Sodom was an ancient city of organized cruelty. Its laws were meant to rob and kill indigent strangers who might wander into their midst. Any resident of Sodom caught giving a stranger food or shelter could be tortured to death in public.
For this heartless cruelty the psalmist wrote “[G-d turns] a fruitful land into barrenness, because of the wickedness of its inhabitants.”[1] And so Sodom was destroyed. The ground cracked open beneath it and the city fell amid fire and brimstone. The Dead Sea, a salt lake, now covers the place where many believe Sodom once stood. There is so much salt in the water that the water cannot hold it all. Hard, sharp salt crystals coat the lake’s shoreline and bottom, making it unsafe to wade in without shoes.
How did the Dead Sea become so salty? Not only is it in a desert valley, but it’s at the lowest elevation on earth. The water’s surface is 423 meters (1,388 feet) below sea level. Several rivers, the largest of which is the Jordan, flow into it. These tributary rivers carry small amounts of salt and other minerals dissolved from the soil and rocks of higher lands that they pass through. But water can’t flow uphill. Therefore the Dead Sea loses water only through evaporation, leaving the solid minerals behind. Little by little, year after year, it grows saltier.
Every hundred pounds of ocean water contains about three and a half pounds of dissolved solids. Dead Sea water is eight times saltier. One hundred pounds of its water contains about twenty-four pounds of dissolved solids.[2] Almost all of the salt in ocean water is edible sodium chloride. Dead Sea water, however, has a very different make-up. Besides sodium chloride, it’s full of bitter and poisonous compounds of calcium, magnesium and potassium, sulfur, bromine and iodine. A mouthful of Dead Sea water swallowed by a careless swimmer can damage throat and nerves. It’s been known to cause loss of consciousness and even death![3]
Actually most of these salty toxins are also present in ordinary sea water, but in much smaller quantities. A mouthful of typical sea water might make you sick, but probably wouldn’t kill you. In fact, much of the commercial salt we use on our tables came originally from the sea. How is the bad stuff removed? Here’s a traditional way, still used in some modern saltworks:[4]
From Sea Salt to Table Salt
Near to the ocean, two areas wide enough to be seen from low space orbit are dug flat and then lined with clay or plastic sheeting. They will become “evaporation ponds.” One pond is close to the ocean. The other may be a small distance away, at a slightly lower elevation than the first. Pipes that can be opened or closed through valves separate the ponds from each other. The process starts with the pipes sealed off. Pumps move water into the pond closest to the ocean. Here, heated by the sun, the water starts to evaporate. With less water to move around in, the dissolved salts become crowded; their concentrations increase and the water becomes saltier. Soon, calcium carbonate, which needs the most water to stay dissolved, precipitates (“undissolves”). It forms solid crystals, which sink to the bottom of the pond.
Evaporation continues until the sodium chloride concentration has reached about 26% (26 grams per 100 grams of seawater). Then workers open the pipe between the ponds, letting the very salty water fill the second pond. Here the water evaporates further. Finally, when the amount of water shrinks to where sodium chloride now makes up about 36%, the desired sodium chloride (table salt) begins to precipitate. It deposits on the bottom and sides of the second evaporation pond. The bitter magnesium salts remain dissolved. Workers now enter the second pond with scoops and trucks to collect the sodium chloride crystals. The product is washed clean with in saturated solution of sodium chloride, dried, crushed to size, and packaged for you to buy at your nearest grocery store.
Relative solubility
For thousands of years, people have harvested salt this way. Modern chemists have a name for the method: fractional crystallization. It is based on the fact that substances differ in solubility. That is, they differ in how much of them a given amount of water can dissolve. For example, 100 grams of water can dissolve only 1.3 thousandths of a gram of calcium carbonate. But the same amount of water can dissolve about 36 grams of sodium chloride and 55 grams of magnesium chloride.[5] That’s why the calcium carbonate was the first to come out of solution as crystals and the magnesium chloride remained dissolved.
Fractional crystallization used this way accomplishes a process called birur in Jewish thought. Birur consists of selecting something desirable from a mixture that also contains undesirable items, then rejecting the latter. Which would you rather sprinkle on your chips: ocean water or pure table salt? The physical act of separating pure, edible sodium chloride from seawater improves upon raw nature. It’s an example of a physical act having spiritual consequences, the kind called, in Jewish thought, tikun olam, improving or repairing the world.
Salt of Sodom in Tradition
Even in its unrefined, bitter state, Salt of Sodom found uses in Jewish tradition. The Mishna lists Salt of Sodom as an ingredient in the incense used in the Temple service.[6] Perhaps it’s included because even the sinners among Jews must be included for the collective of Jewish souls to be complete. (However, the great medieval commentator Rabbi Shlomo ben Yitzhak (Rashi) notes, regarding the incense, that any fine-grained salt might be called“Salt of Sodom” .[7] He explains in Gemora Menachos that the Dead Sea splashes water up onto its banks, where it then evaporates, leaving a very fine grained solid.)
Bitter foods like coffee or beer, sharp foods like hot chili peppers, all kinds of foods that some people avoid, others consider delicious. Salt of Sodom also may have been used as a pungent seasoning with meals. At any rate, the fate of Sodom inspired the custom—still followed by some Jews today—of rinsing one’s fingers with water after a meal and reciting the words “This is the portion of the evildoer from G-d, and his inheritance, says the Almighty.”[8]
Tradition states that allowing Salt of Sodom to touch one’s eyes can make one blind. Actually any salt touching one’s eyes can cause pain and injury. However, the Salt of Sodom is singled out for warning because the people of Sodom were “blind” to the needs of their fellow human beings.
[1] Psalms 107:35
[2] J. Floor Anthoni, in www.seafriends.org.nz/oceano/seawater.htm
[3] Porath, A. et al. Dead Sea water poisoning. Annals of Emergency Medicine 1989 Feb.18(2) 187-91. Abstract viewed online May 29, 2018.
[4] www.saltinstitute.org/salt-101/production-industry, retrieved July 10, 2018.
[5] John A. Dean, Lang’s Handbook of Chemistry, 14th edition, McGraw Hill, New York 1992, Table 3,2.
[6] Talmud Bavli, Kereisos 6a
[7] Maharshal to Beitzah 39a, cited in a note to Gemora Menachos 21a, Talmud Bavli, Tractate Menahos vol 58 of the Artscroll series, Schottenstein Edition, Mesorah Publications, 2nd edition, 2002, note 25 to p. 21a.
[8] Siddur “Tehillat Hashem,” Nusach HaAri, Seder Birkat Hamazon