Waidan, translated as 'external alchemy' or 'external elixir', is the early branch of Chinese alchemy that focuses upon compounding elixirs of immortality by heating minerals, metals, and other natura
Baopuzi
…techniques span two types of Chinese alchemy that Tang dynasty scholars later differentiated into neidan 內丹 "internal elixir; internal alchemy" and waidan 外丹 "external elixir; external alchemy". The word dan 丹 "cinnabar; red; pellet; [Chinese medicine] pill" means "pill of immortality, or elixir of life…
Chinese woodblock illustration of a waidan alchemical refining furnace, 1856 Waike tushuo 外科圖説 (Illustrated Manual of External Medicine)