Aqua Regia

I've been reading more than a few things about chemistry lately, in an effort to assist with a chemistry class while not appearing wholly incompetent. Of the many chemical compounds I've come across in the last few weeks, the most interesting substance has to be Aqua Regia.

For starters, it has a cool name (translation: Royal Water). Way cooler than things like "regular water", or "Deuterated 1,1-difluoro-2,2dihaloethyl difluoromethyl esters". Secondly, it's produced by mixing concentrated nitric and hydrochloric acids together in a beaker until they start to fume, bubble and turn orange. Awesome.

Also, by virtue of the way the two acids in the mixture behave, it's one of few compounds that is able to dissolve gold and other precious metals (which led medieval alchemists to give it its colourful name).

The most famous use of aqua regia involves Hungarian chemist George de Hevesy during World War II. He was in Denmark when the Nazis invaded. Knowing that the Nazis had a habit of helping themselves to any gold they came across, George came up with a way of ensuring the safety of two gold Nobel Prize medals, belonging to fellow scientists Max von Laue and James Franck. He whipped up some aqua regia and dropped the medals in, dissolving the gold into solution. He then placed the vials with the remaining liquid on a shelf with many other unlabelled chemicals. Surely enough, the Nazis came through and ignored the seemingly worthless chemicals sitting on the shelf. When they finally left, George precipitated the gold and sent it back to the Nobel Committee who recoined the prizes and returned them to von Laue and Franck.

Take that Nazis, you got out-scienced!