Of all salts found in the body, the most abundant and valuable is sodium chloride (NaCl), common salt; it exists in all tissues, secretions, and fluids of the body, with exception of enamel of the teeth. The amount found in food is not always sufficient; therefore salt is used as a condiment. It assists digestion, inasmuch as it furnishes chlorine for hydrochloric acid found in gastric juice.

Common salt is obtained from evaporation of spring and sea water, also from mines. Our supply of salt obtained by evaporation comes chiefly from Michigan and New York; mined salt from Louisiana and Kansas.

Salt is a great preservative; advantage is taken of this in salting meat and fish.

Other salts— lime, phosphorus, magnesia, potash, sulphur, and iron— are obtained in sufficient quantity from food we eat and water we drink. In young children, perfect formation of bones and teeth depends upon phosphorus and lime taken into the system; these are found in meat and fish, but abound in cereals.