Why is common salt so important?
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. Its 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 meat-packing 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 for refrigeration purposes.
Salt is extensively used in the chemical industry; in the
manufacture of baking soda, sodium bicorbonate; 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.