#aqua fortis

• Etching — An artistic method of engraving metal plates (especially copper or zinc) through the corrosive action of nitric acid, followed by printing the resulting design onto paper; also, the traditional name given to the diluted nitric acid used for this purpose. This structural term describes a fundamental technique in graphic arts, famous for line precision and texture depth.
• Aqua fortis — An archaic, alchemical, and technical name for diluted nitric acid (HNO₃), an extremely corrosive and toxic liquid capable of dissolving most base metals, except for gold and platinum. In the past, this chemical solution was widely used in engraving workshops and by jewelry craftsmen for the controlled etching of metallic plates or for testing silver purity.
• Aqua fortis — A compound form spelled with a hyphen designating diluted nitric acid (HNO₃), an extremely corrosive and toxic liquid capable of dissolving most base metals. This compound was historically used in jewelry guilds and engraving workshops for the controlled etching of copper or zinc plates.
• Nitric — Containing nitrogen, pertaining to nitrogen, or derived from it; a term utilized almost exclusively to designate nitric acid (HNO3), a strong, highly corrosive, and oxidizing inorganic acid, widely used in industry for manufacturing fertilizers, explosives, and in metallurgy.