AQUA REGIA OFF-GASES

The composition and concentration of gases expected to be evolved from boiling aqua regia alone and from aqua regia during stainless steel dissolution were surveyed When aqua regia was boiled alone, the first gases evolved contained more than 50% Cl/sub 2/ by volume. The Cl/sub 2/ soon dropped and the concentration of NOCl rose to 80% with traces of NO and NO/sub 2/. In stainless steel dissolution, the offgases contained varying quantities of N/sub 2/O, N/sub 2/, H/sub 2/, and HCl in addition to the gases found with boiling aqua regia alone. (J.R.D.)