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(From *Yaoxing Lun*)

[Names] Bailong Fen (White Dragon Powder).
Li Shizhen stated: "Xuan" refers to the color of water; "Ming" means crystal clear. The *Yuyuan Fang* calls it Bailong Fen.

[Preparation] Li Shizhen stated: The preparation method is as follows: Take ten jin of pure white Puxiao (Mirabilite), add one shi of running water, boil until dissolved, and filter out impurities. Expose it overnight under the stars and moon, drain the water, and collect the salt crystals. For every dou of salt crystals, use one jin of sliced radish, cook them together thoroughly, filter cleanly, and expose again overnight before collecting. For every jin of salt crystals, use one liang of Gancao (Licorice Root), decoct together, remove dregs, and expose again overnight before collecting. Place in a large clay pot, pack it tightly, seal the seams thickly with salt mud half an inch deep, leave the mouth uncovered, and place it in a furnace. Use ten jin of charcoal fire, starting from gentle heat to strong heat. When boiling stabilizes, cover the mouth with a tile, reseal with salt mud, and continue roasting with fifteen jin of top-fire. Allow to cool for one shichen (two hours), then take out. Place on the ground covered by paper, and cover with a basin for three days to eliminate fire toxicity. Grind into powder. For every jin of powder, mix in one liang of raw Gancao (Licorice Root) powder and one liang of honey-fried Gancao (Licorice Root) powder evenly. Store in a bottle for use.

[Flavor and Nature] Acrid, sweet, cold, non-toxic.

[Indications] Heart heat with restlessness, and stagnation/syndromes of the five zang organs (Zhen Quan). Brightens the eyes, clears deficiency heat above the diaphragm, reduces swelling and detoxifies (Meng Shen).

[Elucidations] Cao (Zhang Yuansu) said: Xuanming Fen is sinking and yin. It has two functions: clearing excess heat in the stomach and sweeping away old fecal matter in the intestines. Generally, it is used to replace Puxiao (Mirabilite).

The *Xuanming Fen Zhuan* records: Emperor Ming of Tang heard that Liu Xuanzhen, a Daoist priest from Mount Zhongnan, lived long due to its consumption, so he summoned him to ask. Xuanzhen said: According to the *Immortal Scriptures*, refining Puxiao (Mirabilite) yields Xuanming Fen. Only taking this prescription leads to disease-free longevity. This medicine has no residue and is warm in nature, containing yang within yin, capable of curing 120 types of diseases. Raw administration can even save lives in emergencies, let alone refined long-term use. It benefits essence, strengthens qi, assists yang, and harmonizes yin. It applies to men and women, infants and children, regardless of season or temperature. It treats all heat toxins, wind-cold, phlegm-heat distension, five exhaustion and seven injuries, bone-stealing tuberculosis, headache with fever, blockage of internal qi, obstruction of large and small intestines, sanjiao damp-heat strangury, zhuyu (pestilential influences), cough and vomiting, bitter taste and dry tongue, throat obstruction, palpitations and forgetfulness, disharmony of ying and wei, alcohol intoxication, overeating, cold pain in waist and knees, soreness and numbness of limbs, chronic cold or heat, limb congestion, stiffness of back and shoulders, blurred vision and vertigo, weakness after prolonged eye use, intestinal wind and hemorrhoids, blood dyscrasia, postpartum conditions in women, infant malnutrition, yin poison shaoyin syndrome, and epidemic diseases affecting interior and exterior. Long-term use makes one radiant, opens orifices, strengthens spleen, preserves youth, brightens eyes, lightens the body, and extends life; effects are too numerous to record. Usually, one liang is divided into twelve doses, adjusted according to circumstances. If one feels symptoms of heat accumulation or shaoyin syndrome, such as headache, nasal congestion, inability to move limbs, difficulty eating, irritability, and abdominal distension, requiring purgation for relief, dose 2.5 qian or 0.5 liang based on age. Taking it with peach blossom decoction is best; scallion decoction is secondarily effective; if still not unblocked, hot water induces immediate effect. For poisoning from fish, lotus root, vegetables, or other toxic foods, take two qian mixed with scallion white decoction to immediately expel toxins. Pregnant women taking it long-term ensure safe childbirth and prevent sores/diseases. To maintain mild unblockage without constipation, long-term use gradually improves morning intake and evening response without depleting the five zang, bringing peace. Initially, take two qian on an empty stomach with wine, tea, or broth; after a while, take another three qian. Within seven days, slight diarrhea of yellow-black fluid and saliva occurs, indicating the expulsion of disease roots; do not fear. After seven days, warmth is felt in the abdomen, digestion improves, and qi descends. Long-term use eliminates old pathology and nourishes new growth, daily calming qi and blood. Using hemp seed decoction as a guide is recommended; avoid Kushen (Sophora Root). See *Taiyin Jing* for details.

Hao Gu (Wang Haogu) stated: The statement that Xuanming Fen treats yin poison is only applicable when yang is concealed internally. If used for true yin poison, it kills rapidly.

Zhen Heng (Zhu Danxi) said: Xuanming Fen is formed by fire refining, so its nature should be warm. Claims that long-term use lightens the body, secures fetus, preserves youth, and greatly tonify contradict logic? I personally witnessed friends dying because they did not heed my words, so I write this as a warning.

Li Shizhen stated: The *Shennong Bencao Jing* mentions that refined Puxiao (Mirabilite) taken orally makes one light-bodied and immortal; this was likely inserted by alchemists. Later generations made Xuanming Fen from it, refining it multiple times and adding Gancao (Licorice Root) to remove its salty-cold toxicity. For youths with robust constitution suffering from excess heat and stagnation in the sanjiao and intestines, appropriate dosage yields rapid effects; however, for those with spleen-stomach deficiency-cold or yin deficiency with fire hyperactivity, taking it accelerates disaster.

[Attached Prescriptions] Three new prescriptions.

Heat jue with qi pain: Sanqian (3 qian) of Xuanming Fen, mixed with hot child's urine and taken orally. (*Jijian Fang*)

Shaoyin syndrome with mania: Erqian (2 qian) of Xuanming Fen, one qian of Zhusha (Cinnabar). Grind to powder. Take with cold water. (*Shanghan Yunyao*)

Unstopping epistaxis: Erqian (2 qian) of Xuanming Fen, taken with water. (*Shengji Zonglu*)