chlorides of metals other than heavy ones, e.g., `Hg^(2+)`, on reacting with conc. `H_(2)SO_(4)` and `K_(2)Cr_(2)O_(7)` produce orange acetate produce yellow ppt. of `PbCrO_(4)`. Orange colour vapours are that of chromyl chloride, `CrO_(2)Cl_(2)` hence the test is so named.
