The External Alchemy Skill of Refining the Yellow and the White
"External Alchemy" refers to the refinement of 'elixirs' with minerals such as gold and stone. Mr. Chen Guofu points out that 'elixir' also refers to the cinnabar from which it was thought that gold could be refined. The skill of refining gold is called 'Feilian' in which 'fei' refers to transformation. The whole technical process is called External Alchemy. "Yellow and White" refers to gold and silver. In fact, the 'gold' described in some early Taoist texts was nothing but the yellow remains of burned minerals, which, in the early Taoists' eyes, were the equivalent of real gold. It was not until the Tang dynasty that they were finally distinguished by calling them 'alchemical gold'. Meanwhile, the silver used in external alchemy was called 'alchemical silver'. According to Chinese linguistic practice as well as the fact that, in alchemical practices, 'gold' is a more important substance than 'silver', the external alchemy arts were named 'Gold Transformation Arts'. ( 點金術 Dianjin Shu )
The Daoist Golden Elixir sect ( 金丹派 Jindan Pai ) used to consider 'golden elixir' as the best way to attain longevity and even immortality. In his book The Inner Book of the Master Who Embraces Simplicity ( 抱樸子內篇 Baopuzi Neipian ), Ge Hong argued that the longer the elixir was refined, the more precious it would be, just as well-refined gold never decays even in deep soil. Logically, taking substances such as elixirs and alchemical gold, he claimed, would refine a man's body, and make him immortal. These ideas characterize the main theories upheld by the golden elixir tradition, which used to rely on natural substances, such as gold and silver, for immortality.
In China, the 'external alchemy skill of refining the yellow and the white' ( 金丹黃白術 Jindan Huangbai Shu ) can be traced back to some stories of immortals of the period of the Warring States, as well as the Qin and Han dynasties. During Emperor Wu's reign of the Han dynasty, Li Shaojun, a famous magician, submitted to the emperor a secret of immortality which involved notions that cinnabar can be refined into gold, and that drinking cups and food containers made of gold can help a man live longer. This story provides us with proof about how 'external alchemy skill' was valued in the imperial court during the Han dynasty. Since then, it has been significantly improved by Daoism, from which emerged such figures as Ge Hong and Tao Hongjing. They appeared during the Jin, and the Southern and Northern dynasties. Historically, 'external alchemy skill' has contributed a lot to the appearance and subsequent development of chemistry and pharmacology in ancient China although, undeniably, taking elixirs can be blamed for many deaths in Chinese history as well.