Library

Nixiao (Potassium Nitrate), also known as Yanxiao (Flame Nitrate), is the same as Huoxiao (Fire Nitrate). It is produced in saline-alkali lands everywhere, with particularly abundant production in counties such as Qingyang in Hebei and in Sichuan. In autumn and winter, white crystals grow all over the ground; they are swept up and refined through boiling and smelting. Merchants often handle it carelessly, resulting in impurities. It must be dissolved again in water, poured into a basin, and left overnight to crystallize. This is also called Shengxiao (Raw Nitrate), meaning nitrate generated after refining. The part that settles at the bottom resembles Puxiao (Mirabilite); the part that crystallizes on top may have sharp edges or resemble the angles of a jade tablet. Therefore, Nixiao is also named Mangxiao (Mangxia) and Yaxiao (Tooth Nitrate). Although it shares the names "Mang" and "Ya" with Puxiao, its nature regarding fire and water is different. (Li Shizhen) Since the Jin and Tang dynasties, various scholars have speculated based on names without definitive views, failing to realize that nitrate is divided into two types: water-based and fire-based. Although their form and texture are similar, their properties and qi are vastly different. Only the entries for Puxiao and Nixiao in the *Shennong Bencao Jing* (Divine Farmer's Materia Medica) are orthodox. The Puxiao listed by Shennong is Water Xiao, which has two types: fine crystals formed during refining are called Mangxiao; horse-tooth-shaped crystals are called Yaxiao; blocks condensed at the bottom are generally called Puxiao. Their taste is salty and cold. The Nixiao listed by Shennong is Fire Xiao, which also has two types: fine crystals formed during refining are also called Mangxiao; horse-tooth-shaped crystals are also called Yaxiao, also known as Shengxiao; blocks condensed at the bottom are generally called Nixiao. Their taste is pungent, bitter, and greatly warm. This is taken as the standard. (Note) Nixiao is a Yin stone, but it is not a mineral stone; it is made from boiling saline water and is not produced in southern regions. (Cui Fang)

(Taste and Properties) Pungent, bitter, slightly salty, with slight toxicity. It belongs to Yang within Yin. Fire acts as its guiding herb. It mainly treats heat dispersion and resolving stagnation, treating latent summerheat injuring cold, cholera with vomiting and diarrhea, breaking down accumulations and masses, dissipating phlegm-fluids, treating headache due to kidney deficiency with rebellious qi, damp-heat jaundice, female-labor jaundice, wind-heat throat obstruction, red and swollen eyes, double tongue, goose-mouth, and early-stage back carbuncle. When used with Chenpi (Tangerine Peel), its property becomes soothing and refreshing.

(Another View) Taste pungent and bitter, qi greatly warm. Treats wind-heat epilepsy, pediatric convulsions due to fright, wind-dizziness headache, lung congestion, deafness, mouth sores, throat obstruction with swallowing difficulty, swelling and pain of teeth and jaw, red and hot eyes, excessive discharge and tearing. When used together with Liuhuang (Sulfur), it combines two types of qi, harmonizes Yin and Yang, and possesses the function of ascending and descending water and fire, treating diseases of cold, heat, slackness, and urgency. When used to process Mengshi (Calamine), it eliminates accumulation and phlegm-fluids. Generally, Liuhuang's nature is warm and purgative, with a downward direction; Nixiao's nature is warm and dispersing, with an upward direction; Mengshi's nature is cold and downward, while Nixiao's nature is warm and upward. One ascends, one descends; one is Yin, one is Yang. This is the subtlety of prescription formulation. (Li Shizhen) Among pungent and bitter substances, none are greatly cold. This substance is born from flame, sharing the same nature as Zhangnao (Borneol) and Huojiu (Distilled Wine). The statement in the *Benjing* and *Bielu* that it is cold-natured is erroneous. Today, military gunpowder uses Xiaoshi (Nitrate), shooting straight into the clouds, indicating its ascending nature is clear. (Li Shizhen) For severe brain pain, blowing Xiaoshi powder into the nose utilizes its ascending and pungent-dispersing property, following the principle of contrary treatment. (*Preface to Paozhi Lun*) The beautiful lady of King Chuan was pregnant but could not lactate. Chunyu Yi treated her with medicine, and she lactated immediately. His pulse diagnosis showed agitation, indicating excess pathogenic factors. He administered one dose of Nixiao, causing the expulsion of bean-sized blood clots. After about five to seven clots, she recovered. This verifies the removal of stagnation. (*Records of the Grand Historian*) Ganlu Wan (Sweet Dew Pill) treats latent summerheat dysentery and intestinal wind bleeding, or alcohol-induced bleeding. One dose is effective; for chronic cases, no more than three doses are needed. Formula: Nixiao and Liuhuang each 1 liang, Baifan (Alum) and Huashi (Talcum) 0.5 liang, Feimian (Refined Flour) 4 liang. Grind into powder, add water dropwise to make pills the size of wutong seeds. Take 30–50 pills with fresh well water per time.

Huang family experiences fever and chills at dusk, caused by female-labor jaundice. The bladder feels urgent, the lower abdomen is full, the whole body is yellow, the forehead is black, and the feet feel hot, thus forming black jaundice. The abdomen is distended like water, stool is black, sometimes loose, not due to water retention. Abdominal fullness is difficult to treat. Use Xiaoshi Fanshi San (Nitrate and Alum Powder): equal parts of Xiaoshi and Fanshi, calcined into powder, mixed with barley porridge juice, taken as a square-inch spoonful, three times a day. The disease exits via large and small intestines; yellow urine and black stool are signs of improvement. This utilizes the cold-water qi of Fanshi to return to Yin and dry dampness, while simultaneously using Xiaoshi to ascend the fire within water to reach Yang and transform dampness. This is another method for treating damp-heat. For throat obstruction and winding throat wind, use Yuyaochi (Jade Key): 1.5 liang Yanxiao, 0.5 liang Pengsha (Borax), 1 qian Baijiangcan (Silkworm), 1 zi Naobing (Camphor). Grind into powder and blow into the affected area. This formula uses Xiaoshi as the main herb, assisted by Pengsha to remove phlegm-heat, Jiangcan to dispel wind, and Longnao (Borneol) to open congestion. It is another aspect of treating wind-heat. For double tongue and goose-mouth, apply Zhuli (Bamboo Sap) mixed with Yanxiao. For internal and external eye cataracts ineffective after 3–5 months, a single application restores vision. Formula: 1 liang Yanxiao, melt in a copper vessel, add 2 fen Huangdan (Minium) and 2 fen Piannao (Borneol), stir quickly with a copper spoon and store in a jar. Apply a small amount locally; miraculous effect. For early-stage back carbuncle with chills, or existing sores/rashes, use 3 liang Nixiao dissolved in 1 sheng warm water. Fold green cloth three layers thick, apply warm to the red area, replace when hot, change frequently until healed.

[Discussion] Nixiao derives from fire, with an ascending and dispersing nature. (The fire within water naturally ascends to disperse.) It mainly treats pathogenic heat in the Qi level, unlike Puxiao which enters the Blood level. Furthermore, it originates from the initial Yang of the earth, dispersing pathogenic stagnation with true Qi, unlike Puxiao which transforms using conquering Qi. When used with Liuhuang, it is named Erqi Dan (Two Qi Pill). (Treats epigastric fullness/stagnation with vomiting or obstruction), possessing the function of ascending and descending water and fire, especially pertinent to illnesses caused by latent summerheat injuring cold leading to the intermingling of two Qi. Since summerheat first affects the Pericardium, only Liuhuang and Xiaoshi are most effective: one descends Yang and returns it, the other ascends Yang and disperses it. (Liuhuang enters the Mingmen Gate, tonifies True Fire, its action is fluid, hence described as descending and returning. Latent summerheat damages the Xinbao, causing it to descend and return to Mingmen, which is exactly the mutual attraction of one Qi. Moreover, with Xiaoshi to ascend and disperse, it is called ascending and descending two Qi. If latent summerheat involves abdominal distension and pain, add Huashi to promote stagnant heat, and add Baifan to gather Yin and transform Yang, ensuring latent pathogens are not retained. Thus, Yulong Wan is also an important agent.) According to Erqi Laifu and Da Huang Long formulas, Liuhuang and Xiaoshi are used in equal parts. However, in Yuzhen Wan, which treats insufficient Kidney Qi with rebellious Qi ascending to cause severe head pain, Liuhuang is doubled compared to Xiaoshi. Because Yuzhen Wan aims to tonify Kidney Qi downwards, the rebellious Yang above relies on Xiaoshi to ascend and disperse, further adding Shigao (Gypsum) to descend fire and Banxia (Pinellia) to dissipate stagnation.

[General Discussion on Puxiao and Nixiao] Puxiao and Nixiao both originate in saline lands, borrowing the elements of Water and Fire to form their substance. However, their superiority and inferiority differ, leading to distinct applications of Water and Fire. Water Xiao has inferior Fire and superior Water potential, so its Fire aspect seems hidden while its Water function is prominent. Fire Xiao has inferior Water and superior Fire potential, so its Water aspect seems hidden while its Fire function is prominent. Secondly, upon initial formation in saline land, Nixiao is white and easy to refine, whereas Puxiao is yellow-red and requires repeated refining. (Su Zhe) Puxiao belongs to Water, tastes salty and is cold in nature, with a downward-moving property that cannot ascend, making it Yin within Yin. Thus, it can only cleanse gastrointestinal stagnation and subdue pathogenic fire in the Triple Burner. Nixiao belongs to Fire, tastes pungent with bitterness and slight saltiness, and is greatly warm in nature, with an ascending property, making it Fire within Water. Thus, it can break accumulations and disperse hardness, treat various heat diseases, ascend and disperse Triple Burner fire depression, and harmonize visceral cold deficiency. (Li Shizhen) Puxiao and Nixiao share the same origin in Water and converge in treating heat. However, Water Xiao treats heat *stagnation* (Jie), which mostly belongs to the Blood level, where Yin does not descend and Yang does not transform. By moving Yang stagnation within Yin, Yin descends and Yang transforms. Fire Xiao treats heat *depression* (Yu), which mostly belongs to the Qi level, where Yang does not ascend and Yin does not flow smoothly. By reaching Yin depression within Yang, Yang transforms and Yin flows smoothly. Even distinguishing by taste reveals significant differences. Water Xiao is dominated by saltiness, slightly bitter, originating from saltiness and moving downward, thereby returning to the source of Fire. Fire Xiao is dominated by pungency, with much less saltiness than Water Xiao and slightly more bitterness, originating from pungency and moving upward, thereby achieving the function of Fire. When Fire function is achieved, bitterness becomes more pronounced. More clearly, when Fire Xiao is thrown into fire, flames arise; Water Xiao does not. Substances producing flame in fire share the same Qi as fire. Those not harmonizing with fire indicate Water conquers Fire. Both are named "Xiao" (Dissolve/Destruct) and can break hardness and open stagnation, but one should judge whether the syndrome requires descending movement or ascending dispersion, and use them accordingly. All living things in the world originate from Water and Fire. Those who generate them are Water and Fire; thus, those who transform them cannot be outside the Qi of Water and Fire. Lu Shi stated that the division of Water and Fire in the two "Xiao"s is like the division of Yin and Yang in Taiji, with Yang within Yin and Yin within Yang, which is the subtlety of Kan and Li mutually rooting. Just as Water Xiao transforms heat with cold and hardness with saltiness, it is not purely Yin. How can solitary Yin transform Yang stagnation? This is what Dongbi Shi (Li Shizhen) had not yet expounded. Yuanming Fen (Refined Potassium Nitrate) refined with Licorice root and升华 (sublimed) is used to replace the harshness of Mangxiao etc. When Yanxiao is processed, Licorice root is added during melting to suppress fire, showing that Water and Fire Qi both return to Earth (Soil).