Library

[Black Tin]
Also known as Heixi (Black Tin).
Sweet, cold in nature, non-toxic. When using Heixi, one must take new lead that has not undergone silver smelting, melt it clean to remove dross, melt it again into liquid, mix with Sulfur (Liu Huang), and when flames arise, sprinkle with vinegar. Wait until it becomes black ash, grind it until it is no longer sticky. If the reaction is not thorough, taking it will cause headache, because Yin descends too rapidly, leaving Yang fire without support.

[Invention/Analysis]
Heixi inherits the nature of Gui Water of the North, being the essence of extreme Yin, internally connecting to the Kidney. Therefore, Heixi Pill (Heixi Dan) from *Ju Fang* (Formulas of the Bureau of People's Welfare Pharmacy) and Zhenzhen Pill (Zhenzhen Dan) from *Xuanming* are both used with it. When interacting with Mercury (Gong), it can treat all disorders of Yin-Yang confusion, excess above and deficiency below, Qi ascending without descending, dysphagia, regurgitation, vomiting, vertigo, and other diseases. Furthermore, if hammered into thin sheets and placed in distilled spirits for about half a month, white frost forms. Taking this wine slowly is the quickest way to descend Yin Fire, but its nature carries Yin toxicity, which may damage the Heart and Kidney; thus, it should not be taken in large amounts. Lead penetrates flesh; therefore, if a woman uses it to plug the ear canal, the ear canal will naturally perforate.

[Hufen / Lead Carbonate]
Also known as Hufen.
Pungent, cold in nature, non-toxic.
*Shennong Bencao Jing* states it treats latent corpse-poison and insect stings, and kills three types of parasites.

[Invention/Analysis]
Lead Carbonate (Hufen) is of the same category as Yellow Lead Oxide (Huandan), containing bean powder and clam shell powder, but lacking saltpeter. It primarily enters the Qi level, with functions specialized in relieving pain and generating flesh. It can also be used in plasters to replace Yellow Lead Oxide. The statement in *Shennong Bencao Jing* regarding treating latent corpse-poison and killing parasites relies on the heavy nature of lead to suppress pathogenic factors. In *Jingui Yaolue*, Gancao Fenmi Tang (Licorice, Lead Carbonate, and Honey Decoction) treats ascariasis with salivation and heart pain, specifically utilizing Lead Carbonate to kill parasites, Licorice to calm the Stomach, and honey to lure the parasites into the mouth. Tao Hongjing stated that it is excellent for treating corpse-worms.

[Yellow Lead Oxide]
Also known as Huandan.
Pungent, slightly cold in nature, non-toxic.
*Shennong Bencao Jing* states it treats vomiting and reverse flow, convulsive epilepsy, removes heat, and directs Qi downward.

[Invention/Analysis]
Yellow Lead Oxide (Huandan) is heavy and sinking in nature, with a taste combining salt and alum, entering the Blood level, capable of sinking phlegm and stopping malaria. *Shennong Bencao Jing* mentions stopping vomiting and reverse flow, treating convulsive epilepsy, removing heat, and directing Qi downward, relying on its heavy nature to suppress rebellion and fullness. Zhang Zhongjing uses it in Chaihu Longgu Muli Tang (Bupleurum, Dragon Bone, and Oyster Shell Decoction) to enter the Gallbladder channel and dispel phlegm accumulation; however, if there is no internal accumulation, mistaken use will inevitably harm the Stomach and cause loss of appetite. Promoting flesh growth in sores, sinking phlegm, and killing parasites are all inherent properties of lead. For sudden redness and pain of the eyes, applying Yellow Lead Oxide mixed with honey to the Taiyang acupoint yields immediate results.