Noun
sodium sulfite (plural sodium sulfites)
(chemistry) The sodium salt of sulfurous acid, Na2SO3, used as a food preservative, in photography and in many industrial applications.
After nitration, TNT is stabilized by a process called sulfitation, where the crude TNT is treated with aqueous sodium sulfite solution to remove less stable isomers of TNT and other undesired reaction products. Source: Internet
The trinitrotoluene is separated, washed with a dilute solution of sodium sulfite and then recrystallized from alcohol. Source: Internet