- Aqua fortis
Aqua fortis, or "strong water," in
alchemy, is a corrosive solutionof nitric acidmade from saltpeter. It was used in alchemy as a solvent for dissolving silverand most other metals with notable exceptions of goldand platinumthat can be dissolved using aqua regia. Aqua fortis was prepared by mixing either sand, alum, or vitriol, or the last two together, with saltpeter, then distilling it by a hot fire. The gas collected from this condenses into aqua fortis.
The discovery of aqua fortis is credited to
Jabir ibn Hayyansometime around 800AD.
Aqua fortis was useful to refiners for parting or separating silver from gold and
copper; to the workers in mosaicfor staining and coloring their woods; to other artists for coloring of bone and ivory, which is done by tinging the items with copperor verdigris, then soaking in aqua fortis. Some also turn it into aqua regia, by dissolving in a quarter of its weight of sal ammoniac, and then use this to stain ivory and bone, of a fine purple color. Book binders also put it on leather, making fine marble covers for books. Diamond cutters used it to separate diamonds from metalline powders. It was also used in etching copper or brassplates. It was mixed with oil of vitrioland used to stain canes to appear like a tortoise shell by applying several coats while the cane is over hot coals. The canes were then given a gloss with a little soft wax and a dry cloth.
Aqua fortis is actually a solution of HNO3,
nitric acid, in water.
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