Nitric acid (HNO3), also known as aqua fortis and spirit of niter, is a highlycorrosive mineral acid. The pure compound is colorless, but older samples tend to acquire a yellow cast due to decomposition into oxides of nitrogen and water. Most commercially available nitric acid has a concentration of 68%. When the solution contains more than 86% HNO3,it is referred to as fuming nitric acid.Depending on the amount of nitrogen dioxide present, fuming nitric acid is further characterized as white fuming nitric acid or red fuming nitric acid, at concentrations above 95%.The main industrial use of nitric acid is for the production of fertilizers. The other main applications are for the production of explosives, nylon precursors, and specialty organic compounds.