An alchemy, a method of alchemy. "Bao Piaozi's article? Then it was mentioned that there are so-called "nine kinds of elixirs" in the Shen Dan Classic of Huangdi Jiuding, and the seventh one is called "Roudan", which means "one dose will not die for a hundred days". Today's Taoist Collection contains the formula of Huangdi Jiuding Shen Dan Jing, whose author is unknown. Buddhist scriptures are based on the experience of the Yellow Emperor in Xuan Nv. It is believed that breathing guidance and taking herbs can only cure diseases and prolong life, and only taking Shen Dan can make people become immortals and coexist with heaven and earth. There are nine methods of alchemy recorded in it: Dan Hua, Er Shen Fu, Sanshen Dan, Sihuan Dan, 500 Dan, Liulian Dan, Qirou Dan, Fuba Dan and Jiuhan Dan. The concrete refining method of Roudan is: put mercury and yellow mud into a container sealed with mud, dry it for ten days, then burn it for thirty-six days and let it cool for one day. Finally, open the container, sweep away the refined medicine attached to the container wall with feathers, and take it with the corresponding medicine juice, which can play a role in blackening hair and white hair and countless future generations. This classic prescription clearly lists the dosage of drugs used, the duration of alchemy, the method and effect of taking pills, and is an important material for studying Taoist alchemy, chemistry and pharmacology.

Kim? Ge Hong: Chapter of Bao Puzi, then. See Collected Taoist Scriptures, Volume 28. For the formula of Huangdi Jiuding God single crystal, see Collected Taoist Scriptures 18.