This strong corrosive mineral acid has been put to numerous uses for centuries both industrially and commercially. Hydrochloric acid is a colorless and highly pungent solution composed of hydrogen chloride and water. When an organic base reacts with hydrochloric acid, it produces hydrochloride salt. This particular concentration of hydrochloric acid (36.8%-38%) is used primarily for chemical analysis when preparing what are known as digest samples. This highly concentrated hydrochloric acid is capable of dissolving numerous metals, forming both metal chlorides and hydrogen gas. These concentrated hydrochloric acid solutions also react with calcium carbonate and copper oxide, producing dissolved chlorides ready for analysis. High quality hydrochloric acid such as this 36.5-38% concentration is also used in the regeneration of ion exchange resins. Hydrochloric acid is used to rinse cations from the resins in the production of demineralized water. Ion exchangers and demineralized water are used extensively in the chemical industry, production of drinking water, and numerous food industries.