Aqua Regia is the King’s Water, this is because it is strong enough to dissolve gold – the king of metals. It is prepared by mixing three parts of hydrochloric acid with one part nitric acid but in olden days it is prepared to mix and distill salts. For example, we can mix two parts niter with one part Sal. Ammoniac and distill at a high temperature to form Aqua Regia.
“Sulphuric acid” is called the king of acids and “Nitric acid” is called the Queen of acids.