January 24, 1913.

THE COLLIERY GUARDIAN.

179

a direct rapid reading and requiring only a rough
balance. It does not require skilled handling and is
eminently suitable for use in a power station, where
results are required in the shortest possible time. It has
the disadvantage, from a laboratory point of view, of
requiring high-pressure steam ; but if the accuracy
claimed by the author is confirmed, it should take its
place as a standard method for coal.

VIII. This is the method in general use, and is likely
to remain so. The errors to which it is liable require
careful consideration, and it is proposed to devote some
space to them. Correct results will be obtained if—

1.	The temperature of the oven and period of drying
is sufficient to drive off all the moisture.

2.	No moisture is reabsorbed before -weighing.

3.	No volatile substance other than water vapour is
evolved.

4.	No oxidation takes place.

5.	No absorption of carbon dioxide takes place.

6.	No internal chemical change is induced which
may lead to the formation of water in the substance to
be dried by heating it to the chosen temperature. This
error is seldom considerable at 100 degs. Cent.

The local variations of temperature in the ordinary
drying oven are shown to be at times considerable, and
a table of vapour pressures is given as showing the
advantage of drying at a higher temperature than the
boiling point of water.

It is shown that an air oven cannot properly be used
when the temperature of drying enters into a specifica-
tion. Some form of constant temperature jacket must
be used, and for temperatures of 106 to 109 degrees
either- toluene or a mixture of glycerol and water (liquid
used for jacket) appear equally suitable.

Figures taken from the report of the International
Sub-Committee are quoted as illustrating the effect of
a rise of 8 or 9 degrees above the water oven in the
temperature of drying. Similar differences are observed
with other products.

2.	It is well known that many, if not most, dried
powders are hygroscopic.

3.	The evolution of traces of hydrocarbon gases by coal
has been shown by Mahler to be negligible, and, there-
fore, so far as this source of error is concerned, the
method is applicable to coal.

4.	The action of the oxygen of the air on substances
to be dried is in many cases not to be neglected. It is
not always of a simple kind, since frequently the sign
and magnitude of the error caused are both uncertain.

Coal is one among many substances which in the
finely ground state is very sensitive to the action of
oxygen, especially at high temperatures. The sign of
the error affecting indirect determination is uncertain.
Not only is the organic matter of coal easily attacked
by oxygen, but the sulphur of pyrites contained in it
also presents a vulnerable point. It was shown by the
International Committee that the results obtained by
drying at a temperature above the boiling point of
water, but not above that of toluene, were higher than
those obtained in the water oven and corresponded more
nearly to those obtained by drying in a current of inert
gas. For these reasons, the authors feel that the use of
a water oven is indefensible for this material, and agree
with the conclusions of the International reporters on
this matter.

The conclusions and recommendations of the Inter-
national reporters are quoted as being of application
not only to coal but to most other substances.

Some of the methods to which the authors have I
referred were not examined by any member of the
committee, such as the ignition method (obviously
inapplicable to substances containing organic matter or
ammonium salts), the “ water determinator ” method, !
and the gasometric methods. These are applicable to
coal and to many organic materials. It does not appear
that for general work temperatures below 100 degs. are |
nearly as satisfactory as those a few degrees above.

The analyst should make the same careful choice of a ■
method for this determination as be would for that of ,
any other constituent.

South Lancashire Coalmining Developments.--Our local I
representative says vague rumours continue to be put about
to the effect that a syndicate are about to exploit new
coalfields in the neighbourhoods of Croft, Culcheth and
Kenyon, in South Lancashire, but nothing definite can be
gleaned concerning such developments. Meanwhile, the
Pilkington Colliery Company are pushing forward the
arrangements for opening their extensive new collieries at
Astley Green, in South Lancashire, some 4 or 5 miles from
Culcheth, more men having lately been engaged there.
When fully opened out, these pits, which have been sunk
to a depth of 820 yards, Trencherbone measures, will find
employment for 1,400 or 1,500 men and youths. It is not
the intention of the owners to proceed to the Arley seams
(over 1,100 yards) for the present, at any rate. About a
mile away from the Astley Green new collieries the Astley

TWO LARGE GERMAN INSTALLATIONS OF
K0FPERS COKE OVENS.

Most coke oven builders have at some time or other
experienced difficulties in dealing with the expansion of
the brickwork in a battery of coke ovens, and the
consequent strain produced on certain parts of the
ovens. As a result the size of any one battery has been
necessarily somewhat restricted, and it has been the
general rule not to build more than 50 or 60 ovens
in one battery. The Koppers Coke Oven and Bye-
Product Company, to whom we are indebted for these
particulars, have introduced a special form of expansion
joint, designed with the object of counteracting the
total lateral expansion in a battery of coke ovens, and
so enabling larger installations to be built in one setting-
This is of great advantage in all cases, but more
especially when 60 or more ovens are required. This
expansion joint is inserted about every fifth or sixth
oven and its effect is such that even in the largest
battery there is practically no lateral expansion and
hence no strain on any part of the ovens. Such provision
was made in the second battery of Koppers ovens
erected at the Bargoed Colliery in South Wales. Mr.
E. M. Hann, M.Inst.C.E., in describing the coking plant*
spoke as follows :—

In building the second block of ovens, the greatest care
was observed in providing fully for the effects of expansion
by leaving spaces at every fifth oven, and it has answered
perfectly. The provision made seems to have been accurate
and there has been no such movement as we were accustomed
to formerly, displacing the ovens and causing serious
damage at the very start.

i v.w, »1. I-.

Coke Oven Installation at the Kaiser Friedrich Colliery, near Dortmund.

IX. Prolonged exposure in a vacuum to the action of
a drying agent is the last method to be considered.
It is applicable to a large number of substances. Owing
to the low temperature and the absence of oxygen (the
latter condition being effectively secured if after the first
exhaustion an indifferent gas is admitted and again
pumped out) oxidation is completely excluded. The
method has its limitations like all the rest, but direct
comparison with heating at 105 degs. Cent, shows that
the vacuum process usually gives the higher, and
therefore more probably correct results. It is, how-
ever, necessary to see that the sulphuric acid used to
absorb the water is concentrated (1’84), has a large
effective surface, and that the vacuum is as high as
possible. Before moving the samples from the desiccator
the vacuum should be broken by the admission of dry
air. The point as to the necessity for a good vacuum
appears to have been missed by some workers. The
vapour pressure of water at the ordinary temperature is
of the order of 10 to 20 millimetres, and a water pump
gives about this figure. The water on the surface of a
fine powder has a lower effective vapour pressure than
this, and hence the rate of drying of a powder in a
waterpump vacuum over sulphuric acid is practically
the same as in a desiccator of the ordinary pressure.
There is no difficulty in a pump of the Fleuss type in
getting the pressure down to 1mm., and in keeping the
pressure at least under 2 mm. for an indefinite period.
The length of time required for the exposure is difficult
to settle.

and Tyldesley Coal Company Limited are now opening out
new Arley and Trencherbone mines (the first-named reached
at a depth of about 900 yards) at their Kermishaw Nook
pits, Astley. A new engine house has been built and new
engines installed, and other surface improvements have been
effected. Here, too, additional men and youths to the number
of 500 or 600 will be wanted when the new mines are opened
out. Not far away—less than a mile—Messrs. J. Speakman
and Sons are opening out a second Trencherbone mine,
besides carrying out other improvements below and on the
surface at their Woodend pits, Bedford Leigh, whilst at
Westleigh, on the western side of the town of Leigh,
the Westleigh Colliery Company are rapidly opening out
new mines there. The Tyldesley Coal Company Limited
are also opening out a new Trencherbone mine at their
Cleworth Colliery, Tyldesley, besides effecting improvements
with a view to increasing output at the Peelwood Colliery,
Tyldesley. Following the erection of a new engine house
and the putting down of compressed air coal-cutting plant
at the Ashton Field Colliery, Farnworth, Lord Ellesmere is
having new engine houses built and other surface improve-
ments made in connection with his Mosley Common
Collieries, in addition to constructing an additional railway
between his Linnyshaw pits, Walkden, and the newly-
reopened Swinton Moss Colliery. In the adjoining Pendle-
bury locality Messrs. A. Knowles and Sons Limited are
adopting electricity for haulage purposes at the Wheateheaf
and Clifton Hall collieries. Messrs. Platt Brothers and the
Chamber Hall Colliery Company have opened out new mines
and made arrangements for augmenting the output from
their collieries in the Moston and Ashton-under-Lyne
districts respectively. The Brynn Hall Colliery Company
and the Clifton and Kersley Coal Company are also
increasing the output at their pits in the Badcliffe district.

This liability to damage is, of course, considerably
increased as the number of ovens is increased, but by
making use of this joint, the Koppers Company has been
enabled to build what must rank as two of the largest
single batteries of coke ovens ever built. These are the
installations at the Kaiser Friedrich Colliery, Barop.,
and the Tremonia Colliery, Dortmund, having 120 ovens
and 95 ovens respectively, each in a single setting. Both
these installations have now been working for some
months and the results are highly satisfactory, the
absence of strain in all parts being evidence of the
suitability of the expansion joint for coke oven work.

The Kaiser Friedrich installation deals with about
700 tons of coal per day, and this yields approximately
8,000 cubic feet of gas per ton of coal. Of this gas, only
about 4,000 cubic feet are required for heating the ovens,
the remainder- being available for the generation of
power in gas engines and for steam-raising purposes.
Koppers’ direct process for the recovery of ammonia
as sulphate is in operation, and is found to work very
satisfactorily, the salt being of good colour and quality.

The installation at the Tremonia Colliery is of special
interest, as it is designed to supply lighting gas to the
town of Dortmund, whilst, at the same time, the usual
quality of metallurgical coke is produced. Lean West-
phalian coal, not compressed, is used. Two gas collecting
mains are erected, one on each side of the ascension

* Proceedings of the South Wales Institute ot Engineers,
1 1909, vol 26, p. 199