Book: The Story of a Piece of Coal

E >> Edward A. Martin >> The Story of a Piece of Coal




The coal-field of Upper Silesia, occupying an area about 20 miles long by
15 miles broad, is estimated to contain some 10,000 feet of strata, with
333 feet of good coal. This is about three times the thickness contained
in the South Wales coal-field, in a similar thickness of coal-measures.
There are single seams up to 60 feet thick, but much of the coal is
covered by more recent rocks of New Red and Cretaceous age. In Lower
Silesia there are numerous seams 3-1/2 feet to 5 feet thick, but owing to
their liability to change in character even in the same seam, their value
is inferior to the coals of Upper Silesia.

When British supplies are at length exhausted, we may anticipate that
some of the earliest coals to be imported, should coal then be needed,
will reach Britain from the upper waters of the Oder.

The coal-field of Westphalia has lately come into prominence in
connection with the search which has been made for coal in Kent and
Surrey, the strata which are mined at Dortmund being thought to be
continuous from the Bristol coal-field. Borings have been made through
the chalk of the district north of the Westphalian coal-field, and these
have shown the existence of further coal-measures. The coal-field extends
between Essen and Dortmund a distance of 30 miles east and west, and
exhibits a series of about one hundred and thirty seams, with an
aggregate of 300 feet of coal.

It is estimated that this coal-field alone contains no less than 39,200
millions of tons of coal.

Russia possesses supplies of coal whose influence has scarcely yet been
felt, owing to the sparseness of the population and the abundance of
forest. Carboniferous rocks abut against the flanks of the Ural
Mountains, along the sides of which they extend for a length of about a
thousand miles, with inter-stratifications of coal. Their actual contents
have not yet been gauged, but there is every reason to believe that those
coal-beds which have been seen are but samples of many others which will,
when properly worked, satisfy the needs of a much larger population than
the country now possesses.

Like the lower coals of Scotland, the Russian coals are found in the
carboniferous limestone. This may also be said of the coal-fields in the
governments of Tula and Kaluga, and of those important coal-bearing
strata near the river Donetz, stretching to the northern corner of the
Sea of Azov. In the last-named, the seams are spread over an area of
11,000 square miles, in which there are forty-four workable seams
containing 114 feet of coal. The thickest of known Russian coals occur at
Lithwinsk, where three seams are worked, each measuring 30 feet to 40
feet thick.

An extension of the Upper Silesian coal-field appears in Russian Poland.
This is of upper Carboniferous age, and contains an aggregate of 60 feet
of coal.

At Ostrau, in Upper Silesia (Austria), there is a remarkable coal-field.
Of its 370 seams there are no less than 117 workable ones, and these
contain 350 feet of coal. The coals here are very full of gas, which even
percolates to the cellars of houses in the town. A bore hole which was
sunk in 1852 to a depth of 150 feet, gave off a stream of gas, which
ignited, and burnt for many years with a flame some feet long.

The Zwickau coal-field in Saxony is one of the most important in Europe.
It contains a remarkable seam of coal, known as Russokohle or soot-coal,
running at times 25 feet thick. It was separated by Geinitz and others
into four zones, according to their vegetable contents, viz.:--

1. Zone of Ferns.

2. Zone of Annularia and Calamites.

3. Zone of Sigillaria.

4. Zone of Sagenaria (in Silesia), equivalent to the culm-measures of
Devonshire.

Coals belonging to other than true Carboniferous age are found in Europe
at Steyerdorf on the Danube, where there are a few seams of good coal in
strata of Liassic age, and in Hungary and Styria, where there are
tertiary coals which approach closely to those of true Carboniferous age
in composition and quality.

In Spain there are a few small scattered basins. Coal is found overlying
the carboniferous limestone of the Cantabrian chain, the seams being from
5 feet to 8 feet thick. In the Satero valley, near Sotillo, is a single
seam measuring from 60 feet to 100 feet thick. Coal of Neocomian age
appears at Montalban.

When we look outside the continent of Europe, we may well be astonished
at the bountiful manner in which nature has laid out beds of coal upon
these ancient surfaces of our globe.

Professor Rogers estimated that, in the United States of America, the
coal-fields occupy an area of no less than 196,850 square miles.

Here, again, it is extremely probable that the coal-fields which remain,
in spite of their gigantic existing areas, are but the remnants of one
tremendous area of deposit, bounded only on the east by the Atlantic, and
on the west by a line running from the great lakes to the frontiers of
Mexico. The whole area has been subjected to forces which have produced
foldings and flexures in the Carboniferous strata after deposition. These
undulations are greatest near the Alleghanies, and between these
mountains and the Atlantic, whilst the flexures gradually dying out
westward, cause the strata there to remain fairly horizontal. In the
troughs of the foldings thus formed the coal-measures rest, those
portions which had been thrown up as anticlines having suffered loss by
denudation. Where the foldings are greatest there the coal has been
naturally most altered; bituminous and caking-coals are characteristic of
the broad flat areas west of the mountains, whilst, where the contortions
are greatest, the coal becomes a pure anthracite.

It must not be thought that in this huge area the coal is all uniformly
good. It varies greatly in quality, and in some districts it occurs in
such thin seams as to be worthless, except as fuel for consumption by the
actual coal-getters. There are, too, areas of many square miles in
extent, where there are now no coals at all, the formation having been
denuded right down to the palaeozoic back-bone of the country.

Amongst the actual coal-fields, that of Pennsylvania stands
pre-eminent. The anthracite here is in inexhaustible quantity, its output
exceeding that of the ordinary bituminous coal. The great field of which
this is a portion, extends in an unbroken length for 875 miles N.E. and
S.W., and includes the basins of Ohio, Maryland, Virginia, Kentucky, and
Tennessee. The workable seams of anthracite about Pottsville measure in
the aggregate from 70 to 207 feet. Some of the lower seams individually
attain an exceptional thickness, that at Lehigh Summit mine containing a
seam, or rather a bed, of 30 feet of good coal.

A remarkable seam of coal has given the town of Pittsburg its name. This
is 8 feet thick at its outcrop near the town, and although its thickness
varies considerably, Professor Rogers estimates that the sheet of coal
measures superficially about 14,000 square miles. What a forest there
must have existed to produce so widespread a bed! Even as it is, it has
at a former epoch suffered great denudation, if certain detached basins
should be considered as indicating its former extent.

The principal seam in the anthracite district of central Pennsylvania,
which extends for about 650 miles along the left bank of the Susquehanna,
is known as the "Mammoth" vein, and is 29-1/2 feet thick at Wilkesbarre,
whilst at other places it attains to, and even exceeds, 60 feet.

On the west of the chain of mountains the foldings become gentler, and
the coal assumes an almost horizontal position. In passing through Ohio
we find a saddle-back ridge or anticline of more ancient strata than the
coal, and in consequence of this, we have a physical boundary placed upon
the coal-fields on each side.

Passing across this older ridge of denuded Silurian and other rocks, we
reach the famous Illinois and Indiana coal-field, whose
coal-measures lie in a broad trough, bounded on the west by the uprising
of the carboniferous limestone of the upper Mississippi. This limestone
formation appears here for the first time, having been absent on the
eastern side of the Ohio anticline. The area of the coal-field is
estimated at 51,000 square miles.

In connection with the coal-fields of the United States, it is
interesting to notice that a wide area in Texas, estimated at 3000 square
miles, produces a large amount of coal annually from strata of the
Liassic age. Another important area of production in eastern Virginia
contains coal referable to the Jurassic age, and is similar in fossil
contents to the Jurassic of Whitby and Brora. The main seam in eastern
Virginia boasts a thickness of from 30 to 40 feet of good coal.

Very serviceable lignites of Cretaceous age are found on the Pacific
slope, to which age those of Vancouver's Island and Saskatchewan River
are referable.

Other coal-fields of less importance are found between Lakes Huron and
Erie, where the measures cover an area of 5000 square miles, and also in
Rhode Island.

In British North America we find extensive deposits of valuable
coal-measures. Large developments occur in New Brunswick and Nova Scotia.
At South Joggins there is a thickness of 14,750 feet of strata, in which
are found seventy-six coal-seams of 45 feet in total thickness. At Picton
there are six seams with a total of 80 feet of coal. In the lower
carboniferous group is found the peculiar asphaltic coal of the Albert
mine in New Brunswick. Extensive deposits of lignite are met with both in
the Dominion and in the United States, whilst true coal-measures flank
both sides of the Rocky Mountains. Coal-seams are often encountered in
the Arctic archipelago.

The principal areas of deposit in South America are in Brazil, Uruguay,
and Peru. The largest is the Candiota coal-field, in Brazil, where
sections in the valley of the Candiota River show five good seams with a
total of 65 feet of coal. It is, however, worked but little, the
principal workings being at San Jeronimo on the Jacahahay River.

In Peru the true carboniferous coal-seams are found on the higher ground
of the Andes, whilst coal of secondary age is found in considerable
quantities on the rise towards the mountains. At Porton, east of
Truxillo, the same metamorphism which has changed the ridge of sandstone
to a hard quartzite has also changed the ordinary bituminous coal into an
anthracite, which is here vertical in position. The coals of Peru usually
rise to more than 10,000 feet above the sea, and they are practically
inaccessible.

Cretaceous coals have been found at Lota in Chili, and at Sandy Point,
Straits of Magellan.

Turning to Asia, we find that coal has been worked from time to time at
Heraclea in Asia Minor. Lignites are met with at Smyrna and Lebanon.

The coal-fields of Hindoostan are small but numerous, being found in all
parts of the peninsula. There is an important coal-field at Raniganj,
near the Hooghly, 140 miles north of Calcutta. It has an area of 500
square miles. In the Raniganj district there are occasional seams 20 feet
to 80 feet in thickness, but the coals are of somewhat inferior quality.

The best quality amongst Indian coals has come from a small coal-field of
about 11 square miles in extent, situated at Kurhurbali on the East
Indian Railway. Other coal-fields are found at Jherria and on the Sone
River, in Bengal, and at Mopani on the Nerbudda. Much is expected in
future from the large coal-field of the Wardha and Chanda districts, in
the Central Provinces, the coal of which may eventually prove to be of
Permian age.

The coal-deposits of China are undoubtedly of tremendous extent, although
from want of exploration it is difficult to form any satisfactory
estimate of them. Near Pekin there are beds of coal 95 feet thick, which
afford ample provision for the needs of the city. In the mountainous
districts of western China the area over which carboniferous strata are
exposed has been estimated at 100,000 square miles. The coal-measures
extend westward to the Mongolian frontier, where coal-seams 30 feet thick
are known to lie in horizontal plane for 200 miles. Most of the Chinese
coal-deposits are rendered of small value, either owing to the
mountainous nature of the valleys in which they outcrop, or to their
inaccessibility from the sea. Japan is not lacking in good supplies of
coal. A colliery is worked by the government on the island of Takasima,
near Nagasaki, for the supply of coals for the use of the navy.

The British possession of Labuan, off the island of Borneo, is rich in a
coal of tertiary age, remarkable for the quantity of fossil resin which,
it contains. Coal is also found in Sumatra, and in the Malayan
Archipelago.

In Cape Colony and Natal the coal-bearing Karoo beds are probably of New
Red age. The coal is reported to be excellent in quantity.

In Abyssinia lignites are frequently met with in the high lands of the
interior.

Coal is very extensively developed throughout Australasia. In New South
Wales, coal-measures occur in large detached portions between 29 deg. and 35 deg.
S. latitude. The Newcastle district, at the mouth of the Hunter river, is
the chief seat of the coal trade, and the seams are here found up to 30
feet thick. Coal-bearing strata are found at Bowen River, in Queensland,
covering an area of 24,000 square miles, whilst important mines of
Cretaceous age are worked at Ipswich, near Brisbane. In New Zealand
quantities of lignite, described as a hydrous coal, are found and
utilised; also an anhydrous coal which may prove to be either of
Cretaceous or Jurassic age.

We have thus briefly sketched the supplies of coal, so far as they are
known, which are to be found in various countries. But England has of
late years been concerned as to the possible failure of her home supplies
in the not very distant future, and the effects which such failure would
be likely to produce on the commercial prosperity of the country.

Great Britain has long been the centre of the universe in the supply of
the world's coal, and as a matter of fact, has been for many years
raising considerably more than one half of the total amount of coal
raised throughout the whole world. There is, as we have seen, an
abundance of coal elsewhere, which will, in the course of time, compete
with her when properly worked, but Britain seems to have early taken the
lead in the production of coal, and to have become the great universal
coal distributor. Those who have misgivings as to what will happen when
her coal is exhausted, receive little comfort from the fact that in North
America, in Prussia, in China and elsewhere, there are tremendous
supplies of coal as yet untouched, although a certain sense of relief is
experienced when that fact becomes generally known.

If by the time of exhaustion of the home mines Britain is still dependent
upon coal for fuel, which, in this age of electricity, scarcely seems
probable, her trade and commerce will feel with tremendous effect the
blow which her prestige will experience when the first vessel, laden with
foreign coal, weighs anchor in a British harbour. In the great coal
lock-out of 1893, when, for the greater part of sixteen weeks scarcely a
ton of coal reached the surface in some of her principal coal-fields, it
was rumoured, falsely as it appeared, that a collier from America had
indeed reached those shores, and the importance which attached to the
supposed event was shown by the anxious references to it in the public
press, where the truth or otherwise of the alarm was actively discussed.
Should such a thing at any time actually come to pass, it will indeed be
a retribution to those who have for years been squandering their
inheritance in many a wasteful manner of coal-consumption.

Thirty years ago, when so much small coal was wasted and wantonly
consumed in order to dispose of it in the easiest manner possible at the
pitmouths, and when only the best and largest coal was deemed to be of
any value, louder and louder did scientific men speak in protest against
this great and increasing prodigality. Wild estimates were set on foot
showing how that, sooner or later, there would be in Britain no native
supply of coal at all, and finally a Royal Commission was appointed in
1866, to collect evidence and report upon the probable time during which
the supplies of Great Britain would last.

This Commission reported in 1871, and the outcome of it was that a period
of twelve hundred and seventy-three years was assigned as the period
during which the coal would last, at the then-existing rate of
consumption. The quantity of workable coal within a depth of 4000 feet
was estimated to be 90,207 millions of tons, or, including that at
greater depths, 146,480 millions of tons. Since that date, however, there
has been a steady annual increase in the amount of coal consumed, and
subsequent estimates go to show that the supplies cannot last for more
than 250 years, or, taking into consideration a possible decrease in
consumption, 350 years. Most of the coal-mines will, indeed, have been
worked out in less than a hundred years hence, and then, perhaps, the
competition brought about by the demand for, and the scarcity of, coal
from the remaining mines, will have resulted in the dreaded importation
of coal from abroad.

In referring to the outcome of the Royal Commission of 1866, although the
Commissioners fixed so comparatively short a period as the probable
duration of the coal supplies, it is but fair that it should be stated
that other estimates have been made which have materially differed from
their estimate. Whereas one estimate more than doubled that of the Royal
Commission, that of Sir William Armstrong in 1863 gave it as 212 years,
and Professor Jevons, speaking in 1875 concerning Armstrong's estimate,
observed that the annual increase in the amount used, which was allowed
for in the estimate, had so greatly itself increased, that the 212 years
must be considerably reduced.

One can scarcely thoroughly appreciate the enormous quantity of coal that
is brought to the surface annually, and the only wonder is that there are
any supplies left at all. The Great Pyramid which is said by Herodotus to
have been twenty years in building, and which took 100,000 men to build,
contains 3,394,307 cubic yards of stone. The coal raised in 1892 would
make a pyramid which would contain 181,500,000 cubic yards, at the low
estimate that one ton could be squeezed into one cubic yard.

The increase in the quantity of coal which has been raised in succeeding
years can well be seen from the following facts.

In 1820 there were raised in Great Britain about 20 millions of tons. By
1855 this amount had increased to 64-1/2 millions. In 1865 this again had
increased to 98 millions, whilst twenty years after, viz., in 1885, this
had increased to no less than 159 millions, such were the giant strides
which the increase in consumption made.

In the return for 1892, this amount had farther increased to 181-1/2
millions of tons, an advance in eight years of a quantity more than equal
to the total raised in 1820, and in 1894 the total reached
199-1/2 millions; this was produced by 795,240 persons, employed in and
about the mines.




CHAPTER VIII.

THE COAL-TAR COLOURS.


In a former chapter some slight reference has been made to those
bye-products of coal-tar which have proved so valuable in the production
of the aniline dyes. It is thought that the subject is of so interesting
a nature as to deserve more notice than it was possible to bestow upon it
in that place. With abstruse chemical formulae and complex chemical
equations it is proposed to have as little as possible to do, but even
the most unscientific treatment of the subject must occasionally
necessitate a scientific method of elucidation.

The dyeing industry has been radically changed during the last half
century by the introduction of what are known as the _artificial_ dyes,
whilst the _natural_ colouring matters which had previously been the sole
basis of the industry, and which had been obtained by very simple
chemical methods from some of the constituents of the animal kingdom, or
which were found in a natural state in the vegetable kingdom, have very
largely given place to those which have been obtained from coal-tar, a
product of the mineralised vegetation of the carboniferous age.

The development and discovery of the aniline colouring matters were not,
of course, possible until after the extensive adoption of
house-gas for illuminating purposes, and even then it was many years
before the waste products from the gas-works came to have an appreciable
value of their own. This, however, came with the increased utilitarianism
of the commerce of the present century, but although aniline was first
discovered in 1826 by Unverdorben, in the materials produced by the dry
distillation of indigo (Portuguese, _anil_, indigo), it was not until
thirty years afterwards, namely, in 1856, that the discovery of the
method of manufacture of the first aniline dye, mauveine, was announced,
the discovery being due to the persistent efforts of Perkin, to whom,
together with other chemists working in the same field, is due the great
advance which has been made in the chemical knowledge of the carbon,
hydrogen, and oxygen compounds. Scientists appeared to work along two
planes; there were those who discovered certain chemical compounds in the
resulting products of reactions in the treatment of _existing_
vegetation, and there were those who, studying the wonderful constituents
in coal-tar, the product of a _past_ age, immediately set to work to find
therein those compounds which their contemporaries had already
discovered. Generally, too, with signal success.

The discovery of benzene in 1825 by Faraday was followed in the course of
a few years by its discovery in coal-tar by Hofmann. Toluene, which was
discovered in 1837 by Pelletier, was recognised in the fractional
distillation of crude naphtha by Mansfield in 1848. Although the method
of production of mauveine on a large scale was not accomplished until
1856, yet it had been noticed in 1834, the actual year of its recognition
as a constituent of coal-tar, that, when brought into contact with
chloride of lime, it gave brilliant colours, but it required a
considerable cheapening of the process of aniline manufacture before the
dyes commenced to enter into competition with the old natural dyes.

The isolation of aniline from coal-tar is expensive, in consequence of
the small quantities in which it is there found, but it was discovered by
Mitscherlich that by acting upon benzene, one of the early distillates of
coal-tar, for the production of nitro-benzole, a compound was produced
from which aniline could be obtained in large quantities. There were thus
two methods of obtaining aniline from tar, the experimental and the
practical.

In producing nitrobenzole (nitrobenzene), chemically represented as
(C_{6}H_{5}NO_{2}), the nitric acid used as the reagent with benzene, is
mixed with a quantity of sulphuric acid, with the object of absorbing
water which is formed during the reaction, as this would tend to dilute
the efficiency of the nitric acid. The proportions are 100 parts of
purified benzene, with a mixture of 115 parts of concentrated nitric acid
(HNO_{3}) and 160 parts of concentrated sulphuric acid. The mixture is
gradually introduced into the large cast-iron cylinder into which the
benzene has been poured. The outside of the cylinder is supplied with an
arrangement by which fine jets of water can be made to play upon it in
the early stages of the reaction which follows, and at the end of from
eight to ten hours the contents are allowed to run off into a storage
reservoir. Here they arrange themselves into two layers, the top of which
consists of the nitrobenzene which has been produced, together with some
benzene which is still unacted upon. The mixture is then freed from the
latter by treatment with a current of steam. Nitrobenzene presents itself
as a yellowish oily liquid, with a peculiar taste as of bitter almonds.
It was formerly in great demand by perfumers, but its poisonous
properties render it a dangerous substance to deal with. In practice a
given quantity of benzene will yield about 150 per cent of nitrobenzene.
Stated chemically, the reaction is shown by the following equation:--

C_{6}H_{6} + HNO_{3} = C_{6}H_{5}NO_{2}, + H_{2}O
(Benzene) (Nitric acid) (Nitrobenzene) (Water).

The water which is thus formed in the process, by the freeing of one of
the atoms of hydrogen in the benzene, is absorbed by the sulphuric acid
present, although the latter takes no actual part in the reaction.

From the nitrobenzene thus obtained, the aniline which is now used so
extensively is prepared. The component atoms of a molecule of aniline are
shown in the formula C_{6}H_{5}NH_{2}. It is also known as phenylamine or
amido-benzole, or commercially as aniline oil. There are various methods
of reducing nitrobenzene for aniline, the object being to replace the
oxygen of the former by an equivalent number of atoms of hydrogen. The
process generally used is that known as Bechamp's, with slight
modifications. Equal volumes of nitrobenzene and acetic acid, together
with a quantity of iron-filings rather in excess of the weight of the
nitrobenzene, are placed in a capacious retort. A brisk effervescence
ensues, and to moderate the increase of temperature which is caused by
the reaction, it is found necessary to cool the retort. Instead of acetic
acid hydrochloric acid has been a good deal used, with, it is said,
certain advantageous results. From 60 to 65 per cent. of aniline on the
quantity of nitrobenzene used, is yielded by Bechamp's process.

Copyright (c) 2007. knowncrafts.net. All rights reserved.