When chlorine gas is passed through an aqueous solution of a potassium halide in the presence of chloroform, a violet colouration is obtained. On passing more of chlorine water, the violet color disappears and solution becomes colourless, This test confirms the presence of . . .. . .. .. . in aqueous solution.

Free iodine is released when this reagent is introduced dropwise to an iodide solution, turning the solution brown. When the solution is shaken with ${\mathrm{CS}}_2,{\mathrm{CHCl}}_3$, or ${\mathrm{CCl}}_4$, the violet solution that results from this dissolves in the organic layer and settles lower than the watery layer.

$2\mathrm{KI}+{\mathrm{Cl}}_2⟶{\mathrm{I}}_2+\mathrm{KCl}$

${\mathrm{I}}_2+{\mathrm{CHCl}}_3\to$ violet solution