Sodium Hydrosulfide (NaHS) is an economical form of reactive sulfur that is typically a light-yellow colored solution with the accompanying odor of rotten eggs. Hydrogen Sulfide (H2S), a toxic gas, is evolved upon contact of NaHS with acids. NaHS is mildly corrosive to carbon steel and cast iron. Stainless steels are very resistant to corrosion. Copper and its alloys, aluminum and zinc are rapidly attacked. Polyvinyl chloride (PVC) storage systems are to be avoided.