1. Also called soda ash.
an anhydrous, grayish-white, odorless, water-soluble powder, Na 2
, usually obtained by the Solvay process and containing about 1 percent of impurities consisting of sulfates, chlorides, and bicarbonates of sodium: used in the manufacture of glass, ceramics, soaps, paper, petroleum products, sodium salts, as a cleanser, for bleaching, and in water treatment.
the monohydrated form of this salt, Na 2 CO 3 ⋅H 2 O, used similarly, especially in photography.