Reference

Strick- mann cites the following passage describing the fates of historical figures who had eaten the Langgan elixir: Those who feigned construction of a tomb after swallowing Efflorescence of Langgan are Yan Menzi, Gao Qiuzi, and Master ...

The langgan huadan 琅玕華丹 "Elixir Efflorescence of Langgan" name of the waidan "external alchemy" elixir of immortality is the best-known usage of the word langgan. ... people will practice alchemy to create immortality drugs, ... an eminent scholar of Tang dynasty literature and history, discussed langgan in several books and articles.

Many times over the course of history happened that two scientists independently discovered something. ... actually a couple of other alchemical substances that grant immortality, among other things: the Cup of Jamshid and the Elixir of Langgan Efflorescence. For all we know, Flamel and his wife weren't the only immortal wizards wandering ...