| 1. | Also called soda ash. an anhydrous, grayish-white, odorless, water-soluble powder, Na2CO3, 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. |
| 2. | Also called sal soda, soda, washing soda. the decahydrated form of this salt, Na2CO3·10H2O, used similarly. |
| 3. | the monohydrated form of this salt, Na2CO3·H2O, used similarly, esp. in photography. |
| washing soda n. A hydrated sodium carbonate used as a general cleanser. |