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 by its work function, and so dissimilar metals can show an electric potential difference even at equilibrium. The Volta potential is "not" an intrinsic property of the two bulk metals under consideration, but rather is determined by work function differences between the metals' surfaces. Just like the work function, the Volta potential depends sensitively on surface state, contamination, and so on. The potential is given by the formula: formula_1, where V is the potential, The Volta potential can be significant (of order 1 volt) but it cannot be measured directly by an ordinary voltmeter. A voltmeter does not measure vacuum