Human beings have used canning and artificial refrigeration for the preservation of food for approximately the last two hundred years. However, in the millennia before then, salt provided the best-known food preservative, especially for meat. The harvest of salt from the surface of Xiechi Lake near Yuncheng in Shanxi, China dates back to at least 6000 BC, making it one of the oldest verifiable saltworks.:18â€“19
Another very ancient saltworks operation (rivaling the Xiechi Lake in China for oldest) has been discovered at the Poiana Slatinei archaeological site next to a salt spring in Lunca, Neamt County, Romania. Evidence indicates that Neolithic people of the Precucuteni Culture were boiling the salt-laden spring water through the process of briquetage to extract the salt as far back as 6050 BC. The salt extracted from this operation may have had a direct correlation to the rapid growth of this society's population soon after its initial production began.
Salt was included among funereal offerings found in ancient Egyptian tombs from the third millennium BC, as were salted birds and salt fish.:38 From about 2800 BC, the Egyptians began exporting salt fish to the Phoenicians in return for Lebanon cedar, glass, and the dye Tyrian purple; the Phoenicians traded Egyptian salt fish and salt from North Africa throughout their Mediterranean trade empire.:44
Along the Sahara, the Tuareg maintain routes especially for the transport of salt by Azalai (salt caravans). In 1960, the caravans still transported some 15,000 tons of salt, but this trade has now declined to roughly a third of this figure.
Salzburg, Hallstatt, and Hallein lie on the river Salzach in central Austria, within a radius of no more than 17 kilometres. Salzach literally means ``salt water`` and Salzburg ``salt city``, both taking their names from the Germanic root for salt, salz. The root hal(l)- also gave us Gaul, the Roman exonym for the Celts, Halle and SchwÃ¤bisch Hall in Germany, Halych in Ukraine, and Galicia in Spain: this list of places named for Celtic saltworks is far from complete.
Hallstatt gave its name to the Celtic archaeological culture that began mining for salt in the area in around 800 BC. Around 400 BC, the Hallstatt Celts, who had heretofore mined for salt, began open pan salt making. During the first millennium BC, Celtic communities grew rich trading salt and salted meat to Ancient Greece and Ancient Rome in exchange for wine and other luxuries.
It is widely, though incorrectly, believed that troops in the Roman army were paid in salt. Even widely-respected historical works repeat this error.:63 The word salad literally means ``salted,`` and comes from the ancient Roman practice of salting leaf vegetables.:64
Mahatma Gandhi led at least 100,000 people on the ``Dandi March`` or ``Salt Satyagraha``, in which protesters made their own salt from the sea, which was illegal under British rule, as it avoided paying the ``salt tax``. This civil disobedience inspired millions of common people, and elevated the Indian independence movement from an elitist struggle to a national struggle.
In the King James Bible, forty-one verses mention salt, the earliest being the story of Lot's wife, who was turned into a pillar of salt when she disobediently looked back at the wicked cities of Sodom and Gomorrah (Genesis 19:26). When King Abimelech destroyed the city of Shechem, he is said to have ``sown salt on it;`` a phrase expressing the completeness of its ruin. (Judges 9:45.) In the Sermon on the Mount, Jesus referred to his followers as the ``salt of the earth``. The apostle Paul also encouraged Christians to ``let your conversation be always full of grace, seasoned with salt`` (Colossians 4:6).
In one of the Hadith recorded in Sunan Ibn Majah, Prophet Muhammad is reported to have said that: ``Salt is the master of your food. God sent down four blessings from the sky - fire, water, iron and salt``
Salt is mandatory in the rite of the Tridentine Mass. Salt is used in the third item (which includes an Exorcism) of the Celtic Consecration (cf. Gallican rite) that is employed in the consecration of a church. Salt may be added to the water ``where it is customary`` in the Roman Catholic rite of Holy water.
Salt is considered to be a very auspicious substance in Hindu mythology, and is used in particular religious ceremonies like housewarmings and weddings.
In Judaism, it is recommended to have either a salty bread or to add salt to the bread if this bread is unsalted when doing Kidush for Shabat. It is customary to spread some salt over the bread or to dip the bread in a little salt when passing the bread around the table after the Kidush. To preserve the covenant between their people and God, Jews dip the Sabbath bread in salt.
In Wicca, salt is symbolic of the element Earth. It is also used as a purifier of sacred space.
In the native Japanese religion Shinto, salt is used for ritual purification of locations and people, such as in sumo wrestling.
In Aztec mythology, Huixtocihuatl was a fertility goddess who presided over salt and salt water.
The ancient Egyptians, Greeks and Romans invoked their gods with offerings of salt and water. This is thought to be the origin of the Holy Water used in the Christian faith.
Small particles of sea salt are the dominant cloud condensation nuclei well out at sea, which allow the formation of clouds in otherwise non-polluted air.
Salt is used for snow removal, to make travel easier and safer and decrease the long term impact of a heavy snowfall on human populations. Salt and other chloride-based chemicals reduce snow and ice from road surfaces and sidewalks by lowering the temperature at which ice melts.
Different natural salts have different mineralities, giving each one a unique flavor. Fleur de sel, natural sea salt harvested by hand, has a unique flavor varying from region to region.
Some advocates for sea salt assert that unrefined sea salt is healthier than refined salts. However, completely raw sea salt is bitter because of magnesium and calcium compounds, and thus is rarely eaten. The refined salt industry cites scientific studies saying that raw sea and rock salts do not contain enough iodine salts to prevent iodine deficiency diseases.
Unrefined sea salts are also commonly used as ingredients in bathing additives and cosmetic products. One example are bath salts, which uses sea salt as its main ingredient and combined with other ingredients used for its healing and therapeutic effects.
Refined salt, which is most widely used presently, is mainly sodium chloride. Food grade salt accounts for only a small part of salt production in industrialised countries (3% in Europe) although worldwide, food uses account for 17.5% of salt production. The majority is sold for industrial use. Salt has great commercial value because it is a necessary ingredient in the manufacturing of many things. A few common examples include: the production of pulp and paper, setting dyes in textiles and fabrics, and the making of soaps and detergents.
The manufacture and use of salt is one of the oldest chemical industries. Salt can be obtained by evaporation of sea water, usually in shallow basins warmed by sunlight; salt so obtained was formerly called bay salt, and is now often called sea salt or solar salt. Rock salt deposits are formed by the evaporation of ancient salt lakes, and may be mined conventionally or through the injection of water. Injected water dissolves the salt, and the brine solution can be pumped to the surface where the salt is collected.
After the raw salt is obtained, it is refined to purify it and improve its storage and handling characteristics. Purification usually involves recrystallization. In recrystallization, a brine solution is treated with chemicals that precipitate most impurities (largely magnesium and calcium salts). Multiple stages of evaporation are then used to collect pure sodium chloride crystals, which are kiln-dried.Salt Crystals at