The Torch Magazine

That Wondrous Product Salt

by

Anne Miller

    Why is salt exciting? A substance so ubiquitous could make a dull subject, but salt has a fascinating story. In this paper I will present a brief history of how salt has been produced and used for diverse purposes, including the preservation of food, the creation of wealth, influencing the outcome of wars and the quality of medical care.

        I first became interested in salt forty-five years ago during a family visit to a salt factory in Syracuse, New York, a city built over a vast salt bed. In the factory, brine was pumped up from underground, partially dried, and then treated by one of three different methods. Brine that cooled slowly in long troughs formed large salt crystals that were scraped from the bottom. Brine that was kept in motion in a large rotating open-ended barrel resulted in fine crystals that were sold in two-pound containers of table salt. (The workers discussed which store's label was to be put on the containers that day.) Salt for livestock, to which color-coded chemicals were added, was subjected to great pressure, producing larger, solid blocks of salt for the animals to lick.

    The processes I saw in the factory that day were the outcome of a long development, for the history of salt extends back thousands of years (Kurlanksky passim). Hunter-gatherers obtained enough sodium chloride from the meat they ate, but about 10,000 years ago, grains began to be cultivated as a supplemental source of food. Since grains contain mostly potassium chloride rather than the sodium chloride that our bodies require, an additional source of salt was needed. Domesticated animals, such as sheep and goats, also required sodium chloride in their diet.

        The earliest written mention of salt is a Chinese account from 800 BCE of a long tradition of making sea salt by evaporating ocean water in clay pots. In 250 BCE, an engineer named Li Bing developed a way to obtain a steady inland supply of salt from a brine spring. He reasoned that the brine bubbled up from underground, so he had a wide bore bamboo pipe driven deep into the ground. A narrower bore bamboo with a flexible closure at the end was inserted inside it to the level of the brine. When the smaller pipe was raised, the weight of the liquid would close the end of the pipe, so the brine could be raised to the surface. The brine was then boiled in iron pots to precipitate the salt. Salt was such a valuable product that Chinese emperors took over salt production. This monopoly meant they could hold down the cost of making salt but charge a high price for it, in effect creating a salt-tax. This tax was used on and off for many centuries by China to support wars and even to help build the Great Wall of China.

        Meat and fish rot quickly if there is no refrigeration, but salted foods last a long time because the salt draws liquid out of the flesh and kills any bacteria. There is evidence that Egyptians used salt obtained from the seawater in the Nile Delta to preserve meat and fish as early as 2000 BCE. They also used it during mummification. The eviscerated bodies of wealthy Egyptians were covered with a mixture of salts called natron to preserve the bodies, while there is some evidence that less affluent people were mummified using plain salt.

        Thick salt beds lie on the surface of some areas of the Sahara Desert. This salt was very hard and difficult to dig into but was desirable enough to become an important trade object. Salt is heavy and bulky to transport, so when camels became available they were used to transport the salt. The salt was molded into 200–pound cones, one of which was suspended from each side of a camel. Caravans of large numbers of camels traveled as far as 400 miles to Timbuktu, a major trading center on the Niger River, where the salt was so valuable it could be traded for gold.

    The Phoenicians traveled by ship throughout the Mediterranean, establishing cities at various locations. Trapani was established on the west coast of Sicily, where there is little rain. Along the coast south of the city, low earthen dikes were used to enclose flat beds. Salt water was introduced into these beds and the water was evaporated by the hot sun and dry winds. Some of the salt was traded, but it was more profitable to use the salt to preserve the blue-fin tuna that were caught in the area. The salted fish could then be shipped wherever the ship owners traded.

    The Romans were especially fond of salty foods and consumed much more salt than we do. They spread salt on greens, giving us the word "salad." Soldiers were sometimes paid in salt, giving us the word "salary." And one of the earliest Roman roads was the Via Salaria, built so that salt could be transported from near the port of Ostia to the capital Rome, and then on to the center of the country.

    The islands of Venice were settled by people trying to escape from invaders from the north. After the mainland became safe, the Venetians extended the mainland by filling the coast with soil and using this area to create salt ponds like those in Sicily. When these salt beds were ruined by a storm in the thirteenth century, instead of rebuilding them, the Venetians created a salt administration through which all salt brought into Venice had to go. Venice then sold this salt at a high price; that is, they used it as a salt-tax. A portion of the tax was returned as a subsidy to ship owners, who then sailed to the eastern end of the Mediterranean to buy expensive items, such as herbs and spices. Because of the subsidies, the captains could sell these products at prices that undercut their competitors, and some of the buildings we admire in Venice were paid for by their profits.

    The area around Parma is the only dairy region in Italy. For hundreds of years salt has been used there to preserve the milk products. Farmers bring the evening milking to the cheese factory, where it is spread in long troughs. The next morning, the cream is collected from the surface and used to make butter. (The butter is salted so it will keep longer than sweet butter.) Meanwhile the farmers bring in the morning milking, which is added to the skim milk in the trough. The mixture is heated slightly, and rennet is added to curdle the milk. A cheese-master determines when the curds are ready, and the mixture is then filtered. The whey that drains out is used to feed the pigs, thus contributing to the hams for which the region is famous. The curds are packed into ninety-pound molds, which are suspended in a brine solution. After three days the molds are removed, and the cheese is aged for up to two years until the salt has reached the center of the cheese and the Parmesan cheese is sent to market. The people of the region do almost everything one can do with milk—except drink it.

    The Breton coast of France has been a salt producing area for centuries. Traditionally, the salt makers used the same system as did the Phoenicians: flat beds of clay were surrounded by low earthen dikes, the enclosed areas were filled with sea water, and the water was evaporated using solar energy. Large crystals were raked from the bottom, and fine crystals collected from the surface (Sciolino). The Breton salt makers had been excused from the high French salt tax, but needed markets for their salt. One market was the production of French cheeses, of which there are as many as 265. Another market was the Norse, who could not produce salt by solar evaporation of seawater because they did not have a long, hot season. As early as 1000 AD, the Norse used Breton salt to preserve their herring. There was a large market for salt fish in Europe because the Catholic Church proscribed eating meat, but not fish, on Friday. This trade was so important that the Hanseatic League was formed during the thirteenth century to ensure the quality of the products, as well as to protect the ships from pirates. During the sixteenth to eighteenth centuries, salt cod largely replaced salt herring. A non-oily white fish that can be preserved by drying and salting, cod keeps well and tasted better than the salted fish from the Mediterranean.

    Access to salt played a role in both our Revolutionary and Civil Wars. The British created a salt monopoly in their North American colonies by controlling all the salt producing facilities and selling salt shipped from England to the colonists. During the Revolutionary War, individuals used small salt works to provide their needs. Such sources of salt could be found by following animal trails to a place where wild animals obtained their salt. Such a brine spring was called a salt lick, accounting for many of the town names in Kentucky, where these salt licks were abundant.

    The settlers' need for salt figures in one of the many anecdotes about the legendary Daniel Boone. In January, 1775, Boone took thirty men from the new town of Boonesborough to Lower Salt Lick, hoping to prepare enough salt for a year (Morgan 225-38). Preparing salt was one of the most dangerous activities on the frontier because of possible Indian attacks. The men worked all day, either collecting brine in iron pots, chopping down trees for wood, or tending the fires to boil off the water—about 500-600 gallons of water had to be evaporated to get each bushel of fifty pounds of salt. Meanwhile, Boone hunted for meat for the men to eat. Unfortunately, one day when Boone was on horseback pulling a kill behind him, he was discovered by two young Indians who were seeking revenge for the death of one of their chiefs. Boone tried to escape by untying the leather thong that attached the carcass to his saddle, but the knot was frozen. He then tried to cut the thong, but he had neglected to wipe his knife after cutting up the meat, and his knife was frozen in the sheath. He had no choice but to surrender and go with the Indians to the salt making area, which they already knew existed. The Boonesborough men were captured and led back to the Shawnee village ruled by Blackfish, a chief who admired Boone for his strength and hunting abilities. Boone convinced the chief that it would be wiser to attack Boonesborough when the weather was warmer by reasoning that many of the women and children would die if they were forced to travel during cold, snowy days. He reminded Blackfish that a prisoner could be sold to the British as a slave for $100, while a scalp was worth only $50. As a result, Boone and sixteen men were adopted into the tribe and ten were sold to the British in Detroit. Later, Boone escaped back to Boonesborough to help fortify the town. When the Indian attack took place, Boone saved the town by parleying with the Indians for long enough that the Indians finally left to find easier targets (Morgan 255-75).

    During the Civil War, the South suffered from a lack of salt for the men and their many horses and pack animals, as well as for curing leather. The salt areas on which the South depended were located in northern areas, especially in Kentucky and Virginia. The Union armies prevented access to these salt factories and destroyed the railroads used to transport the salt to the south. The South had also depended on salt imported from England, but after the Union ships blockaded the Southern ports, this source of salt was no longer available, hastening the defeat of the South.

    Another instance of the role of salt in American history is the fabled Erie Canal, built in 1825 so that the salt produced in Syracuse, New York, could be shipped by water all the way to the port of New York. The underground salt bed beneath Syracuse extends as far west as Detroit, where an extensive salt mine was developed. Rock salt is mined in the same way as coal: holes are drilled into the wall, dynamite sticks are inserted, and the chunks of salt are blown out. The mine under Detroit is 1200 feet deep, covers 1500 acres, and has 100 miles of road (Detroit Salt). This mine cannot be visited, but the active Strataca mine in Hutchinson, Kansas, provides tours for visitors (Strataca). A section of this mine, off limits to visitors, is used to store reels of Hollywood films because the mine is clean, dry and a constant temperature.

    Two companies in the United States, Cargill (Diamond Crystal) and Morton, control our contemporary salt production. The total amount produced per year is over forty million metric tons, larger than that of any other country in the world. Only about 8% is consumable, including our table salt. About 50% is used for de-icing roads here and in northern Europe.

    The salt we have in our kitchens usually contains additives. For instance, salt tends to cake in damp climates, but in the 1920s the Morton company found that caking can be prevented by adding a small amount of magnesium chloride to the salt, leading to Morton's slogan, "It never rains but it pours" (Morton Salt). Another change in the 1920s was the addition of iodine. The upper Midwest of the United States was once known as the "goiter belt" because individuals without sufficient iodine in their diet developed an unsightly and unhealthy enlarged thyroid, a goiter (Gladwell 78). In 1925, half the school children in the northern Michigan region bordering Lake Superior had a goiter. The government suggested that because salt was inexpensive and widely used, it would be an ideal medium for introducing iodine into the diet, which Morton did. In only a few years, goiters no longer developed in the school children (Tisdale 124-26).

    We are accustomed to cooking with fine white grains of salt, which are about 97% sodium chloride. Large grains, such as Kosher salt, are also used for cooking. Salt is available in various other colors, including red or pink (for example, Hawaiian coral, Himalayan and Bolivian), gray (such as ocean salts from the Breton and Camargue coasts of France) or black (Hawaiian black and alder smoked), each of which has a slightly different salty flavor. The colors are due to the incorporation of minerals or even dirt in the salt crystals; colored salts are not usually used for cooking, but rather are spread on already cooked food to enhance the food's appearance as well as flavor. Internet sources such as www.nothingbutsalt.com and www.saltworks.com describe various kinds of salt, such as sea salt, which contains only about 87% sodium chloride because it includes a variety of other minerals present in seawater.

    Most of the articles about salt in current newspapers and magazines are concerned with how much salt should be in one's diet (Kolata). The U.S. Department of Health and Human Services and the U.S. Department of Agriculture recommend an upper limit of 2300 milligrams per day (about a teaspoon), reduced to 1500 for older individuals. Although it is known that lowering salt intake can lead to lower blood pressure, there is no good experimental evidence for these amounts nor it is clear that reducing blood pressure would lead to less illness or longer life. A critical experiment would involve keeping a large number of individuals on a low salt diet for many years and another group on a high salt diet, in order to compare their rates of illness and death. This will probably never be feasible, among other reasons because the low salt diet is less palatable. There is even evidence from some smaller studies that those on a low salt diet die at a more rapid rate than those on a high salt diet. Therefore, the best advice is to consult your doctor—although he or she probably cannot be certain either.

    We might say that the advice one gets about salt should be taken, in the old Latin expression, cum grano salis—with a grain of salt.

Works Cited

Detroit Salt Company website. www.detroitsalt.com.

Gladwell, Malcolm. "Man and Superman." The New Yorker, September 9, 2013, 76-80.

Kolata, Gina. "No Benefit Seen in Sharp Limits on Salt in Diet," New York Times, May 15, 2013.

Kurlansky, Mark. Salt. A World History. New York: Penguin, 2002.

Morgan, Robert. Boone, A Biography. Chapel Hill, NC: Algonquin Books, 2007.

Morton Salt Company website. www.mortonsalt.com.
Sciolino, Elaine. "Magic Measured in a Pile of Salt." New York Times, August 27, 2012.

Strataca Kansas Underground Salt Museum website. www.underkansas.org.

Tisdale, Sarah. Lot's Wife. Salt and the Human Condition. New York: Henry Holt, 1988.

Author's Biography

Anne Miller received her BA from Wilson College, Chambersburg, PA (Magna cum laude in Chemistry) and her PhD from Yale University (in Biochemistry). After having three children, she turned her interest to genetics, studying the chromosomes of diverse species including human, mouse, gorilla and even prehensile tailed porcupine. She taught graduate students and carried out research at Columbia University, New York, NY and at Wayne State University in Detroit, MI. As Dorothy A. Miller she has published more than 100 papers in scientific journals.

Anne and her husband Jack retired in the 1990's and now live in northern Virginia. They are active members of the Blue Ridge Torch Club of Leesburg, Virginia. Their daily activities include a two mile walk (in non-freezing weather), relaxing with jigsaw puzzles, and taking part in conversations with neighbors. They enjoy seeing their seven grandchildren who are scattered across the country