Various chemical processes which involve use of Sodium Sulphide and Sodium hydrogen Sulphide evolve Hydrogen Sulphide gas as a by-product. Hydrogen Sulphide gas is also evolved in the process of decaying of organic wastes and in sewage systems. The gas is highly toxic and in higher concentration it is fatal for human life. Sodium permanganate solution can neutralise Hydrogen Sulphide gas by reducing it in to elemental sulphur and water this rendering it harmless to humans and environment.
