出西戎，形块方棱如石，明莹而青。戎盐。
咸，寒，无毒。坚骨固齿，明目乌须。助水脏而平血热，消症积而除疥癣；止吐尿舌齿
诸血
治同食盐。
姜汁煮，研粉用。
甘，寒，无毒。凉血降火，坚牙明目，退热消积，除烦解渴。
生于卤地积盐之下，精液渗于土中，年久至泉，结而成石，清莹如水晶。
咸，寒，无毒。治上盛下虚，救阳助阴，有扶危拯逆之功。
咸卤精液，流渗入土，年久结成石片，状如龟背之形，大者如杏叶，小者如鱼鳞。
乃皮硝炼成者。石苇为使，恶三棱。煎炼成棱者，曰马牙硝。
辛，苦，咸，寒，无毒。入手少阴心、足太阳膀胱经。利二便而破五淋，退壅热而除留
血，化积聚而坠痰结，通经
脉而下胎孕。平瘰 而明目，息黄胆而消肿。
硝有三品∶生川蜀曰川硝，最胜；生河东曰盐硝，次之；生河北、青、齐者曰土硝。皆
生于
汁，经宿结成，犹有沙土猥杂，故名朴硝。一经煎炼，澄去渣脚，则成芒硝。
腹中痞块，同大黄、独头蒜捣饼贴之，以消为度。（验方第一。）
口舌疮红，含之良。（第二。）
丹毒如火，水合敷之。（第三。）
碧雪 芒硝 皮硝 石膏 寒水石（水飞，各一斤） 甘草（一斤，煎汁去渣）
入诸药同煎，搅之令化。再入青黛一斤，和匀，经宿结成。或含咽，或吹之，或煎服。
治一
肿口疮等症。（诸方第一。）
Originating from the Western Regions (Xirong), it appears in blocky, square-prismatic shapes resembling stone, bright and translucent with a bluish-green hue. Also known as Rongyan (Rong Salt).
Salty, cold, non-toxic. Strengthens bones and secures teeth, brightens the eyes, and darkens hair. Assists the Kidney (Water Zang) to calm blood heat, resolves masses and accumulations, and eliminates scabies and tinea; stops bleeding from vomiting, urination, tongue, and teeth. Its therapeutic actions are identical to those of common salt.
Boil with ginger juice, then grind into powder for use.
Sweet, cold, non-toxic. Cools blood and descends fire, strengthens teeth and brightens eyes, reduces fever and dissipates accumulations, relieves irritability and quenches thirst.
Grows in saline-alkali lands, beneath accumulated salt deposits. The essence seeps into the soil, and over many years reaches underground springs, condensing into stones that are clear and lustrous like crystal.
Salty, cold, non-toxic. Treats conditions of excess above and deficiency below, rescues Yang and assists Yin, possessing the merit of supporting critical cases and reversing adverse conditions.
The essence of salty brine flows and seeps into the earth, condensing over long periods into stone flakes shaped like a turtle’s back. Large pieces resemble apricot leaves, while small ones resemble fish scales.
This is refined from Pixiao (Crude Natrium Sulfate). Shiwei (Pyrrhosiae Herba) serves as the guiding herb; it is incompatible with Sanleng (Sparganii Rhizoma). Those that form prismatic shapes after decoction and refining are called Mayaxiao (Horse Tooth Nitre).
Pungent, bitter, salty, cold, non-toxic. Enters the Hand-Shaoyin Heart Meridian and the Foot-Taiyang Bladder Meridian. Promotes urination and defecation, breaks through five types of strangury, clears stagnant heat and removes retained blood, transforms accumulations and drops phlegm nodules, unblocks meridians, and induces abortion. Resolves scrofula and brightens the eyes, alleviates jaundice and reduces swelling.
Nitre is categorized into three grades: Chuanxiao produced in Sichuan and Shu regions is the finest; Yanxiao produced in Hedong is second best; Tuxiao produced in Hebei, Qingzhou, and Qizhou is third. All originate from juices that crystallize overnight, still containing impurities such as sand and soil, hence named Puxiao (Unrefined Natrium Sulfate). Once decocted and refined, clarifying and removing the sediment, it becomes Mangxiao (Mirabilite).
For abdominal痞块 (masses/lumps), combine with Dahuang (Rhei Radix et Rhizoma) and single-clove garlic, pound into a paste, apply externally until the mass dissipates. (Verified Formula 1.)
For red sores on the mouth and tongue, hold in the mouth; this is effective. (Formula 2.)
For erysipelas resembling fire, mix with water and apply externally. (Formula 3.)
Bixue (Prescription: Mangxiao, Pixiao, Shigao [Gypsum Fibrosum], Hanshuishi [Aqua Calcitae] each one jin, all processed by water levigation; Gancao [Glycyrrhizae Radix et Rhizoma] one jin, decocted to extract juice and remove dregs). Decoct all herbs together, stir to dissolve. Add Qingdai [Indigo Naturalis] one jin, mix evenly, and allow to crystallize overnight. Can be held in the mouth to swallow, insufflated into the lesion, or decocted for oral administration. Treats various swellings, mouth sores, and other symptoms. (General Formulas 1.)