April 5, 1917.

THE COLLIERY GUARDIAN

675

CURRENT SCIENCE

The Gas Standard of the Future.

The members of the Midland Association of Gas
Engineers and Managers met in their annual general
meeting at Birmingham on the 22nd ult., when the
president, Mr. Geo. Stevenson, gave his presidential
address, in the course of which he said: “ The official
substitution of a lighting standard by one of 500 B.Th.U.
calorific value, marks an epoch in the industry. At
Long Eaton our standard is 14 candles, No. 2 burner,
but for many years we have adopted a calorific test;
and in this connection one is glad to testify to the
great usefulness of recording calorimeters, etc., when
calibrated daily against standard types.

“ Although about 15 per cent, of our output is
absorbed by flat flames, our experience suggests that a
500 B.Th.U. gas gives satisfaction with the new burner;
but we expect and, in fa ;t, get trouble with anything
much below this figure. There is a big difference
between a 500 B.Th.U. straight washed gas and one of
the same heating value accompanied by 20 per cent, to
30 per cent, of inert material. We have recently had
figures claiming that the flame temperature of such a
gas is only slightly reduced, but even so, the supply is,
in my opinion, against the true interests of gas under-
takings in active competition with live opponents. The
question is of the-utmost national importance, but it
must be remembered that no exact uniform standard
will find general approval. In the interest of both
buyer and seller there are economical limits to be
ascertained. In our case, e.g., the supply of non-
luminous gas would immediately mean the sacrifice of
such a proportion of output as could only be recovered
by great capital expenditure—if even then.

“ The higher standards are gone beyond recall, and
there is much to be said for a straight coal gas of from
450 to 500 B.Th.U.; but in my district I see no
practical or economic prospect of a gas much lower
than this, if the quality is to remain at all constant, a
necessity increasingly important. It is always to be
remembered that we are selling heat units in a given
quantity of gas at a given price, and from the buyer’s
point of view there is a limit to adulteration. In the
present special circumstances, occasional deviation from
working standards are inevitable; but I hope and
believe our electrical friends will not make capital out
of our difficulties. It ought to be impossible to-day for
any gas consumer to substitute electricity on account of
the impoverished gas supply, and I hope any such case
will be brought to light at once ,so that we may not
be (victimised for our efforts and penalised for our
patriotism ’ by the loss of business from causes beyond
our control.”

Coal Mining Efficiency in South Africa.

In the annual report of the Inspector of Mines for
the Middelburg district of the Transvaal for last year
appears an interesting table, showing the results
obtained at several of the principal collieries in that
district. This statement has the advantage of applying
to collieries working,the same seam over an area where
the underground conditions are similar. Still the
results vary somewhat, and it may prove of interest to
attempt to explain the cause of the variations. Mr.
R. B. Gascoyne discusses these in a recent issue of
Coed Age. The system of working is similar through-
out, with one exception, the method adopted being the
pillar and stall. The stalls or bords are 20 ft. wide
and driven from 60 ft. centres. The seam of coal runs
practically level, and has a gross thickness of about
20 ft., but only the lowest portion is worked, the greatest
proportion of the seam being too inferior to find a sale.
The portion worked varies from 3 to 11 ft. 'The table
mentioned is as follows :—

	Total	Coal mined	
	men	per head	Thickness
Colliery.	employed.	per month.	- worked.
		Tons.	Ft.
Transvaal & Delagoa Bay 788 ..		....	66-6	...	... 11
Tweefontein 		....	774 ..	....	59-7	...	6
Cassel		.... 482 ..	. ..	56’0	...	6
Coronation 		....	528 ..	....	54’9	...	9
Witbank 		.... 1,374 ..	....	52-0	...	51
Middelburg		.... 438 ..	....	47’3	...	9
Oogies 		.... 1,199 ..	....	39-3	...	3|
The most striking	influence	on the production per	

head shown on this table would appear to be that of
thickness, the Transvaal and Delagoa Bay collieries
being easily first with an average of 66’6 tons of coal
mined per head per month. At this colliery no coal
cutters are used, which makes the influence of thickness
all the more striking. If we turn to the Oogies colliery,
at the bottom of the table, we find that the thickness of
the seam extracted is only 3J ft., and the average
amount of coal mined per month only 39 3 tons. To
obtain this result at Oogies 70 coal cutters are employed,
as against none at the Transvaal and Delagoa Bay
collieries. The results at Oogies would further seem
to show that in the Transvaal, with coal selling at
1 dol. per ton, a 3 ft. seam of coal is as thin as can be
worked by pillar and stall at a profit.

In the Transvaal the use of coal cutters generally
increases the output by 50 per cent. Last year 70 per
cent, of the coal mined was produced by coal cutters.
A native, however, can rarely cut a length of 50 ft.
six feet under in a day of nine hours.

The table of results obtained in the Middelburg
district of the Transvaal shows that the thickness of
the seam worked is the most important factor governing
results. Hardness of coal and character of roof come
next, inclination of seam follows, and under normal
mining conditions the size of the mine car comes last;
always provided, of course, that a size of mine car has
been selected well suited to conditions underground.

It must not be understood, however, that the efficiency
throughout the Transvaal is in all cases equal to that

AND TECHNOLOGY.

of the Middelburg district, the average for the whole of
the Transvaal being 48 tons per head per month. In
Natal, where the seam worked averages only 4 ft. thick,
and the coal is somewhat difficult to work on account of
bad roof, spontaneous combustion and firedamp, the
average is only 28 tons per head per month. In the
Orange Free State, with a seam 7 ft. thick, but unusually
hard in structure, the average mined per month per
head is 35 tons. In the Cape Province, where the
collieries are small and the seams are thin, and carry
more waste than coal, the average last year was as low
as 7 tons per head; but here the collieries are often idle
most of the time.

Potash as a By-Product from the Blast Furnace,

In the course of the discussion of a paper by R. J.
Wysor, presented at the New York meeting of the
American Institute of Mining Engineers in February
last, Mr. Charles H. Rich remarked that not all furnace
burdens are as rich in alkalies as those noted by
Mr. Wysor. In his own experience he bad never gone
into any extended examination of the materials entering
the furnace burdens, but had made a number of
determinations of the water-soluble alkalies of flue and
boiler dust and found a maximum of about 4J per cent.
KoO—too small for profitable reclamation. He had,
however, frequently encountered the smoky gas
described by Mr. Wysor. Such gas carried heavy
fume, and burned with a fitful flame difficult to main-
tain. So pronounced was the inhibitory effect of the
fume that, in extreme cases, the flame of a lighted
match was extinguished by the current of gas and it
was found impossible to conduct calorimeter tests
without preliminary washing of the gas. When the
gas was led through a washer filled with distilled watel-
and pieces of coke, the fume was absorbed and the gas
burned without difficulty.. Careful analyses conducted
on the water solution from the washer showed cyanides
in increasing amounts in proportion to the difficulty
experienced in burning the gas. The determinations
were conducted in such manner as to preclude possibility
of interference by chlorine.

Some results obtained in a test are :—

COo.... 12’00...	8-50...	9-50...	9*20	p c.

CO ....... 26-00...	29-00...	29'20 ...	29’60 p.c.

CO/COo	2’16 ...	3’40 ...	3'18 ...	3’21

Ho ........ 3-60...	4-20...	4’00...	4’00	p.c.

B.T.U...	101’70 ...	113-50 ...	109 50 ...	110’80	Anal.

B.T U ..	100-60 ...	114-10 ...	114-10 ...	111'30	Caloiimeter.

It will be noted that the CO/CO2 ratio of the gases is
high. This seems to obtain in such gases to increasing
extent in proportion to the difficulty of burning the gas.
The gas represented by the three last tests could not be
burned without preliminary washing. They calculated
from analyses of the water solution, about 1 grain of
cyanides to 1 cu. ft. of gas.

Whether the fume indicated the presence of finely-
divided chlorides or was due to cyanides, he agreed with
Mr. Wysor's conclusion that the inhibitory effect was
mechanical and was due to the absence of intimate
mixture of air and gas molecules. The high CO/CO2
ratio observed in such gas probably had no bearing
upon the observed phenomenon and was mentioned
only incidentally.

Chemical Engineering.

The Faraday Society recently initiated a discussion
on “ The Training and Work of the Chemical Engineer ”
at their last meeting on the 6th ult. The meeting was
presided over by the president, Sir Robert Hadfield,
F.R.S.

Sir George Beilby gave the keynote to the discussion
in his definition, “ Chemical engineering has for its
function the design and construction of apparatus
required for the carrying out of chemical processes
on a manufacturing scale.” The discussion practically
centred round two standpoints: On the one hand, the
view of the great majority that for the construction of
chemical plant a man combining within himself the
qualities of both chemist and engineer is the type to be
aimed at; on the other hand, the view that a man
cannot be both chemist and engineer, and that what is
needed is closer co-operation between the two.

Sir George Beilby summarised his scheme as follows :

1.	A sound and practical training in chemistry and
chemical physics extending over three years. During
the third year special subjects to be introduced.

2.	At the end of the third year at latest the case of
each student to be considered by the heads of the
departments, so that he may be advised in what
direction he should specialise.

3.	Average students with no special bent to complete
their course by general advanced studies during the
fourth year.

4.	No degree or “ hall-mark ” to be given in chemistry
till the complete four years’ curriculum has- been taken.

5.	Chemical engineers, research chemists, and spe-
cialists in other branches to devote one or two years to
higher post-graduate study.

Prof. F. G. Donnan, who spoke on “ The Training
of the Works Chemist,” sub-divided chemists into
(1) research chemists, (2) engineer chemists, (3) chemical
engineers, and the sub-division was generally adopted
as useful. Men of class 1 are the discoverers of new
compounds and reactions, and are, of course, absolutely
necessary, but to be useful in industry they should, in
Prof. Donnan’s opinion, be men of broad outlook whose
horizon is not confined to the laboratory. To this end
he advocated teaching them engineering principles and
the elements of such practice as may bear on their
work, so that they can co-operate intelligently with the
other classes. The danger to be borne in mind was
stated by Prof. E. G. Coker and others, and was clearly
indicated by Sir George Beilby. There is an essential

difference between the chemist’s and the engineer’s type
of mind. The former thinks in terms of molecules, the
latter in terms of masses. Many first-rate chemists
were quite uninterested in engineering, and the training
should, therefore, be permissive to some extent, and not
obligatory.

Men of the second class—engineer chemists—are
required in large numbers, and, although essentially
chemists, they should receive a considerable amount of
specialised engineering training, in which stress is laid
on thermophysics and thermochemistry, the properties
and testing of materials of construction, the principles
of design, and the problems of power. The work of
these men is really applied physical chemistry. Men of
class 3 are thoroughly trained engineers with a chemical
sense and some chemical knowledge, the more the
better. Prof. Donnan went on to outline the manner
in which the work of the three classes of industrial
chemists should be co-ordinated for the successful
development of a new process after the research
chemists have worked it out in the laboratory. Men
of classes 2 and 3 should combine to design and test a
small trial plant in order to obtain special chemical
engineering data, and all three classes should then
combine to - deal with a technical unit plant fully
working, above all quantitatively the thermochemistry
and thermodynamics of the process. There can be no
doubt that our tendency to keep apart the work of the
chemist and the engineer has seriously impaired our
industrial efficiency, and Prof. Donnan’s suggestions
merit the most serious consideration.

ELECTRIFICATION OF COLLIERIES.

The electrification of a group of collieries was the
subject of a paper and discussion at a joint meeting
held at the Mining School, Stoke, on the 31st ult., of the
National Association of Colliery Managers (North
Staffordshire Branch) and the Association of Mining
Electrical Engineers (Lancashire, Cheshire and North
Staffordshire Branch). The paper, which presented
some unusual features in colliery electrical work, par-
ticularly in regard to the system of signalling, was read
by Mr. Harold Green, A.M.I.E.E., electrical engineer
to the Earl of Ellesmere’s Collieries, Worsley, Lanca-
shire.

The paper described the gradual change over from
steam and compressed air to electrical driving of the
existing plant at the Earl of Ellesmere’s group of
collieries. The change over commenced about six years
ago, and electricity has gradually superseded other
drives as these required replacing. The scheme embraces
eight collieries, linked up by a private railway, which
has been tak en advantage of for running the overhead extra
high-tension wires alongside. The power is supplied by
gas engines using waste gas from coke ovens, and by mixed
pressure turbo-alternators. Power is transmitted at
10,000 volts. Two outstanding features had been aimed
at—duplication and standardisation.

Special attention has been paid to avoid, as far as
possible, the paralleling of alternators or transformers,
and the complete system is worked entirely on what
might be termed a change-over system. It might be
urged that paralleling presents no difficulties, but, if it
can be avoided, it is better to do so. There are certain
grave possibilities with alternating current apparatus in
parallel, and a switchboard attendant is a necessity.
This is not so with the change-over system, as
the enginemen take this as part of their regular
duty, the switchboards requiring very little attention.'
Of course, this system cannot be carried out indefinitely,
because a time must come, as generating plant is added,
when the plant must be paralleled.

The whole group of collieries is linked up by two sets
of high-tension lines, one of which is connected with the
gas-engine plant and the other with the mixed pressure
turbine plant. At each colliery there is a sub-station
provided with change-over switchgear, so that the
supply can be taken from either generating station as
desired.

The author demonstrated by means of model installa-
tion his method of underground signalling and also a
system of visual signals, which displayed considerable
ingenuity. The signalling system was described as
follows:—Every 400 yards or so along the haulage road
a specially designed magneto is fixed, similar to the
ordinary telephone ringing magneto, but more robust.
The armature is driven through a train of gears as
usual. On the slow-speed shaft a free wheel is fixed,
similar to the bicycle free wheel. The line wire, which
is also the pull wire, is taken over this free wheel,
and terminates with a weight. The other end of the
line wire is made fast. This is repeated, say, every
400 yards, and all the magnetos connected in series, as
also any bells required. The two extreme ends of the
line are earthed. If the line is pulled at any point along
the road, the nearest magneto armature will be rotated,
generating alternating current, which is transmitted
along the line and through all the bells or buzzers.
Experiments on this system have exceeded expectations.

With regard to the visual signal installation, the
indicator is of the luminous type. The signals given
appear as a luminous stencil on an opaque ground,
showing the number of rings given, the nature of the
signal, and the level the signal has been sent from.

The coal mine operators of Nova Scotia have had a
conference with Sir George Foster, the Dominion Minister
of Trade and Commerce, with a view to a large increase
in output.

End of Barrow Strike. — The strike of engineers at
Barrow is ended. A ballot of the men was taken, and
resulted in a majority (1,623 votes to 1,250) in favour of
resuming work. Arrangements are being made for a
joint conference relative to the matters in dispute.