Barium chloride is the most important soluble barium salt, also known as "barium salt". The chemical formula is BaCl2. There are two kinds of crystals: colorless monoclinic and colorless cubic. The monoclinic crystal changes into cubic crystal at 962 ℃. At normal temperature, it is white and shiny monoclinic crystal, odorless, bitter and salty. Soluble in water, insoluble in acetone, ethanol and ether, slightly soluble in acetic acid and sulfuric acid. Barium chloride crystallized from aqueous solution often contains two crystalline waters. When heated to 113 ℃, the crystal water is lost and becomes anhydrous chlorine barium chloride in the form of white powder. It can be used to identify and separate SO2-4 ions and purify salt brine. It is mainly used to manufacture barium salt and pigment. It can also be used as hard water softener, mordant in wool and leather industry, insecticide for controlling plant pests, etc. Industrial preparation of barium chloride is mainly made from barite with high barium sulfate content as raw material and calcined with pulverized coal and calcium chloride. The reaction formula is as follows: BaSO4 + 4C + CaCl2 → BaCl2 + CAS + 4Co ↑.