Chinese woodcut: Alchemical refining furnace

Woodblock illustration from Waike tushuo (Pictorial Manual of External Medicine), published in 1856 (6th year of the Xianfeng reign period of the Qing dynasty). It shows implements for creating and refining bagua da jiangdan (Eight-Trigram Grand Descending Elixir), with special attention given to the internal structure of the alchemical furnace. Eight-Trigram Grand Descending Elixir is a type of Hydrargyrum chloratum compositum - jiangdan or bai jiangdan -- obtained through the mixed crystallization of mercuric chloride (HgCl2) and mercurous chloride (Hg2Cl2), by heating mercury together with various minerals in the furnace. It was used to treat ulcers, fistulas, luoli (scrofula), xirou (polyps), wanxuan (chronic itchy skin condition), etc.

PICTURE TITLE: Eight-Trigram Grand Descending Elixir (bagua da jiangdan, Hydrargyrum chloratum compositum). OTHER LETTERING: Formula for Eight-Trigram Grand Descending Elixir (bagua da jiangdan, Hydrargyrum chloratum compositum). Vessel for producing the Infant (tai, homunculus). The Pillar of Heaven supports it (Tianzhu cheng). Yin and Yang contend (Yin yang ge). Man and the vessel (Ren he guan). The earth and the square brick (Di fang zhuan). Mountains and rivers, and the basin.