Waidan
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 natural substances in a luted crucible. The later branch of esoteric neidan 'inner alchemy', which borrowed doctrines and vocabulary from exoteric waidan, is based on allegorically producing elixirs within the endocrine or hormonal system of the practitioner's body, through Daoist meditation, diet, and physiological practices.