辛苦咸寒，有毒。黄者伤人，赤者杀人。入药必取白者。以水煎化，澄去滓，入
莱菔自然汁同煮，入盆中，经宿结成如冰，谓之盆硝。齐卫之硝，上生锋芒，谓之芒硝。川
晋之硝，上生六棱，谓之牙硝。取芒硝再三以莱菔汁炼去咸味，悬当风处吹去水气，轻白如
粉，谓之风化硝。以芒硝、牙硝同莱菔汁、甘草煎过，鼎罐升 ，谓之玄明粉。
《本经》主五脏积热，胃胀闭，涤蓄结饮食，推陈致新，除邪气。（向错简在硝石条内
，今正之。详治五脏等证，皆热邪固积，决非硝石所能。）
发明 热淫于内，治以咸寒，坚者以咸软之，热者以寒消之，不出《本经》推陈致新之
妙用。仲景大陷胸汤、大承气汤、调胃承气汤，皆用芒硝软坚去实，且带微辛，所以走而不
守。若热结不至坚者，不可轻用。小儿赤游风，以消倾汤中取布蘸湿拭之。
《御药院方》名白龙粉
辛甘微寒，无毒。
发明 玄明粉用芒硝 过多遍，佐以甘草缓其咸寒之性。用治膈上热痰，胃中实热，肠
中宿垢，非若芒硝之力峻伤血也。然脾胃虚寒及阴虚火动者，慎勿轻用，以取虚虚之咎。
甘咸寒，无毒。
发明 风化硝甘缓轻浮，故治上焦心肺痰热，而不致于泄利者宜之。并治经络之痰湿，
但重着而非酸痛者用之有效。指迷茯苓丸治痰湿流于肩背之阳位，而隐隐作痛，最为合剂，
然惟体肥气实者为宜。眼睑赤肿，和人乳点之。
【朴硝】
味辛苦、咸，性寒，有毒。黄色的朴硝会伤害人体，红色的朴硝会导致死亡。入药必须选用白色的朴硝。将朴硝用水煎煮溶化，澄清后去除杂质，加入莱菔自然汁（萝卜汁）一同煮沸，倒入盆中，经过一夜结成如冰一样的晶体，称为“盆硝”。齐地、卫地产的朴硝，表面生成针状结晶，称为“芒硝”。川地、晋地产的朴硝，表面生成六棱柱状结晶，称为“牙硝”。取芒硝，反复用莱菔汁炼制以去除咸味，悬挂在通风处吹干水分，变得轻白如粉末，称为“风化硝”。将芒硝、牙硝与莱菔汁、甘草一起煎煮，通过蒸馏升华工艺制成，称为“玄明粉”。
《神农本草经》记载朴硝主治五脏积热、胃胀闭塞，能涤荡体内蓄积结滞的饮食糟粕，推陈出新，祛除邪气。（此前此段文字错简位于硝石条内，现予以纠正。详细分析治疗五脏等证候，皆因热邪固结积滞，绝非硝石所能治疗。）
【发明】
热邪淫溢于体内，治疗当用咸寒之品。坚硬之物可用咸味软化，热邪可用寒凉消除，这不出乎《神农本草经》所述“推陈致新”的妙用。张仲景的大陷胸汤、大承气汤、调胃承气汤，都使用芒硝来软化坚结、去除实邪，且芒硝带有微辛之性，因此具有走窜而不守静的特性。如果热结尚未达到坚硬程度，不可轻易使用。小儿赤游风病，可用消倾汤中的药布蘸湿擦拭患处。
【玄明粉】
出自《御药院方》，又名白龙粉。
味辛、甘，性微寒，无毒。
【发明】
玄明粉是将芒硝经过多次炼制，并佐以甘草以缓和其咸寒之性。用于治疗膈上热痰、胃中实热、肠中宿垢，不像芒硝那样药力峻猛而损伤气血。然而，脾胃虚寒及阴虚火旺者，切勿轻易使用，以免犯“虚虚”之戒（使虚者更虚）。
【风化硝】
味甘、咸，性寒，无毒。
【发明】
风化硝性质甘缓、轻浮，因此适用于治疗上焦心肺痰热，且不会导致腹泻泄利。同时也用于治疗经络中的痰湿，但对于沉重感而非酸痛感的症状使用有效。指迷茯苓丸是治疗痰湿流注于肩背阳位而隐隐作痛的极佳方剂，但仅适合体质肥胖、正气充实的人适用。眼睑红肿，可配合人乳滴眼治疗。
[Puo Xiao]
Taste: bitter, pungent, salty; Nature: cold; Toxicity: toxic. Yellow Puo Xiao harms the body, and red Puo Xiao is lethal. For medicinal use, only white Puo Xiao must be selected. Dissolve Puo Xiao in water, clarify to remove dregs, add fresh juice of Raphanus sativus (radish), boil together, pour into a basin, and let stand overnight until it crystallizes like ice; this is called "Basin Nitre" (Pen Xiao). Nitre from Qi and Wei regions forms needle-like crystals on the surface, called "Mang Xiao" (Ming Nitre). Nitre from Sichuan and Shanxi regions forms hexagonal prismatic crystals on the surface, called "Ya Xiao" (Tooth Nitre). Take Mang Xiao, repeatedly refine it with radish juice to remove the salty taste, hang it in a ventilated place to blow away moisture until it becomes light and white like powder; this is called "Feng Hua Xiao" (Weathered Nitre). Boil Mang Xiao and Ya Xiao together with radish juice and Gancao (Licorice Root), then process through distillation/sublimation; this is called "Xuan Ming Fen" (Dark Bright Powder).
The *Shennong Bencao Jing* states that it treats accumulated heat in the five zang organs, stomach distension and obstruction, purges accumulated and bound food residues, pushes out the old to bring forth the new, and eliminates pathogenic factors. (This passage was previously misplaced in the entry for Xiaoshi [Niter]; it has now been corrected. A detailed analysis of treating conditions of the five zang organs reveals they are caused by fixed accumulation of heat pathogens, which Xiaoshi cannot treat.)
[Commentary]
When heat pathogens overflow within, treatment should employ salty-cold substances. Hard accumulations are softened by salty flavors, and heat is cleared by cold properties. This does not exceed the wonderful application of "pushing out the old to bring forth the new" described in the *Shennong Bencao Jing*. Zhang Zhongjing's formulas, such as Da Xianxiong Tang (Major Chest-Stagnation Decoction), Da Chengqi Tang (Major Order-the-Qi Decoction), and Tiaowei Chengqi Tang (Regulate-the-Stomach Order-the-Qi Decoction), all use Mang Xiao to soften hardness and eliminate excess. Mang Xiao possesses a slight pungency, allowing it to circulate freely without staying static. If heat accumulation is not yet hard, it should not be used lightly. For pediatric Chi You Feng (Red Roaming Wind), cloth soaked in Xiao Qing Tang (Clear-Heat Decoction) can be applied to wipe the affected area.
[Xuan Ming Fen]
Named "Bai Long Fen" (White Dragon Powder) in the *Yuyao Yuan Fang*.
Taste: pungent, sweet; Nature: slightly cold; Toxicity: non-toxic.
[Commentary]
Xuan Ming Fen is made by refining Mang Xiao multiple times and adding Gancao (Licorice Root) to moderate its salty-cold nature. It is used to treat phlegm-heat above the diaphragm, excess heat in the stomach, and retained fecal matter in the intestines. Unlike Mang Xiao, it does not have a harsh potency that damages blood and qi. However, individuals with spleen-stomach deficiency-cold or yin-deficiency with fire hyperactivity must avoid using it lightly to prevent the error of "depleting the deficient."
[Feng Hua Xiao]
Taste: sweet, salty; Nature: cold; Toxicity: non-toxic.
[Commentary]
Feng Hua Xiao has a sweet, moderating, and light-floating nature. Therefore, it is suitable for treating phlegm-heat in the upper jiao (heart and lungs) without causing diarrhea. It also treats phlegm-dampness in the meridians, proving effective for symptoms characterized by heaviness rather than soreness or pain. Zhi Mi Fu Ling Wan (Confusion-Dispelling Poria Pill) is an ideal formula for treating phlegm-dampness flowing into the yang regions of the shoulders and back, causing dull pain, but it is only suitable for individuals who are obese and have robust qi. For red and swollen eyelids, apply mixed with human milk.