When moist chlorine gas is reacted with hypo then colloidal sulphur, $\mathrm{HCl}$ and sodium sulphate products are formed.
$\mathrm{Na}_2 \mathrm{~S}_2 \mathrm{O}_3+\mathrm{H}_2 \mathrm{O}+\mathrm{Cl}_2 \rightarrow \mathrm{Na}_2 \mathrm{SO}_4+2 \mathrm{HCl}+\mathrm{S}$