Regia

Coordinates: 41°53′31″N 12°29′12″E / 41.891967°N 12.486595°E / 41.891967; 12.486595

The Regia was a two-part structure in Ancient Rome lying along the Sacra Via at the edge of the Roman Forum that originally served as the residence or one of the main headquarters of kings of Rome and later as the office of the Pontifex Maximus, the high priest of Roman state religion. It occupied a triangular patch of terrain between the Temple of Vesta, the Temple of Divus Julius and Temple of Antoninus and Faustina. Only the foundations of Republican/Imperial Regia remain. Like the Curia it was destroyed and rebuilt several times, as far back as the Roman monarchy. Studies have found multiple layers of similar buildings with more regular features, prompting the theory that this "Republican Regia" was to have a different use.

History

According to ancient tradition it was built by the second king of Rome, Numa Pompilius, as a royal palace. Indeed, the Latin term regia can be translated as royal residence. It is said that he also built the Temple of Vesta and the House of the Vestal Virgins as well as the Domus Publica. This created a central area for political and religious life in the city and Kingdom. When Caesar became Pontifex Maximus, he exercised his duties from the Regia.

Aqua regia

Aqua regia (Latin, lit. "royal water" or "king's water") is a mixture of nitric acid and hydrochloric acid, optimally in a molar ratio of 1:3. Aqua regia is a yellow-orange fuming liquid. Aqua regia was so named because it can dissolve the noble metals gold and platinum. However, titanium, iridium, ruthenium, rhenium, tantalum, niobium, hafnium, osmium and rhodium are capable of withstanding its corrosive properties.

Applications

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

Aqua regia is also used in etching and in specific analytic procedures. It is also used in some laboratories to clean glassware of organic compounds and metal particles. This method is preferred over the "traditional" chromic acid bath for cleaning NMR tubes, because no traces of paramagnetic chromium can remain to spoil spectra. While chromic acid baths are discouraged because of the high toxicity of chromium and the potential for explosions, aqua regia is itself very corrosive and has been implicated in several explosions due to mishandling.