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Mercury (Hydrargyrum), saltpeter (Natrii Nitras), alum (Alumen), green vitriol (Vitriolum Ferrosum), and fried white salt (Sal Alba Coctus) are each used in the amount of nine qian.
The above medicines are ground together into a fine powder until no silver specks of mercury are visible, then placed in a new, large silver crucible, and melted over a mild fire. If the fire is too fierce, the mercury will rise; one must guard against "Zou Lu" (loss of medicinal efficacy or spillage), and it is best to use charcoal. The mixture is boiled until no white smoke rises from the crucible, then stirred with a bamboo or wooden stick until no medicinal residue is lifted, indicating that the medicine has adhered to the bottom of the crucible, a process called "Jie Tai" (formation of the embryo). Once the embryo is formed, take a large wooden basin filled with water, and place a clean iron fire basin inside the wooden basin. The water in the wooden basin should reach half the height of the iron basin. Then, invert the previously formed embryo along with the crucible into the iron basin. Seal the mouth of the crucible tightly with a mixture of salt water and yellow earth to prevent gas leakage; leakage also causes "Zou Lu". Spread clean ash inside the iron basin up to the waist of the crucible, leveling the ash without disturbing the medicinal crucible, as shaking or damaging the seal will also cause "Zou Lu". After spreading the ash, pile red-hot chestnut charcoal around the bottom of the crucible, and gently fan it with a fan for the duration of one incense stick; this is called "Wen Huo" (gentle fire). Then, fan slightly harder to refine for another incense stick's duration; this is called "Wu Huo" (strong fire). Add charcoal as needed, ensuring the fire does not break and the bottom of the crucible is not exposed. Refine for another incense stick's duration, then remove the heat. Wait until the next day for the ash in the basin to cool and settle. Sweep away the ash with a broom, remove all the sealing earth, and open the container to find the white frost-like substance inside the iron basin, which is called "Dan" (cinnabar/mercurial pill). Store it in a porcelain bottle for later use; the older, the better. The original embryo remaining in the crucible, when ground and applied, is extremely effective for treating tinea (fungal skin infections). If there is concern that the embryo did not form properly, and upon heating in the inverted position, the embryo falls into the iron basin, no Dan will precipitate, which is also termed "Zou Lu". A safe method is to make a small three-legged stand from iron wire to support the Dan embryo inside the furnace. When this Dan encounters any malignant sores such as carbuncles, back boils, or ding toxic swellings, apply about one li (a very small unit of weight) mixed with saliva to the top of the toxic swelling, then cover it with a plaster. The next day, the root of the toxicity will be completely extracted, forming a piece of black flesh on the top of the swelling, which will fall off after three to four days. Applying Sheng Yao (sublimated mineral medicine) a few more times will complete the cure.
This Dan can be made by moistening steamed rice cake flour with a little water, mixing it thoroughly into a fine powder, rolling it into strips, drying them, and storing them. For any toxic sore that has formed a sinus tract, measure the depth of the tract appropriately, insert the medicinal strip, and cover with a plaster. Squeeze out pus the next day. Repeat this once or twice until the tract turns into pus and drains. Once the tract is cleared, apply Sheng Yao a few more times to achieve healing. This Dan acts ten times faster than Sheng Dan, but its nature is most fierce, and applying it to the toxin causes severe pain. To mitigate this, mix it with raw Ban Xia (Pinelliae Rhizoma) and add a small amount of Bing Pian (Borneolum Syntheticum); this will cause numbness in the flesh and eliminate pain.
Geng Sheng notes: Jiang Dan (descending cinnabar) is a substance for treating stubborn sores, malignant toxins, and dead tissue. It must never be used excessively or indiscriminately; utmost caution is required.