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
Cupronickel so much more the extraordinary as this sort of copper is found no where but in China and that only in the Province of Yunnan". Notwithstanding what is here said, of the colour of the copper being owing to no mixture, it is certain the Chinese white copper as brought to us, is a mixt [sic: mixed] metal; so that the ore from which it was extracted must consist of various metallic substances; and from such ore that the natural "orichalcum" if it ever existed, was made." During the peak European importation of Chinese white-copper from 1750 to 1800, increased