soda ash

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Sodium carbonate in powdery white form, used especially as an industrial chemical.

Century Dictionary and Cyclopedia

1. n. The trade-name of sodium carbonate. See soda.

Wiktionary

1. n. industrial-grade sodium carbonate

GNU Webster's 1913

1. n. crude sodium carbonate; -- so called because formerly obtained from the ashes of sea plants and certain other plants, as saltwort (Salsola). See under Sodium.

WordNet 3.0

1. n. a sodium salt of carbonic acid; used in making soap powders and glass and paper