The Arabs say, “There is salt between us,” and the Persians speak of a person “untrue to salt” (disloyal or ungrateful). Because of its preservative qualities, the word ‘salt’ came to have connotations of high esteem and honor both in ancient languages and in modern ones.
Some Historical Facts
Throughout history, salt has been such a precious commodity that wars were even fought over it. One of the contributing causes of the French Revolution was the high tax on salt imposed by Louis XVI. Salt was also used as a valuable medium of exchange. Moorish merchants traded salt for gold, gram for gram, and some central African tribes used slabs of rock salt as money. The English word `salary` comes from the Latin salarium (from sal, salt), referring to the early Roman soldier’s wages, part of which was an allowance of salt. The Greeks paid for slaves with salt, giving rise to the expression “not worth his salt.”
During the Middle Ages, certain superstitions developed around salt. The spilling of salt was considered to be a portent of doom. For example, in Leonardo da Vinci’s painting of the `Last Supper,` Judas Iscariot is depicted with an overturned saltcellar in front of him. Up until the 18th century, sitting above or below the position of the salt at a banquet table indicated one’s social rank, the honored position being above the saltcellar, near the head of the table.
From early times man learned to extract salt from natural brines, seawater, and rock salt. An ancient Chinese treatise on pharmacology deals with more than 40 kinds of salt and describes two methods of extracting salt that are amazingly similar to those used today. For instance, solar energy is used to extract salt from seawater at the solar saltworks located on the shores of the Bahía Sebastián Vizcaíno in Baja California Sur, Mexico.
According to the Encyclopædia Britannica it has been estimated that if all the oceans in the world were completely dried up, `they would yield at least 4.5 million cubic miles [19 million cubic km] of rock salt, or about 14.5 times the bulk of the entire continent of Europe above the high-water mark.` And the Dead Sea is about nine times as salty as the ocean!
Use of Salt Today
Today salt continues to be a precious commodity, used for seasoning food, preserving meat, and manufacturing soap and glass, among other things. Sales of dry salt jumped 37.2% in 2007 to 31.7 million tons, according to the annual Salt Institute Statistical Report of US Salt Sales released in February, 2008. Over 200M tons of salt is produced worldwide every year. North America produces more than one-quarter of it.
But a particularly interesting use is in the public health field. For example, in many countries of the world, salt is fortified with iodine to combat endemic iodine deficiency, characterized by goiter (an enlargement of the thyroid gland) and in severe cases by mental retardation. Also, some countries add fluoride to salt to prevent dental caries, though this practice has proved somewhat controversial, with some even suggesting it is detrimental to health.
In the chemical industry, salt is used in the manufacture of sodium bicarbonate (baking soda), sodium hydroxide (caustic soda), hydrochloric acid, chlorine, and many other chemicals. Salt is also employed in soap, glaze, and porcelain enamel manufacture and enters into metallurgical processes as a flux.
When applied to snow or ice, salt lowers the melting point of the mixture. Thus, large amounts are used in northern climates to help clear streets of accumulated snow and ice. Salt is used in water-softening equipment that removes calcium and magnesium compounds from water.
While salt is essential for good health-regulating blood volume and pressure-what about the association between salt intake and high blood pressure? Doctors have routinely restricted salt and sodium intake in hypertensive patients. About one third to one half of people with high blood pressure are salt sensitive. In this case a lower salt intake has been shown to lower blood pressure. The recommended daily limit for the normal person is 6g of salt.