inside the tube. Volta's
Volta potential electrostatic potentials, but instead the difference in Fermi level between the two materials, a difference that is exactly zero at equilibrium. The Volta potential however corresponds to a real electric field in the spaces between and around the two metal objects, a field generated by the accumulation of charges at their surfaces. The total charge formula_2 over each objects' surface depends on the capacitance formula_3 between the two objects, by the relation formula_4 where formula_5 is the Volta potential. It follows therefore that the value of the potential can be measured by varying the capacitance between the materials by a