Group 12 element people in the 17th century. German chemist Andreas Marggraf is usually given credit for discovering pure metallic zinc in a 1746 experiment by heating a mixture of calamine and charcoal in a closed vessel without copper to obtain a metal. Experiments on frogs by the Italian doctor Luigi Galvani in 1780 with brass paved the way for the discovery of electrical batteries, galvanization and cathodic protection. In 1880, Galvani's friend, Alessandro Volta, invented the Voltaic pile. The biological importance of zinc was not discovered until 1940 when carbonic anhydrase, an enzyme that scrubs carbon dioxide from blood, was shown to
Metallic bonding of this form of condensation. At high pressures it is a metal. The core of the planet Jupiter could be said to be held together by a combination of metallic bonding and high pressure induced by gravity. At lower pressures however the bonding becomes entirely localized into a regular covalent bond. The localization is so complete that the (more familiar) H gas results. A similar argument holds for an element like boron. Though it is electron deficient compared to carbon, it does not form a metal. Instead it has a number of complicated structures in which icosahedral B clusters dominate.