Manufacture of sodium carbonate or soda ash, Na₂CO₃from salt (sodium chloride), ammonia, carbon dioxide, and limestone by a sequence of reactions involving recovery and reuse of practically all the ammonia and part of the carbon dioxide. Limestone is calcined to quicklime and carbon dioxide. The carbon dioxide is dissolved in water containing the ammonia and salt, with resulting precipitation of sodium bicarbonate. This is separated by filtration, dried, and heated to form sodium carbonate. The liquor 3005 from the bicarbonate filtration is heated and treated with lime to regenerate the ammonia. Calcium chloride is a major byproduct.