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what do you mean by aqua regia?

Aqua regia(lit."royal water"),aqua regis(lit."king's water"), or nitro-hydrochloric acid is a highly corrosive mixture of acids, a fuming yellow or red solution. The mixture is formed by freshly mixing concentrated nitric acid and hydrochloric acid,usually in a volume ratio of 1:3. It was named so because it can dissolve the so-called royal noble metals,gold and platinum. However,titanium,iridium, ruthenium,tantalum, osmium,rhodium,and a few other metals are capable of withstanding its corrosive properties.

Aqua regia is primarily used to produce chloroauric acid , the electrolyte in the Wohlwill process. This process is used for refining highest quality (99.999%) gold.

Aqua regia is also used in etching and in specific analytic . It is also used in some laboratories to clean glassware of organic compounds and metal particles.