The Wonder Book Of Knowledge Part 60

_Courtesy of the Railway Age Gazette and Standard Steel Car Co._]

The car consists of heavy steel plate structure, erected upon a flat car of standard type. The interior is divided into three compartments. The end compartments are for use of troops operating machine guns and rifles through the port-holes shown on side of car. The center compartment, which is not the full height of the car, is used for ammunition storage, and is capable of holding a large quant.i.ty of ammunition, either for small arms or for the rapid-fire gun which is mounted on top of the car.

The rapid-fire gun here shown is a model of a three-inch field gun mounted upon a special carriage. The well in which the gun is located may also be used as a fighting top for troops armed with rifles or machine guns.

[Ill.u.s.tration: THE FIRST OF A NEW TYPE OF ARMORED CARS[55]]

[Ill.u.s.tration: THE HEAVY STEEL PLATE STRUCTURE IS ERECTED UPON A FLAT CAR OF STANDARD TYPE[55]]

This car is known as a light-armored car. It is armed with a three-inch rapid-fire gun, two machine guns and any number of rifles which the troops occupying it may carry. The service for which this car is intended is primarily to guard railroads and depots adjacent to railroads. It is not ordinarily to be employed in aggressive movements.

In effect, it is a movable block-house which may be used at any point along the line, or it may be used as a retreat for troops when necessary. It may also be used for transporting troops past danger points, and for transporting explosives or other perishable material which might be damaged by fire from the ends. The car as constructed weighs 86,200 pounds. It is 47 feet long, 9 feet 3 inches wide, and 7 feet high at the ends. When used for transportation of troops, it will accommodate a company of infantry seated on camp stools or benches. When used for patrol purposes, there would not be more than twelve men in the car, to operate the rapid-fire gun and machine guns.

[Ill.u.s.tration: THE INTERIOR IS DIVIDED INTO THREE COMPARTMENTS

_Courtesy of the Railway Age Gazette and Standard Steel Car Co._]

The car was shipped to the Sandy Hook proving grounds to be equipped with rapid-fire guns and ammunition and thoroughly tested and inspected by the Engineer and Ordnance Officer of the U. S. Army.

What is an "Electric Eel"?

This is an eel abundant in the fresh waters of Brazil and the Guianas, which possesses organs capable of developing a strong electric current and thus of giving a violent shock to any one touching the eels. These organs replace the lower muscles along the sides of the tail. The eels can be taken by driving horses into the water to be shocked and seizing them when thus weakened.

The Story of Salt[56]

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

[Ill.u.s.tration: A SALT WELL]

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.

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.

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

[Ill.u.s.tration: SALT HEATERS AND FILTERS]

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.

[Ill.u.s.tration: _Photo by Brown Bros._

SALT BEDS NEAR SALT LAKE CITY

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.

[Ill.u.s.tration: BOLTERS FOR SIFTING SALT]

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.

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.

[Ill.u.s.tration: FILLING SALT PACKAGES]

[Ill.u.s.tration: FILLING SALT BAGS]

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.

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 coa.r.s.er 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.

Why do We Call it "Denatured Alcohol"?

Under a law pa.s.sed by the United States Congress in 1907, on alcohol intended for use as fuel or for illuminating purposes, or other mechanical employment, the internal tax need not be paid. But to avoid taxation it must be rendered unfit for drinking by the addition of such unpalatable substances as wood alcohol, pyridin, benzola, sulphuric ether or animal oil. Thus treated, it is spoken of as denatured.

What is the Difference Between a Cruiser and a Battleship?

A cruiser is a vessel built to secure speed and fuel capacity at the expense of armor and battery strength.

The modern cruiser may be regarded as the offspring of the frigate of the eighteenth and nineteenth centuries. The later construction has been designed for a minimum speed of twenty-five knots an hour, with a possible attainment of thirty knots or over, under favorable conditions.

The battleship and one form of cruiser were evolved from the conflicting opinions of two opposite schools of design. The battleship is the expression of the thoughts of those who stood for extremely developed battery power, great thickness of armor plate, and moderate speed. The cruiser is the result of the triumph of those who contended for high speed at the sacrifice of heavy armor protection and excessive battery strength.

The armored cruiser was the particular development of the antagonistic views prevailing among naval architects. The type of this cla.s.s in the United States navy was the "Brooklyn," which figured prominently in the war with Spain in 1898.

Recently the armored cruiser has been superseded by the battle cruiser.

The armor protection in this type of ship is much lower than that of the battleship, while the ordnance, on the other hand, is practically the same. High speed, wide radius of action and great battery strength are the characteristics of this type; and to meet these requirements the battle cruiser is planned of a size considerably larger than the battleship.

The protected cruiser is a later development of naval construction. Its distinguishing features are certain modifications in the distribution of the ma.s.s of protective armor of the ship.