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
Christopher Schutz to mine and process the ore, being joined in some of their licences with Thomas Smythe, William Williams and Humfrey Cole. Only a few months later, in early 1566, William Humfrey and Schutz found calamine in the Mendip Hills, and Daniel Hoechstetter designed a refining process by which it could be used in Schutz' furnace at Tintern. As a reward for his work at Tintern, Schutz was granted denization on 9 April 1568, but the extraction of calamine ore at Worle Hill proved prohibitively expensive for the production of brass, and on 28 May the Company of Mineral and Battery