Aqua Regia was made simply by combining aqua fortis, nitric acid, with spirit of salt or with common salt and a vitriol, in careful proportion, producing an unstable, deep orange, fuming liquor that had to be used soon after mixing since it loses potency on standing as its active components decompose. Its discovery is generally credited to the medieval alchemical tradition associated with Pseudo-Geber, the Latin author whose influential works, distinct from the historical Jabir ibn Hayyan, describe a mixture of the strong acids capable of dissolving gold, though the precise attribution and date remain a matter of ongoing scholarly reconstruction rather than settled fact. What made aqua regia remarkable to its discoverers was precisely that neither of its two component acids, however strong on its own, would touch gold at all, yet the combination succeeded where both separately failed, a genuinely striking chemical phenomenon that alchemists rightly treated as significant even without a theory to explain the synergy.
Once gold could be dissolved, it could be recovered by precipitation, refined to remove other metals, or, mixed with other reagents, carried forward into preparations such as aurum potabile that depended on getting gold into a liquid, apparently digestible form. Aqua regia's corrosive fumes and its violent reaction with organic matter made it one of the more hazardous standard reagents of the workshop.