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
mass, 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 masses, 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.
[Illustration: 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 luster 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 quantities 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 brass. The frames of opera glasses
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 coarse 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 shores 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.
[Illustration: 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 passes
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 scrapes the pipes clean.
The pipes go over hills and through swamps. They cross rivers
sometimes by means of bridges, and sometimes they are anchored 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 passes 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 pass 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 deg. F. and a burning point of not less than 125 deg. 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.