Salt is a chemical compound composed of two elements, sodium and chlorine. Chemically it is known as sodium chloride.

It is one of the things which comes into our lives daily, perhaps more than any other, with the exception of water. Probably no other thing than water is used more by all civilized people than salt.

A Salt Well.

Nature provides salt for us in three different forms. First, in sea water in solution; second, in salt springs; and third, in the form of salt rock.

From time immemorial man has obtained salt from sea water. This is still being done on our sea coasts, but the salt obtained by evaporating the water is very crude and usually contains many impurities.

It has been possible to obtain a large supply of salt from what are known as salt springs. These springs are usually the result of water flowing over a deposit of salt rock. The amount of salt obtained from evaporating this spring water is, however, so small that salt springs are an impractical source of supply when it comes to making salt for commercial purposes.

* Illustrations by courtesy of Diamond Crystal Salt Co.

Rock salt forms the most common and practical source of supply. It is found in all parts of the world and reasonably near the surface. The deposit is said to be what is left of ancient salt seas. In the United States the largest deposits of salt are found in the states of Michigan, New York, Ohio, Utah, Louisiana, Kansas,

Salt Heaters and Filters.

Texas and California. The above-mentioned states are the largest producers of salt in this country.

One of the largest sources of salt supply in Europe is at Wielizka in Poland. This deposit of salt is said to be the largest in the world, the bed of salt rock being 500 miles long, 20 miles wide and 1,200 feet thick. Some of the salt mines in Poland are so extensive that it is said some of the miners spend all of their lives in them, never coming to the surface of the earth.

Most of the deposits of salt rock contain impurities which need to be removed before the salt is fit for use commercially; however, some deposits show a very pure salt rock and when ground up this rock salt is suitable for table use. In general, however, the salt made from crude salt rock is only fit for the crudest commercial uses. The most common impurity is gypsum and it is necessary to remove this gypsum before the salt can be considered pure.

Photo by Brown Bros. SALT BEDS NEAR SALT LAKE ClTY.

These extensive salt beds about eighteen miles from Salt Lake City are part of the deposit left when Lake Bonneville dwindled to Great Salt Lake.

The general way of obtaining salt from the earth is by means of salt wells. These wells are drilled in the same way that wells are bored for oil and gas. A pipe about six inches in diameter is lowered to the surface of the salt rock and then an inside pipe is put down, water is forced down between the two pipes and the pressure exerted brings up the dissolved rock or salt brine through the inside pipe.

As the salt brine reaches the surface the salt is extracted from it in various ways. At present the crude open-pan system, where the brine was poured into open pans and fires were built below the pans, is almost obsolete. The most practical methods of refining salt today are known as the Grainer, Vacuum Pan and Alberger systems.

The Grainer system is similar in its operation to the old open-pan system. The brine is run through long, shallow tanks and the heat is applied through steam pipes inside of the pan. The salt settles to the bottom of the pan and large rakes operated either by hand or machinery collect the salt.

Bolters for Sifting Salt.

In the Vacuum Pan process tiny cubes of salt are formed and settle to the bottom of the pan in which a vacuum has been created. The salt is then drained out and is ready for drying.

Variations of the two above processes make possible the production of certain grades of table salt. Oftentimes the brine is relieved of impurities through the action of certain chemicals. In some instances a chemical known as "barium chloride" is used, but the wisdom of this process has been much questioned, owing to the fact that barium chloride is a deadly poison.

The Alberger system of salt manufacture is a mechanical process which subjects the salt brine to a much higher temperature and removes the impurities by means of mechanical filters. This process is known to make a very pure salt and has been used for some time as a practical method for manufacturing high-grade dairy and table salt. Unlike the other two common methods of making salt, it forms tiny salt flakes instead of the usual cubes or lumps.

Filling Salt Packages.

Filling Salt Bags.

After manufacturers obtain the salt from the brine they usually put it through drying processes. After drying, the salt is sifted and the fine table salt is separated from the coarser products. When salt is sifted it is ready for packing in bags or packages suitable for shipment to the consumer.

According to recent government reports, it is estimated that the average consumption of salt per capita for all purposes is about 100 pounds per year. The salt industry is now said to have reached a very stable basis and the demand for salt in the United States is practically all supplied by American manufacturers. Salt can be put to a great many uses in addition to the usual requirements for table and cooking. It is used by food manufacturers and performs highly important functions in certain commercial fields.