（宋《嘉 》）
【气味】甘，大寒，无毒。
时珍曰∶咸、微甘。即英硝也。
【主治】除五脏积热伏气（甄权）。末筛点眼赤，去赤肿障翳涩泪痛，亦入点眼药中用
（大明）。功同芒硝（时珍）。
【发明】成无己曰∶《内经》云∶咸味下泄为阴。又云∶咸以软之。热淫于内，治以咸
寒。气坚者以咸软之；热盛者，以寒消之。故张仲景大陷胸汤、大承气汤、调胃承气汤皆用
芒硝，以软坚去实热，结不至坚者不可用也。
好古曰∶本草云∶朴硝味辛，是辛以润肾燥也。今人不用辛字，只用咸字，咸能软坚也
。其义皆是。本草言芒硝利小便而堕胎，然伤寒妊娠可下者用此，兼大黄引之，直入大肠，
润燥软坚泻热，而母子俱安。《经》云∶有故无殒，亦无殒也，此之谓欤？以在下言之，则
便
溺俱阴。以前后言之，则前气后血。以肾言之，总主大小便难。溺涩秘结，俱为水少火盛。
《经》云∶热淫于内，治以咸寒，佐之以苦，故用芒硝、大黄相须为使也。
元素曰∶芒硝气薄味浓，沉而降，阴也。其用有三∶去实热，一也；涤肠中宿垢，二也
；破坚积热块，三也。孕妇惟三、四月及七、八月不可用，余皆无妨。
宗 曰∶朴硝是初得一煎而成者，其味酷涩，所以力紧急而不和，治食 不消，以此荡
逐之。芒硝是朴硝淋过炼成，故其性和缓，故今多用治伤寒。
时珍曰∶朴硝澄下，硝之粗者也，其质重浊。芒硝、牙硝结于上，硝之精者也，其质清
明。甜硝、风化硝，则又芒硝、牙硝之去气味而甘缓轻爽者也。故朴硝只可施于卤莽之人，
及敷涂之药；若汤散服饵，必须芒硝、牙硝为佳。张仲景《伤寒论》只用芒硝，不用朴硝，
正此义也。硝，禀太阴之精，水之子也。气寒味咸，走血而润下，荡涤三焦肠胃实热阳强之
病，乃折治火邪药也。唐时，腊月赐群臣紫雪、红雪、碧雪，皆用此硝炼成者，通治积热诸
病有神效，贵在用者中的尔。
【附方】旧十七，新一十五。
紫雪∶疗伤寒温疟，一切积热烦热，狂易叫走，瘴疫毒疠，猝死香港脚，五尸五疰，心腹
诸疾，疠刺切痛，解诸热毒，邪热发黄，蛊毒鬼魅，野道热毒，小儿惊痫百病。黄金一百两，
石膏、寒水石、滑石、磁石各三斤。捣碎，水一斛，煮四斗，去滓；入犀角屑、羚羊角、青
木香、沉香各五两，玄参（洗焙）、升麻各一斤，甘草（炒）八两，丁香一两，入前汁中煮
取一
斗五升，去滓；入炼朴硝十斤，硝石三十二两，于药汁中，微火煎之，柳木不住搅，至水气
欲尽，倾木盆中。待欲凝，入麝香一两二钱半，朱砂末三两，搅匀，收之。每服一、二钱，
凉水服。临时加减，甚者一两。（《和剂局方》）
红雪∶治烦热，消宿食，解酒毒，开三焦，利五脏，除毒热，破积滞。治伤寒狂躁，胃
烂发斑，温瘴香港脚，黄胆头痛，目昏鼻塞，口疮喉痹，重舌肠痈等病。用川朴硝十斤（炼去
滓），羚羊角（屑）、黄芩、升麻各三两，人参、赤芍药、槟榔、枳壳（麸炒）、生甘草、淡
竹
叶、木香各二两，木通、栀子、葛根、桑白皮、大青、蓝叶各一两半，苏方木六两。并锉片。
水二斗五升，煎至九升，去滓，滤过煎沸；下硝不住手搅，待水气将尽，倾入器中；欲凝，
下朱砂一两，麝香半两，经宿成雪。每服一、二钱，新汲水调下。欲行，则热汤化服一两（《和
剂方》）
碧雪∶治一切积热，天行时疾，发狂昏愦，或咽喉肿塞，口舌生疮，心中烦躁，或大小
便不通，胃火诸病。朴硝、芒硝、马牙硝、硝石、石膏（水飞）、寒水石（水飞）各一斤，
以甘
草一斤，煎水五升，入诸药同煎，不住手搅，令硝熔得所；入青黛一斤，和匀，倾盆内，经
宿结成雪，为末。每含咽，或吹之，或水调服二、三钱。欲通利，则热水服一两。（《和剂
局方》）
凉膈驱积∶王 山人甘露饮∶治热壅，凉胸膈，驱积滞。蜀芒硝末一大斤。用蜜十二两，
冬加一两，和匀，入新竹筒内，半筒以上即止，不得令满。却入炊甑中，令有药处在饭内，
其虚处出其上，蒸之。候饭熟取出，绵滤入瓷钵中，竹篦搅勿停手，待凝，收入瓷盒。每卧
时含半匙，渐渐咽之。如要通转，即多服之。（刘禹锡《传信方》）
乳石发动烦闷∶芒硝，蜜水调服一钱，日三服。（《圣惠方》）
骨蒸热病∶芒硝末，水服方寸匕，日二服良。（《千金方》）
腹中痞块∶皮硝一两，独蒜一个，大黄末八分。捣作饼。贴于患处，以消为度。（邵氏
《经验方》）
食物过饱不消，遂成痞膈∶马牙硝一两，吴茱萸半斤。煎汁投硝，乘热服之。良久未转，
更进一服，立效。窦群在常州，此方得效也。（《经验方》）
关格不通，大小便闭，胀欲死，两三日则杀人。芒硝三两，泡汤一升服，取吐即通。（《百
一方》）
小便不通∶白花散∶用芒硝三钱，茴香酒下。（《简要济众方》）
时气头痛∶朴硝末二两，生油调涂顶上。（《圣惠方》）
赤眼肿痛∶朴硝，置豆腐上蒸化，取汁收点。（《简便方》）
风眼赤烂∶明净皮硝一盏。水二碗煎化，露一夜，滤净澄清。朝夕洗目。三日其红即消，
虽半世者亦愈也。（杨诚《经验方》）
退翳明目∶白龙散∶用马牙硝光净者，浓纸裹实，安在怀内着肉，养一百二十日，研粉，
入少龙脑。不计年岁深远，眼生翳膜，远视不明，但瞳人不破散者，并宜日点之。（《经验
方》）
诸眼障翳∶牙硝十两，汤泡汁，浓纸滤过，瓦器熬干，置地上一夜，入飞炒黄丹一两，
麝香半分。再罗过，入脑子。日点。（《济急仙方》）
逐月洗眼∶芒硝六钱。水一盏六分，澄清。依法洗目，至一年，眼如童子也。正月初三，
二月初八，三月初四，四月初四，五月初五，六月初四，七月初三，八月初一，九月十三，
十月十三，十一月十六，十二月初五日。（《圣惠方》）
牙齿疼痛∶皂荚浓浆，同朴硝煎化，淋于石上，待成霜。擦之。（《普济方》）
食蟹龈肿∶朴硝敷之，即消。（《普济方》）
喉痹肿痛∶《外台》∶用朴硝一两，细细含咽，立效。或加丹砂一钱。气塞不通，加生甘
草末二钱半，吹之。
小儿重舌∶马牙硝涂于舌上下，日三。（姚和众）
口舌生疮∶朴硝含之，良。（孙真人方）
小儿鹅口∶马牙硝，擦舌上，日五度。（《简要济众》）
豌豆毒疮未成脓者。猪胆汁和芒硝末涂之。（《梅师》）
代指肿痛∶芒硝煎汤渍之。（《圣惠方》）
火焰丹毒∶水调芒硝末涂之。（《梅师》）
一切风疹∶水煮芒硝汤拭之。（《梅师》）
漆疮作痒∶芒硝汤，涂之。（《千金》）
灸疮飞蝶∶因艾灸火疮痂退落，疮内鲜肉片子，飞如蝶状，腾空飞去，痛不可言，是血
肉俱热，怪病也。用朴硝、大黄各半两。为末。水调下，微利即愈。（夏子益《奇疾方》）
妇人难产∶芒硝末二钱，童子小便温服，无不效者。（《信效方》）
死胎不下∶方同上。丰城曾尉有猫孕五子，一子已生，四子死腹中，用此灌之即下。又
治一牛亦下。（《信效方》）女人扎足∶脱骨汤∶用杏仁一钱，桑白皮四钱。水五碗，新瓶煎
三碗，入朴硝五钱，乳香一钱，封口煎化。置足于上，先熏后洗。三日一作，十余次后，软
若束绵也。（《闺阁事宜》）
风化硝
【修治】时珍曰∶以芒硝于风日中消尽水气，自成轻飘白粉也。或以瓷瓶盛，
挂檐下，待硝渗出瓶外，刮下收之。别有甜瓜盛硝渗出刮收者，或黄牯牛胆收硝刮取，皆非
甜硝也。
【主治】上焦风热，小儿惊热膈痰，清肺解暑。以人乳和涂，去眼睑赤肿，及头面暴热
肿痛。煎黄连，点赤目（时珍）。
【发明】时珍曰∶风化硝甘缓轻浮，故治上焦心肺痰热，而不泄利。
(Sourced from the Song Dynasty "Jia You Ben Cao")
[Flavor and Properties] Sweet, extremely cold, non-toxic.
Li Shizhen states: Salty, slightly sweet. It is Ying Xiao (Sal Nitre).
[Indications] Clears accumulated heat and latent qi in the five zang organs (Zhen Quan). Ground into fine powder and sifted for eye application to treat redness, remove swelling, pterygium, astringency, tearing, and pain; can also be added to eye drops (Tang · Da Ming). Its efficacy is the same as Mang Xiao (Rhinoceros Horn Salt / Mirabilite) (Li Shizhen).
[Elucidation] Cheng Wuji states: The "Nei Jing" (Classic of Internal Medicine) says: Salty flavor drains downward and belongs to Yin. It also says: Use salty flavor to soften hardness. When excessive heat lurks within, treat with salty-cold substances. For solidified masses, use salty flavor to soften them; for excessive heat, use cold to dissipate it. Therefore, Zhang Zhongjing's Da Xian Xiong Tang (Major Drain the Chest Decoction), Da Cheng Qi Tang (Major Order the Qi Decoction), and Tiao Wei Cheng Qi Tang (Regulate the Stomach and Order the Qi Decoction) all use Mang Xiao to soften hardness and eliminate excess heat. If the accumulation is not hard, it should not be used.
Kou Zongshi states: The Materia Medica records that Pu Xiao (Crude Saltpeter) has a pungent flavor, which is using pungency to moisten kidney dryness. Nowadays, people do not use the character "pungent," only "salty," because saltiness can soften hardness. Both interpretations are correct. The Materia Medica states that Mang Xiao promotes urination and causes abortion; however, in cases of Shang Han (Cold Damage) where purgation is indicated for pregnant women, this herb can be used, guided by Da Huang (Rhubarb), entering directly into the large intestine to moisten dryness, soften hardness, and purge heat, thereby keeping both mother and fetus safe. The "Jing" (Scripture) says: "When there is an existing pathogen, there will be no destruction [to the healthy qi], nor will there be destruction [to the fetus]." This refers to such cases. Speaking from the lower part, both urine and stool belong to Yin. Speaking from front and back, the front relates to Qi and the back to Blood. From the perspective of the Kidney, it governs difficulties in both urination and defecation. Urinary difficulty and constipation are both due to insufficient Water and excessive Fire. The "Jing" says: "When heat lurks excessively within, treat with salty-cold substances, assisted by bitter substances." Therefore, Mang Xiao and Da Huang are used together as mutual assistants.
Wang Haogu states: Mang Xiao has a thin Qi and strong flavor, sinking and descending, belonging to Yin. Its uses are threefold: first, to remove excess heat; second, to cleanse old filth in the intestines; third, to break up firm accumulations of heat blocks. Pregnant women should avoid it during the third and fourth months, and the seventh and eighth months, but it is otherwise harmless.
Zhang Yuansu states: Pu Xiao is formed from the first boiling, has a very astringent taste, so its action is urgent and unharmonious, used to sweep away food stagnation. Mang Xiao is Pu Xiao that has been percolated and refined, so its nature is mild and slow, thus it is now mostly used to treat Shang Han.
Li Shizhen states: Pu Xiao settles at the bottom, being the coarse form of nitre, with a heavy and turbid quality. Mang Xiao and Ya Xiao (Marble Nitre) crystallize at the top, being the purest forms, with a clear and bright quality. Tian Xiao (Sweet Nitre) and Feng Hua Xiao (Effloresced Nitre) are further processed from Mang Xiao and Ya Xiao, removing their flavors to become sweet, mild, light, and refreshing. Therefore, Pu Xiao is only suitable for rough constitutions or external applications; for decoctions or powders taken internally, Mang Xiao and Ya Xiao are superior. Zhang Zhongjing's "Shang Han Lun" (Treatise on Cold Damage) uses only Mang Xiao, not Pu Xiao, precisely for this reason. Nitre inherits the essence of Tai Yin (Lung/Large Intestine system/Yin aspect), being the child of Water. Its Qi is cold and its flavor salty, it enters the Blood level and moistens downward, sweeping away excess heat and Yang hyperactivity in the San Jiao (Triple Burner) and stomach/intestines; it is a drug that subdues Fire pathogens. In the Tang Dynasty, in the twelfth lunar month, Purple Snow, Red Snow, and Green Snow were bestowed upon court officials, all refined from this type of nitre. They have miraculous effects in treating various accumulated heat diseases, depending entirely on the appropriateness of their use.
[Attached Formulas] Seventeen old formulas, fifteen new formulas.
Zi Xue (Purple Snow): Treats Shang Han, warm malaria, all types of accumulated heat and irritability, mania and running about, miasma and epidemic toxins, sudden death from foot-qi (gouty arthritis), Five Corpses and Five Tuo (parasitic diseases), various heart and abdominal disorders, stabbing pain, resolves various heat toxins, yellowing from evil heat, gu poison and ghostly influences, heat toxins from wild paths, and pediatric convulsions and epilepsy. Gold 100 liang, Shi Gao (Gypsum Fibrosum), Han Shui Shi (Alumen), Hua Shi (Talcum), Ci Shi (Magnetitum) each 3 jin. Crushed, boiled in 1 hu of water until reduced to 4 dou, strained; add Xi Jiao (Rhinoceros Horn), Ling Yang Jiao (Antelope Horn), Qing Mu Xiang (Aucklandiae Radix), Chen Xiang (Aquilariae Lignum Resinatum) each 5 liang, Xuan Shen (Scrophulariae Radix, washed and dried), Sheng Ma (Cimicifugae Rhizoma) each 1 jin, Gan Cao (Licorice Root, fried) 8 liang, Ding Xiang (Caryophylli Flos) 1 liang. Add to the previous liquid, boil to obtain 1 dou 5 sheng, strain; add refined Pu Xiao 10 jin, Xiao Shi (Natrii Sulfas) 32 liang. Simmer over low fire, stirring constantly with willow wood, until moisture is nearly gone, pour into a wooden basin. When nearing coagulation, add She Xiang (Moschus) 1 liang 2 qian half, Zhu Sha (Cinnabaris) powder 3 liang, mix well, and store. Take 1-2 qian each time, with cool water. Adjust temporarily; for severe cases, take 1 liang. ("Tai Ping Hui Min He Ji Ju Fang")
Hong Xue (Red Snow): Treats irritability, digests retained food, resolves alcohol toxicity, opens the San Jiao, benefits the five zang organs, removes toxic heat, breaks stagnation. Treats Shang Han with mania, gastric ulceration with macules, warm miasma foot-qi, jaundice headache, blurred vision, nasal congestion, mouth ulcers, throat obstruction, double tongue, intestinal abscess, etc. Use Chuan Pu Xiao 10 jin (refined and strained), Ling Yang Jiao (shredded), Huang Qin (Scutellariae Radix), Sheng Ma each 3 liang, Ren Shen (Ginseng Radix), Chi Shao Yao (Paeoniae Radix Rubra), Bing Lang (Arecae Semen), Zhi Ke (Aurantii Fructus, bran-fried), Sheng Gan Cao (Licorice Root), Dan Zhu Ye (Lophatheri Herba), Mu Xiang (Aucklandiae Radix) each 2 liang, Mu Tong (Akebiae Caulis), Zhi Zi (Gardeniae Fructus), Ge Gen (Puerariae Lobatae Radix), Sang Bai Pi (Mori Cortex), Da Qing (Isatidis Folium), Lan Ye (Isatidis Folium) each 1.5 liang, Su Fang Mu (Sappan Lignum) 6 liang. All sliced. Boil in 2.5 dou of water until reduced to 9 sheng, strain, filter, and boil again; add nitre, stirring continuously until moisture is nearly gone, pour into a container. When nearing coagulation, add Zhu Sha 1 liang, She Xiang 0.5 liang. After overnight, it becomes snow-like. Take 1-2 qian each time, mixed with fresh drawn water. To promote movement, dissolve 1 liang in hot soup. ("Tai Ping Hui Min He Ji Ju Fang")
Bi Xue (Green Snow): Treats all accumulated heat, seasonal epidemics, mania and fainting, or swollen throat obstruction, mouth and tongue ulcers, mental restlessness, or urinary and fecal retention, and various stomach fire diseases. Pu Xiao, Mang Xiao, Ma Ya Xiao (Marble Nitre), Xiao Shi, Shi Gao (water-ground), Han Shui Shi (water-ground) each 1 jin. Use Gan Cao 1 jin, boil in 5 sheng of water, add all herbs and boil, stirring constantly until nitre melts properly; add Qing Dai (Indigo Naturalis) 1 jin, mix evenly, pour into a basin, leave overnight to form snow, then grind into powder. Each time, hold in mouth and swallow, or insufflate, or mix with water and take 2-3 qian. To promote unblocking, take 1 liang with hot water. ("Tai Ping Hui Min He Ji Ju Fang")
Liang Ge Qu Ji (Cool Diaphragm and Expel Accumulation): Wang Shanren Gan Lu Yin (Sweet Dew Drink): Treats heat congestion, cools chest and diaphragm, expels stagnation. Shu Mang Xiao powder 1 da jin. Use honey 12 liang, add 1 liang more in winter, mix evenly, put into fresh bamboo tubes, filling more than half but not full. Place in a steamer, ensuring the medicine is inside the rice, with empty space above. Steam until rice is cooked, remove, filter through silk into a porcelain bowl, stir constantly with a bamboo spatula until solidified, store in a porcelain box. At bedtime, hold half a spoon in mouth and gradually swallow. To promote bowel movement, take more. (Liu Yuxi "Chuan Xin Fang")
Ru Shi Fa Dong Fan Men (Irritability caused by Mineral Drug Activation): Mang Xiao, mixed with honey water, take 1 qian, three times daily. ("Tai Ping Sheng Hui Fang")
Gu Zheng Re Bing (Bone-steaming Heat Disease): Mang Xiao powder, taken with water, one fang cun bi each time, twice daily is good. ("Qian Jin Fang")
Fu Zhong Pi Kuai (Abdominal Mass): Pi Xiao 1 liang, one clove of garlic, Da Huang powder 8 fen. Pound into a cake. Apply to the affected area until resolved. (Shao Shi "Jing Yan Fang")
Food Overeating Leading to Stagnation: Ma Ya Xiao 1 liang, Wu Zhu Yu 0.5 jin. Boil juice, add nitre, drink while hot. If no movement after a long time, take another dose, immediate effect. Dou Qun in Changzhou, this formula was effective. ("Jing Yan Fang")
Guan Ge Bu Tong (Obstruction of Guan and Ge), closure of urination and defecation, distension leading to death, killing within two or three days. Mang Xiao 3 liang, steep in 1 sheng of hot water, take, vomiting leads to unblocking. ("Bai Yi Fang")
Xiao Bian Bu Tong (Urinary Retention): Bai Hua San (White Flower Powder): Use Mang Xiao 3 qian, taken with Fennel wine. ("Jian Yao Ji Zhong Fang")
Shi Qi Tou Tong (Seasonal Headache): Pu Xiao powder 2 liang, mixed with raw oil, applied to the vertex. ("Tai Ping Sheng Hui Fang")
Chi Yan Zhong Tong (Red Eye Swelling and Pain): Pu Xiao, placed on tofu, steamed until melted, collect juice for application. ("Jian Bian Fang")
Feng Yan Chi Lan (Wind Eye Redness and Ulceration): Clear Pi Xiao 1 zhan. Boil in 2 bowls of water, expose overnight, filter clear. Wash eyes morning and evening. Redness disappears in three days, even chronic cases heal. (Yang Cheng "Jing Yan Fang")
Tui Yi Ming Mu (Remove Pterygium and Improve Vision): Bai Long San (White Dragon Powder): Use clean Ma Ya Xiao, wrap tightly in thick paper, keep against the flesh in the bosom for 120 days, grind to powder, add a little Long Nao (Borneol). Regardless of how long the opacity has existed, if the pupil is intact, apply daily. ("Jing Yan Fang")
Zhu Yan Zhang Yi (Various Eye Opacities): Ya Xiao 10 liang, soak in hot water, filter through thick paper, boil dry in a clay vessel, leave on the ground overnight, add Fei Chao Huang Dan (Lead Oxide) 1 liang, She Xiang 0.5 fen. Sieve again, add Long Nao. Apply daily. ("Ji Ji Xian Fang")
Monthly Eye Washing: Mang Xiao 6 qian. 1.6 zhan of water, clarified. Wash eyes according to method. After one year, eyes resemble those of a child. Dates: Jan 3, Feb 8, Mar 4, Apr 4, May 5, Jun 4, Jul 3, Aug 1, Sep 13, Oct 13, Nov 16, Dec 5. ("Tai Ping Sheng Hui Fang")
Ya Chi Teng Tong (Toothache): Thick soap pod juice, boiled with Pu Xiao until dissolved, poured onto stone to form frost. Rub teeth. ("Pu Ji Fang")
Shi Xie Yin Zhong (Gum Swelling from Eating Crab): Apply Pu Xiao, swelling subsides immediately. ("Pu Ji Fang")
Hou Bi Zhong Tong (Throat Obstruction with Swelling and Pain): "Wai Tai Mi Yao": Use Pu Xiao 1 liang, slowly suck and swallow, immediate effect. Or add Dan Sha 1 qian. For Qi blockage, add Sheng Gan Cao powder 2.5 qian, insufflate.
Xiao Er Chong She (Pediatric Double Tongue): Smear Ma Ya Xiao on upper and lower tongue, three times daily. (Yao He Zhong)
Kou She Sheng Chuang (Mouth and Tongue Ulcers): Hold Pu Xiao in mouth, effective. (Sun Taoren Formula)
Xiao Er E Kou (Pediatric Thrush): Wipe Ma Ya Xiao on tongue, five times daily. ("Jian Yao Ji Zhong")
Wan Dou Du Chu Wei Cheng Nong (Pea Poison Sores Not Yet Suppurated): Mix pig bile with Mang Xiao powder, apply. ("Mei Shi")
Dai Zhi Zhong Tong (Swollen and Painful Fingertips): Soak in Mang Xiao decoction. ("Tai Ping Sheng Hui Fang")
Huo Dan Dan Du (Flame Erysipelas): Mix Mang Xiao powder with water, apply. ("Mei Shi")
Yi Qie Feng Zhen (All Wind Urticaria): Wipe with boiled Mang Xiao decoction. ("Mei Shi")
Qi Chuang Zuo Yang (Itching from Lacquer Poison): Apply Mang Xiao decoction. ("Qian Jin")
Jiu Chuang Fei Die (Flying Butterfly from Moxibustion Wound): Due to moxibustion blister scab falling off, fresh meat pieces inside the wound fly like butterflies, causing unbearable pain, a strange disease of combined blood and flesh heat. Use Pu Xiao and Da Huang each 0.5 liang. Grind to powder. Mix with water and take, slight diarrhea indicates cure. (Xia Zi Yi "Qi Ji Fang")
Fu Ren Nan Chan (Difficult Labor): Mang Xiao powder 2 qian, taken warm with urine from a young boy, always effective. ("Xin Xiao Fang")
Si Tai Bu Xia (Dead Fetus Retained): Same formula as above. A magistrate in Fengcheng had a cat carrying five kittens; one born, four died in womb. Administered this, and they were expelled. Also treated a cow successfully. ("Xin Xiao Fang")
Nu Ren Za Zu (Women's Foot Binding): Tuo Gu Tang (Bone-Removing Decoction): Use Xing Ren 1 qian, Sang Bai Pi 4 qian. Boil in 5 bowls of water in a new jar until 3 bowls remain, add Pu Xiao 5 qian, Ru Xiang 1 qian, seal and boil until dissolved. Place feet above, steam first then wash. Do once every three days, after ten-plus times, feet become soft as cotton. ("Gui Ge Shi Yi")
Feng Hua Xiao (Effloresced Nitre)
[Processing] Li Shizhen states: Place Mang Xiao in wind and sunlight until moisture evaporates completely, naturally becoming a light white powder. Or store in a porcelain bottle, hang under eaves, wait for nitre to seep out, scrape and collect. There are methods using melons to collect seeping nitre, or using cattle gallbladders, but these are not Tian Xiao (Sweet Nitre).
[Indications] Upper Jiao wind-heat, pediatric convulsive heat and phlegm in the diaphragm, clears Lung and resolves summerheat. Mixed with human milk and applied, removes eyelid redness and swelling, and sudden heat swelling/pain of head and face. Decoct Huang Lian for red eyes (Li Shizhen).
[Elucidation] Li Shizhen states: Feng Hua Xiao is sweet, mild, and light/floating, thus treating phlegm-heat in the Upper Jiao Heart and Lung without causing diarrhea.