Sodium carbonate

Sodium carbonate, Na₂CO₃, (also known as washing soda, soda ash and soda crystals) is the inorganic compound with the formula Na₂CO₃ and its various hydrates. All forms are white, water-soluble salts. All forms have a strongly alkaline taste and give moderately alkaline solutions in water. Historically it was extracted from the ashes of plants growing in sodium-rich soils. Because the ashes of these sodium-rich plants were noticeably different from ashes of wood (once used to produce potash), sodium carbonate became known as "soda ash."  It is produced in large quantities from sodium chloride and limestone by the Solvay process.