Sunday, February 21, 2010

Salt: The good, the bad, and the tasty

To the layperson, salt seems to be a very contrary compound. On the table, it has always seemed monochromatic, but an aerial photograph (1st image) reveals its vibrance in evaporation ponds. On the streets it is spread to melt snow, but it can also be used to superchill beverages.

Salt has been used to appease the palate for millenia. But it is only recently that the modern palate has been treated to prehistoric salt. Sur la table offers slabs of pink Himalayan salt (2nd image) handcut from ancient mineral deposits and used to grill, fry, bake, chill, or serve food. Ingestion of some salt is necessary, and the iodine deficiency that results from the lack of it is responsible for reduced mental capacity, goiter, and other problems. But eating more than the recommended daily allowance can lead to health complications, something several U.K. councils have tried to forestall by taking the controversial step of introducing salt shakers with fewer holes.

Salt can in fact actively kill you or your unborn child. Injecting a saline solution into the uterus is a means - rarely used today - of ending a pregnancy. And hypernatremia - having more salt in the bloodstream than the body can process - is an electrolyte imbalance that can cause death. Salt poisoning can result from drinking seawater, perspiring or urinating excessively, or eating large amounts of salt - as has occurred with people suffering from pica. It would also seem to be a potential problem of people with sleep-related eating disorder, who have been known to munch on salt sandwiches.

But salt can also cure you or the meat you eat. Between 1993 and 2005, several "salt mummies" were found in Iran. The bodies of 6 men dating to roughly 2,000 years ago were well-preserved in a functioning salt mine, with hair, clothing, and stomach contents surviving intact. It was the salt natron that the ancient Egyptians used to preserve their dead, a method replicated by New York schoolchildren mummifying chickens with table salt.

Salt sometimes features in newsworthy events, such as when its use in de-icing the streets causes underground transformers to explode. It's occasionally mentioned in the weird news, for instance when a vendor decided to offer an alternative to kosher salt and began offering "Christian salt." Or when a man from India attributes his survival of hundreds of snakebites to never eating salt. And salt is often the subject of science news. The world's oldest DNA was discovered in an ancient salt deposit in Michigan. Researchers in New Mexico have found signs of ancient life in salty halite crystals. Climate scientists from Maine are using the saltiness of Antarctic ice samples to determine which way the wind was blowing 700 years ago. And German scientists have theorized that the salt in the earth's crust "cooked" the chemicals necessary to form the prebiotic molecules that led to life on earth.

And still it is of two minds. In piles salt will not necessarily hold its shape, except when used on a chladni plate to demonstrate sound waves, but formed into bricks - as is done in the salt desert of southwestern Bolivia - it can be used to construct buildings (3rd image). Salt water is being used in Washington to combat an invasive species of snail, but is being worked around by Australian biologists who are working to develop salt-tolerant crops. Salt is not the complement of pepper, it appears, but the complement of itself.

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