Sodium hydroxide (NaOH), an inorganic compound.
The alkalies called caustic soda and caustic potash ( potassium hydroxide) are very important industrial chemicals, with uses in the manufacture of soaps, glass, and numerous other products. They have been easily extracted since ancient times by soaking wood ashes in water (see lye ). Industrial methods of caustic-soda production developed in the 18th century (the Leblanc process) and 19th century (the Solvay, or ammonia-soda, process) have been largely displaced by electrolysis .