The yearly output of the anthracite mines is upward of fifty-five million long tons a year, or somewhat less than five million tons per month. In winter the rate of consumption is somewhat greater than that of production. A shortage in the summer production is therefore apt to be keenly felt in the winter. Before shipment to the market the coal is crushed at the breakers, sorted in different sizes, and washed.

Most of the anthracite coal-mines are owned by the railway companies centring at New York and Philadelphia, or else are operated by companies controlled by the railways. About one-fourth of the output is produced by independent operators who, as a rule, sell their coal to the railway companies. The Reading, Pennsylvania, Central of New Jersey, Lackawanna, Lehigh Valley, Ontario & Western, Erie, and Delaware & Hudson are popularly known as "coalers" because the larger part of their eastern business consists in carrying anthracite coal.

[Ill.u.s.tration: A VIEW OF THREE COLLIERIES IN THE ANTHRACITE COAL BASIN NEAR MAHANOY CITY, PA.]

Formerly much of the coal was shipped by ca.n.a.ls, but the latter were not able to compete with the railways, and most of the coal-ca.n.a.ls have been abandoned. The price of anthracite at tide-water (New York) varies from $3.20 to $4.50 per long ton. At Philadelphia the price is about one-fourth less. Buffalo is the chief lake-port for anthracite. Steam sizes are about two-thirds the price of house fuel.

[Ill.u.s.tration: COAL FIELDS IN UNITED STATES]

Bituminous, or soft coal furnishes the larger part of the house fuel in the United States, and nearly all the house coal used in other parts of the world. It contains from fifteen to more than forty per cent. of volatile matter, burning with a long and smoky flame. The coal which contains twenty per cent. or less of volatile matter is a free-burning coal that may develop heat enough to partly fuse the ash, forming "clinkers"; it is therefore called "caking" coal, and is not only well adapted for use as fuel and steam-making, but it is also a good smelting coal.

Coal which contains more than thirty per cent. of volatile matter is known as "fat" coal and is generally used in the manufacture of c.o.ke and illuminating gas. Western Pennsylvania produces the largest amount of fat coal, but it is found here and there in nearly all soft-coal regions. A so-called smokeless bituminous coal occurs in various localities; its low percentage of volatile matter makes it an excellent house fuel.

Bituminous coal is mined in twenty-five States of the Union, Pennsylvania, Illinois, West Virginia, and Ohio heading the list. In about half the mines the coal is cut from the seam by means of machinery and is known as machine-mined coal. A very large part of the product is consumed within a short distance of the mines, and this is especially true of the region about the upper Ohio River.

[Ill.u.s.tration: COAL PRODUCTION]

Most of the product is shipped to the large manufacturing cities of the middle west, where it is used for steam as well as fuel; a very large amount also is sent down the Ohio in barges to the lower Mississippi River. The spot value of bituminous coal varies from $0.80 to $1.60 per ton; the product of the Pacific coast mines, however, is from $3 to $5.

The output of the mines of the United States aggregates about two hundred and forty million long tons yearly, and this is about one-third of the world's product. For many years there has been an export trade to Canada, the West Indies, Central and South America, amounting in 1900 to 8,000,000 tons. Within a few years, however, the decreased cost of mining due to machinery, and the low rates of transportation to the seaboard has developed an export trade to Russia, Germany, and France.

[Ill.u.s.tration: COAL]

A small amount of coal is imported into the United States. A superior quality of Australian coal finds a ready market in Pacific coast points as far north as San Francisco, and large quant.i.ties of Nanaimo, B.C., coal are sold in Oregon, Washington, and California. A small quant.i.ty of the "slack" or waste of the Nova Scotia mines is imported to Boston to be made into c.o.ke. The Canadian fields supply a considerable part of the coal used in Montana.

=c.o.ke and Coal-Tar Products.=--In the manufacture of iron and steel a fuel having a high percentage of carbon free from volatile matter is essential. The great cost of wood charcoal forbids its use, and so a charcoal made from soft coal is used. Fat coal is heated in closed chambers until the volatile matter is driven off. The product is "c.o.ke"; the closed chamber is an "oven." The ovens are built of stone or fire-brick, in a long row. They are usually on an abrupt slope, so that the coal can be dumped into the top, while the c.o.ke can be withdrawn from the bottom, to be loaded into cars.

About three thousand one hundred and forty pounds of coal are required to make a short ton of c.o.ke; from three thousand to five thousand cubic feet of illuminating gas, together with varying amounts of coal-tar and ammonia, are driven off and generally wasted. In a few instances "scientific" ovens are in use for the purpose of saving these products; but in the coal-mining regions such devices are the exception and not the rule. The great waste of energy-products in the manufacture of c.o.ke is partly offset by the employment of refuse and slack, which could not be otherwise used.

There are more than five hundred and eighteen thousand c.o.ke-ovens in the United States, of which eighty per cent. are in use. Most of them are in the region about the upper Ohio River, and nearly half the total number is in the vicinity of Connellsville. The region around Birmingham, Ala., ranks next in number. The c.o.ke product of the United States is more than twenty million short tons a year. This is considerably less than the product of Great Britain, which is upward of twenty-five million tons.

Most of the "scientific" ovens are near or in large cities where the gas, after purification, is used for illuminating purposes. In some instances the c.o.ke, and not the gas, is a by-product. The coal-tar is used in part for fuel, but a portion of it goes to the chemical laboratory, where it is made to yield ammonia, benzine, carbolic acid, and aniline dyes to the value of nearly seven million dollars.

=Graphite.=--Graphite, plumbago, or "black lead," as it is popularly named, is found in many parts of the United States, but only a few localities produce a good commercial article; these are Ticonderoga, N.Y., which yields from six hundred to two thousand tons a year, and Chester County, Pa., which yields a small but increasing amount; a good quality is mined near Ottawa, Canada. It is extensively mined in Ceylon, and this island produces the chief bulk of the world's ordinary product.

The finest grade comes from the Alibert mine in Siberia. A good article is manufactured artificially at Niagara Falls.

Graphite is used as a stove polish and for crucibles; in the main, however, it is employed in the manufacture of lead[41] pencils; for this purpose only a very soft mineral, absolutely free from grit, is employed, and the Siberian output is used almost wholly. One German firm and two American firms supply most of the pencils used.

=Petroleum.=--Petroleum is the name given to a natural liquid mineral from which the well-known illuminating oil "kerosene" is derived, and to obtain which it is mined. Petroleum is a mixture of various compounds known as hydrocarbons. Some of these compounds are gaseous, some are liquid, and some are solid; all of them are articles of commercial value. The petroleum from different localities differs greatly in appearance and composition.

The pitch that coated Noah's ark, the slime of the builders of the Tower of Babel, and the slime-pits of the Vale of Siddim all refer to mineral products a.s.sociated with petroleum. Under the name of "naphtha" it has been known in Persia for thirty centuries, and for more than half as long a flowing oil spring has existed in the Ionian Islands. The Seneca Indians knew of a petroleum spring near the village of Cuba, N.Y., and used it as a medicine long before the advent of the white man.

As early as 1850 illuminating oil, known as "coal" oil, was made in the United States by distilling cannel coal, but this product was supplanted within a few years by the natural petroleum discovered in Pennsylvania.

In 1859 Colonel Drake completed a well bored in solid rock near t.i.tusville, Pa. The venture proved successful, and in a few years petroleum mining became one of the great industries of the United States.

Petroleum is known to exist in a great many parts of the world; the United States and Russia, however, produce practically all the commercial product; a very small amount is obtained from a horizon on the south slope of the Carpathian Mountains, situated in Rumania and Galicia, Austria-Hungary. There are also a few producing wells in Peru, Germany, Italy, Burma, Argentina, and Sumatra.

[Ill.u.s.tration: PETROLEUM FIELDS IN THE UNITED STATES]

In the United States the largest horizon is that of the Appalachian region. Since 1859 it has produced more than forty million gallons of crude oil. The Lima, Ind., horizon produces about twenty million barrels. The California and Texas horizons have become very important factors. The crude petroleum is transported partly in tank cars, but mainly by means of long lines of pipe, flowing from one pumping station to another by gravity. There are pipe-line terminals on the Great Lakes and at Pittsburg, but the princ.i.p.al are at the refining and exporting stations in New York, Philadelphia, and on the Delaware River.

A considerable amount is exported to European countries to be there refined, but in the main the crude oil is refined before exporting it.

Some of the refined oil is exported in barrels, and some in tin cases; the greater part, however, goes in tank steamers, and from these it is pumped into tank cars to be distributed. Most of the product is controlled by the Standard Oil Company, and it reaches nearly every country in the world. It is carried into Arctic regions on sledges, and over the African deserts by caravans. Great Britain, Germany, and the Netherlands are the chief purchasers and distributors. The value of the entire product is about one hundred and eighty-five million dollars.

The Russian oil-producing region is on and near the Apsheron peninsula, a small area of Trans-Caucasia, that extends into the Caspian Sea; the region is commonly known as the Baku field, and in 1900 the production of crude oil surpa.s.sed that of the United States. The petroleum is conveyed by pipe lines to the refineries at Baku. From this port it is shipped in tank cars by rail to Batum, whence it is conveyed to the various European markets. A considerable part of the product is sent by tank steamers to Astrakhan, and thence up the Volga to Russian markets.

Great Britain takes about one-third; about the same amount is shipped to Port Sad for China, India, and other Asian markets; the rest is consumed in central Europe.

=Petroleum Products.=--The various const.i.tuents of crude petroleum differ greatly in character, some being much more volatile than others. They are separated by distillation at different temperatures. By this process naphtha, rhigoline, gasoline, benzine, and other highly inflammable products are obtained in separate receivers. By a similar process the illuminating or refined oil and the lubricating oils are also separated.

The residuum consists of a gummy ma.s.s from which paraffine and petroleum jelly are extracted.

_Naphtha_ usually contains several volatile compounds, including _benzine_ and _gasoline_. It is used as a solvent of grease and also of crude india-rubber, but chiefly the manufacture of illuminating gas.

_Kerosene_ is the name commonly given to the refined oil. A good quality should have a fire test of not less than one hundred and fifty degrees; that is, when heated to that temperature, it should not give off any inflammable gas. This test is now mandatory in most States.

_Lubricating oil_ is used almost wholly for the lubrication of heavy machinery. It varies greatly in composition and quality.

_Paraffine_ or petroleum wax has largely superseded beeswax; it is used mainly in the manufacture of candles and as an insulator for electric wires. A native mineral paraffine, known as ozocerite, is mined in Utah and Galicia; it is used as an insulating material.

"_Vaseline_," "_cosmoline_," or _petroleum "jelly"_ is very largely used in pharmacy as the basis of ointments and also as a lubricant for heavy machinery.

_Asphalt_ is produced by the distillation of petroleum, but the greater part of the world's product comes from two "pitch lakes"--one in Bermudez, Venezuela, the other in the island of Trinidad, off the Venezuelan coast. The former is the larger and produces a superior quality. Small deposits occur near Los Angeles, Cal., and in Utah. The output of the Venezuelan asphalt is used almost wholly for street pavement.

Probably no other mineral has had a wider influence on both social and economic life, and the industrial arts, than petroleum and its compounds. The kerosene lamp, the aniline dye, the insulation of electric wires, the lubrication of machinery, the cosmetic, the india-rubber solution, and the physician's sedative dose represent only a few of the devices that are derived from petroleum.

=Natural Gas.=--A natural inflammable gas occurs in or near several of the petroleum horizons. One important belt extends through western Pennsylvania and New York, and another through northwestern Ohio and northeastern Indiana. It is conveyed through pipe-lines and used both as fuel and for lighting. Natural gas occurs in a great many localities, but is used commercially only in the regions noted. It is better adapted for making gla.s.s than any other fuel, and on this account extensive gla.s.s-making establishments have concentrated in the natural-gas belt of western Pennsylvania.

QUESTIONS FOR DISCUSSION

The statement is sometimes made to the effect that coal is "condensed sunlight"; is it true, or untrue; and why?

Why are the coal areas of Europe and America also areas of various manufactures?

A recent cartoon had for its t.i.tle--"John Bull and his coal piles (_i.e._, coaling stations) rule the world"; show why this statement contains a great deal of truth.

What are some of the advantages of steam-vessels over sailing-vessels?

Whale oil, crude turpentine, kerosene, and gas have been used each in turn for illuminants; what is the advantage of each over the preceding?

Describe the structure of an ordinary kerosene lamp-burner, an argand burner, a Welsbach burner.

For what are aniline, paraffine, naphtha, and carbolic acid used?

FOR STUDY AND REFERENCE

Obtain specimens of anthracite, bituminous, and cannel coal, and c.o.ke for comparison and study.