Salt is important in many ways. It is an essential part of the diet of both humans and animals and is a
part of most animal fluids, such as blood, sweat, and tears. It aids digestion by providing chlorine for
hydrochloric acid, a small but essential part of human digestive fluid. Persons with hypertensive
heart disease often must restrict the amount of salt in their diet.
Salt is widely used as a seasoning for foods and is used in curing meats and preserving fish and other
foods. Iodized table salt usually contains small amounts of potassium iodide, sodium carbonate, and
sodium thiosulfate. As a chemical salt is used in making glass, pottery, textile dyes, and soap. It is used in large amounts to melt ice and snow on streets and highways. The major use of salt is as a raw material for the production of chlorine, sodium
metal, and sodium hydroxide; it is also used in large amounts in the Solvay process for making sodium
carbonate. Historically, salt has been used as money; a high tax on salt was a contributing cause
of the French Revolution.