Chalcanthitum (natural hydrated copper sulfate, CuSO4·5H2O; the refined article is blue vitriol)
Nature and flavour. Sour, astringent, acrid, cold; classed as toxic. Liver and Gallbladder systems.
A copper sulfate mineral, and the reason a vitriol appears in a herbal at all: it was one of the things that would make a person vomit. Classical texts place it among the emetics and describe it as drawing up wind-phlegm and expelling a swallowed poison, and record it for phlegm blocking the throat, for poisoning, and for the wind-phlegm type of convulsive disorder; externally it is recorded as a wash for eye complaints and for sores, and as a caustic to eat away proud flesh and warts. All of those are recorded uses, and nearly all of them belong to a period before safer options existed — induced vomiting is no longer how poisoning is managed, and copper sulfate on the eye is not a household practice. Outside medicine the same salt has been used far more widely: as a fungicide in agriculture, in electroplating, and as a mordant in dyeing. Its bright blue crystals are attractive, which is precisely why accidental drinking has been reported in children.
性味归经。酸、涩、辛，寒；有毒。归肝、胆经。
一味硫酸铜矿物，也是一份本草里为什么会出现「矾」类矿物的原因：它曾是能让人呕吐的东西之一。古籍把它列在涌吐药中，记载涌吐风痰与毒物，用于痰涎壅塞咽喉、误食毒物以及风痰所致的痫证；外用记载作洗剂治目疾与疮疡，并以腐蚀性蚀去胬肉与疣赘。这些都属于记载用途，而且几乎都属于还没有更安全办法的年代 —— 催吐早已不是处理中毒的方法，硫酸铜入眼更不是家庭能做的事。在医药之外，同一种盐的用途要广得多：农业杀菌剂、电镀、染色媒染剂。它明亮的蓝色晶体很好看，而儿童误服的报告正因此而来。
一味腐蚀性与刺激性盐类；本页对内服与外用都不写任何份量。误服会灼伤口腔与食道，引起剧烈呕吐、腹痛与可能带血的腹泻；除消化道外，还可破坏红细胞、引起高铁血红蛋白血症，并损伤肾与肝，已有死亡报告。Wilson 病（肝豆状核变性）患者处理铜的能力异常、G6PD 缺乏者风险尤其高，儿童亦然。这味药的传统用途 —— 中毒后催吐 —— 不是急救：现代中毒处理不催吐，腐蚀性物质或石油类产品摄入后更不催吐，因为呕吐会加重损伤。入眼属腐蚀性损伤，是急症。须远离食物、置于儿童拿不到之处；不要用看似装过食物或饮料的容器盛放。任何可疑误服都应联系中毒救治机构或前往急诊。