ALKALI MANUFACTURE. The group of materials in cludes sodium carbonate (soda ash), caustic soda, bicarbonate of soda, soda crystals (washing soda), sodium silicate (water-glass), sulphate of soda (salt cake) and sodium sulphide. Certain other substances are linked with these in manufacture, such as chlorine, which is produced simultaneously with caustic soda by certain processes, and which in turn gives rise to bleaching powder, hydro chloric acid and so forth. Alkali and chlorine are, under modern practice, inseparable, and form one comprehensive and intimately connected group of manufactures (the "heavy chemical" trade). The principal products (soda ash, caustic soda and chlorine) form raw materials for other industries.
The chief centres of alkali pro duction are England, Belgium, France, Germany and the United States.