Sodium sulfide is also called stinky alkali, stinky soda, yellow alkali, and alkali sulfide. Sodium sulfide is an inorganic compound, and pure sodium sulfide is a colorless crystalline powder. It has strong moisture absorption and is easily soluble in water. The aqueous solution is strongly alkaline. It can cause burns when touching the skin and hair. So sodium sulfide is commonly called alkali sulfide. Sodium sulfide deliquescence in the air, and carbonation and deterioration, continuously releasing hydrogen sulfide gas. Industrial sodium sulfide is pink, brown-red, and ocher due to impurities. The specific gravity, melting point, and boiling point also vary due to the influence of impurities.