Salt is essential to all life; it regulates fluid balance and absolutely necessary for movement, nerve impulses, digestion and healing of wounds. All vertebrates have the same amount of salt in their blood (9 grams per liter), which makes it four times saltier than seawater.
Chemically, table salt consists of two elements, sodium and chlorine - sodium is a highly unstable metal in presence of water and chlorine a deadly gas. Yet the way salt is combined becomes necessary food for survival. In Mecca, Saudi Arabia, pilgrims are given salt tablets and urged to take them daily. Salt does not deteriorate when exposed to oxygen, thus "salt freshness" is an oxymoron. Aging salt serves no purpose.
Chemical laboratories analyzed table salt (rock salt) and sea salt to determine a difference. There was none, yet sea salt tastes better due to other minerals present in seawater.
Sources of Salt
There have been two main sources for salt: sea water and rock salt. Rock salt occurs in vast beds of sedimentary evaporite minerals that result from the drying up of enclosed lakes, playas, and seas. Salt beds may be up to 350 m thick and underlie broad areas. In the United States and Canada extensive underground beds extend from the Appalachian basin of western New York through parts of Ontario and under much of the Michigan basin. Other deposits are in Ohio, Kansas, New Mexico, Nova Scotia, and Saskatchewan. In the United Kingdom underground beds are found in Cheshire and around Droitwich.
Salt is extracted from underground beds either by mining or by solution mining using water or brine. In solution mining the salt reaches the surface as brine, which is then turned into salt crystals by evaporation.
The socio-political history of salt
In antiquity, salt was a precious commodity. Marco Polo reported that in Tibet cakes of salt were pressed with images of their ruler and used as currency.
Salt bars were used as currency of exchange for more than 1000 years in Ethiopia and travelers report that some are still circulating among the nomads of the Danakil plains.
In ancient Greece, slaves were traded for salt, and unruly slave was not "worth his salt".
Chinese emperor Hsia Yu (2200 BC) was the first to levy a tax on salt. This was also the first tax ever. Since then, practically everything is taxed, including public toilets in the Roman Empire.
Romans and Middle Ages
It is believed that Roman soldiers were at certain times paid with salt, and this is still evident in the English language as the word "salary" derives from the Latin word salarium that means payment in salt (Latin sal), as well as the phrases "worth one's salt" and "with a grain of salt" (i.e. of little value). The Roman Republic and Empire controlled the price of salt, increasing it to raise money for wars, or lowering it to be sure that the poorest citizens could easily afford this important part of the diet.
It was also of high value to the Hebrews, Greeks and other peoples of antiquity.
Already in the early years of the Roman Republic, with the growth of the city of Rome, roads were built to make transportation of salt to the capital city easier. An example was the Via Salaria (originally a Sabine trail), leading from Rome to the Adriatic Sea. The Adriatic Sea, having a high salinity due to its shallow depth, had more productive solar ponds if compared with those of the Tyrrhenian Sea, much closer to Rome.
During the late Roman Empire and throughout the Middle Ages salt was a precious commodity carried along the salt roads into the heartland of the Germanic tribes. Caravans consisting of as many as forty thousand camels traversed four hundred miles of the Sahara bearing salt, sometimes trading it for slaves.
Biblical Reference
In the New Testament, Matthew 5:13 Jesus said, "You are the salt of the earth." Jesus said this in order to show his disciples how valuable they were and this saying is commonly used today to describe someone who is of particular value to society. In addition, the preservative quality of salt is in view here to show how the disciples were called to preserve the society and the world around them from moral decay.
Cities and wars
Salt has played a prominent role in determining the power and location of the world's great cities. Timbuktu was once a huge salt market. Liverpool rose from just a small English port to become the prime exporting port for the salt dug in the great Cheshire salt mines and thus became the source of the world's salt in the 1800s.
Salt created and destroyed empires. The salt mines of Poland led to a vast kingdom in the 1500s, only to be destroyed when Germans brought sea salt (often, to most of the world, considered 'superior' to rock salt). Venice fought and won a war with Genoa over salt. However, Genovites Christopher Columbus and Giovanni Caboto would later destroy the Mediterranean trade by introducing the New World to the market.
Cities, states and duchies along the salt roads exacted heavy duties and taxes for the salt passing through their territories. This practice even caused the formation of cities, such as the city of Munich in 1158, when the then Duke of Bavaria, Henry the Lion, decided that the bishops of Freising no longer needed their salt revenue.
The gabelle - a hated French salt tax - was enacted in 1286 and maintained until 1790. Because of the gabelles, common salt was of such a high value that it caused mass population shifts and exodus, attracted invaders and caused wars.
During many wars in American history, salt has been a major factor in the outcome. In the Revolutionary War, the British used Tories to intercept the rebels' salt supply and destroy their ability to preserve food. During the War of 1812, salt brine was used to pay soldiers in the field, as the government was too poor to pay them with money. Before Lewis and Clark set out for the Louisiana Territory, President Jefferson spoke in his address to Congress about a mountain of salt supposed to lie near the Missouri River, which would have been of immense value. (However, by 1810, new discoveries along the Kanawha and Sandy Rivers had greatly reduced the value of salt.)
During India's independence movement, Mohandas Gandhi organized the Salt March protest to demonstrate against unfair taxation by the British.
Salt trade
Salt was much more valuable in the past than it is now. Before refrigeration, salt was the main ingredient to preserve food, as it draws water out of bacteria, causing it to shrivel and die. The vast majority of meat, and fish was salted and shipped. Even butter was heavily salted. Our diet today is much lower in salt than it was in the 20th century, but still North American per capita salt consumption is high, since a considerable amount of convenience food contains a lot of sodium chloride.
During more modern times, it became more profitable to sell salted food than pure salt. Thus sources of food to salt went hand in hand with salt making. The British controlled saltworks in the Bahamas as well as North American cod fisheries. This may have added to their economic clout during their 19th century imperial expansion period. The search for oil in the late 1800s and early 1900s used the technology and methods pioneered by salt miners, even to the degree that they looked for oil where salt domes were located.
Salt was put in bowls (salt cellars), which were placed in the middle of a rhomboid table. A guest's proximity to the host, who sat at the head of the table - "above the salt" or "below the salt" - reflected his/her importance. Once moisture-absorbing agents were added, starting early in the 20th century, salt could be sold ground and "salt cellars" were quickly replaced by "salt shakers".
Since 1949 many governments mandated the addition of iodine, a deficiency which causes goiter, a swelling of the thyroid gland. (Goiter used to be prevalent in mountainous inland regions with limited or no access to salt).
Salt production
There are some 14,000 commercial applications for salt ranging from use in pulp-and-paper production to explosives. Ands then of course there is road salt, which makes Canada the world's highest salt consumers with 360kg.
The world's largest salt mine is in Goderich, Ontario extending several kilometers under Lake Huron., In Canada, salt was at one time sold in blocks, then ground at home, much like roasted coffee beans that are roasted just before grinding for brewing. This way the aromatics of coffee can be appreciated much better.
On an industrial scale salt is produced in one of two principal ways: the evaporation of salt water (brine) or by mining. Evaporation can either be solar evaloration or using some heating device.
Solar evaporation of seawater
In the correct climate (one for which the ratio of evaporation to rainfall is suitably high) it is possible to use solar evaporation of sea water to produce salt. Brine is evaporated in a linked set of ponds until the solution is sufficiently concentrated by the final pond that the salt crystalises on the pond's floor.
Open pan production from brine
One of the traditional methods of salt production in more temperate climates is using open pans. In an open pan salt works brine is heated in large, shallow open pans. Earliest examples date back to prehistoric times and the pans were made of ceramics known as briquetage, or lead. Later examples were made from iron. This change coincided with a change from wood to coal for the purpose of heating the brine. Brine would be pumped into the pans, and concentrated by the heat of the fire burning underneath. As crystals of salt formed these would be raked out and more brine added.
Closed pan production under vacuum
The open pan salt works has effectively been replaced with a closed pan system where the brine solution is evaporated under a partial vacuum.
Salt mines
In the second half of the 19th century industrial mining and drilling techniques originally from China made the discovery of more and deeper deposits possible, mine salt. Although more expensive than solar evaporation of seawater and extracting solar salt from brine, the result of this was that the price of salt became more reasonable due to less monopolisation. Extraction of salt from brine is still heavily used: for example vacuum salt produced by British Salt in Middlewich has 57% of the UK market for salt used in cooking.
The above facts came from the following websites:
From Wikipedia, the free encyclopedia
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