Zinc for discovering pure metallic zinc, even though Swedish chemist Anton von Swab had distilled zinc from calamine four years previously. In his 1746 experiment, Marggraf heated a mixture of calamine and charcoal in a closed vessel without copper to obtain a metal. This procedure became commercially practical by 1752. William Champion's brother, John, patented a process in 1758 for calcining zinc sulfide into an oxide usable in the retort process. Prior to this, only calamine could be used to produce zinc. In 1798, Johann Christian Ruberg improved on the smelting process by building the first horizontal retort smelter. Jean-Jacques Daniel
Ore Mountains last silver mines closed and the company was disbanded. Mining in the Ore Mountains was given new life during the First and Second World Wars in order to supply raw materials. The Third Reich also saw the resumption of silver mining. Afterwards the people returned to the manufacture of wooden products and toys, especially in the Eastern Ore Mountains. The clock industry is centred on Glashütte. In the Western Ore Mountains, economic alternatives were offered by the engineering and textile industries. In 1789 the chemical element uranium was discovered in St. Joachimsthal; then in pitchblende from the same area, radium