March 3, 1916.

THE COLLIERY GUARDIAN.

411

arsenic. He also asked Mr. Cooper whether it was more
profitable and belter to work, in the recovery of
ammonia, ia 15 or 25 per cent, solution.

Mr. Cooper pointed out that more was obtained for a
25 per cent, than a 15 per cent, solution, but a solution
of more than 15 per cent, was more difficult to work,
and it was frequently found that the condenser top
became blocked. The usual custom was by a sliding scale
based on 15 per cent, liquor. There was also the diffi-
culty of storing a solution stronger than 15 per cent.—
at 17 per cent, his experience was that the liquor would
solidify at atmospheric temperature. With regard to
the acid strength, it was assumed that it was bought at
144 Twaddell, and could be diluted to correspond.

Mr. Haigh said some coke oven managers had anti-
cipated that the acid would be arsenical, and had hoped
to get some suggestions as to how to deal with it out-
side the saturator. Whenever there was extra arsenic
in the acid at his works, the men complained; and they
certainly were affected. He did not know if anyone had
ever tried to treat the acid by passing hot gases in some
way through the deposit—a sort of de-arsenicating plant.
With regard to pitch, he did not think its use would
greatly increase the coke output.

Mr. Cooper said the mother liquor tank supplied in
some plants could be made use of foir the purpose of
running down the 144 Twaddell acid — it could be
regarded as an extra tank, and it was quite practical to
bring in the crude gas, diluted, if necessary, with still
gas, straight into the tank.

The President expressed his cordial agreement with
Mr. Cooper that the Government should consult prac-
tical men before offering suggestions which were imprac-
ticable. In that respect, the council of the association
had already protested in very strong terms against some
of the advice which had been sent to coke oven firms.
More than that he could not at present say. The use
of nitre cake he did not consider very feasible, when
they considered how much nitre cake would be required
to produce, say, the equivalent of what would be got
from 30 tons of acid a day. Inside a month the exist-
ing stocks would be absolutely wiped out. With regard
go arsenical sulphuric acid, he was afraid there was not
much chance of getting non-arsenical acid. The ores
from which non-arsenical acid was made came from
Sweden or Norway, and, at the present time, Swedish
and Norwegian ore was absolutely impossible to obtain.
The majority of ores now being used came from Spain,
and these were highly arsenical. Chamber acid at 110
Twaddell was fairly free from arsenic, but it was within
the means of anybody to have a little de-arsenica;or of his
own, and with the amount of sulphuretted hydrogen at
his disposal, a coke oven man could have his filter so
arranged that he could quite well filter, say, four tons of
acid a day on a filtering area of about 30 sq. ft. Filter
slabs could be bought at about 9d. per sq.ft., and 100
sq. ft. would filter all the acid they wanted, by means of
a shallow tank, in which the acid was passed in and out,
but it must be at a temperature very little above atmo-
spheric. With regard to the use of pitch, there was a
suggestion that they should experiment with non-coking
coal, to which pitch was added. He hoped to carry out
certain experiments in that direction, and he might have
something to tell them about it at a future meeting. It
was, of course, a matter which must be thoroughly
threshed out.

Mr. J. T. Price (hon. secretary) described some
experiments he had undertaken with various acids, some
highly arsenical, as the result of which he put down a
small de-arsenicator used as the president suggested.
He took a supply of gas after the exhaust had bubbled
out through ;he ordinary storage tank with a lead coil,
and ran the acid afterwards through a filter, using the
slabs of which Mr. Chnisp spoke, and he found that the
acid coming away gave a very good sulphate.

On the proposition of Mr. Lee, seconded by Mr.
Myers, Mr. Cooper was then heartily thanked for his
paper.

. Mr. Myers then moved, on behalf of the Staffordshire
members : “ That sections be formed in different areas
of the country, the formation of such sections to be
sanctioned by the association, and each section to have
one representative on the council of the central associa-
tion. Such increase in the numbers of the council
caused by the election of district representatives shall
be sanctioned ad lib. until the whole of the areas of the
country have been apportioned to respective branches.”
He felt that the rapid growth of the association
warranted this step; it was obviously impossible for
members residing so far distant as South Wales, Durham
and Scotland to enjoy the same advantages as Yorkshire
members if all the meetings were held in Yorkshire.

Mr. Price, in seconding, said the association had
now 89 members, and of these there were in Durham
and Cumberland 14, Staffordshire 10, South Wales 5,
and the remainder in Yorkshire. The majority of the
members in those districts joined on the understanding
that branches would be formed, and unless this was done
he feared they would not continue their membership
after the present year.

The President expressed his cordial agreement with
the proposal, and said the council were also unanimously
in favour of it, and only awaited the authority of the
general body of members before submitting a scheme.

The association was originally started as a Midland or
Sheffield organisation, but so well was the idea taken
up that it very soon assumed national proportions.

Mr. Lee, while in sympathy with the object in view,
thought a definite scheme should be submitted before
vhe members were asked to vote; but on a vote Mr.
Myers’ motion was unanimously agreed to.

The President announced that the next meeting of
the association would be at Leeds University, on
March 25, when Prof. Cobb would read a paper on
“ Refractory Materials and Salty Coals.”

PRECISE SETTING-OUT IN UNDER-
GROUND ROADWAYS.

By P. Wilson Brown.

In modern and difficult mining, the work of precision
in connection with setting-out and keeping straight the
more important roadways is now fully realised. Every
opportunity is given to surveyors to carry out their work
in the most accurate manner, and anyone who does not
avail himself of those opportunities has no respect for
fine work. Very often, part of the work is accurately
done, while the other and more important part is gone
about in a somewhat slip-shod fashion. This statement
may be illustrated by the methods usually adopted to
drive an underground roadway at a certain inclination

a il line. The work of surveying necessary to decide
upon line and gradient is carried out in a very accurate
manner, yet the n.ore important part, namely, keeping
to that line and gradient, does not meet with the atten-
tion and care that are called for by the difficult position
and conditions met with underground. Usually the
roads which are required to be driven at a certain
gradient are stone drifts, or roads cutting metals or
rocks between the respective seams of coal. These rocks

w

Fig.

m.

are more or less of -a hard, solid nature, able to with-
stand a great crushing strain, and admitting of good
marks and fixtures being made with very little fear of
disturbance. Thus the conditions are very suitable
indeed for accurate work.

When these drifts are to start from and extend to
certain definite points in the underground workings, or
where excavations are being conducted from two points,
any significant error will often result in the work being a
total loss. The extreme points to be joined by such roads
must be carefully surveyed and levelled with the bes.
class of instruments, correctly adjusted, after which the
horizontal and vertical angles have to be found.

The road can first be driven a few yards in the
approximate line, or until solid rock is found upon which
to set the plugs for the sight lines. In the case of a
dipping mine, plugs should not be put in till the end
of the flat landing is reached. After selecting a suitable
place, the theodolite is set up, levelled truly, and point-
ing in the line along which the road is to be driven.
The direction is then given by inserting wooden plugs
in the roof, about 6 ft. apart, in the proposed line. An
apparatus as shown in fig. 1 is next fixed to the plugs
by means- of screws. A fine brass wire is threaded
through the hole A, and by means of the adjusting
screws B, is brought to coincide with, or on to, the
vertical web of the telescope.

This method of suspending sight lines is a great
improvement on the cord and staple method, for in the
latter, if the staple is not inser.ed truly vertical, repeated
dropping of the cord will tend to move it, and eventually
put it out of alignment. The cord requires renewal,
especially in damp atmosphere, and the staple is apt
to become loose; or it may be maliciously moved. With
the new method, a micrometer reading of the distance
between the wire and point C can be taken. The chief
advantage is the fine adjustment which can be ob.ained
or the ease with which the wire can be placed in true
alignment. To check- any movement of the roof plugs,
other plugs are placed in the floor vertically underneath
and having a small brass plate with a fine centre dab
immediately under the point of a plummet suspended
from a wire. Three sight lines are often advocated, but
the writer does not approve of them, as the first and
third may move the same distance in opposite directions
and still be in line. The better sys'.em is floor plugs, or
a check mark as far back along the roadway, as possible.

Inclination Plugs.

From the same setting of the theodolite, two plugs
are inserted on each side of the road, at a distance of
about 6 ft. apart, and at the required angle of inclina-
tion. An apparatus similar to fig. 1 is screwed on to
each, only that the two on one side of the road have
wires attached, a small groove being cut in the centre
of the spindle of the other two. Each wire in turn is
now stretched taut across the road, and adjusted at each
end to correspond with the horizontal web of the
telescope.

The general method is to use what is known as a
“ grade stick,” an instrument too well known to need
description. This, however, should never be used for
important work, as the results obtained are very
inaccurate.

Fig. 2 shows one of the horizontal or grade wires in
position. Care must be taken that the wire, when in
use, is sufficiently tight to prevent sagging. The line
and gradient wires should not foul each other, though
if set close together, the line and gradient can be taken
at one observation.

COAL AMD COKE SUPPLIES.

Owing to the increasing demands of industries connected
with the war, the difficulties with regard to fuel supplies, to
which the Board of Trade called attention on December 1 last,
have become more pressing in certain districts. It was
decided, therefore, to appoint, on the nomination of the various
coal owners’ associations, district coal and coke supplies com-
mittees, with the object of ensuring that munition firms and
other important consumers obtain the supplies they need with
as little delay and friction as possible.

Committees have been formed, or are in course of formation,
in the following districts :—

(1)	Scotland. Secretary, Mr. Robert Baird, 105, St.

Vincent-street, Glasgow.

(2)	Northumberland. Secretary, Mr. R. Guthrie, Coal
Trade Offices, Newcastle-on-Tyne.

(3)	Durham. Secretary, Mr. R. Guthrie, Coal Trade
Offices, Newcastle-on-Tyne.

(4)	Cumberland. Secretary, Mr. Tom P. Martin, 19,
Falcon-street, Workington.

(5)	Lancashire, Cheshire, and North Wales. Secretary,
Sir T. R. Ratcliffe-Ellis, 18, King-street, Wigan.

(6)	West Yorkshire. Secretary, Mr. A. B. Smith,
Central Bank-chambers, Leeds.

(7)	South Yorkshire. Secretary, Messrs. Parker Rhodes
and Company, 14, Moorgate-street, Rotherham.

(8)	Nottingham, Derby, and Leicester. Secretary, Mr.
Wm. Saunders, Bank-chambers, London-road, Derby.

(9)	Staffordshire, Warwickshire, and Shropshire. Secre-
tary, Mr. S. J. Keeling, New-road, Netherton, Worcester-
shire.

(10)	South Wales. Secretary, Mr. Finlay A. Gibson,
Park-place, Cardiff.

(11)	Somersetshire and Gloucestershire. Secretary, Mr.
J. G. Dennehy, Albion-chambers, Bristol.

It will be the business of these committees to see that the

resources of their districts are utilised to the best advantage,
and that the requirements of important industries are fully
met. The question whether licences for the export of coal
and coke can be issued will necessarily depend largely upon
the home demand being satisfactorily supplied. Any recom-
mendations that the committees may be able to make with a
view to greater economy in the use of coal will be carefully
considered.

It is hoped that both coal owners and consumers will
realise that the industries connected with.the war must have
precedence, and that some interference with the normal distri-
bution of coal at the present time cannot altogether be
avoided. It will probably be necessary for the committees
from time to time to ask for information, in the form of
returns or otherwise, as to the distribution of the output or
portions of the output of mines in their districts. The Board
feel sure that coal owners will recognise the propriety of
placing at the disposal of the committee all the information
that they think necessary for the performance of their duties,
and will regard a request from a district committee as a
request from the Board of Trade.

Should serious objection be felt to furnishing any
particular information, the matter should be submitted at
once to the Board of Trade, who will consult the Central
Committee, if necessary.

The Board of Trade have appointed the following Com-
mittee to consider all questions relating to the distribution
of coal and coke that may be referred to them from time
to time by the Board, or submitted by the District Coal and
Coke Supplies Committees :—Mr. W. F. Marwood, C.B.
(Board of Trade), chairman; Sir Richard A. S. Redmayne,
K.C.B. (H.M. Chief Inspector of Mines), vice-chairman;
Mr. H. F. Carlill (Board of Trade); Commander T. Fisher,
R.N. (Admiralty); Mr. J. C. Hamilton Greig, Mr. F. J.
Jones, Mr. Leonard W. Llewelyn (Ministry of Munitions),
Mr. Arthur F. Pease, Mr. K. W. Price (Ministry of
Munitions), Mr. F. Tatlow (Railway Executive Committee),
Mr. W. Walker (Deputy Chief Inspector of Mines);
secretaries, Mr. W. A. Lee (Board of Trade), Capt. C. E.
Williams (Ministry of Munitions).

The Swedish coal imports from July 1 to December 31,
1915, were 2,796,439 tons, of which 1,031,927 tons, of a
value of L899,239, came from Great Britain, and 1,764,512
tons, valued at 63-20 million mk., were from Germany—
the German exports consisted of 768,285 tons of coals,
254,822 tons of briquettes, and 741,405 tons of coke. For
the previous six months the imports were 2,242,905 tons, and
the total imports for the year 5,039,344 tons, against
5,064,371 tons for 1914, and 5,374,720 tons during 1913.