Salmoniac, also known as ammonium chloride, is a chemical compound with the formula NH4Cl. It is a white crystalline salt that is highly soluble in water and has a slightly salty taste. Historically used in various applications, including as a food preservative, in fertilizers, and in the production of batteries, salmoniac also has roles in the pharmaceutical and textile industries. Its unique properties make it valuable for various chemical processes and reactions.