Essentials of the Alchemical Laboratory 丹房须知

Compiled by Taoist Wu Hou in the Southern Song Dynasty, this book consists of one volume and is included in the Methods category of the The Dongshen Section in The Daozang.

Prefaced by the author's own preface dated the Guiwei year of the Longxing reign (1163 AD), the book states that the author has admired alchemical methods since childhood and encountered Master Wang of Huainan in his later years, who transmitted The Golden and Jade Scripture to him. Thus, he compiled the essentials from various schools to complete this work. The book quotes ancient texts such as Commentary on the Unification of the Three, The Fire Dragon Scripture, The Golden and Jade Scripture, The Primal Unity Scripture, as well as theories from predecessors including Wei Boyang, True Lord Yin, Qingxiazi, and Sima Ziyi, explaining key matters to note in elixir refining.

Its content covers twenty-one items: selecting companions, choosing a location, the alchemy chamber, avoiding defilement, the alchemical well, fetching soil, making charcoal, adding water, blending incense, altar design, mining lead, extracting mercury, cauldrons and utensils, medicinal clay, warming and nurturing, forming the core, using fire, bathing the elixir, fire control, opening the furnace, and ingesting the elixir. The alchemical method described mainly uses black lead and cinnabar as raw materials, extracting true lead and true mercury through mining and refinement; the two substances are ground into powder, put into a cauldron, sealed tightly, and nurtured with fire. "The medicine in the cauldron is like a hen hatching eggs, a fetus in the womb, or fruit on a tree—when it absorbs sufficient Qi, it will mature naturally." After the elixir is formed, toxins are removed, and it can be ingested. The end of the original volume is incomplete.