Han Dynasty: Gradually summed up various alchemy methods, including a large number of chemical reactions. Typical results of alchemy are: Danhua (mercury sulfide is heated to obtain mercury), Shenfu (mercury and black lead are upgraded to mercuric oxide and lead tetroxide), Shen Dan (mixed with realgar and orpiment, mainly composed of sublimated arsenic sulfide) and Huandan. The main components are mercury, mercury sulfide and realgar), alchemy (extracted from cinnabar in August, realgar, orpiment, Zeng Qing, gypsum, gallbladder, ettringite and magnet, with cinnabar and andrographolide as the main components), Roudan (sublimated from mercury, with mercuric oxide as the main component) and Tiedan (Huang Xuan coated Dan).
Fox Gangzi was an alchemist in the mid-Eastern Han Dynasty. He proposed melting drugs such as gallstones (sulfuric acid) and cinnabar, and mentioned that heating copper sulfate and ferrous sulfate can get a kind of smoke, which will hydrate into liquid, which is the earliest known record of preparing sulfuric acid. In addition, he also put forward the grey blank furnace method of tin smelting, which smelted gold and silver ore powder and lead, separated the lead block infiltrated with gold and silver, and blew off the lead oxide after roasting, thus purifying gold and silver, indicating that the alloy formed by gold and silver and other metals has been recognized. Wei Boyang's "The Book of Changes Can Tong Qi" in the Eastern Han Dynasty is the earliest theoretical work of alchemy in China, which emphasizes the view that "change is real and always self-caused" and briefly describes Dante's structure. The book says that "white water and silver are flowing beads", "the sun is flowing beads, and people often want to go" and "the fire is flying, but the dust is gone", which shows that we realize that mercury is flowing and difficult to control. Then we say that "the dead golden flower turns into a white liquid and solidifies into a solid" and find that mercury can form an alloy with lead.
China's earliest herbal work, Shennong Herbal Classic, was strongly influenced by alchemy and recorded 347 kinds of drugs. There are three kinds of drugs: "top grade" is non-toxic, "middle grade" needs to be considered, and "inferior grade" is highly toxic and cannot be taken for a long time. It is wrong to classify cinnabar as non-toxic, but it can also be turned into mercury, and it has been recognized that heating can dig out mercury sulfide.
Wei and Jin Dynasties: A kind of "nine turns to Shen Dan" was mentioned. Red salt (containing mercuric oxide), root snow (mercuric chloride and mercurous chloride) and Bai Xuan (lead acetate) were used as raw materials, and after repeated refining, the "Huandan" (the component may be mercuric oxide) was obtained. [25] Huang Bai also published some prescriptions of Phellodendron amurense collected by him, emphasizing that making gold and silver is a means to prolong life, not a means to get rich. The substitution reaction of iron and copper sulfate was also mentioned.