1090

THE COLLIERY GUARDIAN.

June 9, 1916.

trough really trends south-eastwards. From the
geological map it is evident that Yorkshire Main was
sited on a foundered keystone between a pair of faults,
and the great depth at that pit may therefore be more of
local than of general significance.

To the north of the Don fault disturbance the north-
westerly strike and north-easterly dip which are usual
over the greater proportion of the exposed part of the
coal field in South Yorkshire are resumed, and it is seen
that the general effect of the displacement is to set back
the lines of the contours by a distance of some six miles
to the north-east. Near the outcrop of the Barnsley bed
the step is a very sharp one, and the angles of the Z
bend made by the sea level contour are approximately
right angles. Contours of intermediate depth (— 300
yds.) about Manvers Main and Wath Main evidently
swing round more smoothly, and in the district of the
deeper pits north of Doncaster, where the spaces
between successive contours is much wider, what
evidence is available is in favour of the change of direc-
tion (which in that district is through somewhat more
than a right angle) that takes place continuously along
considerable lengths of widely- sweeping curves. The
contours north of the Don faults assume, in fact, the
form of a pitching monocline, which to the east passes
into a narrower, but still broad, arch of an anticline of
less uncommon form. That the displacement due to it
dies out completely in a north-easterly direction is
improbable-, and it is the opinion of the writer that,
along the continuation of its line for many miles north-
east of Doncaster, the coals occur at levels always con-
siderably shallower than in the neighbouring country to
the south.

Of the course of the Don faults disturbance south-west
of Sheffield there is little information. Of the actual
faults, Green has stated that they end oft against other
north-west trending faults within the area of the city.*
That the whole disturbance thus comes abruptly to an
end is improbable, and it may be pointed out that the
outcrop of the Ganister or Halifax Hard bed along the
valley of the Don and Little Don above Sheffield is no
less out of line with that of the same bed across the
Derbyshire moors south of the city than is the outcrop
of the Barnsley coal in ’Wentworth Park out of line with
that at Handsworth and Woodhouse, in the country
south of the Don. It is even probable that the disturb-
ance extends south-westwards, across the whole outcrop
of the millstone grit, and quite possibly the south-west-
ward step in the outcrop of the mountain limestone
between Calver, Great Longstone, and Bakewell, may
be a continuation of the same disturbance.

Within the district of the uplifted monocline north of
the Don disturbance, as far as the latitude of Barnsley,
the structure of the country is of simple type, and such
local bends as affect the north-west'—ranging contours
(for example, at Elsecar) are due to normal block fault-
ing by dip—or strike faults, probably related to the main
disturbance. Except just east of Barnsley, the contours
belonging to- shallow depths appear much closer together
than those at greater depths. East of Barnsley there is
an evident crowding of all the contours down to
— 500 yds.; and although surface relief largely accounts
for the slight westward swell of the outcrop west of the
town, it is clear that between Barnsley Main, Grime-
thorpe, and Frickley an important synclinal trough or
basin is developed, with a more or less well-defined open-
ing by Bullcroft out to the east. This wide and open
trough, to which the name “ Frickley trough ” is very
applicable, is the main tectonic feature of the coal field
north of the Don faults. Its course is well defined by
the contours —500 and —600 yds. between Brodsworth
Main and Askern Main, and as it ranges further east-
wards, it appears to encroach upon and perhaps in part
to help the rounding-off of the monoclinal feature, of the
Don. It may be, also, that the north-westerly strike of
the measures which have been proved at Hatfield Main
has been produced by it. Along the westward continu-
ation of the line of the Frickley trough a rather sharp
anticlinal swell through Wharncliffe Woodmoor and
Carlton Main causes the trunk syncline to divide into- a
south-westerly and a, north-westerly trending arm. The
south-westerly branch is that which trends through
Grimethorpe and Barnsley Main, the effects of which
have just been described. The north-western limb is-
wider and less well defined, but can be traced through
Havercroft and Ryhill Main, south of Sharlston West,,
to Wakefield, and by its continuation may account for'
the preservation of the great expanse of rocks newer
than the Silkstone coal in the country west and north
of Dewsbury. A further trough, also ranging north-
westwards, seems to branch from the Frickley trough
east of South Kirkby, whence it may range as far as;
Rothwell. Hemsworth, Nostell, Sharlston, and perhaps;
St. John’s, are on the line of it; but, as the writer will'
demonstrate shortly, faults in the district about
Normanton render its further continuation difficult to«
trace. Of all the pits sunk through permian limestone
to- the Barnsley coal in Yorkshire, there has been none
at which the depth was more unexpected than that at
Askern Main, which is as yet the only point whence one
can fix the trend of contours across the eight or nine1
miles of country between Hemsworth and Pontefract,,
and the Frickley trough. North-eastward from Askern,,
beneath the permian limestone, only the strike lines of:
the triangle formed by Askern Main, Fryston, and Selby
are available as guides. From Selby, moreover, the*
evidence is not very satisfactory, and the depth assumed.
—2,245 ft.—is adopted on the strength of the guarded:'
statement by Dr.’ Gibson, that “ presumably ” it
belonged to “ one of the bands above the Barnsley
coal, which in the form of the Warren House seam may
have been passed through in the faulted ground at a;
depth of 2,261ft.”. Within the triangle so determined'
the contours have merely been spaced out regularly, and'
are only inflected just sufficiently to make them join:

* “ Geology of the Yorkshire Goal Field,” p. 490.

with the better-proved lines in the country to the west.
Evidently, if Dr. Gibson’s tentative view about Selby is
right (and the rumours spread concerning Pollington tend
to confirm it), the average strike of the coal measures
under the permian limestone between Selby, Hatfield
Main, and Pontefract must be more nearly north and
south, and the average dip more easterly than the trend
which the contours in the exposed coal field in West
Yorkshire would have led one to expect.

From the Don Valley past Barnsley to D ar ton the out-
crop of the Barnsley coal maintains a regular north-
westerly direction, and faults (where present) are not of
sufficient magnitude to deflect its course. Beyond
Haigh and West Bretton, just where the coal seam
changes its character, and, taking on its West York-
shire facies, becomes the Warren House coal in the east
and the Gawthorpe coal in the west of the district, the
structure of the coal field alters, and normal cross-
faulting (often on a considerable scale) becomes the rule.
By this faulting the country is cut up into more or less
rectangular blocks with sides making average angles of
45 degs. with the meridians, and outcrops cease to be
traceable continuously from one block to another. In
following the boundary of the measures newer than the
Barnsley coal across this imbricated country, from
Crigglestone, by Horbury, Ossett, East Ardsley, Loft-
house and Woodiest ord to Kippax, where they disappear
beneath the escarpment of the permian, we find that
generally, wherever the trend of the line is north-
eastwards, it takes that direction by following the course
of some more or less important fault. Within this
boundary the contours, drawn to' fit the ispot-levels from
the pits as listed above, follow a general trend quite
parallel to the north-eastern-ranging faults, and only
when one asks about dips and strikes as proved by
workings at the various collieries does one come to know
how little direct evidence there is that over this most
important West Yorkshire mining district there is no
usual or consistent 'south-easterly dip. Nevertheless,
the Geological Survey map shows that . between Loft-
house and Sharlston, or from Allerton to Pontefract,
the higher measures come on south-eastwards, and on
close enquiry one finds that a rather regular succession
of north-easterly to south-westerly faults, each throwing
down south-eastwards after the manner of a step or
cascade-like structure, does really stimulate a persistent
dip to the south-east and produces the same average
displacement. Among such broken structures the
proximity or otherwise of the pit-sites to- the faults lias
considerable influence in determining the way in whecli
the contours have to bend among them, and too much
reliance cannot therefore be placed on the minor
irregularities which in this district certain of the con-
tours seem to show.

(To be continued.)

THE ESTIMATION OF MOISTURE
IN COAL.*

By T. F. Winmill, B.A., B.Sc.

The determination of the percentage of moisture in
coal is a question which has received much attention
from various investigators, all of whom are agreed that
the usual method of heating coal in an air oven to
110 degs. Cent., and assuming the loss in weight after
such heating to be due to the loss of moisture alone, is
one liable to serious error. Whilst in a very large number
of cases a high degree of accuracy is not required for
local variation and the difficulties of sampling may
introduce uncertainties as great as the experimental
errors, in other cases, however, it is necessary to know
with some'accuracy the percentage of the various con-
stituents of. the coal, and this is especially so when a
selected sample has been the subject of some particular
experiment, or is required for an ultimate analysis. Since
most of the analyses .made in the Doncaster Coal Owners’
Laboratory are on selected samples, some experiments
have been conducted with the object-of devising a simple,
rapid, and accurate method for the determination in
vacuo of the moisture content of coals. The results
obtained have been compared with those arrived at by the
more general method of heating the coal in an air-bath
to 105 to 110 degs. Cent.

-It is obvious that -the loss of weight found by this
latter method is really the balance of five, factors,
namely : (1) Loss in weight due to' the' loss of moisture;
(2) loss in weight due to the expulsion of the gas from
the coal; (3) gain in weight due to the absorption of
oxygen by the coal; (4) loss in weight due to- the forma-
tion of water and carbon dioxide by the interaction of the
carbon and hydrogen of the coal and the oxygen of the
air; ' (5) gain in weight due to the re-absorption of
moisture by the coal from the air during cooling and
weighing.

All these uncertainties may be avoided by heating the
coal in vacuo, and by collecting and weighing the actual
moisture given off. For this purpose an iron tube 41- cm.
in diameter and 20 cm. long is covered with a layer of
asbestos paper, and on this is wound a length of resist-
ance wire. This coil is insulated on the outside with
asbestos paper, and connected through an adjustable
resistance to the lighting mains. By a suitable variation
of this outside resistance any desired temperature can
be obtained inside the iron tube, and without further
attention will remain constant all day to within a few
•degrees. The temperature is read on a thermometer
carried by a cork fitted into the end of the iron tube. A
small flask having a bulk 2| cm. in diameter, a neck
4| cm. long and 1cm. bore, is held by a divided cork
(so as to facilitate its easy removal) in the other end of
the iron tube. Into the neck of the small flask a glass
tube containing anhydrous calcium chlor-ide, is fitted by

* From a paper read before the Institution of Mining
Engineers.

means of a rubber stopper. The other end of the tube
is closed by a well-ground hollow glass stopper, which is
connected by rubber pressure tubing to a second calcium-
chloride tube, which in turn is connected through a two-
way tap to a sulphuric-acid wash-bottle, and thence to
a Bunsen vacuum pump. The calcium-chloride tube is
12 cm. long by 1J cm. bore. The bent portion at the top
is 1| cm. long by | cm. in diameter. Just below this
bend the main portion of the tube is enlarged into a bulb,
so that when the calcium chloride becomes moist by the
absorption of water it may not clog the tube.

When a determination is being made the electric oven
is first brought to a temperature of 105 to 110 degs. Cent.
About 2 grammes of the powdered coal sample are then
weighed into the flask, and the tube is weighed
accurately. The apparatus is then joined up, and the
pump turned on until a pressure of 20 mm. is obtained.
The flask is then put into- the electric oven, and left for
half an hour with the pump still working. If, however,
the coal contains more than 10 per cent, of moisture, it
is well to extend the heating to three-quarters 'of an
hour in some cases. At the end of this time, the flask is
taken out of the oven and allowed to cool for five
minutes, after which the two-way tap is opened to the
atmosphere, and air allowed to- enter. The. apparatus
is then disconnected, the flask securely stoppered, and
the tube again weighed. The increase in weight of the
tube i-s the quantity of water contained in the
sample of coal weighed into the flask. Since oxygen has
been absent, and since calcium chloride will not absorb
the gases given off by the coal, the estimation made in
this way is free from -the errors that may occur when the
coal i-s heated in air.

The results have shown that dried coal has a very con-
siderable power of absorbing moisture, -and a sample,
after being dried, must be protected instantly if it is
to remain free from moisture; but that fairly accurate
estimation may be made by heating the coal in a
current of dry air at 105 to 110 degs. Cent., and collect-
ing the moisture evolved; whilst in cases in which it is
proposed to use the dried coal for any further experi-
ments, the drying must be done in the absence of
oxygen, which can bo done simply and quickly by the
vacuum method described.

SUPPLY OF COAL TO FRANCE.

A second edition (bearing date May 25) of the official
circular (reproduced in our issue of June 2) relating to
the supply of coal to France has been issued. Sections

I.	and II., which specify freight charges and coal prices,
remain unaltered, but new matter has been added to
Section HI., which deals with arrangements for coal
exporters’ services. We append the section in full, the
new matter being printed in italics :—

III.—Coal Exporters’ Services.

1.	The following arrangement is based on the prin-
ciple that exporters, on the one hand, who for the pur-
poses of this arrangement shall include buying agents for
firms in France and coal owners who sell direct to buyers
in France, shall not undercut one another or seek to
obtain undue preferences, and that, on the other hand,
importers in France shall be protected from seeing their
neighbour receive supplies on mote favourable terms
than themselves.

2.	Existing contracts not to be disturbed.

3.	Exporters will undertake the work in connection '
with procuring export licences, all arrangements with
collieries, railways and docks for stemming vessels,
Customs House formalities relating to coal, and atten-
tion to loading, so far as has hitherto been customary at
the different ports.

4.	The exporters, including firms who- are buying
agents for firms in France and coal owners who sell
direct to buyers in France, will charge and receive for
their services remuneration at the rate of 5 per cent, on
f.o.b. price with a maximum of Is. per ton. This
remuneration together with shipping charges or dues
not included in f.o.b. price to exporters and charges for
mixing cargoes on shipment and separation in holds, if
any, to be added to f.o.b. price and paid by buyers. For
example, at present Tyne dues are l^d. per ton; Clyde
dues 3-^-d. per ton; wharfage dues Cardiff, Newport, Port
Talbot, 2d. per ton; and harbour tolls, Swansea, 2^d.
per ton.

5.	In order to facilitate stemming with collieries, the
chartering of vessels will be done, by exporters for
account of buyers, ship paying to all exporters one-third
of 5 per cent, brokerage on freight. In consideration
of this payment exporters will relieve buyers of
demurrage in loading, if any, but will not be responsible
for demurrage at French ports.

6.	Exporters for account of buyers will insure invoice
value plus 10 per cent., and will pay freights advances
not exceeding one-third of estimated freight unless
otherwise arranged.

7^ The basis of this arrangement is payment cash
against bill of lading in London or Paris in exporters’
option. If credit is mutually arranged, interest to be
charged at not less than 1 per cent, above Bank of
England rate.

8. The exporters and coal owners in each district will
appoint a committee, to be called the local com-
mittee. The local committees will keep in close toucji
with the French Central Committee, from whom they
will receive instructions regarding allocation and priority
of orders from France, state of discharging ports, etc.
Failing specific instruction, the local committee will allo-
cate orders equitably. The local committees will in
like manner allocate tonnage available for employment
in their respective districts, but charter parties will be
entered, into between the owner or his broker and the
exporter as charterer. Each district will determine the
number and composition of its committee, and, if
thought fit, fix sub-committees thereof to sit in rotation