aqua regia
A mixture of nitric acid (HNO 3 ) and
hydrochloric acid (HCl), in a solution of one part
of the former to three parts of the latter. Aqua
regia was used in making so-called "killed
spirits," largely in the 18th century, to impart a
wine-like tint to red marbling color. The "killed
spirits" were produced by adding a block of tin to
the acid solution, which resulted in the formation
of tin chloride (HNO 3 + HCl + Sn =
SnCl + NO 2 + H 2 O) (152 )
![[CoOL]](/icons/sm_cool.gif){kind=icon}