6 Every year more than 220 million tonnes of salt are produced worldwide. Salt is not just essential to human life. It is also one of the most important raw materials for the global chemical industry where it’s used in manufacturing everything from glass, soap and cosmetics to PVC and fertilizer.
ater, water, everywhere, nor any drop to drink,” lamented the Ancient Mariner in Coleridge’s famous poem. He was describing the frustration of many a sailor who has run out of drinking water while at sea. It’s one of nature’s great paradoxes that the human body needs water and salt to survive yet cannot stomach sea water. This is because the concentration of salt in sea water is too high for the kidneys to process. To get rid of the surplus salt the body would need to expel more water than it swallowed. The resulting dehydration could cause permanent damage and even death. So what is the right amount of salt? The European Salt Producers Association states that an adult body contains up to 250 grams of salt. Cells depend on both the sodium and chloride ions in salt to perform a variety of essential functions. Sodium helps to generate and transmit the electrical impulses in nerves and muscles while chloride is fundamental to digestion. Although a healthy body can process the amount of salt it needs, doctors usually recommend that people with high blood pressure or kidney disease reduce their salt intake. Salt centers Throughout history, because man needs salt to survive, settlements grew up around sites where this precious mineral could be found. For example, Alexander the Great (356-323 BC) controlled rock salt mines in today’s Pakistan, from where he supplied his empire. Uses were soon found beyond the kitchen. Salt became a vital part of tanning, dyeing and bleaching processes and, as chemical knowledge grew, its uses expanded to glazing pottery, soap-making and the early manufacture of chlorine. The Romans recovered salt from the sea at Ostia, near Rome. They gave their soldiers salt rations – known as salarium argentum – which is where the word ‘salary’ originates. Before the advent of modern chemical cleaners, salt was a staple household cleaning agent. For example, mixed with flour and vinegar, it makes a great brass cleaner. Also, when combined with lemon juice, it’s an effective remover of mildew and rust stains. Because salt is so essential, it was often transported thousands of miles and people regularly fought wars over salt sources. People had discovered early on that, as well as making foods taste better, salt was an excellent preservative. Salting, or curing, meat reduces the water content upon which food-rotting micro organisms depend. There are health and beauty applications, too. For instance, gargling with warm salt water can relieve a sore throat while a mixture of salt and olive oil makes a stimulating facial. 14,000 uses for salt According to the UK Salt Manufacturers Association salt “was the catalyst that inspired what has now evolved into today’s chemical industry”. Today there are around 14,000 uses for salt, from food manufacturing to de-icing roads. SEASONED PERFORMANCE The Japanese used to sprinkle salt on their theatre stages to prevent evil spirits from casting spells on the actors. FRESH MILK Adding a pinch of salt to milk keeps it fresh for longer. In the last 100 years the world’s annual commercial salt production has increased from ten to over 220 million tonnes more than 90 per cent of which is used in industry. Sodium, chlorine and sodium hydroxide are some of the most important basic materials recovered from salt for chemical processes. Chlorine is the base for one of the chemical industry’s most valuable products – polyvinyl chloride (PVC), a versatile material with a seemingly endless number of uses in construction, plumbing, clothing and for blood transfusion bags, to name but a few. FATAL DEFICIENCY Thousands of Napoleon’s troops died during the retreat from Moscow because they suffered from salt deficiency which meant their wounds could not heal. OLD CURRENCY The ancient Greek practice of trading salt for slaves gave rise to the expression, “not worth his salt”. WOOD STAIN A thin paste of salad oil and salt will remove white rings left on wooden surfaces by hot dishes or glasses. Rub the solution into the stain and leave for an hour before wiping off. The importance of salt to modern life cannot be overstated. If anyone were to question this view you would, naturally, to quote the well-known phrase, “take it with a pinch of salt.” GENERATE MAGAZINE ISSUE 08 7
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