AQUA fortis, a corrosive liquor, made by distilling purified nitre with calcined vitriol, or rectified oil of vitriol, in a strong heat; the liquor, which rises in fumes red as blood, being collected, is the spirit of nitre or aqua fortis; which serves as a menstruum for dissolving of silver, and all other metals, except gold. But if sea-salt, or sal ammoniac be added to aqua fortis, it commences aqua regia. Aqua fortis is commonly held to have been invented about the year 1300; though others will have it to have been known in the time of Moses. It is serviceable to refiners, in separating silver from gold and copper; to the workers in mosaic, for staining and colouring their woods; to dyers, in their colours, particularly scarlet; and to other artists, for colouring bone and ivory. With aqua fortis bookbinders marble the covers of books, and diamond-cutters separate diamonds from metalline powders. It is also used in etching copper or brass plates. See CHEMISTRY, Of the nitrous acid.