1332

THE COLLIERY GUARDIAN.

June 20, 1913.

quantities of air flowing through the fan drift. The
same object might be attained even more simply by
introducing into the fan drift a sheet iron diaphragm
with an aperture in it. If a pipe be placed about 5 ft.
from the diaphragm on the up-stream side, and a similar
one some 15 ft. from the diaphragm on the down-stream
side, and these two be connected to either arm of a
sensitive water-gauge, the difference of pressure between
the two sides of the diaphragm would give a direct
measure of the quantity of air flowing. That was, of
course, merely an application of the well-known equiva-
lent or orifice principle of Murgue. By means of a
recording water-gauge, the quantity of air flowing
through the fan drift could thus be easily recorded
continuously. The introduction of the diaphragm would
necessarily increase the resistance of the drift, and thus
throw somewhat more work upon the fan. In most
cases, however, power at a colliery was not a very
expensive item, and it would probably be worth while to
incur this slight additional cost, in order to obtain an
accurate continuous record of the total ventilating
current.

It might be further pointed out that every regulator
in the mine was, in effect, such a diaphragm, and that all
that was required in order to know the quantity of ait-
passing through each split was to connect the two sides
of the regulator by a sensitive water-gauge, when the
quantity of air flowing could be readily calculated from
the formulas. It would be quite easy to put in a regu-
lator with chamfered edges to which it would apply, or
else to determine once for all the coefficients applicable
to the particular form of regulator in use in any given
mine. The simplicity of this method of measuring and,
if desired, recording continuously the quantity of air
flowing through each split had much to recommend it,
and, though it had never yet been tried, he was anxious
to draw special attention to it, and hoped that those in
a position to do so would inaugurate experiments.

MANCHESTER GEOLOGICAL AND MINING
SOCIETY.

A meeting of this society—the last of the present
session—was held on Tuesday of hst week in the
society’s rooms, 5, John Dalton-street, Manchester. Sir
Thomas Holland, F.R.S. (president), was in the chair.

Mr. William Spencer Elphinstone, mining engineer,
Dale House, Oakertborp, Alfreton, Derbyshire, was
elected as member federated, and Mr. J. Norman Wynne,
Mysore Goldmining Company Limited, Marikuppan,
Mysore State, South India, was elected as associate
federated.

The Proposed Charter for the Institution of Mining
Engineers.

The President made an appeal for a quick response
to the request for subscriptions to cover the costs
incident to the effort now being made to have the
Institution of Mining Engineers incorporated by Royal
Charter. He had received, he said, something like 20
promises of subscriptions to this capital fund. So far
as the share that he had privately put down for the
members to subscribe, he thought the response had been
very encouraging. He had now to urge members to use
their influence with royalty owners and colliery owners,
with a view to persuading them to bear a bigger share of
this burden, which, it seemed to him, was only their
duty as a return for the benefits they had got, or hoped
to get, from the operations of a society like this. He
was now going to issue a circular to all the members,
inviting them to subscribe to the fund. The question of
preparing for a charter was not a simple one. Various
constitutional matters had to be considered and the
lawyers were doing that now. It was extremely
important that their institution should be ready to apply
for its charter at the time that the Institution of Mining
and Metallurgy applied for its charter. It was necessary
that both should go together, else one might be granted
a charter and the other afterwards rejected on the
ground that there was only room in this country for one
metropolitan institution of mining engineers. The
other parties were well ahead with their work; they had
their money and their constitution ready, and it was
only a matter of putting their prayer in order for the
Privy Council to consider. The Institution of Mining
Engineers was a little slower, for there were seven
institutes to consider. Some of these were a little ahead
of the Manchester society. The South Staffordshire and
Warwickshire Institute of Mining Engineers, for
instance, had got its money ready. He did not want
Manchester to be the last, seeing that it was the oldest
of the seven bodies that formed the Institution of Mining
Engineers and ought to take the lead, and that it was
in a district which was probably the wealthiest. He
hoped, therefore, that the response to his appeal would

be prompt and that members would persuade their
fellows, not then at the meeting, to do the same. Also,
do not, he would say, forget the colliery and royalty
owners.

Mr. Vincent Bramall asked if the President had
heard from Sir Thomas Ratcliffe-Ellis on the subject
as representing the colliery proprietors.

The President said he had so heard, and understood
the matter was one with which the colliery owners as a
body could not deal. Sir Thomas Ratcliffe-Ellis, however
had sent out circulars to the members of his society.
The sum required was not large; it only amounted to a
fraction of a penny for each ton of coal raised in a year.

Firedamp in Coalmines.

Discussion was invited upon various papers received
at previous meetings, as follows : “ Colliery Cables,” by
Mr. W. T. Anderson; “ Firedamp in Coalmines,” by
Dr. John Harger ; “ A New Mining Dial,” by Mr.
Frederick P. Mills; “ The Relation Between Subsidence
and Packing, with Reference to the Hydraulic Stowing
of G-oaves,” by Mr. Geo. Knox; and “ The Hydraulic
Stowing of Goaves,” by Mr. Geo. Knox.

The President said that some of these papers had
already been fairly well discussed. One of them
probably did not admit of much discussion. The
paper that had been least discussed, and that ought to
be the most important one, he should think, to mining
engineers, was that by Dr. John Harger on “Fire-
damp in Coalmines.” The subject had been discussed
by other branches of the Institution of Mining
Engineers, and it would be remembered Dr. Harger
gave them a paper on a similar subject on a former
occasion, dealing with this problem, which certainly had
been brought to the attention of every coalmining
engineer in the country, and therefore ought to be one
they were ready to consider seriously. He was not
going to add to the discussion in any way himself; it
was quite beyond his province. Some of the subjects
mentioned were of a purely scientific type that chemists
ought to be ready to discuss, but, as he had said before,
the main problem was one for the consideration of
practical mining men, and chemists and scientific men
generally should be willing to give way to the
experienced man who had to deal with these things
as they affected the ordinary working man in the mine-

Mr. Noah T. Williams, lecturer in mining at the
Manchester University, said the detection and estimation
of firedamp in mines was a matter of importance to
mining men, and he was in full accord with Dr. Harger
that coal gas was not a very satisfactory substitute for
methane for the purpose of training men in “ gas caps.”
He had given the results of some of his experiments in
this connection in the discussion on Messrs. Hutchinson
and Evans’ paper, in the South Wales Institute of
Engineers. Mr. Evans has since made a number of
analyses of the coal gas supplied by many gasworks in
South Wales, the results of which were published in the
Proceedings Qi the Institute. These analyses showed
clearly the variation in the composition of the gas.
For instance, the nitrogen present varied from 3 to 24
per cent. Identical caps for the same percentage of
gas and air could not be expected from such a variable
mixture, nor would such caps have exactly the same
qualities as those obtained from firedamp and air. The
preparation of methane by the use of aluminium carbide
might be convenient for a laboratory, but would be a
tedious process to a travelling mining teacher. One
had to remember that most of the officials in the
mining centres throughout the country were instructed
by the visiting teacher, who had poor facilities in most
of the schools, and also not much time at his disposal
for the preparation of methane. It might be interesting
to note that an unabated supply of firedamp had been
issuing from a blower at the Cymmer Pits, Porth, South
Wales, for nearly 50 years. Through the kindness of
Mr. T. Griffiths, the gerieral manager, and Mr. E. S.
Williams the manager of the collieries, he was able to
give the analysis of the gas, which was as follows :—

Per cent.

Methane..................... 95	80

Carbon dioxide................ 0	68

Oxygen ....................... 0	25

Hydrocarbons ................. 0	20

Nitrogen .................. 3’07

100 00

Limit of error, 0 2 per cent.

They had under consideration the question of
supplying the gas from the blower in cylinders for
education authorities. As Mr. Williams pointed out in
a letter he had written, there was plenty of it for the
purpose.

The proposal made by Dr. Harger of reducing the
oxygen in the air for the prevention of explosions was a
very serious one, both from the physiological and
commercial point of view. To gauge rightly the per-

centage of oxygen necessary and to be confident that
such a reduction would not be injurious to life appeared
to him to be a very difficult problem, and the margin
must be a very narrow one. Some men were stronger
and would be better able to withstand those effects and
continue work longer than others, but all men would
have to accommodate themselves daily to the abnormal
atmosphere of the mine.) He remembered an instance
some years ago when three men had to build a masonry
dam in a mine in South Wales at a particular place in
the mine where lights could only burn dimly, due to the
deficiency of oxygen. Two of the men felt the effects
of it, while the third did not apparently suffer. Possibly
the reduction of oxygen might be of some use in con-
nection with electric shot-firing from the surface when
the mine was free from all men. The atmosphere could
then be charged with gases that would be destructive to
life, and nothing could burn but the explosives which
contained their oxygen.

Dr. Coward, of the Manchester Municipal School of
Technology, said: At the request of two members of
the society, I offer the following comments on points
raised by Dr. Harger, more especially in connection
with the chemical problems associated with the gases
present in firedamp. The production of methane by
interaction between aluminium carbide and water was
first observed by Moissan in 1894, and this process has
been generally adopted by chemists who require large
or small quantities of the gas. The removal of
hydrogen by means of heated copper oxide was
employed by Eitner in 1902 (Habilitationsschrift,
Miinchen) who mentions it without giving much detail,
as though it were a well-known process at the time. It
is surprising to me to read that Dr. Harger’s methane
“ is often contaminated with considerable amounts of
nitrogen from leakages and from the water,” for
leakages can be avoided, and the use of liquids other
than water, such for example as a mixture of equal
volumes of glycerine and water, will reduce the nitrogen
content of the gas to a minimum without adding much
to the cost of preparation. Another impurity often
present in the gas prepared from aluminium carbide
and water is acetylene. This is conveniently removed
by bubbling the gas through an ammoniacal solution of
cuprous chloride, a reagent at hand in most gas
chemists’ laboratories, and then through dilute sulphuric
acid to remove ammonia gas carried forward from the
reagent. The preparation of methane from methyl
iodide by reduction with an aluminium mercury couple
is a more tedious and more expensive process than the
above, but sufficient care in washing the gas will remove
methyl iodide vapours, so that no iodine makes its
appearance on combustion. A more important point is
the question as to whether a mixture of methane and
air is inflammable when the oxygen content of the air
has been reduced below 17 per cent. Dr. Harger’s
experiments, unfortunately done with a gas of which
“ he was not at all satisfied with the purity,” are in
sharp contrast with the statements of G. A. Burrell
(Coal Age, 1913, v. 3, p. 104) which, so far as concerns
the present experiments, may be summarised as
follows:—

Percentage composition of mixture.

Carbon dioxide.	Oxygen.	Methane.	Nitrogen.
1. 003	.	..	14’00	.	..	9 40	.,	..	76 57*
2. 0 03	..	..	13 00	.	..	9’40	..	..	77 57f
3. 003	.	..	1200	.	...	9’40	..	..	78 57+
4. 0’03	.,	..	12 00	.	..	600	..	..	8197§

* Mixture was explosive. f Mixture was irflammable.
X Slight inflammation observed. § Flame filled entire
top of jar on strongly sparking.

These mixtures would be obtained by adding a
suitable amount of methane to mixtures (“ air with
deficient oxygen ”) of the following compositions:—

Carbon dioxide.	Oxygen.	Nitrogen.
1. 003	154§	84 52
2. 0 03	1434	85 63
3. 0 03	13 24	86 73
4. 003	12’67	87’30

On the other hand, experiments done some time ago
by Clowes and Feilman (Journ. Soc. Chem. Ind. 1894,
p. 1155) and by Eitner (loc. -cit.) are quite in accord
with Harger’s conclusion. Thus Clowes and Feilmann
found that a small flame of methane burning in air was
extinguished when brought into a mixture of composi-
tion : 17*4 per cent, oxygen, 82 6 per cent, nitrogen.
Eitner gives the following as the composition of two
mixtures, the first being inflammable, the second not.

Methane. Oxvgen Nitrogen.

1.	7 8	...	15 7	...	76 5	...	Inflammable.

2.	7’7	...	15 4	...	76’9	...	Non-inflammable.

Mixtures of these compositions would be obtained by
adding methane in amount just sufficient to be com-
pletely burnt by the oxygen to an air with deficient
oxygen, of the following compositions:—