 He also performed pioneering studies in organosulfur chemistry, discovering the xanthates in 1823.William Christopher Zeise was born 15 October 1789 in Slagelse, the son of an apothecary, Frederick Zeise (1754–1836), who was an old friend of physicist Hans Christian Ørsted's father.Zeise attended Slagelse Latin school until he went to Copenhagen in 1805 to take up an apprenticeship under Gottfried Becker as a pharmacy assistant ("Apoteksmedhjælper") at the Royal Court Pharmacy.