Potash
This substance exists in plants, combined with other organic acids. The plants being burned destroys the combination, the organic acids being decomposed into carbonic acid and water, and the liberated potash unites with some of the carbonic acid formed by the combustion, thus producing carbonate of potash. This salt is highly alkaline, is used to prepare caustic potash, and for the manufacture of soap, glass, etc. Wood-ashes furnish from 20 to 50 per cent of their weight of carbonate of potash, being obtained from them by leaching and boiling the solution to dryness in iron pots. See ALKALI; ASHES.