SALT. Common salt is simply chloride of sodium—a compound containing about 35 parts of chlorine and 23 of sodium. It is obtained principally in three ways—by evaporation of the brine from brine wells or springs, from salt mines and by evaporation of sea water.
The greater part of the salt used in the United States to day is obtained from domestic brine wells or springs. The chief producing states are New York, Michigan, Ohio and Kansas.
There is still some salt imported, but it consists almost en tirely of a few fancy table varieties.
Brine wells are of two kinds—the natural brine springs (natural springs flowing through salt deposits) and the springs or wells made by man to change the salt deposits to brine, to be pumped out, instead of digging out the salt itself. The latter are the more numerous and the more important commercially. The method is more economical than mining when the deposits lie at a considerable depth below the surface of the ground.
In operation, the well is dug to the necessary depth and water is forced through pipes into the salt beds. In deep beds, the general method is to use a 3-inch pipe inside a 6-inch pipe, the 3-inch pipe going to the bottom of the salt layer and the 6-inch pipe stopping at its upper surface. The fresh water is pumped down the small pipe and dissolves the salt with which it comes in contact, being pumped back as brine through the large pipe.
The brine, in the up-to-date plant, passes through a succession of heaters, each with higher temperature, the last at about 280° Fahr. In this process, the lime, found in all brines, and other impurities are precipitated. It is next filtered and finally passes into the evaporator, where the water passes off and the salt forms. The first quick evaporation produces the fine Table Salt. The second, slower evaporation, produces the thin salt flakes known as Dairy Salt, for butter, cheese, meat curing, etc.
The product is finally dried, sifted and separated into various grades and packed in boxes, bags and barrels.
Solar Salt is produced by sun-evaporation. In manufacture from the Onondaga salines of New York State, the brine is placed in vats to which lime is added to precipi tate the magnesia, and thence it flows into wooden trays, where it is slowly evaporated by the sun's rays, forming into large cubic-shaped crystals. There is always a demand for this salt at good prices for large packers.
Rock Salt is ground in crushers and sifted and refined to the numerous grades found on the market.
The water of the ocean contains on an average nearly 3% of salt by weight. The Mediterranean Sea contains a higher percentage, and the Dead Sea is famous for its still larger proportion, the water being so dense as to render it impossible for a person to sink in its depth.
Salt is the one item of food which every nation and every race demands—and has apparently always demanded. Savage races have lived without it, but wherever it has been obtainable, even at great expense and much trouble, human beings have sought and fought for it. The New York Indians obtained salt at Onondaga long before the settlers commenced its manufacture, and the Indians of the West from the vicinity of the Arkansas River.
There is good scientific reason for its popularity—the sodium it contains forms part•of the soda which is needed in the bile to digest food, and the chlorine fur nishes a necessary acid gastric fluid. It is less important where raw meat is an article of diet, as raw meat itself contains salt, but it is essential where vegetables and vegetable products constitute a con siderable proportion of the food con sumed.
Salt is frequently mentioned in the Bible—the expression "Ye are the salt of the earth" is familiar to all readers. Its history is indeed practically that of civili zation. It was the chief commodity of the early caravans, at that time being a very valuable article, and a street in Rome was named the Salarian Way because the salt dealers dwelt there.