_Prevention._--Since these spirit compos_Dangerous trades

to paint the inside of peaks, bunkers, and tunnels of ships, without

running considerable risk to the workmen, clearly their employment

ought to be prohibited in confined spaces. It is courting disaster

to paint the inside of any cramped space, ingress to or egress from

which can only take place through a man-hole. No naked lights should

be allowed in these places. Illumination should be secured either

by a safety lamp or by the electric light. All the workmen whom I

have interrogated are unanimously of opinion that the work should be

periodically interrupted. Every hour or two, according to the more or

less confined character of the chamber in which the paints are being

used, the workmen should go into the open air for several minutes.

Six hours’ work a day should be the maximum, and this ought to be

divided into equal halves, separated at least by one and a half hour’s

interval. Since there is considerable risk from fire and explosion, no

young or inexperienced person should be allowed to use these paints,

and under all circumstances men on being employed for the first time

should be informed of the dangers and of the risks they are running.

Where a workman is painting the inside of a confined space in a ship

with spirit paint he should be frequently visited by a foreman, to see

that all is well.

When an individual has become intoxicated through the vapours given

off by composite paints, the best treatment is to take him into the

open air, and to wrap him up in rugs so as to avoid the chance of his

being chilled. When the workman has sufficiently recovered, he should

be accompanied home by some of his mates, put to bed, kept warm, and a

saline aperient administered at the earliest opportunity.

THOMAS OLIVER.

CHAPTER XXXV

ACETYLENE AND ITS DANGERS

All details relating to the manufacture of coal-gas, water-gas, or

oil-gas, and to the incidental risks both to the worker and the

consumer, are well known, having been treated by many reliable

authorities. Acetylene gas, however, is a comparatively modern

illuminant, growing in public favour, and now that the manufacture of

calcium carbide is not confined to the United States, Canada, and the

Continent, but is produced also in the United Kingdom, it is probable

that the adoption of acetylene will become more general.

For country houses, country churches, railway stations, isolated

factories and workshops, Indian bungalows, and other places where a

cheap and ready supply of coal-gas or electricity is not available,

acetylene will be particularly appreciated. Its uses, however, are more

extended. On the Continent many towns are lighted with this gas. The

Town Commissioners have expressed satisfaction with it as an illuminant

for the town of Boyle. For photographic purposes, carriage lamps, magic

lanterns, bicycle lamps, etc., acetylene is largely used.

A brief description of the manufacture will be interesting. The

writer, owing to the fact that there are as yet few carbide of calcium

manufactories in the United Kingdom, can speak with only a limited

experience, but he is indebted for information to the Read-Holliday

Acetylene Company, to an article which appeared in the _Public Health

Journal_ for 29th September 1900, to one on “Electrical Furnaces”

recently published in the _Windsor Magazine_, and to other sources.

The introduction of electrical furnaces capable of producing intense

heat has rendered it possible to melt and join together such infusible

elements as lime and carbon. When the furnaces are cool, the compound

formed is known as “calcium carbide.” If dropped in water it

decomposes; some authorities say, almost with an explosion. If simply

damped, the decomposition is slower, the product given off being

the gas known as “acetylene,”--a colourless gas, stated to contain

by weight 24 parts of carbon and 2 parts of hydrogen. In England the

electrical furnaces are practically arc lamps on a large scale, the

bottom of the furnace being a large carbon block electrically connected

to the positive pole of the generator, whilst the upper carbon is

connected to the negative. By a simple arrangement the negative pole

can be raised or lowered at will, to strike the arc or regulate the

intensity of the furnace. A mixture of lime and coke, in the form of

fine powder, is thrown into the furnaces for fusion, and when cool it

is taken away in lumps ready for use.

Seeing that this industry is one of very modern date, it is of interest

to consider whether acetylene gas, during the process of manufacture or

in use, is likely to produce injury to health or life. This question

may be considered under the following heads:--

(_a_) The inhalation of dust during the crushing processes and in

feeding the furnaces.

(_b_) The fumes evolved from the furnaces.

(_c_) The danger of electric shock to the workers.

(_d_) Explosion during the stages of manufacture.

(_e_) Explosion, or risk of inhalation of gas, when in use.

During the operation of grinding carbon and lime, and when feeding

the furnaces, more or less fine dust must of necessity arise, unless

this is prevented by mechanical appliances of a somewhat expensive

kind. Some of this dust will be held in suspension by the atmosphere

and inhaled by the workers, but as the work is done in practically

open sheds, and as the industry is of comparatively recent origin, it

is impossible at present to say whether injury to health is caused.

Labourers engaged in quarrying limestone are said to be healthy

men. The late Dr Arlidge, when referring to workmen employed about

lime-kilns, stated that there are grounds for believing that the

carbonic acid of respiration is capable of acting upon lime-dust and

ridding the lungs of it.

(_b_) Fumes must of necessity be given off from the furnaces, but

mechanical ventilating fans render these harmless.

(_c_) Little fear of electric shock need be apprehended in this

country, the voltage being low, although the current is strong--a

result attained by the aid of several brushes and heavy copper strips

for conveying the current to the carbons forming the furnaces. An

interesting article recently published in the _Windsor Magazine_

describes a visit to Niagara Falls, where the largest furnaces in the

world are operated, and where, amongst other industries, is found the

manufacture of calcium carbide. Furnaces on the arc and incandescent

principle are employed. The current enters the building at a voltage

of 2200, to be transformed to about 100 volts, which approximates the

pressure found in English works.

(_d_) An accident of a serious (but happily a non-fatal) nature

recently occurred at works in which the calcium carbide, when cool,

is stored in 8 cwt. metal tanks, ready to be sent away. It appears

that some moisture had found its way into a returned tank. This was

unobserved by a worker, who placed about 4 cwts. of the material

into it, screwed the lid down, and left the works for the night. The

tank stood about 15 feet from the electric furnace. A mechanical fan

for ventilating purposes was running, and caused a current from the

direction of the tanks to the furnace. As a natural result, gas was

generated in the tank during the night. The workman, before resuming

work in the morning, took off the lid, liberating the gas, which was at

once ignited by the furnace, causing explosion, and seriously injuring

the man. The obvious lesson is, that tanks should be carefully examined

for moisture or leakage before filling, and that under no circumstances

should the filling be done near the furnaces, but in another room, in

which there are no lights and no probability of “sparking” from any

electrical machine.

(_e_) On the first adoption of acetylene, accidents happened,

giving rise to a general belief that it was dangerous. The following

extracts from Orders in Council issued at various times will show that

the Government officials were fully alive to this danger, and that

from time to time precautions to safeguard the public have been taken.

By an Order in Council dated 26th February 1897, certain parts of the

Petroleum Acts, 1871–1881, were made to apply to carbide of calcium,

and it was laid down that:--

“The label on the vessel containing the carbide of calcium shall

bear in conspicuous characters the words ‘Carbide of Calcium,’

‘Dangerous if not kept dry,’ and with the following caution:

‘The contents of this package are liable if brought into contact

with moisture to give off a highly inflammable gas,’ and with

the addition:--

“(_a_) In the case of a vessel kept, of the name and

address of the consignee or owner.

“(_b_) In the case of a vessel sent or conveyed, of

the name and address of the sender.

“(_c_) In the case of a vessel sold or exposed for

sale, of the name and address of the vendor.”

On the 7th July 1897, an Order in Council amended the Order of 26th

February 1897, by prescribing that:--

“Notwithstanding anything to the contrary in the said Order,

the quantity of carbide of calcium which may be kept without a

licence shall be as follows:--

“(_a_) Where it is kept in separate substantial hermetically closed

metal vessels containing not more than

1 lb. each 5 lbs.

“(_b_) Where it is kept otherwise None.”

By a further Order in Council, dated 26th November 1897, it was laid

down that:--

“Acetylene when liquid, or when subject to a pressure above

that of the atmosphere, capable of supporting a column of

water exceeding one hundred inches in height, and whether or

not in admixture with other substances, shall be deemed to

be an explosive within the meaning of the Explosives Act of

1875, subject to the following exception; that if it be shown

to the satisfaction of the Secretary of State that acetylene,

declared to be explosive by this Order when in admixture with

any substance, or in any form or condition, is not possessed

of explosive properties, the Secretary of State may, by Order,

exempt such acetylene from being deemed to be an explosive.”

The Order further prescribed that:--

“Whereas by section 43 of the Explosives Act, 1875, it is

provided that Her Majesty, from time to time by Order in

Council, may prohibit, either absolutely, or except in pursuance

of a licence of the Secretary of State under the said Act, or

may subject to conditions or restrictions, the manufacture,

keeping, importation from any place out of the United Kingdom,

conveyance, and sale, or any of them, of any explosive which is

of so dangerous a character, that in the judgment of Her Majesty

it is expedient for the public safety to make such Order.

“And whereas it is in the judgment of Her Majesty expedient for

the public safety that acetylene, when an explosive within the

meaning of this Order, shall be prohibited.

“Now, therefore, in pursuance of the above-mentioned provision

of this Act, Her Majesty is pleased, by and with the advice

of Her Privy Council, to order and prescribe that acetylene,

declared to be an explosive by this Order, shall be prohibited

from being manufactured, imported, conveyed, or sold.”

An Order of the Secretary of State, dated 28th March 1898, provided as

follows:--

“Acetylene in admixture with oil-gas in a proportion not

exceeding twenty parts by volume of acetylene in every one

hundred parts of the mixture, when subjected to a pressure not

exceeding one hundred and fifty pounds to the square inch, shall

not be deemed to be an explosive within the meaning of the

Explosives Act, 1875.

“Provided that the acetylene and oil-gas shall be mixed together

in a chamber or vessel before the gases are subjected to

compression.”

Lastly, an Order of 15th May 1900 required:--

“That acetylene in admixture with air or oxygen, declared to

be an explosive by this Order, shall be prohibited from being

manufactured, imported, conveyed, or sold.

“Provided that nothing in this Order shall apply to acetylene

in admixture with air when such admixture takes place only in

a burner or contrivance in which the mixture is intended to be

burnt.

“Provided also that nothing in this Order shall be held to apply

to an admixture of acetylene and air which may unavoidably

occur in the first use or re-charging of an apparatus, properly

designed and constructed with a view to the production of pure

acetylene.”

A Committee of the Society of Arts, London, was appointed to

investigate the subject and frame rules for the safe construction

of acetylene apparatus, and it is claimed (justly I believe) by

manufacturers such as the Read-Holliday Acetylene Company, Lockerby and

Wilson Limited, and others, that their apparatus fulfils the conditions

laid down by the Committee, and that now their appliances may be used

with perfect safety. Messrs Tinker & Holliday, of Huddersfield, who

manufacture carbide of calcium, give their assurance that they have

sold more than 1000 machines, mostly of a large size, some of 600

lights, and that there has never yet been an accident of any kind.

On the other hand, it must be remembered that, as acetylene is more

explosive than coal-gas, exceptional care should be taken as to where

generators are placed, and to avoid the use of lights where leakage

is suspected. Early last November a representative of an acetylene

firm visited an hotel in a country town in Derbyshire to inspect the

generator. The newspapers state that immediately after striking a match

a loud explosion occurred, in consequence of which his face and hand

were injured.

The _Chemical Trade Journal_ for 16th June 1900 contains a

paragraph of public interest, relating to the safety of calcium

carbide, which may perhaps with advantage be here reproduced:

“The large army of insurance agents and adjusters who are now

in Ottawa settling the losses incurred through the recent fire

have lately had before them an object lesson which should remove

any doubts that may have been entertained as to the safety of

storing carbide of calcium. According to a communication we have

received from Mr Andrew Holland of the Board of Trade, Ottawa,

when the fire reached the furnace-room of the Dominion Carbide

Works, everything in it that would burn was consumed. Three pigs

of carbide, however, in three crucibles remained in perfect

condition as evidence that they did not explode. The grinding

and mixing department and warehouse were in another building,

and every effort was made to prevent the fire from reaching it;

but the very strong wind blowing, and the vast rush of flame,

enveloped all the buildings in the vicinity, and they were in a

few minutes reduced to ruins. In the carbide warehouses there

were 15 tons of carbide, packed in rolled steel cans with screw

covers. When the floor burned, the carbide dropped through into

the cellar, in which a foot of water had collected from the

firemen’s hose. Here was an ideal combination for an explosion,

if carbide is an explosive. Several cans were broken in the

fall, owing to the intense heat having opened the seams, and the

carbide was dumped into the water. Gas was generated in immense

quantities, but it simply burned with a low steady flame, making

less show than two cartloads of coke on fire in the immediate

vicinity. Had the cellar been dry, the carbide could have been

all saved after the fire; but it continued to soak up the water

and make gas for some days, and the burning gas kept the carbide

so hot, that it could not be handled. As it was, about a ton

of it was shovelled out and packed in new cans. Two of the

cans were dug out whole from the hot mass, and saved with the

carbide, though they were burned like old, worn-out stove-pipes.

The insurance agents admit that they have had a practical

demonstration which had convinced them how much the ‘risks’ of

calcium carbide have been over-estimated.”

It is claimed by the manufacturers of acetylene that it possesses

certain hygienic advantages over other gases, these being--a less

consumption of oxygen, a less addition of carbonic acid to the

atmosphere, less heating of the air, and freedom from sulphur

compounds. The illumination is stated to be brilliant, but not

injurious to the eyes. On this point, however, it does not appear that

oculists in this country have pronounced definite opinions, although

individual medical practitioners have reported favourably. Dr W. A.

M’Keown, in his _Treatise on Unripe Cataract_, in a chapter on

“Suitable Light and Optical Aids,” says: “Fortunately, however, it is

now within the power of the surgeon to whom the electric light is not

available to have acetylene light, an illuminant at least as good as

the electric light, and very well borne by the eyes.”

An article by Professor Thomas Oliver, published in the _British

Medical Journal_ of 23rd April 1898, and entitled “Acetylene, the

New Illuminant, and the Dangers arising from its Inhalation,” is

probably the only authoritative statement yet published dealing with

the physiological effects of acetylene gas. In a brief paper such as

this, many details describing the methods of experiment adopted by Dr

Oliver must be omitted, but the following is an attempt to summarise

the conclusions arrived at by him:--

A mixture of air and acetylene commences to be explosive when it

contains 5 per cent. of acetylene (Captain Thomson, H.M. Chief

Inspector of Explosives, thinks 3 per cent.), whereas it requires

the presence of 8 per cent. of coal-gas to make a similar mixture

explosive. It is therefore more explosive than coal-gas. Acetylene

has an excessively pungent and disagreeable odour, but this, although

a disadvantage in some ways, acts as a warning to individuals of its

presence. Generators for private mansions, etc., should be placed in

the open air, or in a covered shed open at the sides. In the case of

coal-gas and water-gas, death supervenes by asphyxia, owing to the

carbon-monoxide entering into extremely stable combinations with the

hæmoglobin of the blood. If a rabbit is placed in a bell-jar into which

ordinary air and acetylene are pumped, the animal for a long period

experiences little inconvenience. If atmospheric air is excluded, and

acetylene only admitted, symptoms gradually and slowly develop. After

more lengthened exposure to acetylene than that which is necessary for

coal-gas, the animal becomes intoxicated, stupor stealing over it,

apparently painlessly. When somnolence has been induced and asphyxia

not pushed too far, the rabbit, if placed in atmospheric air, shortly

afterwards moves about in as lively a manner as if it had not been

interfered with. Should the inhalation, however, have been pushed

further, and the animal be deeply narcotised, death may ensue. In the

minor stages of asphyxia, vascular tension is maintained, but in the

deeper stages the vessels are so deeply contracted, that it is almost

impossible to obtain a drop of blood. On spectroscopic examination,

the blood of a rabbit at different stages of intoxication from

acetylene always exhibits the well-marked bands of oxyhæmoglobin, but,

unlike the blood in coal-gas poisoning, it is capable of undergoing

reduction. In this respect it behaves like ordinary blood. If asphyxia

caused by acetylene is not too profound--and under ordinary domestic

circumstances it would not be a pure acetylene atmosphere that would

be inhaled by an individual, but one mixed with a large proportion

of common air--the danger to life seems to be less than it would

be in coal-gas poisoning, and the prospect of recovery by removal

to atmospheric air greater. Death may supervene, however, if the

inhalation has been lengthened, and atmospheric air excluded. In the

treatment of unconsciousness caused by the inhalation of acetylene gas,

it is necessary to remove the individual into the open air, and to try

artificial respiration.

Since this brief article was framed, a handbook for the student and

manufacturer has been published by Professor Vivian Lewis, dealing

in an exhaustive form with everything relating to acetylene. It is

illustrated profusely, and doubtless will become a standard book of

reference.

In November 1900, the Foreign Office published a Consular Report by Dr

Frederick Rose, H.M. Consul at Stuttgart, on “The Rise, Progress, and

Present Condition of the Carbide and Acetylene Industries in Germany,”

containing statistics and detailed information of considerable value,

but which cannot well be here reproduced. It is shown that thirty towns

or villages in Germany, with populations varying from 6000 to 382, are

lighted by acetylene. In Berlin the Imperial Post Office has made a

beginning by lighting two of its branch post offices with this gas, and

has installed an apparatus with sixty jets in the head post office. In

July 1898, 62,000 jets of acetylene were installed in Germany. In the

first months of 1899 the number had increased to 170,000. Reference

is made to a new application of calcium carbide in the production of

pure metals from their ores by its use as a reducing agent; to the

manufacture of lampblack, it being stated that acetylene gives three to

four times as much lampblack as good oil-gas; and to an invention which

utilises carbide for the production of converted steel, as well as for

hardening armour-plate after Harvey’s process.

On 1st December 1900, _The Public Health Engineer_ devoted the

whole of its issue to acetylene, and as the article gives in detail

descriptions of generators and other appliances made by practically

all recognised firms, together with a statement of what is claimed in

regard to safety and economy in use, it may be helpful to mention this

publication, for the benefit of inquirers.

HAMILTON P. SMITH.

CHAPTER XXXVI

FLOUR MILLS

Flour-milling as conducted in this country a few decades ago was,

despite the fact that most of the mills were situated in the country,

an unhealthy industry. Flour millers died from pulmonary consumption

and chest diseases in a larger proportion than men engaged in other

trades in the same district. The average life of a miller was said to

be forty-three years. Hirt compiled tables of the comparative sickness

of millers and bakers, and he showed that while of one hundred bakers

seven died from pulmonary phthisis, out of the same number of millers

the deaths were ten. Bakers and millers seemed to him to be about

equally predisposed to emphysema of the lungs, but as regards pneumonia

the mortality figure for bakers was 8.4 per cent. as against 42 per

cent. for millers. These statistics are taken from a German source, and

it is difficult to explain the very heavy mortality rate from pneumonia

in millers compared with that of bakers.

Until within thirty years ago all the wheat and oats in this

country were ground between revolving stones. During the grinding

a considerable amount of fine dust was given off, the continual

inhalation of which was held responsible for much of the ill-health of

the operatives. So unhealthy was the occupation of milling believed

to be twenty years ago, that Friendly Societies would not accept

operative millers as members. To-day no objection is raised. In

addition to injury to health from breathing the dust-laden atmosphere,

there was a risk from fire owing to the highly explosive character

of the dust. While danger to life from explosions in flour mills

still to some extent prevails, both it and the risk to health from

inhalation of the dust have materially diminished. There is the widest

divergence possible between the old and the new methods of milling. The

introduction of the steam roller system of milling from Buda-Pesth, and

the fact that nearly all the various processes are carried on inside

closed machinery, have cleared the atmosphere of modern flour mills

and converted what was admittedly a dangerous trade into one that

compares very favourably with most occupations. Wherever the old method

of milling is still carried on the atmosphere is found laden with a

very fine dust, mostly flour. This with each inspiration is drawn into

the bronchial tubes of the miller, and forms plugs with the mucus

secreted by these passages. The plugs, owing to their tenacity, are

dislodged with difficulty. It is not contended that the flour itself

reaches the lungs; probably the whole, or at any rate the most of it,

becomes entangled in the mucus of the smallest bronchial tubes, but

in the dust there are other things than flour present, _e.g._,

portions of the husks of harder grain than wheat, portions of hairs

of oats, bristles of rye, and particles of mineral from the grinding

stones (see Microphotographs, page 276), so that through one thing and

another, and in consequence of the repeated bronchial irritation and

the cough caused by respiring the dust-laden air, a strain is imposed

upon the lungs that leads to over-distension of the air cells, or what

is known as pulmonary emphysema. That portions of bristle, etc., are

capable of being inhaled into the deeper recesses of the respiratory

passages is shown by the presence of these bristles on microscopical

examination of the expectoration that has been discharged after hard

coughing.

As a nation we are dependent upon foreign countries for our food

supplies, especially wheat. Some of the wheat that is imported is

extremely dirty, particularly that from the River Plate, India, and

Persia. It not only contains small stones and sand, and the husks of

other seeds, but often particles of soil that have been contaminated by

manure. In going over a large modern flour mill one is struck by the

amount of dirt that is taken out of wheat. It is therefore necessary to

clean the grain, which is done by first removing all solid impurities

and then washing it. To clean it, the wheat is passed through a

separator composed of sieves that are kept vibrating. By this means the

larger impure particles are removed, while by the operation of a strong

current of air the lighter dust is sucked away. After this preliminary

cleaning the wheat is taken to rotatory sieves, which size the grain

and thereby separate the larger from the smaller seeds. It is now ready

to be washed. This is done by allowing the wheat to fall into a tank of

warm water, through which a stream is constantly running. From this it

is removed to dryers and coolers. It is only the very dirty wheat that

is washed. Some of it is simply scoured and brushed inside a conical

iron cylinder by means of beaters or brushes that are revolving

rapidly. The dust given off escapes through fine slot holes.

In modern flour mills the dangers that operatives are exposed to are:

(1) those incidental to the machinery; (2) fire and explosions; and

(3) inhalation of dust. It is with the latter that we are here most

concerned. The cleaning of wheat is a dusty process, but it is usually

carried on within enclosed machinery, and so long as this and all the

covered-in spaces are provided with fans that are kept in good order,

and the pipes leading away from these to the dust chambers are kept

patent, the workmen do not seem to incur any great risk to health.

Attention, however, must be given to keeping the suction-pipes clean

and the fans in good order, otherwise, as cleaning is a very dirty

process, the men would assuredly suffer in their chest. At several of

the large flour mills where Oriental wheat is ground, and to the grains

of which particles of manure are often adherent, I have on several

occasions interrogated the men as to whether any illness had ever

followed the washing of the foreign wheat, but in no instance could I

learn of any illness being traceable to such a source. Once the wheat

has been cleaned and brushed or washed, it is put through the rollers

and is milled into flour. This consists of not one but many processes,

all of which are conducted in enclosed chambers, the product at each

particular stage being lifted and carried onwards by self-regulating

machinery and elevators from one part of the mill to another. Where

the fittings of the machinery are good, no dust practically escapes.

Hence it is that flour-milling has ceased to be the harmful industry it

formerly was. In filling the sacks with flour, and in cleaning returned

sacks, there is often a considerable amount of dust given off, but

mechanical contrivances are now in operation that greatly minimise the

amount of dust, so that this particular operation too has become less

dangerous than it once was.

THOMAS OLIVER.

CHAPTER XXXVII

MINING

The industry of mining, touching as it does the boundaries of nearly

every field of human activity, necessarily presents itself under so

many and such different aspects, that the complete study of the risks

to life, limb, and health to which those engaged in it are exposed,

involves an unusually large number of diversified considerations. It

is here proposed to examine only the risks that are more directly

incidental to mining proper, and these again only in so far as they

affect the miners themselves, leaving out of consideration entirely

the dangers to which mining operations may expose the population in

whose midst they have to be carried on, although these are far from

unimportant, including, for example, such accidents as a fall down an

unfenced shaft, the destruction caused by the explosion of a dynamite

magazine, the possibility of being struck by a stone projected by a

blast, the injurious effects of fumes arising from smouldering waste

heaps, or from the calcination of pyritic ores, and extending in

extreme cases to the collapse of entire districts, as, for instance, in

the salt-mining area of Cheshire.[109]

The entire subject of mining is generally looked upon as divisible into

three main branches, namely, “prospecting,” or the search for mineral

deposits; “mining” properly so called, or the exploitation of these

deposits; and “dressing,” or the preparation for the market of the

minerals produced.

Of these three branches the risks incidental to the last named are

practically those to which workers in any ordinary factory are exposed,

and need not be further considered here; whilst minor accidents, such

as cuts and bruises, are common enough, especially when mineral is

broken by hand, serious casualties, on the other hand, are fortunately

rare. The only precautions needed are those indicated in all cases

where men, and in the case of dressing works, often boys, girls, and

women also are at work in the midst of machinery in motion. It may just

be mentioned that, in certain branches of gold mining, a solution of

cyanide of potassium is used as a solvent for extracting the gold; this

solution is not only extremely poisonous when taken internally, but

also produces in many instances painful sores on the hands and arms of

the men working with it.

The life of the prospector is necessarily a most arduous one, and for

which men of exceptionally good physique and sound health are alone

suitable. The typical prospector starts off, generally by himself,

sometimes with a mate, to examine an unknown and at times uninhabited

district; or worse still, the inhabitants may be uncivilised races,

hostile to the white man, and thus their presence only introduces

another and a serious danger to the prospector. At the best he can only

carry a limited amount of food with him, and has often to depend on his

gun for a great part of his supplies. He has, therefore, to time his

journeys accurately, so as to enable him to get back to civilisation

before his stock of provisions or ammunition is exhausted, and many

a poor fellow has paid with his life for the rash eagerness that has

led him too far afield in his search for valuable minerals. In some

countries, such as Western Australia, not only has food to be arranged

for, but drink also, great areas being absolutely without potable

water; there is no doubt that many an explorer in this great auriferous

continent has perished of thirst[110] in his search for the precious

metal.

When mining operations have to be undertaken by the prospector, these

usually take the form of sinking small shafts, less rarely of driving

levels. In either case the timbering is of the crudest character,

any branch of a tree, piece of bamboo, or similar weak support being

generally looked upon as sufficient. The windlass is usually a rough

concern, made entirely, or almost entirely, of wood, and the writer was

once a witness of the remarkably narrow escape of a prospector who was

being hoisted up a shaft by a couple of natives with the aid of such a

rudimentary windlass, after having lit a couple of shots in the shaft

bottom, when one of the rough wooden handles of the windlass suddenly

broke. To the risks incidental to working with imperfect appliances

must be added those due to the fact that only native labour, always

utterly inexperienced in mining and often unused to work of any kind,

is available, whilst the prospector has to undertake, single-handed,

the task of both instruction and supervision.

It but rarely happens that the prospector is fortunate enough to

find a healthy climate at the scene of his operations, although such

is the case in some parts of Australia, South Africa, etc. As the

greater portion of the temperate zone habitable by civilised man has

been pretty well ransacked for minerals, the prospector is generally

compelled to resort to tropical regions for his hunting ground, and

is, therefore, often subject to all the risks of an unhealthy climate,

amongst which malarial fever in its various forms is perhaps the most

formidable. Prospecting in Central America, the northern half of South

America, West Africa, and Central Africa, parts of India, Siam, Burma,

the Malay Archipelago and Peninsula, and some parts of Australia means

in each case the strong probability, amounting almost to a certainty,

of being attacked by malaria, which, though not necessarily fatal,

only too often undermines the strongest constitution. Finally, it must

be remembered that whenever a rich “strike” has been made and a rush

sets in to any small area, the townships that spring up thus suddenly

are invariably unhealthy at first, even in the healthiest climates.

“What is everybody’s business is nobody’s business,” and the most

elementary rules of sanitation are disregarded with the most frightful

recklessness, until the number of victims becomes so serious as to

compel attention. In this way Kimberley, Johannesburg, Coolgardie,

Menzies, etc., have all been visited by epidemics of typhoid or enteric

fever.

That the Polar regions are no more favourable to the prospector than

are the Tropics is only too clearly shown by the death-roll of those

who have been seeking their fortunes of recent years in the Yukon and

other similar parts of far North-Western America. Statistics of the

mortality of prospectors, whether by disease or by accident, are, of

course, not available in any form, but no one who has had much to

do with prospecting can fail to recognise that there are few more

dangerous, just as there are few more fascinating, occupations.

Turning next to mining proper, as carried on in civilised countries,

it becomes necessary to investigate separately the accidents and the

diseases incidental to the miners’ calling. Careful statistics of

mining accidents are kept by many countries, notably Germany, France,

Belgium, and Great Britain, and a comparison of these statistics would,

no doubt, enable us to deduce results of the highest importance if

these statistics were at all comparable. Unfortunately, however, the

definitions of what constitutes a mining accident on the one hand, and

of what constitutes a fatal mining accident on the other, are either

extremely vague, or else will be found to differ in each country.

In Great Britain we have no legal definition at all. The Coal Mines

Regulations Act, section 35, merely says that “loss of life” or

“serious personal injury” due to an accident must be reported, unless

the accident be due to “any explosion of gas, or of any explosive, or

of any steam-boiler,” when every personal injury whatever, whether

serious or not, has to be reported. The Act, construed literally,

seems to require only the reporting of any accident that is instantly

fatal, or of a serious accident that terminates fatally under the

head of “Loss of Life.” If a trivial accident, such as would not need

reporting under the Act, happens to end fatally, as, _e.g._, when

a slight cut or scratch causes blood-poisoning and ultimately death,

the Act seems to deliberately exclude such accidents from the list of

fatalities. In the absence of clear legal guidance, most inspectors

seem to include in their list of fatal accidents all accidents of any

kind whatever that terminate fatally within a year and a day from

the date of the occurrence of the accident. This may not be law, but

it is certainly common sense. The term “serious personal injury” is

interpreted very differently in different places, the ultimate decision

resting with the colliery manager and the colliery doctor. Thus one

doctor may hold that a simple fracture is not a “serious” accident,

and need not be reported; whilst another may consider a bad cut or

bruise, perhaps not sufficient even to lay a man off for a day, as a

“serious” accident, though the majority rather incline to the view that

no accident is “serious” unless there is rather more than a possibility

that it will end fatally. This wide discrepancy of opinion makes it

very difficult to compare fairly the accident statistics of different

parts of the Kingdom, and, as the sequel will show, the British

official non-fatal accident statistics are practically worthless.

In Germany each state or kingdom has its own mining law. The Prussian

law, which is the most important by far of any, and which all the

others follow more or less closely, merely says, that any accident

that has caused death or serious injury to one or more persons must

be at once reported. The accident statistics based upon these reports

are, therefore, even less satisfactory than our own; it would appear

as though the law contemplated only the inclusion of cases of

instantaneous death in the list of fatal accidents, whilst non-fatal

accidents are quite undefined. The Prussian official statistics record

only fatal accidents in mines, except in the case of explosions of

fire-damp, when injuries are also recorded. Fortunately, however,

accurate statistics have been kept for some time past of all mining

accidents by the Official Miners’ Permanent Relief Fund of the German

Empire. This assurance association defines a fatal accident as one

that causes death, whether instantaneously or after any length of

time. Non-fatal accidents are divided into such as incapacitate the

injured person from working for either a longer or a shorter period,

the limit between these two classes being fixed at thirteen weeks. A

distinction is also made between accidents that permanently, and those

that temporarily, disable a miner, and again between those that cause

total, and those that cause partial, disablement. As this Insurance

Fund of Germany is under the direct supervision of the Governmental

authorities, the statistics published by it have all the character of

official documents.

In France mining accidents are simply divided into those that cause

injuries merely and those that cause death, there being apparently no

precise definitions of either.

In Belgium a mining accident is one that has for its consequences the

death or severe injury of one or more persons--severe injury being

defined as an injury of such a nature as to cause the ultimate death

or to interfere with the regular work of the victim. Apparently the

Belgian law, strictly interpreted, would include amongst the fatal

accidents only those where the injured person is killed on the spot,

but in the published statistics, a fatal accident is understood to be

one that causes death within thirty days of its occurrence. Obviously

this definition is much narrower than that used in Great Britain,

a fact that must not be lost sight of when statistics of the two

countries are compared.

Perhaps the most exhaustive analysis of mining accidents is to be found

in a work published in 1897 by the above-mentioned Official Miners’

Permanent Relief Fund of the German Empire,[111] which covers the

period from 1st October 1885 up to 1st January 1895. This Relief Fund,

administered under Government supervision, deals with all accidents

that incapacitate the victims from work for a longer period than

thirteen weeks, all accidents of lesser importance, here called minor

accidents, being dealt with by a separate fund worked in conjunction

with the former. The total number of persons insured for one year

during the period covered by this work was 3,623,175; the total

number of accidents of all kinds notified was 278,371, distributed as

follows:--

Per 1000

Persons

Numbers. Employed.

Fatal accidents 7,721 2.13

Accidents causing total permanent

disablement 1,427 0.39

Accidents causing partial permanent

disablement 14,367 3.97

Accidents causing temporary disablement 8,164 2.25

---- 8.74

Minor accidents 246,692 68.09

------- -----

Total 273,371 76.83

======= =====

Although, as will be seen subsequently, the ratio of fatal accidents

is slowly but steadily decreasing in all the more important mining

countries, the ratios between the various classes of accident appear

to remain approximately constant. It is, however, notorious that ever

since the laws providing compensation for accidents have received their

present form, the number of non-fatal accidents reported in Germany

has been steadily increasing year by year, there being no satisfactory

explanation that can be assigned for this fact. The serious accidents

are classified in various ways, the most interesting of which are those

that refer to the causes of the accidents. Thus, of the above serious

accidents, it is shown that the distribution was as follows amongst the

various branches of mining:--

+--------------------------+---------+-----------------+-----------------+

| | No. of +-------+---------+-------+---------+

| | Persons | |Per 1000 | |Per 1000 |

+--------------------------+---------+-------+---------+-------+---------+

|(_a_) Coal Mines |2,378,673| 6020 | 2.53 |19,130 | 8.04 |

|(_b_) Lignite Mines | 331,522| 617 | 1.86 | 1,354 | 4.08 |

| and Smelting Works | 58,853| 870 | 1.14 | 2,750 | 3.62 |

| Works | 95,423| 143 | 1.50 | 450 | 4.71 |

| Mining | 58,704| 71 | 1.21 | 274 | 4.66 |

+--------------------------+---------+-------+---------+-------+---------+

It is interesting to note that the ratio of accidents above ground to

those below was as follows in the various branches of mining:--

Below Ground. Above Ground.

(_a_) Coal Mines 84.7 per cent. 15.3 per cent.

(_b_) Lignite Mines 45.1 „ 54.9 „

(_c_) Metalliferous Mines and

Smelting Works 73.5 „ 26.5 „

(_d_) Salt Mines and Brine Works 51.4 „ 48.6 „

(_e_) Other forms of Mining 42.3 „ 57.7 „

The information is unfortunately not complete, as the relative numbers

of the workers above and below ground are not given, so that no idea

can be formed from these data of the relative degree of risk of work

above and below ground.

As regards the time at which accidents occur, there are a few more in

the forenoon than in the afternoon, as might well be expected, seeing

that the average number of men at work is greater in the former than in

the latter period. As regards the days of the week, the percentage of

accidents occurring on the respective days is as follows:--

Sunday 2.2 per cent.

Monday 15.1 „

Tuesday 16.2 „

Wednesday 16.6 „

Thursday 15.9 „

Friday 16.7 „

Saturday 17.0 „

Excluding, of course, Sunday, it is noteworthy that the number of

accidents in the second half of the week is notably greater than in the

first half; apparently the only cause that can be suggested for this

circumstance is that the men, being more fatigued towards the latter

end of the week, are on that account more liable to accidents. It may

well be, however, that the facts here noted are themselves merely

accidental, and that observations extended over a larger period would

tend to equalise the numbers.

Two highly interesting series of tables give an objective and a

subjective division of the causes of the accidents, showing in what

manner and by whose fault these originated. The former table may be

summarised as follows:--

KEY:

A: Falls of Rock, Coal, Falling Bodies, etc.

B: Transport, Haulage, Winding, Loading, etc.

C: Falls from Ladders, Steps, or other Heights.

D: Explosions.

E: Machinery in Motion, Motors, etc.

F: Molten Metal, Hot and Corrosive Liquids, Poisonous Gases.

G: Miscellaneous.

+-----------------------------+--------------------------------+

| | Causes of Accident per cent. |

| Branch of Mining. +----+----+----+----+---+---+----+

| | A | B | C | D | E | F | G |

+-----------------------------+----+----+----+----+---+---+----+

|(_a_) Coal Mines |41.1|26.2| 9.1| 9.2|5.7|1.0| 7.7|

|(_b_) Lignite Mines |35.9|28.7|14.8| 3.5|7.9|3.4| 5.8|

| Smelting Works |34.4|20.8|13.1|10.2|5.6|1.9|14.0|

| Works |13.7|31.5|23.6| 7.9|7.3|7.6| 8.4|

|(_e_) Other forms of Mining |31.9|25.2|12.2| 9.6|2.9|...|18.2|

|All Mines |39.4|25.8|10.2| 9.0|5.9|1.3| 8.5|

+-----------------------------+----+----+----+----+---+---+----+

The accidents due to these various causes calculated per 1000 people

employed in the whole mining industry were as follows:--

Falls of Rock, Coal, Falling Bodies, etc. 3.44

Transport, Haulage, Winding, Loading, etc. 2.26

Falls from Ladders, Steps, or other Heights 0.89

Explosions 0.78

Machinery in Motion, Motors, etc. 0.51

Molten Metal, Hot and Corrosive Fluids, Poisonous Gases 0.12

Miscellaneous 0.74

----

Total (Fatal and Serious Accidents) 8.74

====

There were no less than 3.42 accidents per 1000 workers due to falls

of rock and coal in the workings, whilst those due to explosions of

fire-damp were only 0.31 per mil. It will be seen in the sequel that

accidents due to falls of ground of various kinds play by far the most

important part in mining casualties everywhere.

In distributing the blame for these accidents, four main groups are

distinguished, accidents being either apparently unavoidable and

therefore put down to the intrinsic danger of the occupation, or else

due to some fault of omission or commission either of the mine owners

or managers, of the victims themselves or of their fellow-workers. The

numbers for the entire mining industry are given as follows:--

Per cent.

Inherent danger of the occupation 58.2

Per cent.

Defects in or absence of safety appliances 0.2

Insufficient regulations 0.1

Other faults of management 0.9

Faults of the mine owners --- 1.2

Neglect of fellow-workers to use safety appliances 0.1

Contravention of regulations by fellow-workers 1.1

Unskilfulness of fellow-workers 0.3

Carelessness of fellow-workers 2.4

Ignorance of danger on the part of fellow-workers 0.1

Gross negligence of fellow-workers 0.5

Faults of fellow-workers --- 4.5

Neglect of victims to use safety appliances 0.9

Contravention of regulations by victims 6.4

Unskilfulness of victims 4.8

Carelessness of victims 20.3

Ignorance of danger on the part of victims 2.0

Gross negligence of victims 1.5

Fault of victims --- 35.9

Unknown causes 0.2

-----

100.0

=====

This table shows, in the first place, that 41.6 per cent. or two-fifths

of all the accidents could have been avoided by proper care and

intelligent thought on the part of all concerned; and in the second

place, that fully one-third of the accidents can be ascribed to the

faults of the victims themselves. This means that whilst the occupation

is not necessarily much more than half as hazardous as the accident

statistics make it appear, there is but little room for improvement

either in the appliances used or in the regulations framed for the

safety of the miners, and that the remedy lies largely within their

own grasp, the better education of the miner and the development of

his thinking powers being the best protection that can be offered him

against accident. This view is further supported by the fact that in

coal-mining the unavoidable accidents are as high as 61.7 per cent.,

whilst the avoidable accidents fall to 28.2 per cent. (0.1 per cent.

being ascribed to unknown causes). It may be taken as fairly well known

that the coal miners are amongst the better educated and the more

highly trained of all classes of miners, the effect of their higher

intelligence being indicated in these figures.

It is interesting to compare the above data with the results

given in a recent paper by Mr B. M’Laren on “Preventible Colliery

Fatalities,”[112] in which that gentleman analyses the fatal

accidents in Great Britain during the years 1896–98, and points out

that 35 per cent. of the total number of underground fatal accidents

were preventible. In coming to this conclusion, he has included “all

fatalities stated to have been brought about by carelessness or

neglect; those in which a deficiency of props, sprags, bars, chocks,

packs, etc., are mentioned; cases of want of judgment; a moment’s

forgetfulness on the part of some one; acts contrary to the Coal Mines

Regulation Act, special rules, and ordinary regulations; want of care,

etc.; and those which present themselves as possibly preventible; while

all apparently doubtful cases are omitted.” It may be added that this

writer, like most others on this subject, concurs in the view that “the

best preventive for colliery accidents is technical education.”[113]

These German figures have been dealt with at considerable length

because they give the most complete picture anywhere obtainable of the

liability of miners to serious or fatal accidents. Although the tables

in the work dealt with extend only up to the year 1895, they are still

perfectly applicable to the present day; this is perhaps best seen by

taking the proportion of fatal accidents for the decade 1890 to 1899,

when it will be seen that though these fluctuate considerably about the

average for the period under consideration, yet their general average

agrees pretty well with that of the period covered by the work quoted,

namely, 1885 to 1895:--

Death-rate

Year. per 1000 Persons.

1890 2.19

1891 2.44

1892 2.05

1893 2.27

1894 1.91

1895 2.16

1896 2.21

1897 2.05

1898 2.53

1899 2.03

----

Average 2.18

====

No other equally complete data are available for any other country.

In addition to the special report that has been here summarised, this

official Relief Fund publishes annual statistics,[114] and these can

be compared with the official statistics published annually by the

Government from the returns collected by the Inspectors of Mines; it is

true that these latter do not refer to the German Empire as a whole,

but are published separately for the principal mining states, namely

Prussia[115] and Saxony[116]; the Prussian statistics are especially

useful, because, out of the total number of miners employed in the

German Empire, no less than nine-tenths are included in the kingdom of

Prussia.

* * * * *

The following table shows the proportion of Fatal Accidents as given in

the above quoted Prussian statistics for 1899:--

+-------+---------------------------------------------------+

| | Fatal Accidents per 1000 Persons Employed in |

| +-----------+-------+-------------+--------+--------+

+-------+-----------+-------+-------------+--------+--------+

| 1891 | 2.889 | 1.825 | 1.035 | 1.018 | 2.395 |

| 1892 | 2.208 | 1.710 | 1.081 | 2.224 | 1.963 |

| 1893 | 2.619 | 2.089 | 0.794 | 2.298 | 2.245 |

| 1894 | 2.209 | 1.986 | 1.005 | 1.935 | 1.983 |

| 1895 | 2.540 | 2.103 | 1.002 | 1.917 | 2.229 |

| 1896 | 2.577 | 1.664 | 1.137 | 1.649 | 2.241 |

| 1897 | 2.353 | 2.362 | 1.046 | 1.611 | 2.124 |

| 1898 | 2.864 | 1.992 | 0.994 | 1.956 | 2.485 |

| 1899 | 2.314 | 1.945 | 1.393 | 1.231 | 2.114 |

|1890–99| 2.518 | 1.946 | 1.079 | 1.708 | 2.204 |

+-------+-----------+-------+-------------+--------+--------+

These figures refer to the total number of workers both below and above

ground; an analysis for the year 1899 gives the following results:--

Per 1000 Persons

Employed Underground.

Fatal accidents due to explosions 0.079

„ „ haulage and winding 0.874

„ „ falls of coal and stone 1.191

„ „ after-damp 0.112

„ „ blasting 0.121

„ „ miscellaneous causes 0.142

-----

Total fatal accidents underground 2.519

=====

Per 1000 Persons

Employed Above Ground.

Total fatal accidents above ground 1.082

Per 1000 Persons

Employed in Open Workings.

Total fatal accidents in open workings 1.455

It will be seen that the death-rate per 1000 persons employed is very

nearly the same as that given by the Relief Fund Association, an

agreement that goes far to confirm the belief above expressed in the

general reliability of these statistics. It is important to note that

metal-mining is in Germany a far safer occupation than coal-mining, a

state of affairs that would naturally be expected to obtain, having

regard to the conditions of safety of these two classes of work, and

bearing in mind that in Germany the educational level of both classes

of miners is more nearly the same, and that the legislation for both

is practically identical. It should be added that the above statistics

refer only to persons regularly employed in mines, and excludes fatal

accidents that may occur in or about any mine, to persons not comprised

in the category of regular mine employés; the inclusion of such cases

would increase the above total figure by about 2.5 per cent.

In Belgium, careful statistics of accidents are published,[117] and in

spite of the fact that her coal mines present circumstances of special

difficulty, the recorded death-rate is a low one, due partly to the

fact already pointed out, that only deaths within thirty days of the

accident are reported. Moreover, in Belgium, deaths due indirectly to

mine accidents are excluded from the lists. Coal-mining being the chief

mineral industry of Belgium, the mineral statistics of that kingdom are

more particularly devoted to it. The death-rate has been as follows in

the Belgian coal mines from the year 1895 to 1899:--

+-------+---------------------------------------+

| | Death-rate per 1000 Persons Employed. |

| Year. +-----------------+---------------------+

| | At Surface and | Underground only. |

| | Underground. | |

+-------+-----------------+---------------------+

| 1895 | 1.33 | 1.58 |

| 1896 | 1.14 | 1.38 |

| 1897 | 1.03 | 1.31 |

| 1898 | 1.40 | 1.71 |

| 1899 | 0.97 | 1.09 |

+-------+-----------------+---------------------+

In 1899 there were 241 separate accidents underground, causing 101

deaths, and 151 serious injuries; of these, 85 accidents, killing 48

and injuring 43 workmen, were due to falls of rock or coal; accidents

due to haulage produced 63 casualties, of which 19 were fatal, the

majority, or 39 accidents, occurring in roads which were approximately

level. There was only one explosion of fire-damp, causing 4 deaths,

but there are 6 fatal accidents recorded as due to choke-damp. An

interesting table shows that the number of accidents due to falls of

rock or coal has produced an annual average of 0.73 deaths per 1000 men

employed, the year 1899 happening to be considerably below the average

in this particular category.

In France also, great attention is paid to conditions affecting the

security of the miner. Great care is exercised by the Inspectors of

Mines, and the accident death-rate appears to be decreasing steadily

and satisfactorily, but, in comparing the French statistics with these

of other countries, it must be remembered that the former include only

accidents that result fatally within a few days of their occurrence,

there being no rule at all on the subject. The following table shows

the death-rates per thousand since 1894[118]:--

+-----+--------------------------------------------------------------------+

| | Death-rate per 1000 Persons Employed. |

| +--------------------------------------------------------------------+

|Year.+-------+-------+------+-------+-------+------+-------+-------+------+

+-----+-------+-------+------+-------+-------+------+-------+-------+------+

|1894 | 0.97 | 0.55 | 0.85 | 0.92 | 0.54 | 0.81 | 0.96 | 0.55 | 0.84 |

|1895 | 1.41 | 0.68 | 1.19 | 1.73 | 0.31 | 1.32 | 1.43 | 0.65 | 1.20 |

|1896 | 1.62 | 0.50 | 1.30 | 1.97 | 0.90 | 1.67 | 1.65 | 0.53 | 1.33 |

|1897 | 1.34 | 0.41 | 1.07 | 2.52 | 0.84 | 2.06 | 1.44 | 0.44 | 1.10 |

|1898 | 1.26 | 0.60 | 1.07 | 3.06 | 2.00 | 2.75 | 1.41 | 0.72 | 1.21 |

|1899 | 1.62 | 0.66 | 1.29 | 2.11 | 1.02 | 1.78 | 1.67 | 0.70 | 1.39 |

+-----+-------+-------+------+-------+-------+------+-------+-------+------+

Coal-mining forms the principal portion of the French mining industry,

over 90 per cent. of those engaged in mining being employed in

collieries of various kinds. Metal-mining is comparatively unimportant,

and is generally carried on upon a small scale, a fact that in part

no doubt accounts for the relatively high accident death-rate. In

coal-mining, on the other hand, the rate is a very low one. Many French

collieries are controlled by large corporations, and in these large

and well-managed concerns all work is done with the greatest care, and

carried on in the most approved style.

Italy is rarely looked upon as a mining country, yet there are over

60,000 persons annually engaged in mining proper in the kingdom of

Italy, the mining being practically all metalliferous mining. The

following are the recent Italian accident statistics[119]:--

+-----+--------------------------------------------------+

| | Per 1000 Persons Employed. |

| +----------------+----------------+----------------+

| +-------+--------+-------+--------+-------+--------+

+-----+-------+--------+-------+--------+-------+--------+

|1897 | 2.77 | 3.23 | 0.78 | 0.86 | 2.31 | 2.67 |

|1898 | 1.75 | 3.50 | 0.46 | 1.39 | 1.41 | 2.95 |

|1899 | 2.10 | 3.29 | 0.42 | 1.08 | 1.66 | 2.72 |

+-----+-------+--------+-------+--------+-------+--------+

It is worth noting that about two-thirds of the fatal and one-half of

the non-fatal accidents underground are due to falls of stone, this

being here, as elsewhere, the most prolific cause of disaster. The

comparatively high death-rate in Italy cannot well be due to any of the

conditions of mining, none of the mines being particularly deep, or

presenting any conditions of abnormal danger or difficulty. It is more

than probable that the high rate is due to the low educational level

of the Italian miner. Whilst not less naturally intelligent or skilful

than his fellow-worker in Britain, Germany, or France, his technical

training is far inferior, and to this deficiency the higher accident

death-rate in Italy may fairly be ascribed.

In the United States it is only within quite recent years that

any attempt has been made to obtain accurate statistics of mining

accidents, and these are still mainly confined to coal mines; even now

the inspection of these leaves a good deal to be desired. The following

figures are given for miners other than coal miners in an article by

F. L. Hoffman,[120] from which most of the following information is

derived:--

+------------------------------------------------+-------------------+

| |Accident Death-rate|

| Occupation, Locality, and Year. | per 1000 |

| | Persons Employed. |

+------------------------------------------------+-------------------+

|Iron Ore Miners, Michigan (1892–96) | 5.14 |

| „ „ (1899–1900) | 3.62 |

|Copper Mines, Lake Superior (1892–96) | 3.57 |

| „ „ (1898–99) | 2.07 |

|Metal Miners, Colorado (1896–97) | 3.89 |

|Metal Miners (Lead and Zinc), Missouri (1892–97)| 2.59 |

+------------------------------------------------+-------------------+

It is obvious that the collection of accurate statistics in the Western

States, where the mines are much scattered and there is practically no

inspection, is quite out of the question.

The following table, taken from the paper above quoted, shows the

accident death-rate in coal mines in the various States of the Union

during the period 1886–1897, as far as such statistics are available:--

States and Accident Death-rate

Territories. per 1000

Persons Employed.

Alabama 1.63

Colorado 4.72

Illinois 1.82

Indiana 2.32

Indian Territory 3.76

Iowa 2.28

Kansas 1.62

Kentucky 1.50

Maryland 1.63

Missouri 2.19

New Mexico 9.42

Ohio 1.53

Pennsylvania (Anthracite) 3.15

Pennsylvania (Bituminous) 1.88

Tennessee 4.16

Washington 10.70

West Virginia 3.30

In all bituminous coal mines (average) 2.12

In all anthracite mines (average) 3.15

In all coal mines (average) 2.53

The first point that is brought out by this table is that anthracite

mining is evidently more dangerous than bituminous coal-mining, and

this is the more striking seeing that anthracite coal does not give off

fire-damp, so that the dangers of gas explosions are here excluded.

The general conditions of anthracite mining, and more particularly

the steep inclination and great thickness of many of the seams, are

sources of danger that are not met with in ordinary coal-mining.

Although, as has been already pointed out, comparisons between the

statistics of different countries must be made with the utmost caution,

it seems certain that the accident death-rate in the bituminous mines

of the United States is higher than in the more important European

coal-producing countries. There seems to be nothing in the nature of

the bituminous coal mines of America to account for this fact, which is

no doubt largely due to the circumstance that the American coalfields

do not as yet possess a settled coal-mining population properly so

called, and that experienced coal miners are therefore rare, any

working man taking casually to coal-mining for a while, as he might

to any other temporary occupation. Such men can of course never gain

the experience and almost intuitive knowledge of coal-mining that is

acquired by coal miners in the older continent, who are generally born

and bred on the coalfields and imbibe knowledge about coal-mining

matters from their earliest childhood. Another equally potent

factor is the extraordinary mixture of nationalities to be found in

most American coal mines, which seem to be the first refuge for the

immigrant labourer from Eastern or South Eastern Europe. The result,

of course, is that regulations or orders are only half understood,

and are therefore not properly obeyed. Attention has recently been

directed to this source of danger in various parts of the world; for

example, the employment underground of persons who are not acquainted

with the German language has recently been forbidden in the Westphalian

coalfield. It is worth while noting that the States in which machine

coal-cutting is most largely employed, such as Ohio and Illinois, show

death-rates well below the average of the United States as a whole.

Turning now to Great Britain, there is a large mass of statistical

material available by which the liability to accident of the British

miner may be gauged. Each of H.M. Inspectors of Mines in charge of a

district issues an annual report, a great portion of which is devoted

to mining accidents and their causes, and these district reports are

summarised in the General Report and Statistics, Part II., Labour,

whilst an advance proof is also published early in each year. It may be

as well to point out first of all that the death-rate due to accidents

has been steadily diminishing during the last half century,[121] as is

well shown by the following table, worked out for quinquennial periods

from 1851 to 1899:--

+------------+------------------------------------------------------------+

| | Average Annual Death-rate per 1000 Persons |

| | Employed in all Mines in Great Britain. |

| +--------------------------------------------+-------+-------+

| +-----------+--------+-------+-------+-------+-------+-------+

| |Explosions.|falls of|Shafts.| ellan-| all | all | all |

+------------+-----------+--------+-------+-------+-------+-------+-------+

| 1851–1855 | 1.280 | 2.016 | 1.296 | 0.556 | 5.149 | 1.012 | 4.301 |

| 1856–1860 | 1.234 | 1.846 | 0.899 | 0.648 | 4.628 | 0.994 | 3.883 |

| 1861–1865 | 0.618 | 1.714 | 0.668 | 0.790 | 3.791 | 1.105 | 3.240 |

| 1866–1870 | 1.158 | 1.578 | 0.528 | 0.730 | 3.995 | 1.256 | 3.433 |

| 1871–1875 | 0.516 | 1.210 | 0.437 | 0.572 | 2.736 | 0.899 | 2.342 |

| 1876–1880 | 0.811 | 1.132 | 0.317 | 0.449 | 2.709 | 0.847 | 2.306 |

| 1881–1885 | 0.408 | 1.108 | 0.263 | 0.532 | 2.312 | 0.848 | 2.007 |

| 1886–1890 | 0.312 | 1.015 | 0.196 | 0.517 | 2.042 | 0.913 | 1.806 |

| 1891–1895 | 0.244 | 0.798 | 0.188 | 0.470 | 1.704 | 0.820 | 1.524 |

| 1896–1899 | 0.117 | 0.783 | 0.122 | 0.457 | 1.479 | 0.798 | 1.338 |

+------------+-----------+--------+-------+-------+-------+-------+-------+

This table shows that as far as comparisons with other countries are

at all possible, mining in Great Britain has reached a level of safety

with which but few other nations can compare favourably; it also

brings out the very satisfactory fact that the accident death-rate is

steadily decreasing, although further investigation will show that all

branches of the mining industry do not share equally in the decrease.

Great Britain is essentially a coal-mining country, its metal-mining

having been for years constantly diminishing until it is now almost

a negligible quantity; it must, however, be remarked that by one of

those curious legislative freaks that are so familiar to the miner in

this country, the only remaining important branch of metal-mining,

namely, ironstone-mining, is for legal purposes included under the

head of coal-mining, and figures as such in all these statistics.

About 95 or 96 per cent. of all persons employed in mining work in the

coal mines as thus legally defined, over 93 per cent. being employed

in coal-mining properly so called. The following table shows the

death-rates for quinquennial periods from 1875 to the end of 1899 for

coal and metal miners, taken separately, using these words in their

official sense:--

+------------+-----------------------------------------------+

| | Average Annual Death-rate in Great Britain |

| | per 1000 Persons Employed. |

| +-----------------------+-----------------------+

|Quinquennial| | |

| Periods. | In Coal Mines. | In Metal Mines. |

| +-------+-------+-------+-------+-------+-------+

+------------+-------+-------+-------+-------+-------+-------+

| 1876–1880 | 2.752 | 0.936 | 2.396 | 2.170 | 0.432 | 1.472 |

| 1881–1885 | 2.310 | 0.962 | 2.046 | 2.338 | 0.461 | 1.600 |

| 1886–1890 | 2.038 | 0.970 | 1.834 | 2.116 | 0.318 | 1.428 |

| 1891–1895 | 1.686 | 0.874 | 1.526 | 2.250 | 0.392 | 1.482 |

| 1896–1899 | 1.462 | 0.816 | 1.340 | 1.898 | 0.468 | 1.305 |

+------------+-------+-------+-------+-------+-------+-------+

An examination of this table shows very clearly that practically all

the improvement has been confined to coal-mining. Leaving surface

labour out of question for the moment, it is seen that the death-rate

amongst coal miners for the period 1896–99 is little more than half of

what it was in 1876–80, whilst in metal-mining there has only been a

somewhat doubtful improvement of about 12½ per cent. Contrary to the

popular opinion, coal-mining in this country is obviously now a very

much safer employment than metal-mining, and has been so for about the

last twenty years. The death-rates of surface workers have in both

cases remained about stationary during the last twenty-five years. It

is evidently nearly double as high at collieries as it is at metal

mines, the reason for this being undoubtedly the greater complexity of

surface machinery, the far more intensive rate of work at the former,

and above all the fact that the surface works of the vast majority of

collieries are connected by a network of railway lines and sidings.

That these are a grave source of danger needs hardly any proof, but

such is easily obtainable, seeing that the accident death-rate of

all males in Great Britain is about 0.87[122] per 1000, whilst that of

railway employés, such as pointsmen, porters, guards, etc., is no less

than 2.286[122] per 1000. It is evident that the higher death-rate

at the surface of collieries as compared with metalliferous mines is

easily enough accounted for, and the fact is, moreover, indicated in

the statistics themselves. For example, in 1899, nearly 60 per cent. of

the total number of surface accidents at collieries were returned as

due to this cause. The suggestion of a remedy is unfortunately a far

more difficult matter; this necessarily lies largely in the hands of

the men themselves, and whilst it must be admitted that working about

and amongst railway trucks is a dangerous occupation, it is a danger

that can be considerably lessened by the care and attention of the

workers themselves.

An analysis of the causes of fatalities in coal mines leads to several

important conclusions. In the first place it is obvious that the danger

which is most prominently connected in the public mind with coal mines,

that, namely, of explosions, is now one of the least formidable.

The death-rate from explosions within the last five years has been as

follows in all the collieries of the United Kingdom:--

Death-rate

Year. per 1000 Persons

due to Explosions.

1895 0.10

1896 0.31

1897 0.03

1898 0.05

1899 0.09

These figures have now become so small that they are necessarily

irregular, an accident of any magnitude, causing even a dozen deaths,

being sufficient to affect the rate very greatly. The improvement

within the last twenty years is extremely marked, and is due to various

causes, among which may be enumerated better ventilation, the far more

extended use of safety lamps, the substitution in all dangerous mines

of safer explosives for the once universally used black powder, and

above all, of some better method of firing for the highly dangerous

“squib.” It is highly probable that further improvements may be looked

for with every prospect of success in this latter direction, and that

the general adoption of electric firing would be a distinctly valuable

safeguard. The recognition of the fact that coal-dust is an explosive

agent but little less dangerous than fire-damp, due largely to the

labours of Professor W. Galloway and Mr H. Hall, and the precautions in

the form of watering now adopted, have also played an important part

in reducing the death-rate. It need hardly be added that most of these

precautions would have been of little value, even if their introduction

had been possible, unless the scientific training of managers,

officials, and men alike had concurrently made considerable advances.

It is scarcely possible to enforce in a coal mine laws or regulations

of which the more intelligent, at any rate, amongst the miners

themselves do not see the use, and legislation alone could do but

little, unless there existed a general feeling in the mining community

that it was tending in the right direction. It needs a certain amount

of technical and scientific training, however, to enable the average

coal miner to realise such a fact, and that he has been brought to

realise it is one of the main factors in the increased security that

men enjoy nowadays.

The main cause of disaster underground has always been, and still

remains, that classed as “falls of ground,” to which considerably over

half of the deaths underground are due. Explosions have now been so

far brought under control that an explosion has come to be looked upon

as an abnormal accident, due to a fault of omission or commission on

the part of somebody, and therefore requiring careful investigation,

whilst falls of ground are unfortunately still regarded as normal

risks incident to the miner’s calling. These falls may be subdivided

according as they are falls at the working face, when they are either

falls of roof or falls of the coal face, or they are “backbye”

accidents, that is to say, falls of roof in the roadways of the mine.

Falls at the face are accountable for over 70 per cent. of the total

number of deaths due to falls, but unfortunately our statistics do not

discriminate between falls of coal and falls of roof at the face. In

the absence of definite information on this important point, it is

difficult to suggest what remedies should be applied, but these must

depend greatly upon what may be found to be the most fertile causes of

accident; falls of the roof, properly speaking, can only be avoided

by setting more props, or by setting them better; falls of coal may

be due to bad “spragging,” or to the undercut mass of coal falling

forward, or to its coming away at one of the natural cleavage joints

of the coal. In Germany a Government Commission has been appointed to

inquire into the whole question of falls of ground, and no doubt the

report, when issued, will throw much light upon this difficult subject.

It is obvious that the two kinds of falls require entirely different

treatment; systematic timbering, _i.e._, the setting of props at

regular uniform distances apart, whether the roof seems to need it or

not, is being advocated in several quarters, and it should certainly do

something to reduce the number of accidents due to falls of roof. Falls

of coal can hardly be treated in the same way; systematic spragging

might do something, but would probably not of itself be sufficient. A

very obvious mode of reducing the accident rate at the working face

should be found in the more extensive use of coal-cutting machinery;

in the first place the number of men necessary to be employed at the

coal face for a given output would be very considerably reduced, and

hence the number of men exposed to this danger would be proportionally

diminished. Furthermore, as the machine cuts rapidly, and must be kept

moving constantly if it is to be economically successful, the men

working it will always be under a comparatively fresh roof, which is

far less liable to sudden falls than a roof that has been laid bare

for some time, the same being true also of a freshly-cut face of coal,

which should never, under these conditions, be left standing long

enough for the weight of the roof to affect it. Finally, a man working

with a machine has a far better chance of looking about him and seeing

what is going on than has a miner lying on his side, half under the

coal, engaged in “kirving his holing,” that is to say, in hewing out

with his pick a narrow strip of coal along the floor of the seam, an

operation that has to be performed preparatory to breaking down the

mass of coal.

It is highly probable that one of the conditions that has contributed

very largely to the prevention of colliery explosions, namely, the

extended use of safety lamps, has at the same time been a contributary

cause of the non-diminution in the number of accidents due to falls of

ground. Among the conditions that have been laid down from time to time

by Royal Commissions and others as essential to a good safety lamp,

that of giving a sufficient amount of light has been very generally

overlooked, and most of the safety lamps in use give a very poor light,

especially after they have been burning for a few hours. Their shape,

moreover, prevents their giving a top light, so that it is scarcely

possible for a miner to adequately examine the roof of his working

with a safety lamp, so as to see whether it is dangerous or not. Much

was hoped from the introduction of portable electric lamps, but so far

these have not come up to expectations, partly because no entirely

satisfactory electric lamp has yet been devised, partly because the

ordinary electric lamp does not, like the ordinary safety lamp,

indicate the presence of gas, and thus allows the miner to continue

his work without giving him warning that he is in an atmosphere in

which he ought not to remain. A really good safety lamp, giving a light

all round at least equal to that of an ordinary candle, is a great

desideratum at the present moment.

Of the remaining causes of accidents underground, the most serious are

those connected with the transport of the coal; the various systems

of mechanical or self-acting haulage in use in all collieries of any

importance must always give rise to a certain number of accidents,

but it can only be said that the number of these could be greatly

diminished by a stricter attention to colliery regulations. A large

number are due annually to men and lads riding upon the tubs, so as to

save themselves the exertion of walking to or from the shaft bottom.

Shaft accidents have fortunately diminished considerably within the

last twenty years, having come down to about one-third of what they

were; much of the improvement is no doubt due to the greater attention

now being paid to the quality and condition of the winding ropes. A

notable proportion of the accidents classified under this head occurs

not in regular mining, but during the sinking of shafts, an operation

that always of necessity involves a good deal of risk.

Turning next to metal-mining, the most striking fact is that the

conditions of safety have undergone such small improvement; the

figures of course fluctuate a good deal from year to year, because

the total number of men engaged is so small that a very few accidents

more or less affect the ratios very considerably. It should be noted

that metalliferous mines, as defined by law, include a large number

of mines in which no metallic minerals are wrought, and should more

properly be described as all mines not included under coal mines; the

metalliferous mines properly so called show a far higher death-rate

than is returned for the miscellaneous mines legally described as

metalliferous. Here again, as in coal mines, the largest number of

casualties is due to falls of ground, by which nearly two-thirds of

the total number of deaths is caused. In metal-mining, the miner’s

safety must depend far more than in coal-mining upon the worker’s own

judgment, experience, and carefulness; it can only be suggested that

mine managers should see to it that an ample supply of suitable timber

is kept close to all the working places, and that the timbering of

all levels, etc., should be constantly inspected by special officials

appointed for this purpose.

The most interesting problem that presents itself for solution is,

however, the question why the form of mining that was the safer of the

two twenty-five years ago in this country, and which is still far the

safer in Germany, is now the more dangerous, and why the death-rate in

one should have been reduced 50 per cent., whilst in the other it has

remained practically stationary. The only salient point of difference

to be found between the present regulations affecting the two forms

of mining is, that whilst the Coal Mines Regulation Acts insist that

no man shall be allowed to act as either manager or under-manager

of a colliery unless he has passed certain prescribed examinations,

any one is at liberty to manage a metalliferous mine, whether he be

qualified to do so or not. The result has been that the educational

level of coal miners as a whole has been raised; every intelligent

coal miner knows that the only road to ultimate promotion lies through

these examinations, and therefore applies himself to the scientific

study of his work. There are thus growing up in every coalfield in

Great Britain numbers of technically well-educated young men, from

whom colliery managers can select their colliery officials, and the

higher educational standard thus attained by the officials is slowly

but surely affecting both the working miner on the one hand, and the

manager on the other, as it is obvious that the latter dare not remain

on an intellectually lower plane than his subordinates. It is probable

this educational development has played a leading part in the improved

conditions of safety in coal mines, not only directly, by increasing

the knowledge and thinking powers of the miners, but indirectly, as

already said, by rendering legislation easy that would scarcely have

been possible without it, all of which merely amounts to another

repetition of the statement, that improved education is the best

safeguard of the miner against accident. It will be remembered that the

same conclusion was already drawn from the comparison of the accident

death-rates of various countries, the highest death-rates being found

in the most ignorant nations. Although much has been done in this

country within the last twenty-five years, very much still remains to

be done in order to bring up the educational level of all connected

with mining to the high standard of scientific technology that is to be

found in some other countries.

It should here be pointed out that mining, and more especially

coal-mining, is really not the highly dangerous occupation that it is

usually thought to be. The annual average accident death-rate[123] for

all males in Great Britain is 0.870 per 1000, with which the present

rate for coal miners underground of 1.462 per 1000 does not compare

very unfavourably. The true accident risk of the miner is perhaps best

seen by comparing it with a few of the other trades that are usually

classed as dangerous:--

Average Annual Accident

Occupation. Death-rate per 1000

in the years 1891–93.

Bargeman, Lighterman, etc. 3.765

Seaman, Merchant Service 3.219

Dock Labourer, etc. 2.411

Railway Guard, Porter, Pointsman, etc. 2.286

Railway Engine Driver, Stoker 1.340

General Labourer 1.155

As regards non-fatal accidents, it has already been pointed out that

the official statistics of this country are of practically no value,

owing to the absence of any standard or definition of what constitutes

an accident to be reported. The following table shows the number of

persons injured in mines (non-fatal accident cases) _according to the

official statistics_:--

+------+------------------------------+

| |Number of Persons Injured per |

| | 1000 Persons Employed. |

| Year.+--------------+---------------+

| |In Coal Mines.|In Metal Mines.|

+------+--------------+---------------+

| 1895 | 7.49 | 6.96 |

| 1896 | 8.29 | 9.89 |

| 1897 | 6.42 | 8.29 |

| 1898 | 5.74 | 9.75 |

| 1899 | 5.66 | 10.10 |

+------+--------------+---------------+

It will be seen presently that these figures are ludicrously

disproportionate to the real casualties, and although it is difficult

to get accurate data about these, an approximation, at any rate, to the

true facts can be obtained.

Valuable information is afforded by the various Miners’ Permanent

Relief Funds, and by the Central Association for dealing with

distress caused by mining accidents. The latter Association publishes

statistics, from which the following table has been compiled, this

representing the summary of the returns from the nine English societies

(there are no Scotch or Irish ones) which together compose the

Association[124]:--

+------+---------+------------------------------+

| | | No. per 1000 Members. |

| | No. of +---------------+--------------+

+------+---------+---------------+--------------+

| 1889 | 238,892 | 2.12 | 188.3 |

| 1890 | 268,985 | 2.66 | 157.2 |

| 1891 | 287,690 | 1.88 | 149.8 |

| 1892 | 295,676 | 2.17 | 139.8 |

| 1893 | 299,027 | 1.59 | 144.8 |

| 1894 | 313,438 | 2.50 | 159.4 |

| 1895 | 317,004 | 1.99 | 166.8 |

| 1896 | 325,708 | 1.90 | 177.6 |

| 1897 | 334,428 | 1.76 | 192.6 |

| 1898 | 271,536 | 1.81 | 196.3 |

| 1899 | 279,842 | 1.67 | 176.6 |

+------+---------+---------------+--------------+

The accident death-rate reported by the Association is rather higher

than is shown in the Inspectors’ Official Reports, because in the

latter only deaths that occur within a year and a day of the accident

are included, whereas in the tables compiled by the Association all

deaths that can be referred to mining accidents are given, however long

the interval may be between the accident and the death of the injured

person.

The disablement cases in the above table comprise all injuries received

by any member of the Association that are sufficiently serious to

keep the victim off work for at least a week. They are _more than

twenty times_ as numerous as those included in the Inspectors

of Mines’ Reports, and this may be accepted as conclusive evidence

that these reports do not record by any means all cases of “serious

personal injury.” It is true that the two sets of statistics are not

in all respects strictly comparable; the Inspectors of Mines take no

account of an accident unless it happens within the precincts of the

mine as legally defined, while the Associations’ regulations extend to

accidents that may happen to miners going to or returning from their

work. There is also a suspicion that occasional cases of disability

to work are returned as due to accident, when they are really not so

caused, and escape the vigilance of the various societies’ officials.

Making all allowances, however, for these and similar defects, the

above figures may be looked upon as reasonably accurate, and as fairly

representing the risk of minor accidents to which the coal miner is

exposed in this country; it may be added that the figures for each

individual society do not vary very greatly from the general average,

as shown by the Association. It is difficult to see why they should

be about twice as high as the corresponding accidents in Germany, for

although there may be some laxity in admitting supposed accidents, this

circumstance cannot possibly account for one-half of the cases. It

would be a decided advantage if Inspectors of Mines had power to record

and report all cases of “smart money” and of compensation respectively

paid by the collieries in their districts, as fairly accurate

statistics of minor accidents could be obtained in this simple manner.

It would also be more satisfactory if all accidents were subject to

the examination of special medical officers appointed solely for this

purpose. In this way the suspicion would be avoided that a medical

practitioner may at times take too lenient a view of a doubtful case,

biassed perhaps by the fact that his livelihood may depend largely upon

the goodwill of the miners, who often form the bulk of his patients.

By far the most important of the individual societies that make up the

Central Association is the Northumberland and Durham Miners’ Permanent

Relief Fund; from the annual reports of this society useful information

may be gathered, some of which is summarised in the following table:--

+------+---------+-------------------------------------+

| | | No. per 1000 Members. |

| Year.| No. of +-------+--------------+--------------+

+------+---------+-------+--------------+--------------+

| 1896 | 122,257 | 1.33 | 1.96 | 156.6 |

| 1897 | 124,920 | 1.60 | 1.94 | 156.8 |

| 1898 | 127,564 | 1.24 | 1.96 | 152.1 |

| 1899 | 130,552 | 1.50 | 2.00 | 148.4 |

+------+---------+-------+--------------+--------------+

According to the rules of the society an injured man whose injuries

prevent him from working for a week is considered as “temporarily

disabled,” and he continues in this category until he is fit to return

to work, unless he is so badly hurt as to be unable to work for six

months, when he is classed as “permanently disabled”; such a man may

either recover sufficiently to be able to work again, or he may die, or

he may remain disabled for life. The duration of permanent disablement

as above defined has of course risen gradually from the commencement of

the fund, until it amounted to 5.17 years in the quinquennial period

1887–91, its average duration from the formation of the fund having

been 4.42 years.[125]

The duration of temporary disablement was about:--

3.5 weeks in the year 1896

3.6 „ „ 1897

3.55 „ „ 1898

3.55 „ „ 1899

In the Liverpool district, the ratio of permanent disablement is found

to be 4.5 per 1000 members, and of temporary disablement 180 per 1000

members; the duration of the former cases averages 3½ years, and that

of the latter 4.3 weeks.

Annual reports are also issued by the Prussian Official Miners’ Relief

Fund; the report for 1898 gives the accident death-rate of the members

of the Association as 2.69 per 1000 members, the death-rate from all

other causes being 5.39, making a total death-rate of 7.58 per 1000.

It is worth noting that the average age at which members are totally

incapacitated from working is 49.2 years, whilst the average age at

which members are partially incapacitated is about forty-five years;

this includes disablement due to old age as well as to accident.

Coming lastly to the subject of the diseases of miners, it may first

of all be stated that mining is a distinctly healthy occupation. The

mortality of all males[126] in Great Britain during the years 1890–92

was 18.74 per 1000, out of which 0.87 deaths were due to accident,

leaving 17.87 per 1000 due to what may be termed natural causes. On

the other hand the mortality among coal miners from all causes for the

same period was 12.33, that due to accident being given as 2.00,[127]

making the death-rate due to natural causes only 10.35 per 1000. Of

course it must not be forgotten that the working miner’s career covers

just that period of life at which the natural death-rate is lowest.

There are no doubt several circumstances that contribute to the general

healthiness of the miner’s occupation; in the first place, mining is

hard work, and men whose constitution is not tolerably sound, and whose

physique is not fully up to the average, will either select some less

arduous occupation at the outset, or will find themselves, if they

began life as miners, unable to continue at the work. On the other

hand, the work, though arduous, requires steady though only moderate

exertion, and does not expose the worker to the abnormally violent

strains, exerted through brief periods, that characterise some other

occupations. Again, the hygienic conditions are, as far as the coal

mine at least is concerned, far more favourable than in most other

occupations. The miner works in a good atmosphere, ample ventilation

being a prime necessity for ensuring the safety of the coal miner,

in an equable temperature, free from the extremes alike of heat and

cold, he is not exposed to the inclemencies of the weather, and his

working place is usually dry. The same cannot always be said of the

miner in metalliferous mines, where the conditions of work are far less

favourable in every respect, and his mortality is therefore higher. It

may be added that the coal miner, if even moderately industrious, can

always earn a wage ample to keep him in fair comfort, and to supply him

fully with all the necessaries of life. Probably the most unhealthy

part of the coal miner’s work consists in “kirving” or undercutting the

coal, in doing which the miner has to lie on his side on the floor of

the coal seam, swinging his pick with a peculiar sideways stroke over

his head, till he has cut out a narrow groove some 3 feet deep below

the over-hanging mass of coal. Work in this constrained position is

necessarily harmful to some extent; its effect has been most noticed as

affecting the nervous system, and especially the nerves of the eyes,

the disease known as miner’s nystagmus having been often ascribed to

it. Cases of miner’s nystagmus occur, however, also among miners who

do not have to kirve, and it may well be due in great part to the poor

light obtainable in so many cases underground, especially when safety

lamps are used, and the consequent strain on the eyes; at any rate

this seems to be the opinion of several who have suffered from this

complaint. The coal miner working in this position is also bound to

inhale a considerable amount of fine coal-dust, which has an irritating

effect upon the lungs; thus it appears from the tables already

referred to that the percentages of deaths of coal miners due to the

respective causes indicated were as follows:--

Causes of Death. Percentage of

Total Number of Deaths.

Accident 16.2

Phthisis 10.7

Bronchitis 12.4

Pneumonia 10.9

The most obvious remedy for reducing the proportion of diseases due to

the above causes is the one already referred to, namely, the general

use of mechanical coal-cutters, and the replacement of hand kirving

by machine kirving. Another cause besides coal-dust that is probably

answerable for a considerable proportion of diseases of the lungs is

the universal custom among coal miners in this country of walking home

in their damp and dirty pit clothing, instead of changing into warm,

dry clothes at the mine. Colliery owners have tried the experiment of

providing changing houses and baths for the men at the pit’s mouth, but

have always found that the men declined to avail themselves of these

conveniences.

It has been pointed out that the metal miner’s work is far more

unhealthy than that of the collier. This is well seen in the death-rate

among Cornish tin miners, the typical metal miners of Great Britain.

Here we find that the death-rate, instead of being below the average

of the country, is higher, namely 19.66 per 1000 from all causes,

that from accident being given as 1.14, leaving 18.52 per 1000 as the

death-rate from disease. Consumption is extremely fatal amongst tin

miners, bronchitis also claiming many victims. The following table

shows the percentage of the total number of deaths for the period

1890–92, due to the causes specified:--

Cause of Death. Percentage of the

Total Number of Deaths.

Accident 5.8

Phthisis 29.9

Bronchitis 13.5

Pneumonia 5.4

Other diseases of respiratory system 7.1

It is worth noting that according to Dr Ogle’s figures the percentage

of deaths in the period 1880–83 amongst Cornish miners (which may be

taken as practically equivalent to the tin miners quoted above) due

to phthisis was 37.5, and to other diseases of the respiratory organs,

24.9, the death-rate from all causes being rather more than double

that of the average of all males. It is probable that a good deal of

the improvement that appears to have taken place in those ten years is

due to the increasing replacement of ladders by cages for getting the

men to and from their work; there seems little doubt that the fatigue

of having to climb up a good many hundred feet of steep ladders at the

end of a hard day’s work is a prolific cause of chest complaints and

of heart disease. At most Cornish mines of any importance a “dry” is

provided, _i.e._, a room or building in which the miners change

their wet and dirty mine clothes, and leave them to be properly dried

for the day following. As in coal mines, so in metal mines, the dust

produced by the miner’s work is apt to injure the men’s lungs. In

metal-mining this dust is chiefly produced by the action of drilling.

When a drill hole inclines well below the horizontal, water can and

always should be poured in, to convert the dust produced into mud, and

thus to prevent it from flying about. When a hole “looks upwards” or

is pointed above the horizontal, water cannot be poured in, but may

be splashed in from time to time; this, however, involves a certain

amount of trouble, and is rarely done, although it ought to be. It is

especially important in the case of machine drills, which work very

much faster and cause much more dust than hand drilling. The compressed

air by which these drills are usually actuated can easily be employed

to force a small jet of water into the drill hole; this is done by some

machines, and is to be highly recommended. Some Continental makers

have extended this idea, and use drills pierced longitudinally with

a small hole, through which water is injected; this plan seems to be

very effective in preventing dust, but may be found open to some other

objections in practice.

The fumes produced by blasting, especially when nitro-glycerine

explosives are used, are said to be occasionally injurious to health.

There is no doubt that the explosion of ordinary black blasting-powder

produces a considerable amount of carbonic oxide, and this poisonous

gas is also produced, though apparently in less quantity, by most of

the so-called safety explosives used in coal-mining. There is, however,

never or rarely any good reason why a miner should be exposed to these

fumes, which can be cleared away rapidly, provided that the mine is

properly ventilated. It has been remarked that in most cases where

such ill effects have been complained of, the fault has lain with the

men themselves.

It is very exceptional that mining operations, properly so called,

necessitate working in air under pressure, though this may occur in

some special methods of shaft-sinking or of driving levels through wet

ground; it is well known that men working under these conditions are

liable to suffer from caisson disease. None but sound, healthy men,

not too old, should be employed on such work; they should work short

shifts, remain a sufficient time in the intermediate air-lock, and it

is advisable that they should be under medical observation or periodic

examination as long as the work lasts. In Westphalia the law forbids

men working for more than six hours in any place underground the

temperature of which exceeds 29° C. (84° F.).

Of special diseases that particularly affect miners, there can hardly

be said to be any. On the Continent, particularly in Belgium,[128] and

more recently in Australia, especially in North Queensland, a good deal

of alarm has been caused by the prevalence of a serious disease due to

an intestinal parasite known as Anchylostomum Duodenale. This disease,

once introduced, spreads with alarming rapidity; thus in one Hungarian

pit, 80 per cent. of the workers were found to be affected, and in pits

in the province of Liège from 50 to 69 per cent. were attacked; in

Westphalia, in 1897, there were 275 cases of the disease amongst 56,370

miners. The principal, if not the only remedy for this very serious,

and often fatal disease, consists in the strictest personal cleanliness

on the part of the miners themselves, whilst the management should take

care to provide portable sanitary appliances, properly disinfected, at

suitable places underground, and an ample supply of clean water for

washing purposes. This has been made compulsory by recent legislation

for the Westphalian coal mines. At German collieries bathing facilities

are always provided, but the same Act now compels the use of separate

shower baths in the place of the general plunge bath, the latter having

been found to be a means of propagating not only anchylostomiasis, but

other contagious diseases, such as trachoma (contagious disease of the

eyes), typhus, etc.

There are a few special diseases due to special cases of mining

poisonous minerals, which only just need passing mention. It may be

said that the only poisonous minerals mined are the ores of copper,

arsenic, lead, and mercury. The mining of copper never seems to have

given rise to any trouble, and it is even disputed by some authorities,

whether copper, taken into the system in small quantities, acts as a

poison.[129] Arsenic is usually mined in the form of arsenical pyrites,

and does not seem in this shape to have any injurious effects. It

is said that dust from the mineral smaltite (an arsenide of cobalt,

containing no sulphur when pure), when drawn into the lungs produces

cancer of the lungs,[130] and that this disease is not uncommon amongst

the miners in the Schneeberg district of Saxony, where the above

mineral occurs.

In ordinary lead mines, lead poisoning or plumbism is almost unknown;

in the mortality tables already quoted, only one case of death is

referred to plumbism among 16,827 miners. This is apparently due mainly

to the fact that in all British lead mines the supply of oxidised lead

ores is practically exhausted, and work is confined to the sulphuretted

ores. Galena, the sulphide of lead, is a heavy and difficultly soluble

substance, and it would seem that lead is not readily absorbed from it

into the system. The case is far different when the softer oxidised

ores of lead, such as the carbonates, are worked, and these have been a

source of serious trouble at the mines of the Broken Hill district, New

South Wales. It was found that men could not safely be kept at work in

those parts of the mine which produced the earthy lead carbonates for

more than a fortnight at a time.[131]

Mercurial poisoning is no doubt the most serious of all these special

forms of mining disease, due to the fact that all ores of mercury carry

more or less mercury in the metallic state, as also to the readiness

with which metallic mercury volatilises even at ordinary temperatures.

At the Almaden mines in Spain, and the Idria mines in Carniola, a good

deal of mercurial poisoning is found to occur; the chief remedy adopted

seems to be the working of short shifts, so as to expose the men for

as short a time as possible to the dangerous fumes. At the New Almaden

mines in California statistics have shown that there were amongst the

miners 10.44 per cent. of cases of mercurialism (salivation) in one

year (1890).[132] The following remarks on this subject in the report

are worth quoting:--

“The miners employed in the extraction of ore work by contract as

a rule, and a certain number of careless men, through their own

negligence, become victims to mercurial salivation. Men engaged in ore

chambers, where native mercury is found, are requested not to eat,

drink, or smoke, without first cleaning the face and hands, and using a

solution of potassium chlorate as a mouth wash. Working stripped to the

waist is discouraged.

“As the greatest attention is paid toward the attainment of perfect

ventilation, which is of prime importance in the prevention of

mercurial sickness, it is the physician’s belief that if the miners

were more thorough in the use of the above precautions, the salivation

rate at the mine would be under 1 per cent., whereas it is now over 10

per cent. It is probable that there will always be a slight amount of

mercurial sickness, owing, very likely, to the suspension in the moist

atmosphere of the mine of a small amount of the chlorides, and possibly

other salts of mercury.”

This last example, therefore, serves to repeat and enforce the lesson

that seems to be taught by every portion of this investigation,

namely, that although mining is from the very nature of the occupation

accompanied by certain risks, and although enlightened legislation and

careful and scientific management can do much towards diminishing these

risks, the main prophylactic must always lie in the thoughtfulness and

intelligence of the miners themselves, and that the best thing that can

be done towards increasing the safety of mining operations is to raise

by all possible means the intellectual status of mining communities.

HENRY LOUIS.

CHAPTER XXXVIII

THE AIR OF MINES

The air of mines of whatever kind is extremely liable to vitiation, the

nature and extent of which is of considerable importance in relation

to the health and safety of those working in the mine. The impurities

met with are known to the miners under such names as “black-damp,”

“fire-damp,” “after-damp,” “white-damp,” “gob-stink,” etc.; and these

terms will as far as possible be adhered to in the present account of

the subject.

In all mines a current of air to all parts is secured by means of

the arrangement of the shafts and roads. One shaft, known as the

“downcast,” serves for the supply of fresh air, which is distributed

by means of “intake” roads to the working places. The more or less

vitiated air then passes along a corresponding system of “return” roads

or passages to the “upcast” shaft, by which it leaves the mine. In

coal mines, where a very large ventilation is necessary, the current

is usually maintained by means of a centrifugal fan placed at the top

of the upcast, or in some cases by a furnace at the bottom of the

upcast. In metalliferous mines the warmth of the mine commonly causes

sufficient up-current, without any artificial aid. It is evident that

by analysing the return air, and measuring its rate of flow, we can

obtain the best idea of the nature and amount of the general vitiation

of air throughout the whole mine, while analyses made at particular

points in the mine afford more information with regard to vitiation due

to special local conditions.

_Black-damp._--So far as is known the impurity known to miners

as black-damp is met with to a greater or less extent in all, or

nearly all, mines, and in many wells. Black-damp is recognised by

the fact that when present in small quantities it causes a candle or

lamp to burn dimly, without at the same time producing any distinctly

noticeable effect on men: that in larger amounts it extinguishes

lights; and that in still larger amounts it causes death by

suffocation. It is never explosive when present by itself, and is

almost always heavier than air, unless, as very frequently occurs in

coal mines, it occurs mixed with fire-damp.

Until lately black-damp was believed to issue from coal and other

strata, and was commonly identified with carbonic acid. Investigations

by Mr W. N. Atkinson and the writer[A] have shown that this belief is

erroneous, and that black-damp is nothing else than the residual gas,

resulting from the action of air on oxidisable material present in coal

and other materials. Pure black-damp, free from air and other gases,

consists of a mixture of nitrogen with usually from 5 to 15 per cent.

of carbonic acid.

The following table shows the composition of the black-damp obtained

from various coal-mines, metalliferous mines, and wells. The samples

were usually mixed to a greater or less extent with air, the amount of

which was determined from the percentage of oxygen present:--

ANALYSES OF BLACK-DAMP.

+--------------------------------------------------------+---------+-------------+

| |Nitrogen |Carbonic Acid|

| LOCALITY. |per cent.| per cent. |

+--------------------------------------------------------+---------+-------------+

|Stopping, Podmore Hall Colliery, North Staffordshire | 87.87 | 12.13 |

|Another Stopping, same Colliery | 91.37 | 8.63 |

|Main Return, same Colliery | 87.30 | 12.70 |

|Sladderhill Colliery, Apedale, North Staffordshire | 85.86 | 14.14 |

|Old Road, Talk o’ the Hill Colliery, North Staffordshire| 91.90 | 8.10 |

|Main West Return, Talk o’ the Hill Colliery | 80.66 | 10.31 |

|South Main Return, Great Fenton Col., N. Staffordshire | 89.31 | 12.69 |

|Return, Wallsend Colliery, Newcastle, New South Wales | 89.00 | 11.00 |

|Old Workings, Burghlee Colliery, Midlothian | 86.90 | 13.10 |

|Upcast Shaft, same Pit | 86.91 | 13.09 |

|Upcast Shaft, Tylorstown Colliery, South Wales | 85.97 | 14.03 |

|Old Road, Conygre (Timsbury) Colliery, Somerset | 84.92 | 15.08 |

|Stopping, Nabb Pit, Lilleshall Colliery | 86.48 | 13.52 |

|Stopping, Hamstead Colliery, South Staffordshire | 93.25 | 6.75 |

|Upcast Shaft, Hamstead Colliery, South Staffordshire | 93.31 | 6.69 |

|Old Road, Forge Ironstone Pit, North Staffordshire | 85.30 | 14.70 |

|Issuing from Hole, Foxdale Lead Mine, Isle of Man | 88.07 | 11.93 |

|Issuing from another Hole, same Mine | 79.80 | 21.20 |

|Return Air-way, same Mine | 80.30 | 19.70 |

|Well at Redwick, Gloucestershire | 95.80 | 4.20 |

|Coming over Top, Well at Balcombe, Sussex | 88.93 | 11.07 |

|Well at Charterhouse School, Surrey | 81.86 | 18.14 |

|Well at Northleigh, Oxfordshire | 93.19 | 6.81 |

+--------------------------------------------------------+---------+-------------+

The black-damp met with in coal-pits is probably formed chiefly and

often exclusively from the oxidation of iron pyrites (FeS_{2}) present

in the coal. This is oxidised to sulphuric acid and sulphate of iron,

and as carbonate of lime (calcite) is also present in the coal, the

sulphuric acid usually combines with the lime, liberating carbonic

acid. The whole process may be represented by the following equation:--

4FeS_{2} + 15O_{2} + 8CaCO_{3} = 8CO_{2} + 8CaSO_{4} + 2Fe_{2}O_{3}.

Oxidation occurring according to this equation would yield black-damp

consisting of 87.7 per cent. of nitrogen and 12.3 per cent. of carbonic

acid, which is nearly the composition usually found. On pieces of coal

which have been exposed for some time to air and moisture the red oxide

of iron resulting from this reaction may frequently be seen. On other

pieces where there is no carbonate of lime, crystals of sulphate of

iron, and an acid reaction will be found in the positions previously

occupied by iron pyrites, while the coal itself is unchanged. The

oxygen of air left in contact with coal gradually disappears. Hence old

workings or spaces of any kind left unventilated soon become filled

with black-damp. A fall in barometric pressure leads to an issue of

black-damp from these spaces, though often there is also a constant

issue into the return air-ways on account of a little air being

sucked through from the intakes. In the case of wells the influence

of barometric pressure on the issue of black-damp is very marked. The

black-damp is formed in the pores of the surrounding strata, and issues

out up the well whenever a fall of pressure occurs. Thus the well may

be fairly clear of black-damp at one time, and shortly afterwards full

of it. Accidents to well-sinkers commonly occur through ignorance of

this fact. The air is perhaps tested in the morning with a candle and

found clear. In the afternoon after dinner a further test is neglected,

and if the barometer has meanwhile fallen, the well-sinkers may descend

into black-damp and be asphyxiated or fatally injured, or drowned by

falling from the ladder. In the case of wells and metalliferous mines

the black-damp is probably formed partly by the oxidation of carbonate

of iron.

The return air of coal mines always contains black-damp, about 2 per

cent. being very commonly present in the air of the upcast shaft. As

the air-current passing through a coal mine is enormous, the quantity

of black-damp formed in the pit is very considerable, usually amounting

to over 2000 cubic feet per minute in a large pit. The oxidation

thus represented must liberate a large amount of heat in the mine.

Thus in the case of one pit investigated by the writer and Mr F. G.

Meachem[133] the amount of heat calculated as being liberated in the

mine per minute would have sufficed to raise one ton of water 134°

F. or to heat the whole of the air-current (of 100,000 cubic feet

per minute) to boiling point. Of this heat only about one-ninth was

expended in raising the temperature of the air, two-ninths became

latent through evaporation of moisture, and the remaining six-ninths

escaped by conduction into the surrounding strata. This slow oxidation

is one of the main causes of the high temperatures met with in mines;

and apart from it very deep workings could be kept comparatively

cool by ventilation. It must, however, be borne in mind that air in

descending the shaft of a pit is heated by compression about 5½°F.

for every 1000 feet of descent. There is thus a limit to the cooling

effect of ventilation. Moreover, at great depths oxidation is apt to be

favoured by both the higher temperature and the crushing of the coal by

the weight of superincumbent strata, since in coal which is crushed a

much larger surface is exposed to the oxygen of the air. When a current

of air insufficient to carry off the heat passes through crushed

coal spontaneous combustion is very apt to occur, and is a source of

constant danger in some seams.

Black-damp is ordinarily recognised by its action in extinguishing a

candle or lamp. The percentage which is just extinctive to a tallow

candle or miners’ safety lamp was carefully determined by Mr Atkinson

and the writer. We found that a candle held vertically will not

continue to burn if more than 15.8 per cent. of black-damp is present

(corresponding to an oxygen percentage of 17.6 per cent.): that 17.7

per cent. of black-damp extinguished an ordinary safety lamp; and that

18.6 per cent. extinguished a candle held horizontally. The extinction

is due, practically speaking, to the reduction in the oxygen percentage

of the air and not to the presence of carbonic acid, although dilution

of air with carbonic acid extinguishes a light somewhat sooner than

dilution with nitrogen. A light will still just burn in a mixture of 75

per cent. of carbonic acid and 25 per cent. of oxygen. The presence of

black-damp affects the light given by a candle long before the point

of extinction is reached. The flame becomes smaller, and the rate of

combustion is diminished. Angus Smith[134] found that when a candle was

allowed to burn in air increasingly vitiated by its own combustion and

by respiration, the light diminished to 22 per cent. of its original

value when the oxygen percentage fell to 18.5 (corresponding to 8.9 per

cent. of black-damp).

The effects of black-damp on men are due partly to the carbonic

acid, and partly to the diminished oxygen percentage accompanying

the admixture of black-damp with the air. The influence of excess of

carbonic acid and of deficiency of oxygen must therefore first be

described separately.[135]

When carbonic acid is added to air no noticeable effect is produced

until about 3 per cent. is present, when the breathing begins to be

distinctly deeper and slightly more frequent. No other unpleasant

effects are produced, even after a long exposure; and animals kept in

air containing 3 per cent. of carbonic acid are unaffected in health.

As the percentage of carbonic acid increases, the effects on the

breathing become more and more marked, until at about 6 or 7 per cent.

there is severe panting, the pulse-rate being also more frequent and

vigorous, and the face being flushed. The sensation experienced is

similar to that accompanying hard, muscular work. A long stay in air of

this composition is followed by frontal headache. With 10 per cent. of

carbonic acid the respiratory distress is very great, but with a still

higher percentage a narcotic effect is produced, and the mind becomes

confused. Animals sometimes die from long exposure to air containing

about 25 per cent. of carbonic acid, but even 50 per cent. may not

prove fatal for some time.

Diminution of the oxygen percentage of air usually causes no noticeable

effect until the percentage falls to about 12, when the respirations

begin to be just perceptibly deeper. At 10 per cent. the respirations

are usually distinctly deeper, and the lips begin to become slightly

bluish. At 8 per cent. the lips and face have more or less of a leaden

blue colour, and usually the breathing is deeper and more frequent. In

some persons, however, this is not the case, and nothing is noticed by

the person breathing this vitiated air, although his face presents to

a bystander a most alarming appearance. At 5 or 6 per cent. there is

clouding of the senses, and loss of power over the limbs, and often

complete loss of consciousness, which, to judge from experiments on

animals, would probably soon end in death, either from gradual failure

of the respiratory centre or from stoppage of the heart. The symptoms

described are those observed when the breathing of the vitiated air is

not accompanied by muscular exertion. The danger point is, however,

reached much sooner when any muscular exertion, such as that of

climbing, or even walking, is made. Even at 15 per cent. of oxygen

there is often shortness of breath and dizziness on exertion, and when

the oxygen percentage falls much further fainting is apt to occur, and

this is probably the cause of many accidents in which men fall off

ladders in vitiated air, and are fatally injured or drowned. When the

oxygen percentage falls below 8 or 10 per cent. death may occur in

consequence of muscular exertion. Air vitiated simply by diminution

of the oxygen percentage of the air is exceedingly dangerous, for

the reason that there are hardly any warning symptoms before life is

imperilled; and were it not that a light is usually carried in such

air, and that its extinction gives ample warning, since it occurs at

about 17 per cent. of oxygen, accidents would be much more frequent.

Sudden exposure to air containing less than 3 or 4 per cent. of oxygen

causes in men loss of consciousness within about forty seconds. This is

followed by convulsions, and the respirations soon cease. The heart,

however, continues to beat for some time longer, and during this period

artificial respiration will still restore life.

A reference to the composition of black-damp will show that the effects

produced by it are due, in most cases at least, to carbonic acid as

well as to want of oxygen. When there is just sufficient black-damp

present to extinguish a light no noticeable effect is, as a rule,

produced, since there is 17 per cent. of oxygen, and usually not more

than about 2 per cent. of carbonic acid. Occasionally, however, as in

the case of two of the samples from Foxdale lead mines (see table),

there will be as much as 3 or 4 per cent. of carbonic acid present, in

which case the breathing will be slightly affected. With an increasing

percentage of black-damp the panting due to carbonic acid will usually

become more and more noticeable. Thus with 50 per cent. of black-damp

there will commonly be about 6 per cent. of carbonic acid, and 10.5 per

cent. of oxygen. The panting due to carbonic acid will, therefore, be

very considerable. In some cases, however, as in the black-damp from

Hamstead Colliery or Redwick Well, there will still be insufficient

carbonic acid to produce panting, and the air will be already dangerous

from deficiency of oxygen. With still larger percentages of black-damp,

the symptoms from want of oxygen will predominate more and more, until

at last with about 75 per cent., or 5 per cent. of oxygen, life can no

longer be supported. Death is always due to want of oxygen, and not

to the poisonous action of carbonic acid. The presence of carbonic

acid diminishes the danger, as the panting caused by it not only gives

warning of danger, but also increases the oxygen supply to the lungs,

and thus wards off for a time the effects of the deficiency of oxygen.

_Carbonic Acid._--There is no recorded case of evolution of pure

carbonic acid in a mine in this country, but in one colliery district

in France sudden outbursts of pure carbonic acid have occurred. The

locality is a volcanic one, and possibly the carbonic acid may have

originated from some such cause as the decomposition of limestone by

silicates at high temperatures. The well-known case of the Grotto del

Cane is one in which pure carbonic acid is evolved. The composition

of a sample recently analysed by the writer from near the floor of

the Grotto corresponded exactly to that of a mixture by diffusion of

pure carbonic acid and air. The effects of pure carbonic acid have

already been described, and are, of course, quite different from

those of black-damp. According to Clowes, air containing 15 per cent.

of carbonic acid is just sufficient to extinguish lights. Air of

this composition would produce violent panting and partial loss of

consciousness.

_Fire-damp._--The gas known to miners as fire-damp is recognised

by its forming with air explosive mixtures. So far as is known the

fire-damp met with in English mines is always pure methane (CH_{4}),

although in Germany ethane (C_{2}H_{6}) is also reported to occur

in connection with certain kinds of coal. The writer has carefully

examined many specimens of fire-damp from various English coalfields,

but never found that it consisted of anything else but the methane

described by previous observers. The presence of fire-damp in air is

recognised by miners from the appearance over the ordinary flames of a

lamp of a pale non-luminous “cap” of flame, similar in appearance to

the non-luminous flame of a Bunsen burner, though much paler, unless

the air is nearly explosive. From the size and distinctness of this

cap, the percentage of fire-damp can be approximately determined. In

testing for fire-damp the flame of the safety lamp should be lowered

until only a small blue flame is left. The pale cap can then be better

seen above the lamp flame. With very careful observation about 1 per

cent. of fire-damp in the air can just be detected. With a hydrogen

flame, as in the Clowes lamp, it is possible to detect as little as

0.2 per cent.[136] With increasing percentages of fire-damp, the cap

becomes longer and more distinct, and passes right up the chimney when

the air is nearly explosive. Air containing anything between about 5

and 13 per cent. of fire-damp is explosive.

Fire-damp is given off from coal, within which it is contained in

a highly compressed state. Different seams of coal give off very

different proportions of fire-damp. Those seams which give off much

are known to miners as “fiery.” The amount of fire-damp contained in

the coal seems to depend in large measure on the extent to which the

strata above the coal are gas-tight. If fire-damp can escape upwards it

drains off from the coal. Some idea of the enormous amount of fire-damp

contained in fiery coal can be formed from the amount of fire-damp

which escapes from the mine by the upcast shaft. This is chiefly given

off from the coal as it is exposed in working, so that from the output

of coal and fire-damp from the mine a rough estimate can be made of the

proportion of fire-damp in the coal. In one mine, for instance, about

4500 cubic feet of fire-damp per minute were given off, with an output

of about 1200 tons of coal per day, or nearly one ton per minute. It

would thus appear that 4500 cubic feet of fire-damp per ton raised were

given off, or 150 cubic feet of gas per cubic foot of coal.

The fire-damp met with in mines is commonly mixed with a large

proportion of black-damp; and in consequence of this the fire-damp,

_though still capable of forming an explosive mixture when less air

is present_, may not be recognised unless very carefully looked for,

as the lamp is extinguished before a prominent cap is visible. Such a

mixture may easily be fired by striking a match in the midst of it,

or by a blown-out shot in blasting. The mixture is lighter than air,

whereas pure black-damp is nearly always heavier than air.

Fire-damp has no direct action on man. It only acts by diluting the

oxygen of the air. When a mixture of 79 per cent. of fire-damp and

21 per cent. of oxygen is breathed it cannot be distinguished from

air; and animals may be kept for long periods in a mixture of this

composition. The action of a given mixture of fire-damp and air thus

depends simply upon the oxygen percentage, any effect produced being

merely due to want of oxygen, the symptoms of which have already been

described. As fire-damp is lighter than air, a man affected by it will,

on losing consciousness, usually fall into better air. Were it not for

this, fatal accidents by asphyxiation with fire-damp would be much more

common. It often enough happens that a man is temporarily overcome

by putting his head upwards into a cavity filled with fire-damp. If

the fire-damp contains little or no air loss of consciousness occurs

suddenly, and without previous warning. Fatal accidents sometimes occur

through a man incautiously advancing without a lamp up a road, during

attempts to restore ventilation in a district of a mine which has

become filled with fire-damp. So long as a lamp burns in air containing

fire-damp not the slightest harm results from breathing the air.

_Prevention._--Since these spirit compositions cannot be used