Ammonium chloride is an inorganic compound with the formula NH4Cl and a white crystalline salt that is highly soluble in water. Solutions of ammonium chloride are mildly acidic. The mineral is commonly formed on burning coal dumps from condensation of coal-derived gases. . It is mainly used as a flavouring agent in food industry or as a flux in preparing metals to be tin coated, galvanized or soldered. It is the product from the reaction of hydrochloric acid and ammonia.