SODA

strictly speaking, is the base corresponding to the metal sodium, but used without prefix it generally implies sodium carbonate, Na:CO;. Soda ash is anhydrous sodium carbonate, obtained by evaporating the solution and igniting the residue. Washing soda, or soda crystals, is the dec a hydrated carbonate, Na»CO310H:0, obtained by allowing a hot saturated solution of sodium carbonate in water to cool. Baking soda is the bicarbonate, NaHCO;2H:0; and caustic soda is the hydroxide, NaOH, obtained by electrolyzing a solution of sodium chloride (common salt) in water. See Soprum.