People often say that the latter half of the nineteenth century was the Age of Steel, because so many new uses for steel were found at that time. The twentieth century promises to be the Age of Electricity, and electricity must have copper. Formerly iron was used for telegraph wires; but it needs much more electricity to carry power or light or heat or a telegraphic message over an iron wire than one of copper. Moreover, iron will rust and will not stretch in storms like copper, and so needs renewing much oftener. Electric lighting and the telephone are everywhere, even on the summits of mountains and in mines a mile below the earth's surface. Electric power, if a waterfall furnishes the electricity, is the cheapest power known. The common blue vitriol is one form of copper, and to this we owe many of our electric conveniences. It is used in all wet batteries, and so it rings our doorbells for us. It also sprays our apple and peach trees, and is a very valuable article. Indeed, copper in all its forms, pure and alloyed, is one of our best and most helpful friends.

IX

THE NEW METAL, ALUMINUM

Not many years ago a college boy read about an interesting metal called "aluminum." It was as strong as iron, but weighed only one third as much, and moisture would not make it rust. It was made of a substance called "alumina," and a French chemist had declared that the clay banks were full of it; and yet it cost as much as silver. It had been used in France for jewelry and knicknacks, and a rattle of it had been presented to the baby son of the Emperor of France as a great rarity.

The college boy thought by day and dreamed by night of the metal that was everywhere, but that might as well be nowhere, so far as getting at it was concerned. At the age of twenty-one, the young man graduated, but even his new diploma could not keep his mind away from aluminum. He borrowed the college laboratory and set to work. For seven or eight months he tried mixing the metal with various substances to see if it would not dissolve. At length he tried a stone from Greenland called "cryolite," which had already been used for making a kind of porcelain. The name of this stone comes from two Greek words meaning "ice stone," and it is so called because it melts so easily. The young student melted it and found that it would dissolve alumina. Then he ran an electric current through the melted ma.s.s, and there was a deposit of aluminum. This young man, just out of college, had discovered a process that resulted in reducing the cost of aluminum from twelve dollars a pound to eighteen cents. Meanwhile a Frenchman of the same age had been working away by himself, and made the same discovery only two months later.

Aluminum is now made from a mineral called "bauxite," found chiefly in Georgia, Alabama, and Arkansas. Mining it is much more agreeable than coal mining, for the work is done aboveground. The bauxite is in beds or strata which often cover the hills like a blanket. First of all, the mine is "stripped,"--that is, the soil which covers the ore is removed,--and then the mining is done in great steps eight or ten feet high, if a hill is to be worked. There is some variety in mining bauxite, for it occurs in three forms. First, it may be a rock, which has to be blasted in order to loosen it. Second, it may be in the form of gray or red clay. Third, it occurs in round ma.s.ses, sometimes no larger than peas, and sometimes an inch in diameter. In this form it can easily be loosened with a pickaxe, and shoveled into cars to be carried to the mill. Bauxite is a rather mischievous mineral and sometimes acts as if it delighted in playing tricks upon managers of mines. The ore may not change in the least in its appearance, and yet it may suddenly have become much richer or much poorer. Therefore the superintendent has to give his ore a chemical test every little while to make sure that all things are going on well.

This bauxite is purified, and the result is a fine white powder, which is pure alumina, and consists of the metal aluminum and the gas oxygen. Cryolite is now melted by electricity. The white powder is put into it, and dissolves just as sugar dissolves in water. The electricity keeps on working, and now it separates the alumina into its two parts. The aluminum is a little heavier than the melted cryolite, and therefore it settles and may be drawn off at the bottom of the melting-pot.

There are a good many reasons why aluminum is useful. As has been said it is strong and light and does not rust in moisture. You can beat it into sheets as thin as gold leaf, and you can draw it into the finest wire. It is softer than silver, and it can be punched into almost any form. It is the most accommodating of metals. You can hammer it in the cold until it becomes as hard as soft iron. Then, if you need to have it soft again, it will become so by melting. It takes a fine polish and is not affected, as silver is, by the fumes which are thrown off by burning coal; and so keeps its color when silver would turn black.

Salt water does not hurt it in the least, and few of the acids affect it. Another good quality is that it conducts electricity excellently.

It is true that copper will do the same work with a smaller wire; but the aluminum is much lighter and so cheap that the larger wire of aluminum costs less than the smaller one of copper, and its use for this purpose is on the increase. It conducts heat as well as silver.

If you put one spoon of aluminum, one of silver, and one that is "plated" into a cup of hot water, the handles of the first two will almost burn your fingers before the third is at all uncomfortable to touch.

[Ill.u.s.tration: A "MOVIE" OF AN ALUMINUM FUNNEL

_Courtesy The Aluminum Cooking Utensil Company._

Seventeen other operations are necessary after the thirteenth stamping operation before the funnel is ready to be sold. And after all this work, we can buy it for 35 cents at any hardware store.]

Aluminum is found not only in clay and indeed in most rocks except sandstone and limestone, but also in several of the precious stones, in the yellow topaz, the blue sapphire and lapis-lazuli, and the red garnet and ruby. It might look down upon some of its metallic relatives, but it is friendly with them all, and perfectly willing to form alloys with most of them. A single ounce of it put into a ton of steel as the latter is being poured out will drive away the gases which often make little holes in castings. Mixed with copper it makes a beautiful bronze which has the yellow gleam of gold, but is hard to work. When a piece of jewelry looks like gold, but is sold at too low a price to be "real," it may be aluminum bronze, very pretty at first, but before long its l.u.s.ter will vanish. Aluminum bronze is not good for jewelry, but it is good for many uses, especially for bearings in machinery. Aluminum mixed with even a very little silver has the color and brightness of silver. The most common alloys with aluminum are zinc, copper, and manganese, but in such small quant.i.ties that they do not change its appearance.

With so many good qualities and so few bad ones, it is small wonder that aluminum is employed for more purposes than can be counted. A very few years ago it was only an interesting curiosity, but now it is one of the hardest-worked metals. Automobiles in particular owe a great deal to its help. When they first began to be common, in 1904-05, the engines were less powerful than they are now made, and aluminum was largely employed in order to lessen the weight. Before long it was in use for carburetors, bodies, gear-boxes, fenders, hoods, and many other parts of the machine. Makers of electric apparatus use aluminum instead of bra.s.s. The frames of opera gla.s.ses and of cameras are made of it. Travelers and soldiers and campers, people to whom every extra ounce of weight counts, are glad enough to have dishes of aluminum. The accommodating metal is even used for "wallpaper," and threads of it are combined with silk to give a specially brilliant effect on the stage. It can be made into a paint which will protect iron from rust; and will make woodwork partially fireproof.

Aluminum has been gladly employed by the manufacturers of all sorts of articles, but nowhere has its welcome been more cordial than in the kitchen. Any one who has ever lifted the heavy iron kettles which were in use not so very many years ago will realize what an improvement it is to have kettles made of aluminum. But aluminum has other advantages besides its lightness. If any food containing a weak acid, like vinegar and water, is put into a copper kettle, some of the copper dissolves and goes into the food; acid does not affect aluminum except to brighten it if it has been discolored by an alkali like soda. "Tin"

dishes, so called, are only iron with a coating of tin. The tin soon wears off, and the iron rusts; aluminum does not rust in moisture. A strong alkali will destroy it, but no alkali in common use in the kitchen is strong enough to do more harm than to change the color, and a weak acid will restore that. Enameled ware, especially if it is white, looks dainty and attractive; but the enamel is likely to chip off, and, too, if the dish "boils dry," the food in it and the dish itself are spoiled. Aluminum never chips, and it holds the heat in such a manner as to make all parts of the dish equally hot. Food, then, is not so likely to "burn down," but if it does, only the part that sticks will taste scorched; and no matter how many times a dish "boils dry," it will never break. If you make a dent in it, you can easily pound it back into shape again. It is said that an aluminum teakettle one sixteenth of an inch in diameter can be bent almost double before it will break.

Aluminum dishes are made in two ways. Sometimes they are cast, and sometimes they are drawn on a machine. If one is to be smaller at the top, as in the case of a coffeepot, it is drawn out into a cylinder, then put on a revolving spindle. As it whirls around, a tool is held against it wherever it is to be made smaller, and very soon the coffeepot is in shape. The spout is soldered on, but even the solder is made chiefly of aluminum.

Aluminum dishes may become battered and bruised, but they need never be thrown away. There is an old story of some enchanted slippers which brought misfortune to whoever owned them. The man who possessed them tried his best to get rid of the troublesome articles, but they always returned. So it is with an aluminum dish. Bend it, burn it, put acid into it, do what you will to get rid of it, but like the slippers it remains with you. Unlike them, however, it brings good fortune, because it saves time and trouble and patience and money.

A few years ago the motive power for most manufactures was steam.

Electricity is rapidly taking its place; and if aluminum was good for nothing else save to act as a conductor of electricity in its various applications, there would even then be a great future before it.

X

THE OIL IN OUR LAMPS

Probably the first man who went to a spring for a drink and found oil floating on the water was decidedly annoyed. He did not care in the least where the oil came from or what it was good for; he was thirsty, and it had spoiled his drink, and that was enough for him. We know now that oil comes chiefly from strata of coa.r.s.e sandstone, but we are not quite sure how it happened to be there. The sand which formed these strata was deposited by water ages and ages ago--we are certain of that. Another thing that we are certain of is that where the strata lie flat, there is no oil. Hot substances become smaller as they cool; and as the earth grew cooler, it became smaller. The crust of the earth wrinkled as the skin of an apple does when it dries. In the tops of these great sandstone wrinkles there is often gas; and below the gas is the place where oil is found. There is no use in looking for petroleum where the folds of the strata are very sharp, because in that case the strata crack and let the oil flow away. It is not in pools, but the porous stone holds it just as a sponge holds water. If you drop a little oil upon a stone even much less porous than sandstone, it will not be easy to wipe it off, because some of it will have sunk into the stone.

In many places the gas forces its way out, and is piped to carry to houses for light and heat. Not far above Niagara Falls there was a spring of gas which flowed for years. An iron pipe was put down, and when the gas was lighted, the flame shot up three or four feet. The gas came with such force that a handkerchief put over the end of the pipe would not burn, though the flame would blaze away above it. In the country of the fire worshipers, on the sh.o.r.es of the Caspian Sea, fires of natural gas have been burning for ages, kindled, perhaps, by lightning centuries ago. There is a vast supply of oil in this place; and indeed there is hardly a country that has not more or less of it.

In the United States the colonists soon learned that there was petroleum in what is now the State of New York; but New York was a long way from the Atlantic seaboard in those days, and they went on contentedly burning candles or sperm whale oil, or, a little later, a rather dangerous liquid which was known as "fluid." The Indians believed that the oil which appeared in the springs was a good medicine. They threw their blankets upon the water, and when these had become saturated with the oil, they wrung them out and sold the oil.

Those were the times when if a medicine only tasted and smelled bad enough, people never doubted that it would cure all their diseases, and they gladly bought the oil of the Indians.

When at last it became clear to the members of an enterprising company that oil for use in lamps could be made from petroleum, they secured some land in Pennsylvania that seemed promising and set to work to dig a well. But the more they dug, the more the loose dirt fell in upon them. Fortunately for the company, the superintendent had brains, and he thought out a way to get the better of the crumbling soil. He simply drove down an iron pipe to the sandstone which contained the oil, and set his borer at work within the pipe. One morning he found that the oil had gushed in nearly to the top of the well. He had "struck oil."

This was about ten years after the rush to California for gold, and now that this cheaper and quicker method of making a well had been invented, there was almost as much of a rush to Pennsylvania for oil.

With every penny that they could beg or borrow, people from the East hurried to the westward to buy or lease a piece of land in the hope of making their fortunes. A song of the day had for its refrain,--

"Stocks par, stocks up, Then on the wane; Everybody's troubled with Oil on the brain."

In the course of a year or two, the first "gusher" was discovered. The workmen had drilled down some four or five hundred feet and were working away peacefully, when a furious stream of oil burst forth which hurled the tools high up into the air. Hundreds of barrels gushed out every day, and soon other gushers were discovered. The most famous one in the world is at Lakeview, California. For months it produced fifty thousand barrels of oil a day, and threw it up three hundred and fifty feet into the air in a black column, spraying the country with oil for a mile around. The oil flowed away in a river, and for a time no one could plan any way to stop it or store it. At last, however, a mammoth tank was built around the well and made firm with stones and bags of earth. This was soon full of oil; and with all this vast weight of oil pressing down upon it, the stream could not rise more than a few feet above the surface. Just why oil should come out with such force, the geologists are not quite certain; but it is thought to result from a pressure of gas upon the sandstone containing it. The flow almost always becomes less and less, and after a time the most generous well has to be pumped.

[Ill.u.s.tration: A CALIFORNIA OIL FIELD

For scenery, one should not go to an oil field. Looks, smell, and oil alike are unpleasant, but every oil derrick covers a fortune and helps to make our machinery run smoothly.]

An "oil field" may extend over thousands of square miles; but within this field there are always "pools"; that is, certain smaller fields, where oil is found. When a man thinks there is oil in a certain spot, sometimes he buys the land if he is able; but oftener he gets permission of the owner to bore a well, agreeing to pay him a royalty; that is, a certain percentage of all the oil that is produced. When this has been arranged, he builds his derrick. This consists of four strong upright beams firmly held together by crossbeams. It stands directly over the place where the well is to be dug. It is from thirty to eighty feet in height, according to the depth at which it is hoped to find oil. There must also be an engine house to provide the power for drilling. An iron pipe eight or ten inches in diameter is driven down through the soil until it comes to rock. Now the regular drilling begins. At the top of the derrick is a pulley. Over the pulley pa.s.ses a stout rope to which the heavy drilling tools--the "string of tools,"

as they are called--are fastened. The drilling goes on day and night.

The drill makes the hole, and the sand pump sucks out the water and loose bits of stone. When the drill has gone to the bottom of the strata which carry water, the sides of the bore are cased to keep the water out; then the drilling continues, but now the drill makes its way into the oil-bearing sandstone.

There is nothing certain about the search for oil. In some places it is near the surface, in others it is perhaps three or four thousand feet down. The well may prove to be a gusher and pour out hundreds of thousands of gallons a day; or the oil may refuse to rise to the surface and have to be pumped out even at the first. Naturally, no one is prepared for a gusher, and millions of gallons have often flowed away before any arrangements could be made for storing the oil.

Sometimes a well that gives only a moderate flow can be made to yield generously by exploding a heavy charge of dynamite at the bottom, to break up the rock and, it is always hoped, to open some new oil-holding crevice that the drill has not reached.

Crude petroleum is a dark, disagreeable, bad-smelling liquid; and before it can be of much use, it must be refined. For several years it was carried in barrels from the oil fields to Pittsburgh by wagon and boat, a slow, expensive process, and generally unsatisfactory to all but the teamsters. Then came the railroads. They provided iron tanks in the shape of a cylinder fastened to freight cars, much like those employed to-day. There was only one difficulty about sending oil by rail, and that was that it still had to be hauled by team to the railroad, sometimes a number of miles. At length, some one said to himself, "Why cannot we simply run a pipe directly from the well to the railroad?" This was done. Pumping engines were put in a few miles apart, and the invention was a success in the eyes of all but the teamsters. In spite of their opposition, however, pipe-lines increased.

Before this it had been necessary to build the refineries as near the oil regions as possible in order to save the expense of carrying the oil; but now they could be built wherever it was most convenient.

To-day oil can be brought at a small expense from west of the Mississippi River to the Atlantic seaboard, refined, and distributed throughout that part of the country, or loaded into "tankers,"--that is, steamships containing strong tanks of steel,--and so taken across the ocean. The pipes are made of iron and are six or eight inches or more in diameter. In using them one difficulty was found which has been overcome in an ingenious fashion. Sometimes they become choked by the impurities of the oil and the flow is lessened. Then a "go-devil"

is put into them. This is shaped like a cartridge, is about three feet in length, composed of springs and plates of iron and so flexible that it can turn around a corner. It is so made that as it slips down the current of oil, it whirls around and in so doing its nose of sharp blades sc.r.a.pes the pipes clean.

The pipes go over hills and through swamps. They cross rivers sometimes by means of bridges, and sometimes they are anch.o.r.ed to the bed of the stream. If they have to go through a salt marsh, they are laid in concrete to preserve the iron. If these lines were suddenly destroyed and oil had to be carried in the old way, kerosene would become an expensive luxury.

Getting the oil out of the ground and carried to the refineries is not all of the business by any means. The early oils crusted on the lamp wicks, their smell was unendurable, and they were given to exploding.

Evidently, if oil was to be used for lighting, it must be improved, and the first step was to distil it. To distil anything means to boil it and collect the vapor. If you hold a piece of cold earthenware in the steam of a teakettle, water will collect on it. This is distilled water, and is purer than that in the kettle. Petroleum was at first distilled in a rough way; but now it is done with the utmost care and exactness. The crude oil is pumped into boilers holding six hundred barrels or more. The fires are started, and the oil soon begins to turn into vapor. This vapor pa.s.ses through coils of pipe or long, straight, parallel pipes. Cold water is pumped over these pipes, the vapor turns into a liquid again, and we have kerosene oil.

This is the outline of the process, but it is a small part of the actual work in all its details. Kerosene oil is only one of the many substances found in petroleum. Fortunately, some of these substances are light, like gasoline and benzine; some, like kerosene, are heavier; and paraffin and tar are heaviest of all. There are also gases, which pa.s.s off first and are saved to help keep the furnace going. Then come the others, one by one, according to their weight.

The stillman keeps close watch, and when the color and appearance of the distillate changes, he turns it off into another tank. This process is called "fractional distillation," and the various products are called "fractions." No two kinds of petroleum and no two oil wells are just alike, and it needs a skillful man to manage either.

Even after all this distillation, the kerosene still chars the wick somewhat--which prevents the wick from drawing up the oil properly--and it still has a disagreeable smell. To fit it for burning in lamps, it must be treated with sulphuric acid, which carries away some of the impurities, and then with caustic soda, which carries away others. Before it can be put on the market, it is examined to see whether it is of the proper color. Then come three important tests.

The first is to see that it is of the proper weight. If it is too heavy, it will not burn freely enough; if it is too light, then there is too much of the lighter oils in it for safety. The second test is the "flash test." The object of this is to see how hot the oil must be before it gives off a vapor which will burn. The third, the "burning test," is to discover how hot the oil must be before it will take fire and burn on the surface. Most civilized countries make definite laws forbidding the sale of kerosene oil that is not up to a standard of safety. Oil for use in lamps should have an open flash test of at least 100 F. and a burning point of not less than 125 F.

We say that we burn oil in our lamps, but what we really do is to heat the oil until it gives off gas, and then we burn the gas. To keep the flame regular and help on the burning, we use a chimney on the lamp.

The hot air rises in the chimney and the cold air underneath rushes in to take its place and brings oxygen to the flame. In a close, stuffy room no lamp will give a good clear light, because there is not oxygen enough for its flame. Let in fresh air, and the light will be brighter. If you hold a cold plate in the flame before the chimney is put on, soot or carbon will be deposited. A lamp gives light because these particles of carbon become so hot that they glow. In lamps using a "mantle," there is the glow not only of these particles, but also of the mantle. In a wax candle, we light the wick, its heat melts the wax and carries it to the flame. When the wax is made hot enough, it becomes gas, and we burn the gas, not the wax. Wax alone will melt, but not take fire even if a burning match is held to it. The reason is that the match does not give heat enough to turn the wax into gas. But put a bit of wax upon a bed of burning coals, where there is a good supply of heat, and it will turn into gas and burn.

The products made from petroleum are as different in their character and uses as paraffin and naphtha. Some of them are used for oiling machinery; tar is used for dyes; naphtha dissolves resin to use in varnish; benzine is the great cleanser of clothes, printers' types, and almost everything else; gasoline runs automobiles, motors, and many sorts of engines; paraffin makes candles, seals jelly gla.s.ses, covers the heads of matches so that they are no longer spoiled by being wet, and makes the ever-useful "waxed paper"; printers' ink and waterproof roofing-paper both owe a debt to petroleum. Even in medicine, though a little petroleum is no longer looked upon as a cure-all, vaseline, one of its products, is of great value. It can be mixed with drugs without changing their character, and it does not become rancid. For these reasons, salves and other ointments can be mixed with it and preserved for years.