February 28, 1913.

THE COLLIERY GUARDIAN.

435

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Effect on Man.

Time exposed. Distress. Collapse. Recovery.

20 minutes ...	1 hour ...	—	...	8 hours

Whereas the animals were left in the atmosphere
until they collapsed, the man left the atmosphere
experiencing but little discomfort at the end of
20 minutes. One hour later he became very sick.

Use of Sparrows for Recovery Work.

The Bureau has attempted to use English sparrows
for recovery work in mines, with not much success,
because those so far obtained have not survived captivity.	___________________________

Pigeons are not sensitive enough. At the end of
11 minutes, in an atmosphere containing 0’25 per cent*
of carbon monoxide, they showed but slight signs of
distress. Mice are more sluggish and not so easily
affected as canaries, but, at the same time, useful. A
mouse and a canary together would make a good com-
bination. The usefulness of small animals for detecting
bad air in mines has been so well recognised in England
that it has been recommended that they be kept at all
mines.

Intrusion of Natural Gas into Coalmines.

Natural gas has intruded into some coalmines with
disastrous consequences. Mining men are alert to the
importance of the question. Old abandoned wells are
an especial menace, in that nobody knows the where-
abouts of some of them.

Some comparison between the explosibility of natural
gas and firedamp is interesting. Natural gases of the
Appalachian fields contain other paraffin hydrocarbons
than methane, principally ethane. The following
analysis shows the composition of the natural gas used
at Pittsburg. This gas is drawn largely from West
Virginia. Some comes from Western Pennsylvania:—

Carbon dioxide....... trace (less than 0 10 per cent.)
.............

.............

, Oxygen .............. 0 00

Methane ........... 82*5

Ethane .............. 160

Nitrogen ........... 15

Carbon monoxide, hydrogen or ethylene are not
contained in the gas, not even in traces.

Below are shown the explosive limits of methane-air
mixtures, and natural gas-air mixtures. Ignition was
effected by a small electric spark from an induction
coil. The gases were trapped over mercury:—

Methane. Natural gas.

Low limit..........	5 47 ....	4’92

High limit ........ 12 50 .... 12 00

Below are given the ignition temperatures of methane
and ethane, determined by Dixon and Coward* :—

Degs. Cent.

Methane .............. 650 to 750
Ethane ............. 520 to 630

It does not appear from the above that natural gas is
so much more sensitive to inflammation as<to produce
an added menace from this cause upon intrusion into a
mine. The great danger lies in the sudden inrush of a
large body of inflammable gas which has not always
been controlled in order to avert disaster. The fact
that carbon monoxide is not present in the gas is for-
tunate. Many published analyses show natural gas to
contain this constituent. The statement is erroneous.
Higher paraffin hydrocarbons than methane in natural
gas give to the latter its characteristic odour.

Inflammable Character of the Gases Present in Mine Air.

The Bureau has almost ready for publication a report
showing the exact character of the inflammable gases
present in many samples of mine air. In many text-
books the statement is made that hydrogen, ethylene,
carbon monoxide and ethane may be present in mine
air under normal conditions of operation ; as far as the
authors of these books are concerned, they have been
justified because occasionally analyses showing these
constituents are reported, although, even so, the bulk of
evidence shows them to be of rare occurrence under the
conditions cited. It is believed that some mine air
analyses that have crept into text-books are in error.
Because of the reported presence of these gases in mine
air the question has at times been raised regarding the
application to mining conditions of experiments per-
formed in the laboratory or testing galleries in which
methane or the nearly similar natural gas is used. In
the Bureau’s report, mine gas samples from about 50
mines are listed. Methods of examination are described.
The great effect of very small errors which can hardly be
avoided in the manipulation of many forms of gas
analysis apparatus is shown in that these small errors
may result in the reporting of 1 or more per cent, of
combustible gases other than methane. Of course if a
careful analyst reports other combustible gases than
methane in even a few samples, then one is justified
in believing that they may occur in other samples. The
above statement excepts a few mines around the oil
regions into which natural gas may have escaped.

A rather complete bulletin is also ready having to do

* Chem. News, 99, 139 (1909).

with methods of examination of mine and natural gases.
Apparatus is shown for research work, also sample
machines that can be easily operated at mines.
Chemical analyses are the basis from which safety
lamps and other gas indicators are constructed, and
simple methods for these standard tests are desired. An
abstract from the larger bulletin has also been completed
which contains only those cherqical apparatus suitable
for use at mines.

Use of Birds and Mice for Exploration Purposes.

A publication has also been prepared containing
further work regarding the use of canaries and mice. A
short abstract of these findings is given adove.

Co-operative Work with Illinois.

In co-operation with the State of Illinois, a large
number of samples have been collected in that State
by N. H. Darton, geologist of the Bureau.

This has also been done in the anthracite fields of
Pennsylvania. The results of analyses of these samples
are being shaped into a report, and will show the
composition of the air in many different mines in those
States. Mr. Darton also reports interesting findings
having to do with geological conditions and firedamp
liberation.

Normal Mine Air Samples.

In conjunction with G. S. Kice, chief mining engineer
of the Bureau, a preliminary report is being assembled
showing the composition of the mine air in many
different coalmines, under normal conditions in different
parts of the country. Almost all of the data has been
assembled for this work.

Mine Gases and Explosions.

Mine gases samples have also been collected by
mining engineers of the Bureau, following many mine
explosions. Their significance will be discussed in the
reports of these explosions.

Use of Gasoline Locomotives.

A large number of samples were collected having to
do with use of gasoline motors in mines.

Exhaust samples have been collected, also samples of
the air in the mines where motors were operated.
Special investigations have been made for coal
operators, inspectors, and motor manufacturers at their
request. It seemed best to defei’ a report for publica-
tion, however, until results could be obtained connecting
exhaust gases with power developed, gasoline consump-
tion, different carburetter arrangement, &c. This work
is in progress, and is under the direction of O. P. Hood,
chief mechanical engineer of the Bureau.

Blackdamp in Mine Air.

Enough data has also been collected for the issuance
of a publication on blackdamp in American mines; also
one on afterdamp.

Miners’ Circular.

A miners’ circular is being prepared, having to do
with a discussion of mine gases. No attempt, of course,
is being made to replace those mine gas terms, with
which miners are most familiar, such as blackdamp,
afterdamp, after-gases, firedamp, &c., but a circular
showing the Bureau’s observations on these subjects
will be published. Blackdamp is still sometimes wrong-
fully used as meaning carbon dioxide instead of a
mixture of nitrogen and carbon dioxide, as Dr. Haldane
has shown. The carbon dioxide usually plays but a
small part in the combustion effects produced by the
mixture. The deficiency of oxygen which always
accompanies excessive proportions of blackdamp is the
main factor in flame extinguishment in mines. On the
other hand, physiological effects, if produced in men
when they are in atmospheres in which lamps do not
burn, are frequently due to the carbon dioxide. This
statement has reference to atmospheres in old workings,
&c., and not those that have been vitiated by mine fires,
explosions, &c„ and wherein carbon monoxide might
exist. Different meanings have been attributed to the
word firedamp. To some it means methane, to others
any mixture of methane and air. That other gases than
methane may frequently be present is sometimes stated.
Some persons define it as any inflammable mixture of
methane and air.

Sufficient data are not at hand to describe completely
the constituents in afterdamp, That the products of
incomplete combustion of methane, coaldust and air can
be quite complex is shown by work already performed
on single gases and air. This statement has reference
to the immediate after-products of an explosion. The
Bureau hopes to secure data on this point at the
experimental mine.

After a stagnant mine atmosphere has been clarified
of smoke particles and easily soluble gases and gases
that irritate, there can remain for a long time a clear
atmosphere containing oxygen, carbon dioxide, nitrogen,
methane, hydrogen and carbon monoxide—an atmo-

sphere with only the characteristic odour of burnt coal
and wood, yet one that can be fatal because of the
presence of the carbon monoxide. Oxygen may be
present in sufficient quantity to enable a lamp flame to
burn fairly well, and absolutely no indication given to
an exploring party of the presence of carbon monoxide,
although the latter may be present in sufficient amount
to produce fata] results. Deaths have been caused by
men relying upon the lamp flame to warn them of
carbon monoxide.

MECHANICAL POWER IN THE NORTH-EAST
COALFIELD.

An Interesting Survey by Mr. Robt. Nelson.

Mr. W. 0. Mountain presided over a largely-attended
meeting, held at the Armstrong College, Newcastle-on-
Tyne, on Wednesday, February 19,under the auspices of
the North of England Branch of the Association of
Mining Electrical Engineers. .

Mr. Robert Nelson, H.M. electrical inspector of mines,
delivered an address on t( The Development of Mechanical
Power in the Mines of the North-Eastern Coalfield : A
Comparison and a Contrast.” Mr. Nelson commenced by
referring to a statement made by the late Lord Armstrong,
in his presidential address to the North of England Insti-
tute of Mining and Mechanical Engineers in 1873, that
“ the raising of coal is still foremost amongst the industries
of the north.” That statement was still true, said Mr.
Nelson. In the Proceedings of the North of England
Institute it was stated that the output of coal in 1828 was
5,941,812 tons j in 1844, it was 9,623,922 tons. In the latter
year there werel24collieries in the north-eastern coalfield and
the number of workpeople employed thereat was estimated
to have been 33 900. That latter information was not avail-
able for any earlier year. In 1911 there were 511 collieries
in operation in Northumberland and Durham, and they
produced 56,401,343 tons of coal, whilst the number of work-
people employed was 216,733. The output per man per
annum was actually 8 per cent, less in 1911 than in 1844—-
260 tons against 283. It was right to add that that figure
had not, in the meantime, been steady. It had been subject
to remarkable fluctuations—1854, 396 tons; 1864, 417;
1874, 308 ; 1894, 330; and 1904, 297.

As regarded the output per colliery it would be seen that
the figure for 1844—viz., 77,600 tons—had been increased
to 110,000 tons by 1911. The north-eastern coalfield was
the first developed on a large scale, and therefore it
was natural to expect that, as the other coalfields became
active, its relative importance would decline. That expecta-
tion had, in fact, been fulfilled.

An early mention of the use of mechanical appliances in
connection with mining was made in a book published by
one Grey in 1649.

“ Some south gentlemen,” said Grey, "upon hope of
benefit came into this county (Durham) to hazard their
monies in coal mines. Master Beaumont, a gentleman of
great ingenuity and rare parts, adventured into our
mines with his .£30,000, who brought with him many rare
engines not known then in these parts. Within a few
years he consumed his money, and rode home upon his
light horse.”

The speaker understood that the appliances which Master
Beaumont brought with him were “ rare engines to draw
water out of the pits” and “ wagons with one horse to carry
down coal from the pits to the staithes,” for even then the
seaborne coal trade of Newcastle was considerable. The
above-mentioned authority added that wagonways came
into use about the year 1649. They were certainly in use
at Ravensworth Colliery in 1671, but nothing was said as to
the exact character of the " rare engines,” the operation of
which proved financially so disastrous, nor of these early
mechanical aids to coal conveyance.

Mechanical appliances, dependent upon manual or horse
labour, had, no doubt, long been used for raising coal before
the first attempt was made to employ more powerful
agencies. Wind and water were both successfully used.
But until the first steam engine utilised for drawing coal
was set to work—about the year 1775—the common method
of raising coal was by hand windlass, or, alternatively by
horses. The latter had been used for a long time for raising
coal to bank by " gins,” for the depth from which they
could raise the coal, though limited, was much beyond
manual power. Even before the dawn of the eighteenth
century, however, the step which was eventually to lead to
the general application of steam power three quarters of a
century later had already been taken.

The earliest application of steam power in any mine was
claimed to have been that of Thos. Savery, at the Great
Work Mine, in Cornwall, in 1700. So far as the speaker
had been able to trace, there was no record of a Savery
engine in use in the North of England. The first steam-
engine in that district was erected, it was said, at Oxclose
Colliery, but that erected at Byker Colliery in 1713 was
certainly a very early one, for it was stated there were only
four steam engines in existence in 1714 and that two of
these were at mines near Newcastle. By 1725, Newcomen’s
engine, an inprovement upon Savery’s, was coming into