Aqua Regiæ (literally 'queen's water') is a mixture of concentrated sulphuric acid (oil of vitriol) and nitric acid, or of sulphuric acid and nitre. Either mixture evolves fumes largely, and may be used as a disinfectant.
Aqua Regiæ
Chambers's Encyclopaedia, Volume 1: A to Beaufort, p. 355
Source scan(s): p. 0374