（《唐本草》）
【释名】倒挂尘名乌龙尾（《纲目》）、烟珠。
【修治】 曰∶凡梁上尘，须去烟火大远，高堂殿上者，拂下，筛净末用。
时珍曰∶凡用倒挂尘，烧令烟尽，筛取末入药，雷氏所说，似是梁上灰尘，今人不见用
。
【气味】辛、苦，微寒，无毒。大明曰∶平。
【主治】腹痛，噎膈，中恶，鼻衄，小儿软疮（《唐本》）。食积，止金疮血出，齿龈出
血（时珍）。
【附方】旧七，新十二。
翻胃吐食∶梁上尘，黑驴尿调服之。（《集简方》）
霍乱吐利∶屋下倒挂尘，滚汤泡，澄清服，即止。（《卫生易简方》）
小便不通∶梁上尘二指撮，水服之。（《外台秘要》）
大肠脱肛∶乌龙尾即梁上尘，同鼠屎烧烟于桶内，坐上熏之。数次即不脱也。（《济急》）
喉痹乳蛾∶乌龙尾、枯矾、猪牙皂荚（以盐炒黄）等分。为末。或吹或点皆妙。（《孙氏
集效方》）
牙疼 鼻∶壁上扫土，用盐炒过，为末。随左右 鼻。（《普济方》）
鼻中息肉∶梁尘吹之。（《普济方》）
夜卧魇死∶勿用火照，急取梁尘纳鼻中，即活。（《琐碎录》）
猝自缢死∶梁上尘如豆大，各纳一筒中，四人同时极力吹两耳及鼻中，即活。（《外台
秘要》）
经血不止∶乌龙尾（炒烟尽）、荆芥穗各半两。为末。每服二钱，茶下。（《圣济录》）
妇人胎动，日月未足欲产。梁上尘、灶突墨等分，酒服方寸匕。（《千金方》）
横生逆产∶梁上尘，酒服方寸匕。（《子母秘录》）
妇人妒乳∶醋和梁上尘涂之。（《千金方》）
石痈不脓∶梁上尘灰、葵根茎灰等分。用醋和敷之。（《千金翼》）
发背肿痛∶厨内倒吊尘，为末。以生葱极嫩心同捣膏敷之，留顶，一日一换，干则以水
润之。（《濒湖集简方》）
无名恶疮∶梁上倒挂尘二条，韭地蚯蚓泥少许。生蜜和捻作饼如钱大，阴干，用蜜水调，
频敷之。（杨起《简便方》）
小儿头疮，浸淫成片∶梁上尘和油瓶下滓，以皂荚汤洗后涂之。（《子母秘录》）
小儿赤丹∶屋尘和腊猪脂敷之。（《千金方》）
老嗽不止∶故茅屋上尘，年久着烟火者，和石黄、款冬花、妇人月经衣带为末，水和涂
茅上待干，入竹筒中烧烟吸咽，无不瘥也。（陈藏器《本草》）
(From *Tang Bencao*)
[Names] Hanging Dust is also known as Black Dragon's Tail (from *Bencao Gangmu*) and Smoke Pearl.
[Preparation] Lei Xiao stated: For dust from roof beams, one must select it from areas far away from smoke and fire, sweep it down from high halls and palace roofs, sieve it to obtain pure powder for use.
Li Shizhen stated: When using Hanging Dust, it should be burned until the smoke is exhausted, and the resulting ash/powder sieved for medicinal use. What Lei Xiao described seems to be ordinary dust from beams; nowadays, people no longer use it.
[Flavor and Properties] Acrid, bitter, slightly cold, non-toxic. Ma Zhi stated: Neutral in nature.
[Indications] Abdominal pain, dysphagia (difficulty swallowing), sudden illness caused by foul qi, epistaxis (nosebleed), pediatric soft sores (*Tang Bencao*). Food stagnation, stopping bleeding from traumatic wounds, gingival bleeding (Li Shizhen).
[Attached Prescriptions] Seven old prescriptions, twelve new prescriptions.
Regurgitation and vomiting food: Use dust from roof beams, mixed with black donkey urine, taken orally. (*Ji Jian Fang*)
Cholera with vomiting and diarrhea: Use hanging dust from under eaves, steeped in boiling water, clarified, and taken orally to stop symptoms immediately. (*Wei Sheng Yi Jian Fang*)
Urinary retention: Take a pinch of dust from roof beams (amount held between two fingers), taken with water. (*Waitai Miyao*)
Rectal prolapse: Black Dragon's Tail, which is dust from roof beams, is burned together with rat feces in a bucket. The patient sits on the bucket to fumigate the area. After several times, the prolapse will not recur. (*Ji Ji Xian Fang*)
Sore throat and tonsillar hypertrophy: Equal parts of Black Dragon's Tail, calcined alum, and soap bean pods (stir-fried with salt until yellow). Grind into fine powder. It is excellent whether blown into the throat or applied topically. (*Sun Shi Ji Xiao Fang*)
Toothache and nasal congestion: Sweep soil from walls, stir-fry with salt, grind into powder. Blow into the nostril on the affected side according to left or right. (*Pu Ji Fang*)
Nasal polyps: Blow dust from roof beams into the nose. (*Pu Ji Fang*)
Sudden death during sleep (sleep paralysis/apnea): Do not use light to check. Immediately take dust from roof beams and insert it into the nose; the person will revive. (*Suo Sui Lu*)
Sudden death by hanging: Take dust from roof beams the size of a soybean, insert one piece into each ear and the nose. Four people simultaneously blow forcefully into both ears and the nose; the person will revive. (*Waitai Miyao*)
Menorrhagia (unending menstrual bleeding): Take Black Dragon's Tail (burned until smoke is exhausted) and Schizonepeta spike (Jingjie Sui), half tael each. Grind into powder. Take two qian per dose, washed down with tea. (*Sheng Ji Lu*)
Fetal agitation in pregnant women before term, threatening premature labor: Equal parts of dust from roof beams and chimney soot (Zao Tu Mo), taken orally with wine in a measure of one cun cube. (*Qian Jin Fang*)
Breech presentation/dystocia: Dust from roof beams, taken orally with wine in a measure of one cun cube. (*Zi Mu Mi Lu*)
Breast engorgement due to nursing jealousy (milk stasis): Mix dust from roof beams with vinegar and apply topically. (*Qian Jin Fang*)
Hard abscess without suppuration: Equal parts of dust from roof beams and ash from hibiscus roots/stems. Mix with vinegar and apply as a poultice. (*Qian Jin Yi Fang*)
Back carbuncle with swelling and pain: Dust from inverted containers in the kitchen, ground into powder. Mash with the extremely tender heart of raw green onion into a paste and apply. Leave the center exposed. Change once daily; if dry, moisten with water. (*Bin Hu Ji Jian Fang*)
Nameless malignant sores: Two strips' worth of hanging dust from roof beams, plus a small amount of earthworm mud from leek fields. Mix with raw honey to form cakes the size of a coin. Dry in shade. When used, mix with honey water and apply frequently. (Yang Qi, *Jian Bian Fang*)
Pediatric head sores spreading in patches: Mix dust from roof beams with sediment from oil jars. Wash with soap bean decoction first, then apply. (*Zi Mu Mi Lu*)
Pediatric erysipelas (red dan): Apply house dust mixed with lard from the twelfth lunar month. (*Qian Jin Fang*)
Intractable chronic cough: Take dust from old thatched roofs, specifically that which has been exposed to smoke and fire for years. Mix with realgar (Shi Huang), winter flower buds (Kuandong Hua), and women's menstrual cloth into a powder. Mix with water, spread onto thatch, let dry, place in a bamboo tube, burn, and inhale the smoke into the throat. There are cases where this fails to cure. (Chen Cangqi, *Bencao Shiyi*)