Library

Strong water (Qiangshui, strong acid) manufactured by Westerners has the most violent nature and can corrode the five metals (gold, silver, copper, iron, tin). Mr. Wang Yitang stated: This liquid is extremely potent; it can penetrate and leak through the five metals and eight stones (minerals), and only glass vessels can contain it. The method used by Westerners to produce strong water involves only seven medicinal ingredients boiled in a jar, similar to the modern method of extracting distillates (Lu). A glass bottle is connected to the side with sealed gaps, and heating is alternated between mild fire (Wenhuo) and vigorous fire (Wuhuo). When black gas enters the glass bottle, the liquid drips in along with the gas. Once the black gas is exhausted, the medicine is ready. Due to its violent nature, this liquid must not be ingested.

When Westerners paint Western-style paintings that require engraving on copper plates, they first draw patterns such as landscapes or figures on the copper. They then soak the plate in this liquid for a day and night. The soaked areas naturally corrode, achieving results superior to carving. Highs and lows, hidden and visible details are all rendered vividly. Areas on the copper plate that should not corrode are protected with yellow wax beforehand. After soaking for a week, if corrosion marks appear, the strong water is washed off with water, and the wax traces are wiped clean, completing the drawing on the copper plate. This method is far superior to engraving and is easier and faster. In medicine, it is used for its aroma/vapor.

It treats carbuncles and sores (Yongju) by extracting toxin-filled boils (Ding). Xie Tianshi said: For carbuncles and sores whether ulcerated or not, strong water can cauterize necrotic flesh, being more effective than arsenic trioxide (Sha). One need only place strong water in a glass bottle, position the bottle mouth against the lesion, and cover it briefly. The medicinal vapor will naturally rise into the affected area, turning the diseased tissue white and putrid, thereby extracting the toxin. Subsequently, other medicines can be applied. For toxin-filled boils with roots, this same method causes the root to rot and fall out spontaneously.

*Wuli Xiaoshi* records: There is a type of nitric acid (Xiaoshui). If silver pieces are cut and thrown into it, they immediately dissolve into liquid. Pouring it into a basin allows it to take the shape of the container. To retrieve the nitric acid, a long tube is fired in a glaze kiln, and its airway is obtained by smelting cinnabar. Mr. Zhu told me: In the Gengchen year of the Chongzhen reign, the book *Kunyu Gezhi* was presented, discussing mining and separating the five metals, noting that it requires less labor but yields greater profit. In the Renwu year, Zhu Hongbao, serving as Minister of Agriculture, also proposed this. However, the government did not adopt it. Nowadays, foreign saltpeter is rare; only nitrous fumes exist, whereas true foreign saltpeter can dry mercury. According to this, "nitric acid" refers to strong water; it is merely a difference in ancient and modern names.