味辛甘。性寒无毒，入肺胃二经。主出汗解肌，缓脾益气，生津止渴，清胃消痰，最
理头疼，与方解石相似，须莹净如水晶者真，鸡子为使，恶莽草、马目毒公、巴豆、畏铁。
按∶石膏辛走肺，甘走胃，所以主发散，仲景名为白虎，盖有两义，一则以入肺，一则
以其性雄。苟胃弱不食，及血虚发热者误用之，为害不浅。
雷公云∶凡使勿用方解石，此石虽白，不透明，其性燥。若石膏出剡州若山县义清山，
其色莹洁如水晶，性良善也，凡使之，先于石臼中捣成粉，以密绢罗过，生甘草水飞过，去
水，令干，重研细，用之良。
味咸，性寒无毒，入肾经。主明目。止痛益气，坚筋骨，助水脏，除心腹痛。破聚癣
疥疮。一名戎盐，一名胡盐。
按∶青盐味咸，肾所宜也，故独入之，水脏既补，则明目坚骨等功，何足异耶？
味咸，性温无毒，入肾肺肝三经。主鬼蛊邪疰毒瓦斯，洗下部 疮，吐中焦痰癖，熨疝
气及纳肾气，止霍乱及心腹卒痛，杀虫去风，明目固齿，白如霜雪者佳。炒研用。
按∶食盐之咸，本归肾腑，肺即其母，肝即其子也，故并入之。本草云∶食伤筋损肺水，
肿及咳嗽血虚者忌之何也？盖以咸走肾，过多则肾不能胜而受伤。于是盗食母气，而肺气亦
损，肺损则金还克木，夫肝主筋而藏血，肺主咳嗽而生水，数证之来，宁能免耶？
【石膏】
味道辛、甘。性质寒，无毒，归入肺经和胃经。主要功效是发汗解肌（通过发汗解除肌表之邪），舒缓脾气并益气，生津液止渴，清除胃热并消除痰浊，尤其擅长治疗头痛。其功效与方解石相似，但必须以晶莹剔透如水晶般的为真品。以鸡蛋清为药引，忌与莽草、马目毒公、巴豆同用，且畏惧铁器。
按语：石膏味辛能走散入肺，味甘能缓急入胃，所以具有发散的作用。张仲景将其命名为“白虎”，大概有两层含义：一层是因为它入肺经（肺在五行中属金，对应西方白虎），另一层是因为它的药性雄烈。如果患者胃气虚弱不能进食，或者因血虚导致的发热，误用石膏，会造成很大的危害。
雷公说：凡使用石膏时，不要使用方解石。这种石头虽然颜色白，但不透明，且药性燥烈。如果是出自剡州若山县义清山的石膏，颜色晶莹洁白像水晶一样，药性温和良善。凡是使用这种石膏，先在石臼中捣成粉末，用细密的丝绢筛过，再用生甘草水进行水飞处理（将药物与水共研，利用粗细不同在水中的悬浮速度差异来分离极细粉末的方法），去掉水分，晾干，再次研磨至极细，这样使用效果最好。
【青盐】
味道咸，性质寒，无毒，归入肾经。主要功效是明目，止痛益气，坚固筋骨，辅助肾脏功能，消除心腹疼痛，破除积聚，治疗癣疥疮。又名戎盐，又名胡盐。
按语：青盐味道咸，是肾脏所适宜的味道，所以独入肾经。既然肾脏得到补益，那么明目、坚固筋骨等功效，又有什么奇怪的呢？
【食盐】
味道咸，性质温，无毒，归入肾、肺、肝三经。主要功效是治疗鬼蛊邪疰毒瓦斯（指由不正之气或寄生虫引起的中毒性疾病），清洗下部疮疡，催吐中焦的痰癖（指停积在胸膈脘腹间的痰饮结块），热敷治疗疝气以及收纳肾气，止住霍乱及心腹部突然疼痛，杀虫祛风，明目固齿，以白色如霜雪者为佳。需炒制后研磨使用。
按语：食盐的咸味，本归属于肾腑，肺是肾之母，肝是肾之子，所以也并入这三经。本草书中说：“食用过多会损伤筋脉、损害肺和水液代谢，出现水肿及咳嗽，血虚者忌食。”这是为什么呢？因为咸味走肾，摄入过多则肾脏无法承受而受伤。进而盗取母脏（肺）的气，导致肺气也受损；肺气受损则金克木，影响肝脏。肝主筋且藏血，肺主咳嗽且生水，这些病症的发生，难道能避免吗？
[Shigao (Gypsum Fibrosum)]
Taste: Acrid, Sweet. Nature: Cold, Non-toxic. Meridians Entered: Lung, Stomach.
Indications: Primarily induces sweating to release the muscle layer (releasing exterior pathogens from the muscular level), soothes the Spleen Qi, generates fluids and quenches thirst, clears Stomach heat and eliminates phlegm, and is particularly effective for treating headaches. Its efficacy resembles that of Fajieshi (Calcitum). Authentic Shigao must be translucent and crystal-clear like rock crystal. Egg white is used as an adjuvant. It is incompatible with Mangcao (Aristolochia Manshuriensis Root), Mumingdugong (likely a specific toxic plant/mineral), Badou (Crotonis Fructus), and fears iron.
Commentary: The acrid taste of Shigao disperses and enters the Lung; the sweet taste moderates and enters the Stomach, thus it possesses dispersing properties. Zhang Zhongjing named it "Baihu" (White Tiger), which implies two meanings: first, because it enters the Lung meridian (Lung corresponds to Metal and the White Tiger in Five Elements theory); second, because its medicinal nature is vigorous and potent. If misused in patients with weak Stomach Qi unable to eat, or those with fever due to Blood deficiency, it can cause significant harm.
Leigong stated: When using Shigao, do not use Fajieshi (Calcitum). Although this stone is white, it is not transparent and has a drying nature. Shigao from Yiqingshan, Ruoshan County, Yanzhou Prefecture, is crystal clear like rock crystal and has a mild, benign nature. To process it, first crush it into powder in a stone mortar, sift it through fine silk gauze, then perform water flotation (a purification method involving grinding with water and separating fine particles) with raw Gancao (Licorice Root Decoction). Remove the water, dry it, and grind it again until extremely fine for optimal use.
[Qingyan (Natrii Chloridum Viride / Blue Salt)]
Taste: Salty. Nature: Cold, Non-toxic. Meridians Entered: Kidney.
Indications: Improves vision, relieves pain, benefits Qi, strengthens sinews and bones, assists the Water Organ (Kidney), eliminates epigastric and abdominal pain, breaks up accumulations, and treats tinea and scabies sores. Also known as Rongyan, also known as Huyan.
Commentary: Qingyan tastes salty, which is suitable for the Kidney; therefore, it enters the Kidney meridian exclusively. Once the Water Organ (Kidney) is tonified, what is surprising about its abilities to improve vision and strengthen bones?
[Yanshi (Natrii Chloridum / Table Salt)]
Taste: Salty. Nature: Warm, Non-toxic. Meridians Entered: Kidney, Lung, Liver.
Indications: Treats poisoning from Gui Gu Xie Zhu Du Wa (toxins caused by abnormal qi or parasites), washes lower body ulcers, induces vomiting to expel Tan Pi (phlegm-rheum accumulation in the middle jiao), hot compresses to treat hernia and gather Kidney Qi, stops Huoluan (cholera-like syndrome) and sudden epigastric/abdominal pain, kills parasites, dispels wind, improves vision, and strengthens teeth. The whiter, resembling frost or snow, the better. Use after stir-frying and grinding.
Commentary: The salty flavor of Yanshi naturally belongs to the Kidney Fu organ. The Lung is the Mother of the Kidney, and the Liver is the Child of the Kidney; therefore, it enters these three meridians. The Ben Cao (Materia Medica) states: "Excessive consumption damages sinews, harms the Lung and Water metabolism, causing edema and cough; it is contraindicated in Blood deficiency." Why is this? Because the salty flavor travels to the Kidney. Excessive intake overwhelms the Kidney, causing injury. This subsequently steals Qi from the Mother organ (Lung), damaging Lung Qi. Damaged Lung Qi leads to Metal overacting on Wood, affecting the Liver. Since the Liver governs sinews and stores Blood, and the Lung governs cough and produces Water, how can one avoid these syndromes?