...that

Nitric acid and hydrochloric acid make....... aqua regia

Usually this is in a 1:3 mixture.


FUn Fact: It is one of the few reagents that dissolves gold and platinum. It was so named because it can dissolve the so-called royal, or noble metals, although tantalum, iridium, and a few other metals are able to withstand it. (from wikipedia, but I read it in a book last night!)