<Tr> <Td_colspan="2"> Infobox references </Td> </Tr> <Tr> <Td> </Td> <Td> </Td> </Tr> <P> Aqua regia (/ ˈreɪɡiə, ˈriːdʒiə /; from 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, so named by alchemists because it can dissolve the noble metals gold and platinum, though not all metals . </P> <P> Aqua regia is primarily used to produce chloroauric acid, the electrolyte in the Wohlwill process for refining the highest quality (99.999%) gold . </P>

Name the metals which are soluble only in aqua regia