Humphry Davy (17.12.1778-29.05.1829) was an English chemist and physicist, a Fellow of the Royal Society (1803) and its president in 1820—27. He was born in Penzance. He was apprenticed to an apothecary and then worked as a chemist at the Pneumatic Institution (Bristol); from 1802 he was professor of chemistry at the Royal Institution in London.
His research in physics concerned electricity and heat. He proved that an electric current brings about the decomposition of acids and salts. In 1807 he obtained metallic potassium and sodium. He developed the hydrogen theory of acids, refuting A. Lavoisier's assertion that every acid must contain oxygen. Electrochemistry begins with Davy. In 1810, with the help of a large electric battery made up of 2000 voltaic cells, he demonstrated the phenomenon of the electric arc, which appeared between two pieces of carbon connected to the poles of the battery (the electric arc had already been observed in 1802 by V. V. Petrov). In 1821 he established how the resistance of a conductor depends on its length and its cross-section, and observed the change of resistance with temperature. He built a number of thermometers (with mercury, with alcohol and with water). In 1799 he obtained heat from the friction of two pieces of ice, and in 1812 he put forward the suggestion that heat is kinetic in nature.
A member of the St Petersburg Academy of Sciences (1826). The Copley (1805) and B. Rumford (1816) Medals, and the Royal Medal (1827).