The Tongfu Tiejuan 铜符铁卷

The esoteric text Tongfu Tiejuan (Copper Talisman and Iron Scroll) was passed down by the True Person Wu Meng of the Jin Dynasty. As a classic of external alchemy, it has always been secretly transmitted and is indeed a precious treasure of heaven and humanity.

The so-called "external alchemy" refers to the genuine medicine for resurrecting the dead and achieving immortality. External alchemy is divided into four categories:

Most of the so-called external alchemy books handed down in the world are false and unreliable, mostly focusing onpharmaceutics or mineral smelting, with occasional references to huangbaishu. They are either overly cumbersome and inappropriate or obscure and incomprehensible. Only the esoteric text Tongfu Tiejuan by True Person Wu penetrates the essence, eliminates redundancy, and directly reveals the secrets of heaven. It expounds on the Three Elements (heaven, earth, and humanity) in external alchemy, with particular emphasis on the mysteries of the Divine Elixir of Heavenly Essence. From smelting lead in an ash pool to setting up the "divine chamber," all procedures are fully detailed and systematically arranged, making its text more accessible than other alchemy books.

In his time, Chen Yingning gathered like-minded scholars, accumulated a fortune of ten thousand gold pieces, spent ten years of painstaking effort, and conducted hundreds of experiments to study external alchemy, verifying the authenticity of ancient external alchemical techniques. He highly praised Tongfu Tiejuan, stating: "Those who wish to study the Divine Elixir of Heavenly Essence may refer to Xu Jingyang’s Shihan Ji (Record in a Stone Casket) and Wu Meng’s Tongfu Tiejuan." He further noted that apart from these two texts, there were few other works on external alchemy that truly grasped its essence. This underscores the paramount importance of Tongfu Tiejuan in the field of external alchemy.

In fact, the principles of internal and external alchemy are fundamentally the same, so practitioners of internal alchemy can also use this book as a reference.