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° and 35° 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 Béchamp'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 Béchamp's process.
Stated in a few words, the above is the process adopted on all hands for the production of commercial aniline, or aniline oil. The details of the distillation and rectification of the oil are, however, as varied as they can well be, no two manufacturers adopting the same process. Many of the aniline dyes depend entirely for their superiority, on the quality of the oil used, and for this reason it is subject to one or more processes of rectification. This is performed by distilling, the distillates at the various temperatures being separately collected.
When pure, aniline is a colourless oily liquid, but on exposure rapidly turns brown. It has strong refracting powers and an agreeable aromatic smell. It is very poisonous when taken internally; its sulphate is, however, sometimes used medicinally. It is by the action upon aniline of certain oxidising agents, that the various colouring matters so well known as aniline dyes are obtained.
Commercial aniline oil is not, as we have seen, the purest form of rectified aniline. The aniline oils of commerce are very variable in character, the principal constituents being pure aniline, para- and meta-toluidine, xylidines, and cumidines. They are best known to the colour manufacturer in four qualities—
(a) Aniline oil for blue and black.
(b) Aniline oil for magenta.
(c) Aniline oil for safranine.
(d) _Liquid toluidine.
From the first of these, which is almost pure aniline, aniline black is derived, and a number of organic compounds which are further used for the production of dyes. The hydrochloride of aniline is important and is known commercially as "aniline salt."
The distillation and rectification of aniline oil is practised on a similar principle to the fractional distillation which we have noticed as being used for the distillation of the naphthas. First, light aniline oils pass over, followed by others, and finally by the heavy oils, or "aniline-tailings." It is a matter of great necessity to those engaged in colour manufacture to apply that quality oil which is best for the production of the colour required. This is not always an easy matter, and there is great divergence of opinion and in practice on these points.
The so-called aniline colours are not all derived from aniline, such colouring matters being in some cases derived from other coal-tar products, such as benzene and toluene, phenol, naphthalene, and anthracene, and it is remarkable that although the earlier dyes were produced from the lighter and more easily distilled products of coal-tar, yet now some of the heaviest and most stubborn of the distillates are brought under requisition for colouring matters, those which not many years ago were regarded as fit only to be used as lubricants or to be regarded as waste.
It is scarcely necessary or advisable in a work of this kind to pursue the many chemical reactions, which, from the various acids and bases, result ultimately in the many shades and gradations of colour which are to be seen in dress and other fabrics. Many of them, beautiful in the extreme, are the outcome of much careful and well-planned study, and to print here the complicated chemical formulae which show the great changes taking place in compounds of complex molecules, or to mention even the names of these many-syllabled compounds, would be to destroy the purpose of this little book. The Rosanilines, the Indulines, and Safranines; the Oxazines, the Thionines: the Phenol and Azo dyes are all substances which are of greater interest to the chemical students and to the colour manufacturer than to the ordinary reader. Many of the names of the bases of various dyes are unknown outside the chemical dyeworks, although each and all have complicated; reactions of their own. In the reds are rosanilines, toluidine xylidine, &c.; in the blues—phenyl-rosanilines, diphenylamine, toluidine, aldehyde, &c.; violets—rosaniline, mauve, phenyl, ethyl, methyl, &c.; greens—iodine, aniline, leucaniline, chrysotoluidine, aldehyde, toluidine, methyl-anilinine, &c.; yellows and orange—leucaniline, phenylamine, &c.; browns—chrysotoluidine, &c.; blacks—aniline, toluidine, &c.
To take the rosanilines as an instance of the rest.
Aniline red, magenta, azaleine, rubine, solferino, fuchsine, chryaline, roseine, erythrobenzine, and others, are colouring matters in this group which are salts of rosaniline, and which are all recognised in commerce.
The base rosaniline is known chemically by the formula C_{20}H_{l9}N_{3}, and is prepared by heating a mixture of magenta aniline, toluidine, and pseudotoluidine, with arsenic acid and other oxidising agents. It is important that water should be used in such quantities as to prevent the solution of arsenic acid from depositing crystals on cooling. Unless carefully crystallised rosaniline will contain a slight proportion of the arseniate, and when articles of clothing are dyed with the salt, it is likely to produce an inflammatory condition of skin, when worn. Some years ago there was a great outcry against hose and other articles dyed with aniline dyes, owing to the bad effects which were produced, and this has no doubt proved very prejudicial to aniline dyes as a whole.
Again, the base known as mauve, or mauveine, has a composition shown by the formula C_{27}H_{24}N_{4}. It is produced from the sulphate of aniline by mixing it with a cold saturated solution of bichromate of potash, and allowing the mixture to stand for ten or twelve hours. A blue-black precipitate is then formed, which, after undergoing a process of purification, is dissolved in alcohol and evaporated to dryness. A metallic-looking powder is then obtained, which constitutes this all-important base. Mauve forms with acids a series of well-defined salts and is capable of expelling ammonia from its combinations. Mauve was the first aniline dye which was produced on a large scale, this being accomplished by Perkin in 1856.
The substance known as carbolic acid is so useful a product of a piece of coal that a description of the method of its production must necessarily have a place here. It is one of the most powerful antiseptic agents with which we are acquainted, and has strong anaesthetic qualities. Some useful dyes are also obtained from it. It is obtained in quantities from coal-tar, that portion of the distillate known as the light oils being its immediate source. The tar oil is mixed with a solution of caustic soda, and the mixture is violently agitated. This results in the caustic soda dissolving out the carbolic acid, whilst the undissolved oils collect upon the surface, allowing the alkaline solution to be drawn from beneath. The soda in the solution is then neutralised by the addition of a suitable quantity of sulphuric acid, and the salt so formed sinks while the carbolic acid rises to the surface.
Purification of the product is afterwards carried out by a process of fractional distillation. There are various other methods of preparing carbolic acid.
Carbolic acid is known chemically as C_{6}H_{5}(HO). When pure it appears as colourless needle-like crystals, and is exceedingly poisonous. It has been used with marked success in staying the course of disease, such as cholera and cattle plague. It is of a very volatile nature, and its efficacy lies in its power of destroying germs as they float in the atmosphere. Modern science tells us that all diseases have their origin in certain germs which are everywhere present and which seek only a suitable nidus in which to propagate and flourish. Unlike mere deodorisers which simply remove noxious gases or odours; unlike disinfectants which prevent the spread of infection, carbolic acid strikes at the very root and origin of disease by oxidising and consuming the germs which breed it. So powerful is it that one part in five thousand parts of flour paste, blood, &c., will for months prevent fermentation and putrefaction, whilst a little of its vapour in the atmosphere will preserve meat, as well as prevent it from becoming fly-blown. Although it has, in certain impure states, a slightly disagreeable odour, this is never such as to be in any way harmful, whilst on the other hand it is said to act as a tonic to those connected with its preparation and use.
The new artificial colouring matters which are continually being brought into the market, testify to the fact that, even with the many beautiful tints and hues which have been discovered, finality and perfection have not yet been reached. A good deal of popular prejudice has arisen against certain aniline dyes on account of their inferiority to many of the old dye-stuffs in respect to their fastness, but in recent years the manufacture of many which were under this disadvantage of looseness of dye, has entirely ceased, whilst others have been introduced which are quite as fast, and sometimes even faster than the natural dyes.
It is convenient to express the constituents of coal-tar, and the distillates of those constituents, in the form of a genealogical chart, and thus, by way of conclusion, summarise the results which we have noticed.
COAL.
|
.—————+—————-+——+—————————-+————+——.
| | | | | |
Water House-gas Coal-tar Ammoniacal Coke |
| liquor |
.————-+———-+————-+————-. | Sulphur
| | | | | | (sulphurreted
First Second Heavy Anthracene Pitch | hydrogen:
light light oils (green | sulphurous
oils oils (creosote oils) | acid: oil
| (crude oils) | | of vitriol)
.——+——. naphtha) | Anthracene |
| | | | | |
Ammoniacal Benzene | | Alizarin or |
liquor toluene,| | dyer's madder |
&c. | | |
| | |
| | Sulphuric acid=Carbonate of=Hydrochloric
| | | ammonia acid
| | | (smelling
| | | salts)
| | |
| | Lime=Sulphate of Lime=Chloride of
| | | ammonia | ammonia (sal
| | | | ammoniac)
| | | |
| | .——+——. .——+——.
| | | | | |
| | Ammonia Sulphate Ammonia Chloride
| | of lime of lime.
| | (Plaster of Paris)
| |
| .—+——-+—————.
| | | |
| Crude Carbolic Naphthalin
| Creosote acid
|
.———————+—-+—+———-+————+—————-.
| | | | |
Benzene=Nitric Acid Toluene Nylene Artificial Burning
| turpentine oils
Nitrobenzene= } Iron filings oil (solvent
(Essence de | } and acetic acid naphtha)
mirbane) |
|
Aniline=Various reagents
|
Aniline dyes
INDEX.
A.
Accidents, causes of mining
"Age of Acrogens"
Alethopteris
Alizarin
American coal-fields
Ammoniacal liquor
Aniline
Aniline dyes
Aniline oil, commercial
Aniline salt
Aniline "tailings"
Anthracene
Anthracite
Artificial turpentine oil
Asphalt
Australian coals
Aviculopecten
B.
Béchamp's process
Benzene
Bind
Bitumen in Trinidad
"Blower" a
Boghead coal
Bog-oak
Boring diamonds
Borrowdale graphite mine
Bovey Tracey lignite
British coal-fields
British North-American coal-measures
Briquettes
C.
Calamites, extinct horsetails
Carbolic acid
Carboniferous formation, the
Cardiocarpum, fossil fruit
Carelessness of miners
Causes of earth-movements
Changes of level
Charcoal as a disinfectant
Chemistry of a gas-flame
Chinese coals
Clanny's safety-lamp
Clayton's experiments with gas
Clay, regularity in deposition of
Club-mosses, great height of fossil
Coal-dust, danger from
Coal formed in large lakes or closed seas
Coal formation, geological position of
Coal formed by escape of gases
Coal-mine, the
Coal not the result of drifted vegetation
Coal-period, climate of
"Coal-pipes"
Coal-plants, classification of
Coal-seam, each, a forest growth
Coals of non-carboniferous age
Coal, vegetable origin of
Coke
"Cole"
"Condensers"
Cones of Lepidodendra
Conifers in coal-measures
Current-bedding in sandstone
D.
Davy-lamp
Dangers of benzene
Darwin on the Chonos Archipelago
Diamonds, how made artificially
Disintegration of vegetable substances
Disproportion in relative thickness of coal and coal-measures
E.
Early use of coal
Effects of an explosion
Encrinital limestone
Equiseta
"Essence de mirbane"
European coal-fields
Evelyn on the use of coal
Experiments illustrating fossilisation
F.
Filling retorts by machinery
Firedamp
Fire, mines on
First light oils
First record of an explosion
Flashing-point of oil
Flooding of pits
Fog and smoke
Foraminifera
Fossil ferns
Fructification on fossil-ferns
Furnace, ventilating
G.
Gas, coal
Gasholder, the
Gas, house, constituents of
Glossopteris
Graphite
"Green Grease"
H.
Hannay, of Glasgow
Heavy oils
Humboldt's safety-lamp
Hydraulic Main
I.
Impurities in house-gas
Indian coals
Insertion of rootlets of stigmaria
Insufficiency of modern forest growths
Ireland denuded of coal-beds
Iron, supplies of
L.
Lepidodendra Lepidostrobi Lignite London lit by gas
M.
Mammoth trees
Marco Polo
Marsh gas
Medium oils
Metamorphism of coal by igneous agency
Methods of ventilation
Mountain limestone
Murdock's use of gas
Mussel beds
N.
Napthalin
Neuropteris
Newcastle, charters to
Nitro-benzole
O.
Objections to use of coal
Oils from coal and lignite
Oil-wells of America
Olefiant gas
Orthoceras
P.
Paraffins
Peat
Pecopteris
Pennsylvanian anthracite
Persian fire-worshippers
Pitch
Plumbago
Polyzoa
Prejudice against aniline dyes
Prohibitions of the use of coal
Proportions of explosive mixtures
Psaronius
"Purifiers"
Pyrites in coal
Q.
Quantity of coal raised in Great Britain
R.
Reptiles of the coal-era
Resemblance of American and British coal-flora
Retorts
Roman use of coal
Rosanilines, the
Royal Commission of 1866
S.
Sandstone, how formed
Shales
Sigillaria
South American coals
Spores of lepidodrendron
Spores, resinous matter in
Spores, inflammability of
Steel-mill
Sternbergia
Stigmaria
Subsidence throughout coal-era
Surturbrand at Brighton
Sussex iron-works
T.
Tar
Testing pits by the candle
Texas coal
Toluene, discovery of
Torbanehill mineral
Trappers
U.
Underclays
Uses to which coal is put
V.
Vaseline
Vegetation of the coal age
Ventilation of coal-pits
W.
"Washers"
Waste of fuel
Wealden lignite
Westphalian coal-field
Y.
Young's Paraffin Oil
Z.
Zoroastrians
End of Project Gutenberg's The Story of a Piece of Coal, by Edward A. Martin