In its mineral form sodium chloride, NaCl, is known as common salt. It is
important because it is essential to the health of human beings and of animals.
For domestic use it is fined down to what is known as table-salt, and small
quantities of other chemicals are added to it to keep it free-flowing when in
contact with the atmosphere.
Salt and potassium are combined to produce iodised salt, used when iodine is
lacking in diet. It s absence causes goitre, the swelling of the thyroid gland.
Livestock as well as humans need salt, and this provided in the form of solid
blocks, known as 'salt-licks'.
Salt is also crucial to the food industry. It is used in meatpacking
sausage-making and fish-curing both for seasoning and as a preservative. It is
also used in the curing and preserving of hides and in the form of brine of
brine for refrigeration purposes.
Salt is extensively used in the chemical industry; in the manufacture of baking
soda, sodium bicarbonate; of caustic soda, sodium hydroxide; of hydrochloric
acid, of chlorine etc. It is also used in soap-making, and in the manufacture of
glaze and porcelain enamel. It also enters metallurgic processes as flux, a
compound used to assist the fusing of metals.
Salt lowers the melting point of water, so in combination with grit, it is used
for clearing roads of snow and ice. It is also used for water-softening by means
of removing calcium and magnesium compounds from tap water.