January 31, 1913

THE COLLIERY GUARDIAN.

229

Dr. Elliott went on to say that ashore and afloat the oil
engine had already conquered an enormous territory, but
many of them foresaw this state of affairs 25 years ago. For
this and other reasons—notably the almost universal and
complete expulsion of the coal-fired boiler from the navies
of the world in favour of its more powerful and enormously
more strategically valuable rival, the oil-fire boiler—the
consumption and production of oil had rapidly increased.
For boiler purposes at large the cost still stood in its way
to the extent that if oil, which usually cost nearly twice as
much, could be obtained for 22s. a ton, it would be on about a
footing of equality with good steam coal at 15s. a ton. This
comparison was, of course, in respect of boiler purposes
alone.

Along with oil, the demand for petrol had steadily
increased, and so likewise had the price. A distinguished
chemist not long ago suggested that the difficulties
connected with raising coal to the surface might be obviated
by turning at least some part of the coal into gas in situ. It
had even been proposed that motor cars and so forth should
be operated by compressed gas, which was a new use for
coal. Without giving an opinion on the practicability of
either of those proposals, he would like to carry the dispute,
if dispute it be, into the camp of the chemists. The same
distinguished chemist had gravely announced that the
discovery of synthetic rubber at a cost to “ knock " the pure
commercial article, was an accomplished fact, and only the
other day the discovery of a new and a practicable process
for the synthesis of ammonia was projected. What he
wished to know was why they should not have overflowing
supplies of cheap petrol and petroleum synthesised from
coal and its concomitants, as the natural stuff itself was, or
had been, produced in the earth. Concluding, he said:
Engineers and men of science have strained for long the
eyes of mental vision, peering as it were into what the
future holds, endeavouring to descry the approach of some
practicable method of laying under contribution the over-
flowing solar energy and other sources of natural power,
seen and unseen. Coming events cast their shadows before,
and when one thinks that even a century is a mere short
interval in the life of a nation, we in our anxiety are crying
out for a sign which in the first place will be a shadow no
bigger than a man’s hand.

The Analyses of Mine Air.

After the president had been thanked for his address,
the meeting proceeded to give further consideration to
the notes of Messrs. J. W. Hutchinson, M.I.M.B., and
Mr. Edgar C. Evans, B.Sc., A.I.O., on the analyses of
mine air conducted at the Lewis-Merthyr Consolidated
Collieries Limited, Trehafod.

Prof. Galloway said in a recent German book on
mining he had been interested by figures showing the
quantity of gas given off in the Hibernia mine per ton
of coal produced. The percentage of gas in the air was
one-half; the number of cubic metres given off was
37’5 per minute ; and the total number of cubic metres
of gas given off in 24 hours was 54’00. Taking the
value of this gas at a little over Id. per cubic metre, it
represented a sum of £270; whereas the value of the
coal produced—900 tons—was only £500 per day. It
seemed very remarkable that the actual value of the gas
was half as great as the value of all the coal produced
in the mine, and he had no doubt there were millions of
pounds’ worth of gas given off in the mines of this
country in the same way that could not be made use of

Replying to observations made at the last meeting on
the papers of which he was joint author with Mr. Edgar
Evans,

Mr. J. W. Hutchinson said Mr. Noah Wiliams, in
concurring with the statement made by Prof. Galloway
that inconsistent results could be produced from
insufficient mixing of the gas and air in the tank, went
further and stated that even with sufficient mixing the
same “ cap ” could not be produced at the same place
using the same town gas morning and evening. Again,
Mr. Williams’ experience was that gas supplied from
different gasworks gave varying results. He (the speaker)
agreed with that gentleman on both points—more
especially on the latter one. From careful analyses
made by Mr. Evans, it was clearly proved that the com-
position of gas varied at different parts of the day,
although not to the extent one would suppose. The
chief variation was in the quantity of nitrogen; but
when they came to the analysis of the gas supplied from
various gasworks, there was a marked difference in the
composition of the gas. It was not the authors’ inten-
tion to name any particular gasworks, inasmuch as the
analyses had been made with a view to prove that the
composition of the gas generally used in the apparatus
was entirely different from the methane met with
underground. A sample of gas taken at Messrs.
Insole’s pits, Porth, from a blower which is carried in
pipes to the top of the pit, gave 96 per cent of methane.
Mr. Thomas Griffiths, the general manager, who kindly
consented to Mr. Evans making analyses, informed him
(Mr. Hutchinson) that the blower had been giving off gas
at the present rate for at least 48 years. The most

favourable analysis of town gas which Mr. Evans got
did not give more than 39 per cent, of methane, and the
nitrogen was in some cases over 20 per cent., and in
other cases it was as low as 3 per cent. The composition
of the gas used in the apparatus must affect the “ cap ”
both in height and colour, especially where such large
percentages of nitrogen and hydrogen were present-
Men with many years’ underground experience had
taken into account the colour and density of the “ cap ”
when estimating the percentage of gas present; and a
man who had been accustomed to test for gas and
estimate the quantity from the height, colour and
density of the “ cap ” produced by the gas met with
underground would be liable to miscalculate the per-
centage of gas from a “ cap ” produced by town gas in
the Winstanley apparatus, unless he had been trained
to estimate the percentage of gas from the “ caps ” so
produced from a given table of percentages which
corresponded with the height of such “ caps ” only.

With regard to Noah Williams’ question whether a
3 per cent. “ cap ” would be smaller when observed in
the cavity of the roof than in a place where the
velocity of the mixture was greater, he was of the
opinion that it was not so much the pressure which
affected the “ cap ” as the composition of the gas. Mr.
W. J. Jones had stated that after a daily experience
with the apparatus, morning and evening, extending
over six months, he had observed that the accuracy to
be obtained did not lie entirely on the mixing or the
rate at which the water entered the tank. It appeared
that Mr. Jones’s experience proved that the pressure
did not affect the height of the “ cap ” after the
apparatus was charged with a 4 per cent, mixture, and
the w.g. could vary from J in. to 1| in. without
altering the size of the “cap.” The Coal Mines Regu-
lation Act stated that 2| per cent, was the greatest
percentage they might have in a place and work it; and
he would like to know did a 2J per cent, and a 3 per
cent, mixture remain constant, similar to a 4 per cent,
mixture, under varying pressures. In dealing with Mr-
Noah Williams’ remarks that an identical “cap ” could
not always be produced under similar circumstances
morning and evening, Mr. Jones had contended that
this was due to a larger amount of gas being put into
the tank due entirely to the varying pressure in the gas
main. Personally he (Mr. Hutchinson) did not see how
this could occur to any appreciable extent; and if it
could, then it bore out the statement of the authors that

the Winstanley apparatus was not always reliable.
Once a particular mixture was got in the tank the
pressure should certainly be so controlled as to have no
effect on the mixture. He agreed that careful and
delicate manipulation should be aimed at, but, at the
same time, judging from the remarks of Mr. Williams
and Mr. Jones, it appeared to him to be very difficult
to achieve. With regard to a | in. “ cap ” giving 4 per
cent., he had personally taken samples of air under-
ground where there was a full | in. of blue “ cap,” and
the analysis gave 3 per cent.; J in. of a similar “ cap ”
gave 2’5 per cent., and a f in. gave 2’75 per cent.

Mr. Edgar C. Evans said it was evident, from the
remarks of Mr. Williams and Mr. Jones, that incon-
sistent results could be obtained with the Winstanley
apparatus even with the most careful manipulation.
The question arose, in the first place, whether the “cap”
produced by coal gas was the same in size, colour and
density as that produced by methane. It was difficult,
from a theoretical standpoint, to see that it should give
the same “ cap ” as methane, even when the coal gas
was of a very high quality. There was, in his opinion,
room for considerable work on the effect of the different
constituents of coal gas on the size and visibility of the
“ cap.” In this connection it would be interesting to
know whether any difference could be observed between
“ caps ” obtained when using the natural firedamp of
the Cymmer collieries and those obtained with coal
gas at other centres. However, apart from these
considerations, it was obvious that a gas poor in
combustible constituents could not be expected to give
the same “ cap ” as a gas of good quality. The effect,
for example, of an inert gas like nitrogen in coal gas
would he not only to act as a diluent, but would
actually tend to decrease the “ cap ” produced by the
other constituents. In the face of these facts Mr. N.
T. Williams’ remarks regarding the quality of the gas
used in the Winstanley apparatus were of special
importance. Acting on Mr. Hutchinson’s suggestion, he
(the speaker) had during the past two months made
over 30 analyses of the gas used in different centres for
the examination of the firemen. He was submitting
some typical analyses in writing for the institute
Proceedings; but the deductions obtained from the
results might be now mentioned. In the first place
analyses made of the gas produced at the same works at
different periods of the day certainly showed varia-

tions, but not, on the whole, to a very great extent.
On the other hand, the gas used at different centres
varied enormously in quality. For example, the per-
centage of methane in the gas varied from 96 per cent,
in the Cymmer blower to 23 per cent, in one of the
works. The percentage of incombustible constituents
(including CO2, oxygen and nitrogen) varied from about
3 per cent, to over 30 per cent. The analyses, which
would be reproduced in the Proceedings, of coal gas used
at different centres of firemen’s examinations showed
that if a percentage of 3 per cent, of each of the various
gases analysed was placed in the Winstanley apparatus,
the actual percentages of combustible gas present would
be, approximately,

A. B. C. D.	E.	F.

2| ... 2 ... 2| ... nearly 3 ... over 2f ... nearly 3
Thus in the extreme cases there would be a difference
of 1 per cent, between the “ cap ” shown by the
apparatus and the percentage of gas introduced. The
analyses made certainly bore out Mr. N. T. Williams’
contentions to a very great extent.

Prof. Galloway said his experience quite confirmed
Messrs. Hutchinson and Evans as to the variations
spoken of.

On the motion of the President, seconded by Prof.
Galloway, a cordial vote of thanks was passed to the
joint authors of the “ Notes.”

Speaking in acknowledgment, Mr. J. W. Hutchinson
said when he entered upon this investigation it was with
no idea of preparing a paper upon it, but he subse-
quently thought the results secured would prove of some
interest to the institute.

Reinforced Concrete

Mr. T. E. Thain, author of a paper on this subject’
replied to observations made at a previous meeting.

Closing the discussion and moving a resolution of
thanks to the author, the President stated that the
effectiveness of ferro-concrete for the prevention of
corrosion—that dreadful enemy of steel construction—
had been established. Steelmakers and engineers had
been culpably negligent in the matter of corrosion
prevention. Opportunities of experimenting with the
object of overcoming and extirpating the insidious
enemy of corrosion had been grossly neglected in the
past.

The Yorkshire Boiler.

Mr. W. H. Casmey supplemented a paper which has
been published in the Proceedings, descriptive of the
features of the Yorkshire boiler, which he claimed made
it superior to the Lancashire boiler.

Mr. T. Sugden said the author had not compared
Lancashire and Yorkshire boilers of equal size, but had
dealt only with a long Lancashire boiler and a short
Yorkshire boiler of the same diameter—9 ft. Thefirstpoint
made in the paper was that owing to a reduction in the
sectional area at the end of a Lancashire boiler, this
had the effect of a permanent brake on the draught,
and consequently on the boiler duty. This objection
was of little or no value, seeing that in both
Lancashire and Yorkshire boilers the greatest
restriction was at the bridge, of which the author
had taken no account. The area over the bridge in
either a Lancashire or Yorkshire boiler was not half
that at the ends of the tapered flues of a Lancashire
boiler, a fact which altogether upset the author’s calcu-
lations and conclusions. The authoi’ claimed that by
means of the expanded flues the Yorkshire boiler was
“ foolproof,” inasmuch as, by placing a fusible plug at
the rear end of the boiler flue, this would prevent the
furnace crowns becoming overheated. In all cases of
collapsed furnace flues the damage was done imme-
diately over the fire. To place a plug in the position
advocated—at the back end of the flues—would render
it inoperative. The object of the fusible plug was to
put out the fire in case of shortness of water, but a plug
placed at the rear of the flue would not admit of this
being done. The enlarging of the flue tended to
diminish the velocity of the flame and gases ; and
as the restriction was at the bridge and not at the
end of the Lancashire boiler flue, it followed that
Yorkshire boiler did not possess the advantage claimed
for it—viz., that the velocity was increased. He (the
speaker) further pointed out that the idea of constructing
a flue of smaller diameter in front and expanding
gradually to the rear was not a new one. At one time
boilermakers, for convenience of construction, made the
flues in series of parallel belts arranged in telescopic
form, the increase in diameter in each section being
double the thickness of the plate, so that at the end of
the boiler a considerably enlarged flue was obtained.
Nobody, however, discovered or made a point of the
advantage obtained by an expanded flue of this kind.
Mr. Sugden contended that in the figures of actual tests
furnished by the author there was nothing to indicate that
the Yorkshire boiler possessed any advantage over the