Zheng Xuan
The Han scholar and alchemist Zheng Xuan (127–200) specified that to make "hanshisan", the medically active minerals chalcanthite ("shidan"), cinnabar ("dansha", red mercury sulphide), realgar (the arsenic sulphide "xionghuang" or "xiongshi") and magnetite ("cishi") should be enclosed in an earthen receptacle, continuously heated over three days. The drug obtained from the concoction could then be applied to the affected areas of the sick body.