Sō'dă, n.

n. [It., Sp., & Pg. soda, Fr. soude, Sp. also sosa, from Lat. salsus, salted, salt; N. Lat. salsola, salt-wort, glass-wort, diminutive of salsus.] The protoxide of the metal sodium, formerly called, though not appropriately, mineral alkali.

Carbonate of soda, a salt compounded of carbonic acid and soda, formerly obtained by lixiviating the ashes of sea-weeds, but now chiefly by the conversion of sea-water into sulphate of soda. It is largely used in arts and manufactures, as in those of glass, soap, &c. Ure.— Caustic soda, a compound of protoxide of sodium and water, containing an equal number of equivalents of each; the hydrate of soda.