一名焰硝。即火硝。诸卤地皆产之。河北庆阳诸县。及蜀中尤多。秋冬遍地生白。扫取
煎炼而成。货者苟且。多不洁净。须再以水煎化。倾盆中一夜结成。又名生硝。谓炼过生出
之硝也。澄在下者。状如朴硝。结在上者。或有锋芒。或如圭棱。故硝石亦有芒硝牙硝之名。
与朴硝之芒牙同称。而水火之性则异也。（濒湖）诸硝自晋唐以来。诸家执名而猜。都无定
见。不知硝有水火二种。形质虽同。性气迥别。惟本经朴硝硝石二条为正。神农所列朴硝。
即水消也。有二种。煎炼结出细芒者为芒硝。结出马牙者为牙硝。其凝底成块者通为朴硝。
其气味皆咸而寒。神农所列硝石。即火消也。亦有二种。煎炼结出细芒者。亦名芒硝。结出
马牙者。亦名牙硝。又名生硝。其凝底成块者。通为硝石。其气味皆辛苦而大温。以此为正。
（又）硝石。阴石也。此非石类。乃咸卤煎成。南地不产也。（崔 ）
辛苦微咸。有小毒。阴中阳也。火为之使。主散热行结。治伏暑伤冷。霍乱吐利。破
积块。散痰饮。疗肾虚气逆头痛。湿热黄胆。女劳黑疸。风热喉痹。赤眼肿痛。重舌鹅口。
发背初起。得陈皮。性疏爽。
味辛苦。气大温。治风热癫痫。小儿惊邪螈 。风眩头痛。肺壅。耳聋口疮。喉痹咽塞。
牙颔肿痛。目赤热。多眵泪。与硫黄同用。则配类二气。均调阴阳。有升降水火之功。治冷
热缓急之病。 制礞石。则除积滞痰饮。盖硫黄之性暖而利。其性下行。硝石之性暖而散。
其性上行。礞石之性寒而下。硝石之性暖而上。一升一降。一阴一阳。此制方之妙也。（濒
湖）凡辛苦物。未有大寒者。是物得火焰生。与樟脑火酒性同。本经别录言其性寒者误也。
今兵家火药。用消石者。直入云汉。性升可知。（濒湖）脑痛欲死。鼻投消末。是亦取其上
升辛散。乃从治之义。（炮炙论序）畜川王美人怀子不乳。淳于意药之。旋乳。诊其脉躁。
躁者有余病。即饮以硝石一剂。出血豆。比五六七枚而安。此去结之验也。（史记）甘露丸。
治伏暑泻痢。及肠风下血。或酒毒下血。一服效。远年者不过三服。硝石舶硫黄各一两。白
矾滑石半两。飞面四两。为末。滴水丸梧子大。每新汲水下三五十丸。黄家日晡发热及恶寒
。此为女劳得之。膀胱急。少腹满。身尽黄。额上黑。足下热。因作黑疸。腹胀如水。大便
黑。时溏。非水也。腹满者难洽。用硝石矾石散。消矾等分。烧为末。以大麦粥汁和服方寸
匕。日三。病随大小便去。小便黄。大便黑。是其候也。此乃本矾石寒水之气以归阴。而即
以燥湿。同硝石升水中之火以达阳。而并以化湿。亦治湿热之一则也。喉痹及缠喉风。玉钥
匙。用焰硝一两半。硼砂半两。白僵蚕一钱。脑子一字。为末吹之。此用硝石为主。佐硼砂
以除痰热。僵蚕去风。更合龙脑以开壅结。又治风热之一端也。重舌鹅口。竹沥同焰硝点之
。内外障翳。三五月不效者。一点复明。焰硝一两。铜器熔化。入黄丹二分。片脑二分。铜
匙急钞入罐收之。每点少许。神效。发背初起。恶寒啬啬。或已生疮肿瘾疹。硝石三两。暖
水一升泡化。青布折三重。温拓赤处。热即换。频易取瘥。
〔论〕 硝石从火。性升而散。（水中之火自上升以为散也）主治气分之邪热。不同于
朴硝入血。又本出地之初阳。以真气而散邪结。不等于朴硝之以胜气而为化也。其同硫黄用。
名二气丹。（治中脘痞结或呕或滞）升降水火之功。尤切于伏暑伤冷。致二气交错以为病者。
以暑之中。先于心胞。惟硫硝二味。一降阳而归之。一升阳而散之。乃为最切也。（硫黄入
命门。补真火。其用流动。故曰降而归之。伏暑伤心包。俾之降归命门。正一气相召也。且
有硝石以升散之。故曰升降二气。若伏暑有腹胀疼痛者。更入滑石以利滞热。加白矾以收阴
化阳。庶乎伏者不留耳。是以玉龙丸又为要剂。）按二气来复及大黄龙三方。用硫硝等分。
至玉真丸治肾气不足。气逆上行头痛苦甚者。则硫倍于硝。缘玉真意主归补肾气于下。而上
逆之阳。第藉硝石升散之。更入石膏以降火。半夏以散结耳。
〔朴硝硝石总论〕 朴硝硝石。咸生卤地。假水火二大以为形质。但胜劣有异。故水火
之用迥别。水硝火劣水势。故火体似藏而水用独着。火硝水劣火势。故水体似藏而火用独着。
第二硝初生卤地。硝石色白易炼。朴硝黄赤必再三煎炼始成也。（子由）朴硝属水。味咸而
气寒。其性下走。不能上升。阴中之阴也。故惟荡涤肠胃积滞。折治三焦邪火。硝石属火。
味辛带苦微咸。而气大温。其性上升。水中之火也。故能破积散坚。治诸热病。升散三焦火
郁。调和脏腑虚寒。（濒湖）按朴硝硝石。二者同原于水。同归于治热。但水硝治热之结。
结则多属血分。所谓阴不降而阳不化者也。能行阴中之阳结。则阴降而阳化矣。火硝治热之
郁。郁者多属气分。所谓阳不升而阴不畅者也。能达阳中之阴郁。则阳化而阴畅矣。即就其
味辨之。亦有大异者。水硝以咸胜。却微带苦。本于咸而就下。即以归火之原也。火硝以辛
胜。咸味大逊于水硝。而苦稍加之。本于辛而际上。正以达火之用也。火用达则苦较胜矣。
更有的然知其用殊者。火硝投之火中则焰生。水硝则否。入火生焰者。与火同气也。入火不
谐者。水固胜火也。二者俱以消名。俱能破坚开结。但审夫证治之孰宜降而行。孰宜升而散。
以分用之可耳。盖天地间生人年物。未有不本于水火者。生之者水火。则化之者又焉能外夫
水火之气。卢氏谓二消之分水火。宛如太极之分阴阳。而阴中有阳。阳中有阴。此坎离互根
之妙。即如水硝以寒化热。以咸化坚。固不徒纯阴而已。夫孤阴岂能化阳之结。此又东璧氏
之所未发也。元明粉同甘草坚炼升 。用之所以代芒硝等之峻。而焰硝修治。熔化时投入甘
草。即伏火。可见水火二气。俱归于士也。
硝石，又名焰硝，也就是火硝。在各地含盐碱的土地上都有出产，其中河北庆阳各县以及四川地区尤其多产。秋冬季节遍地生长白色结晶，扫取后经过煎煮提炼而成。市面上售卖的往往草率处理，大多不洁净，需要再次用水煎化，倒入盆中静置一夜结成晶体，这又被称为生硝，意思是经过炼制后生成的硝。沉淀在下部的，形状像朴硝；凝结在上部的，有的带有锋芒，有的像圭角的棱角，所以硝石也有芒硝、牙硝的名称。虽然与朴硝同样有芒、牙之称，但水火之性却不同。（李时珍）自晋唐以来，各家执着于名称猜测，都没有定论，不知道硝分为水、火两种，虽然形质相同，但性气截然不同。只有《神农本草经》中朴硝和硝石两条记载是正统的。神农所列的朴硝，就是水消，有两种：煎炼结出细芒状的是芒硝，结出马牙状的是牙硝，凝结底部成块的通称为朴硝，它们的气味都是咸而寒。神农所列的硝石，就是火消，也有两种：煎炼结出细芒状的，也叫芒硝，结出马牙状的，也叫牙硝，又名生硝，凝结底部成块的，通称为硝石，它们的气味都是辛苦而大温，以此为准。（又注）硝石是阴石，但这并非石类，而是由咸卤水煎制而成，南方不产。（崔昉）
（硝石气味）辛苦微咸，有小毒，属于阴中之阳。以火为引经使药。主治散热行结，治疗伏暑伤冷、霍乱吐泻、破除积块、消散痰饮，治疗肾虚气逆引起的头痛、湿热黄疸、女劳疸、风热喉痹、赤眼肿痛、重舌鹅口、发背初起等症。若与陈皮同用，药性疏爽。
（另一说法）味辛苦，气大温。治疗风热癫痫、小儿惊风抽搐、风眩头痛、肺壅、耳聋口疮、喉痹咽塞、牙颔肿痛、目赤热、多眵泪。与硫黄同用，则配合两类气机，调和阴阳，具有升降水火的功效，治疗冷热缓急之病。用于炮制礞石，则能消除积滞痰饮。大概硫黄的性质暖而利，其性下行；硝石的性质暖而散，其性上行；礞石的性质寒而下，硝石的性质暖而上。一升一降，一阴一阳，这是制药的奥妙所在。（李时珍）凡是辛苦味的药物，没有大寒的，这种药物得火焰而生，与樟脑、火酒的性质相同。《本经》和《别录》说它性寒是错误的。如今兵家火药中使用消石，直入云霄，其性上升可知。（李时珍）脑痛欲死时，将消石粉末吹入鼻中，也是取其上升辛散的作用，这是从治的意义。（《炮炙论序》）汉代川王的美人怀孕不能哺乳，淳于意用药给她治疗，随即恢复哺乳。诊察她的脉象躁动，躁动代表有余的病邪，于是让她服用一剂硝石，排出如豆大的血块，大约五六七枚后就痊愈了。这是去除结聚的验证。（《史记》）甘露丸，治疗伏暑泻痢及肠风下血，或酒毒下血，服一次见效，多年的不过三次。配方：硝石、硫黄各一两，白矾、滑石半两，飞面四两，研为末，滴水制成梧桐子大小的丸药。每次用新汲水送服三五十丸。
黄家日晡时分发热及恶寒，这是女劳疸所致。膀胱拘急，少腹胀满，全身发黄，额头黑，足下热，因此形成黑疸。腹部胀大如水，大便黑，时而溏泄，并非水湿。腹部胀满者难治。使用硝石矾石散，硝石与矾石等分，烧为末，以大麦粥汁调和服用方寸匕，每日三次。病随大小便排出，小便黄，大便黑，这是病情好转的迹象。这是利用矾石的寒水之气以归阴，同时燥湿；配合硝石升水中之火以达阳，共同化湿，这也是治疗湿热的一种方法。喉痹及缠喉风，使用玉钥匙方：焰硝一两半，硼砂半两，白僵蚕一钱，脑子一字，研为末吹入患处。此方以硝石为主，佐以硼砂除痰热，僵蚕祛风，更合龙脑以开壅结，又是治疗风热的一个方面。重舌鹅口，用竹沥同焰硝点涂。内外障翳，三五个月无效的，一点即复明。配方：焰硝一两，铜器熔化，加入黄丹二分，片脑二分，用铜匙迅速搅拌收入罐中保存。每点少许，神效。发背初起，恶寒啬啬，或已生疮肿瘾疹，用硝石三两，暖水一升泡化，青布折叠三层，温热敷贴患处，热则更换，频繁更换直至痊愈。
〔论〕 硝石从火，性升而散。（水中之火自然上升以发散）主治气分的邪热，不同于朴硝入血分。又因为它出自地之初阳，以真气来散邪结，不等于朴硝以胜气来化解。它与硫黄同用，名为二气丹。（治疗中脘痞结或呕或滞），具有升降水火的功效，尤其切合伏暑伤冷导致二气交错为病的病症。因为暑邪先伤心包，唯有硫、硝两味药，一味降阳而归之，一味升阳而散之，最为切要。（硫黄入命门，补真火，其用流动，所以说降而归之。伏暑伤心包，使其降归命门，正是一气相召。且有硝石以升散之，所以说升降二气。若伏暑伴有腹胀疼痛者，更加入滑石以利滞热，加白矾以收阴化阳，庶乎伏邪不留耳。因此玉龙丸也是重要药剂。）按二气来复及大黄龙三方，使用硫、硝等分。至于玉真丸治疗肾气不足，气逆上行头痛苦甚者，则硫黄倍于硝石。因为玉真丸意主归补肾气于下，而上逆之阳，只借硝石升散之，更入石膏以降火，半夏以散结耳。
〔朴硝硝石总论〕 朴硝和硝石，都生于盐碱之地，假借水火两大元素形成形质，只是优劣有异，故水火之用截然不同。水硝火劣水势，所以火体似藏而水用独显；火硝水劣火势，所以水体似藏而火用独显。第二，硝初生于盐碱地，硝石色白易炼，朴硝黄赤必再三煎炼始成也。（苏辙）朴硝属水，味咸而气寒，其性下走，不能上升，属于阴中之阴。所以只能荡涤肠胃积滞，折治三焦邪火。硝石属火，味辛带苦微咸，而气大温，其性上升，是水中之火。所以能破积散坚，治诸热病，升散三焦火郁，调和脏腑虚寒。（李时珍）按朴硝和硝石，二者同源于水，同归于治热。但水硝治热之结，结则多属血分，所谓阴不降而阳不化者也。能行阴中之阳结，则阴降而阳化矣。火硝治热之郁，郁者多属气分，所谓阳不升而阴不畅者也。能达阳中之阴郁，则阳化而阴畅矣。就其味道辨别，也有很大差异。水硝以咸胜，却微带苦，本于咸而就下，即以归火之原也。火硝以辛胜，咸味大逊于水硝，而苦稍加之，本于辛而际上，正以达火之用也。火用达则苦较胜矣。更有明显知道其用途不同的，火硝投入火中则产生火焰，水硝则不然。入火生焰者，与火同气也。入火不谐者，水固胜火也。二者都以“消”命名，都能破坚开结，但审察证治，孰宜降而行，孰宜升而散，分别使用即可。盖天地间生养万物的，无不本于水火。生之者水火，则化之者又焉能外乎水火之气。卢氏谓二消之分水火，宛如太极之分阴阳，而阴中有阳，阳中有阴，这是坎离互根的奥妙。即如水硝以寒化热，以咸化坚，固不徒纯阴而已。夫孤阴岂能化阳之结？这是东璧氏（李时珍）所未阐发的。元明粉同甘草坚炼升华，用之所以代芒硝等之峻烈。而焰硝修治，熔化时投入甘草，即伏火，可见水火二气，俱归于土也。
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).