Barium Chloride: Witherite Dissolved in Dilute Hydrochloric Acid and Cleared over Excess Carbonate (Thorpe 1912)

Witherite, the natural barium carbonate, fizzes away in hydrochloric acid to barium chloride. Leaving the liquor to stand over more carbonate than the acid can take pulls the iron and other foreign metals out, so the crystals come out clean. Result: colourless crystals of barium chloride, BaCl2.2H2O. Poisonous if swallowed. Source: Thorpe, Dictionary of Applied Chemistry vol. 1 (1912), p. 420. Not given: amounts and acid strength. Picture drawn by Youblob.