Sodium sulfide Wikipedia
Sodium sulfide is the chemical compound with the formula Na 2 S, or more commonly its hydrate Na 2 S·9H 2 the anhydrous and the hydrated salts are colorless solids. They are watersoluble, giving strongly alkaline solutions. When exposed to moist air, Na 2 S and its hydrates emit hydrogen sulfide, an extremely toxic, flammable and corrosive gas which smells like rotten eggs.