September 6, 1918.

THE COLLIERY GUARDIAN.

499

by-prochict coking plants. In too many cases the
managers of these plants are deficient in chemical
knowledge and training, and with few exceptions the
chemist, however competent he may be, is entirely
subordinated to the directing engineer, and regarded
as a mere routine analyst. The management of the
plant should always be in the hands of an experienced
chemical engineer of broad training, combined with
force of character and initiative. Indeed, under
proper management there is no reason why the further
working of the crude by-products (tar, benzol and
naphthalene) should not be profitably undertaken on
coke-oven plants, seeing that in many cases there would
be abundance of “surplus” gas or “ waste heat ”
available for power and heating purposes in an ad-
jacent chemical factory.

It is, of course, now universally agreed that the best
arrangement for iron and steel plants is one in which
by-product coke ovens, blast furnaces, steel works and
rolling mills are all assembled on one and the same
site, so that the surplus gases from both coke ovens
and blast furnaces may be fully utilised for power and
heating purposes. Indeed, in the opinion of many
competent judges, the time is now rapidly approach-
ing when, with good management and organisation,
the conversion of the ore into finished steel sections
will require no further expenditure of coal than that
which must be charged into the coke ovens to provide
the coke for the blast furnace, and even then there
may be some surplus of energy to be utilised in other
ways.

In the case of by-product plants which are built
at collieries, and where the whole of the surplus gas
and waste heat cannot be utilised on the spot (i.e.,
for colliery power purposes, or in connection with steel
manufacture or other chemical processes), it is very
desirable that schemes should be devised for turning
such residual gas or heat energy to good account,
either (a) in connection with some public power scheme
or, so far as the gas is concerned (b) for public light-
ing or heating supplies. With regard to (b), it may
be mentioned that several important towns in Rhine-
land and Westphalia (Barmen, Bochum, Bottrop,-
Castrop, Essen, Gelsenkirchen, Heine, Mulheim, Ober-
hausen, Osterfeld, Wesel, Witten, etc.) are lighted
with purified coke oven gas. In this country Middles-
brough is now similarly lighted by gas supplied from
one of the neighbouring ironworks, whilst at the
Birmingham Corporation gasworks by-product coke
ovens, fired by means of “ Mond ” producer gas, have
been erected for the production of metallurgical coke,
gas and residuals.

In conclusion, the writer desires to draw the atten-
tion of the sub-committee to the importance to the
whole coking industry of a systematic chemical survey
of the principal British coking coals and of the special
reservation of the best of such seams in the future
interest of our iron industry.

ABSORPTION OF CASES BY COAL *

By S. H. Katz.

In carrying out their investigations two methods
of experiment were employed, viz., with air and with
an atmosphere of nitrogen.

In the experiment with air the coal was put into a
large bottle containing air, and methane was added.
At intervals for a period of five weeks thereafter
samples of the atmosphere in the bottle were taken
and analysed. During the experiment the coal was
exposed to the action of the oxygen of the air, and
simultaneously to the action of the admixed methane,
the conditions thus representing in part at least those
under which coal mine dust is exposed to mine air.

In the experiment with an atmosphere of nitrogen,
the coal was put into a small bottle and very pure
nitrogen introduced. The bottle was connected to a
burette filled with methane. The gases in the bottle
and burette were quickly mixed, and the change in
volume of the gas read from the burette as the absorp-
tion proceeded.

Experiments with Air.

Apparatus.—A 20 litre bottle was closed with a rubber
stopper through which a millimetre tube extended to
the centre of the bottle. By means of a three-way cock
sealed to the tube above the stopper, the gas in the
bottle could be connected with a mercury manometer,
or samples of gas could be withdrawn for analysis.
One side of the manometer was open to the air.

Coal.—Five selected lumps of Pittsburg coal of
1 kilogramme each were taken from different heights
on a new face in the experimental mine of the Bureau
of Mines at Bruceton, Pa. The next morning the
lumps were crushed, a composite was made of equal
parts of each, and a portion was removed for an
analysis. The air-drying loss of the sample was 0-9
per cent. The analysis of the air-dry coal resulted
as follows: Moisture, 1-61 per cent. ; volatile matter,
37-67 per cent.; fixed carbon, 55-38 per cent.; ash, 5-34
per cent.; sulphur, 1-15 per cent. The rest of the coal
was put into ball mills and ground. At intervals
during the grinding the coal was screened, and what
passed through a 200 mesh sieve was kept from contact
with the air of the room. The next morning two
portions of 400 grammes each of the coal were taken.
One portion was put into a 20 litre bottle for imme-
diate experiment; the other was put into a large
beaker, covered with a cover glass to prevent addition
of dust, and left exposed to the room air. During this
exposure the coal might evolve methane, be oxidised,
and lose some of its water. These changes might
modify its absorbing properties.

Gas.—In the experiment with both the fresh and
exposed coal samples, the bottle contained air when
the coal was introduced. The apparatus was then
assembled and the top of the bottle and the rubber
stopper were sealed over with Khotinsky cement to pre-
vent leaks. After an interval of about ten minutes to
allow the atmosphere in the bottle to come to the same
temperature and pressure as the room air, a measured

* From U.S. Bureau of Mines Technical Paper 147.

amount of methane of known purity was added to the
air in the bottle.

Analyses.—About four hours time was allowed for
the diffusion of the methane to all parts of the bottle.
A mercury-filled pipette was connected to the bottle,
10 c.c. of gas was withdrawn through the connecting
tubes and wasted, in order to fill the tubes with gas
from the bottle, and then 42 c.c. of gas was withdrawn
for analysis. For every analysis made, a like amount
of gas was withdrawn, the total being 52 c.c. Imme-
diately before and after the withdrawal of the samples
the room temperature and barometric pressure were
recorded. The samples were analysed with a Haldane
apparatus, the contraction on ignition and the carbon
dioxide produced being recorded, and the methane
and carbon monoxide being calculated. The other
constituents of the gas were determined in the usual
manner.

Results.—The total amount of C02 evolved from
the fresh coal rose from 15 c.c. after the first day
to 53 c.c. by the 35th day; and in the case of oxidised
coal from 17 cc. to 29 cc. after 37 days. The evolution of
CO from the fresh coal fluctuated between 3 an 16 c.c.
during the first ’ 13 days, attaining a maximum of
24 c.c. on the 21st day, and then receding to 15 c.c.
on the 34th day; in the oxidised coal it varied be-
tween — 2 c.c. and 13 c.c. in 37 days.. The absorption
of methane was fairly constant and progressive, viz.,
from 25 c.c. during the first day to 35 c.c. in 35 days,
by the fresh coal, and from 59 c.c. to 64 c.c.. (37th
day) by the oxidised coal. Oxygen absorption pro-
ceeded on similar lines, the fresh coal occluding
1-631 c.c. by the 35th day, and oxidised coal 0-461 c.c.
by the 37th. The change in the nitrogen absorption
was small, the increase being from 0-073 c.c. to
0-148 c.c. in 35 days by fresh coal; whilst in oxidised
coal it receded from 0-059 c.c. to 0-018 c.c. in eight
days, negative values being obtained thereafter.

The quantities of carbon monoxide formed were
almost within the limits of determination by the
method of analysis used. However, the figures indi-
cate that the evolution corresponds with the amount
of oxidation which the coal undergoes.

Oxygen was absorbed in these experiments in a
manner previously observed by Porter and Ralston,
Winmill and others. There are indications that during
the first hours of contact between the coal and the
methane, oxygen is evolved by the coal while methane
is absorbed.

Nitrogen is not absorbed or evolved by the coal in
amounts capable of being determined by the method
used in the experiment.

The methane absorption by Pittsburg coal is small,
0-08 to 0-16 c.c. per gramme of coal, during the first
few hours under the conditions investigated; there-
after there is little or no absorption or evolution of
methane from the coal, although changes as regards
carbon dioxide, carbon monoxide and oxygen con-
tinue. Fresh coal absorbed about half as much
methane as that which had been exposed and had
evolved the more methane, indicating an equilibrium
between methane and coal/ . '

Experiments with an Atmosphere of Nitrogen.

Apparatus.—The coal and a tube of water to keep
the atmosphere saturated were placed in a bottle of
about 600 c.c. capacity. Through a millimetre tube
the bottle communicated with a sensitive olive oil
manometer. The opposite side of the manometer com-
municated with a large trapped volume of gas and
the water in a closed tube. The trapped air and mano-
meter formed a compensator to correct for changes
in the atmosphere in the bottle due to temperature
variations. The bottle and the closed tube were
immersed in a water bath. Air was bubbled through
the water to cause a circulation in the bath.

The bottle was connected with a calibrated burette
through a capillary tube and various cocks. Also
connected with the burette was an olive oil manometer,
in the further arm of which was a trapped volume
of gas to serve as compensator for the burette. A few
cubic centimetres of water were kept in the burette
and its compensator, both of which were enclosed in
a water jacket. The water in the jacket was made
to circulate by means of air bubbles. At the bottom
the burette connected with a levelling bulb which con-
tained mercury. A by-pass above the burette allowed
all parts of the apparatus to be evacuated and filled
simultaneously with gas. Connections between all
parts of the apparatus were of sealed glass.

The entire volume of the apparatus communicating
with the coal, measured from the level of the oil in
the manometer on the one side to the level of the oil
in the other manometer, was carefully determined.

Coal.—A selected lump of Pittsburg coal from the
Bureau of Mines experimental mine at Bruceton, Pa.,
which had been exposed to room air for five months
was crushed to pass a 200 mesh sieve. Then 50 grammes
of the coal were put into the bottle for experiment.

Gas.—The burette was filled with methane of the
following composition: Methane, 98-8 per cent.;
carbon dioxide, 0-02 per cent.; oxygen, 0-01 per cent. ;
nitrogen, 1-17 per cent. All the remaining parts of
the apparatus were’ then five times alternately
evacuated to about 20 millimetres and refilled to
atmospheric pressure with nitrogen containing 0-02
per cent, oxygen.

Absorption of the Methane.—When equilibrium with
the newly introduced nitrogen had been established,
both as regards the temperature of the apparatus and
that of the nitrogen which the coal itself would
absorb, the volume of methane in the burette was
measured at the pressure of the nitrogen in contact
with the coal. Thereafter all measurements made
were automatically referred to the temperature and
pressure existing at the time of this first measure-
ment through the agency of the compensators. Imme-
diately after its volume had been determined, the
methane was mixed with the nitrogen in contact with
the coal by means of the mercury and the levelling
bulb. Then at intervals the contraction in volume
was read on the burette.

At first there was a comparatively rapid absorption
of gas. In the course of a couple of hours a maximum
was reached and an evolution of gas commenced. This
evolution continued for about a week before compara-
tive constancy was reached. Thereafter the total
volume of gas in the apparatus was seen to increase
with the rise and to decrease with the fall of the room
temperature.

On the twelfth day of exposure of coal and methane
the mixed gas was withdrawn from the burette for
analysis. The burette was again filled with the
methane as before, the pure methane was mixed with
the residual gas in the apparatus, and the changes
in volume were followed. Again there was a rapid
absorption of gas, which soon reached a maximum,
and was followed by a series of decreases and increases
in volume, as were noted before.

Six days later the mixed gas in the burette was
taken for analysis, replaced by pure methane, and
the partial pressure of the methane in contact with
the coal was further increased by mixing the gases.
The changes that followed were the same as those
previously observed.

To overcome changes in the system due to tempera-
ture variations, a small thermostat applied to the
water bath kept the temperature within 0-2 degs. of
25 degs. Cent. Keeping the gas and coal for a few
hours at this temperature brought the volume of the
gas to a point of constancy. Allowing the temperature
to change and bringing it to constancy at 25 degs.
Cent, on other days brought the gas back to the same
point of equilibrium. The composition of the gas in
equilibrium with the coal at 25 degs. Cent, was
determined.

Conclusions.—Carbon dioxide was evolved from the
coal in small amounts. The quantities were so small
that definite conclusions cannot be drawn, but it seems
that as the partial pressure of the carbon dioxide was
reduced by the replacing of the gas by methane, the
coal evolved carbon dioxide in an amount sufficient^
to maintain a constant pressure of that constituent.

Oxygen was present in minute quantities.and did not
disappear. No conclusions are warranted from the
data at hand.

Nitrogen was evolved from the coal, previously in
equilibrium with the gas, at the time that methane
was absorbed. When methane was evolved from the
coal through an increase in temperature, jsome nitrogen
was again absorbed. Hence, the equilibrium between
nitrogen and coal changes with a change of conditions.

Methane was absorbed to the extent of 0-4 c.c. per
gramme of the coal from an atmosphere containing
30 per cent, of methane and 70 per cent, of nitrogen
when at 25 degs. Cent, and atmospheric pressure. The
amount of methane absorbed increased with the partial
pressure of the gas. The absorption was rapid, and
with the coal a state of equilibrium was reached in
two to four hours. Thereafter evolution or absorp-
tion of the gas occurred with rise or fall of the
temperature.

Summary.

At ordinary temperatures newly mined Pittsburg
coal quickly absorbed methane from an atmosphere of
air containing about 3 per cent, of admixed methane,
the absorption being 0-08 c.c. per gramme of coal.
After about four hours contact an equilibrium existed
between the methane and the coal, although changes
in the coal may continue through absorption of oxygen
with resulting oxidation of the coal.

Under the same conditions, coal that had been ex-
posed to the action of room air for five weeks, with
resulting loss of methane, absorbed 0-16 c.c., or twice
as much methane. After about four hours exposure
a condition of equilibrium existed between the coal
and the methane.

The coal in equilibrium with nitrogen absorbed
methane in amounts that increased with increase in the
partial pressure of the methane.

With absorption of the methane there was an evolu-
tion of nitrogen in amounts somewhat less than the
volume of methane absorbed.

Nitrogen may be absorbed and evolved by coal; the
amount varies with the temperature and the partial
pressure of the gas.

Coal in equilibrium with a mixture of nitrogen and
methane absorbs gas with a fall in temperature and
evolves gas with a rise in temperature.

If the temperature is held constant at a certain
point, then allowed to vary and again held constant
at that point, a definite equilibrium between coal
and gas is repeatedly established.

In so far as investigated, the absorption of gases
by Pittsburg coal is closely analogous to the absorption
of gases by charcoal.

Bradford Coal Dealers’ Association.—The first ordinary
meeting of the newly formed Coal Dealers’ (as distinct
from merchants’) Section of the Bradford Chamber of
Trade was held on August 29, under the chairmanship
of Mr. J. W. North. There was a large attendance. Mr.
H. Mosley, local supervisor under the Fuel and Lighting
Order, and Mr. Edward Smith, coal merchants’ repre-
sentative on the local fuel committee, attended in order
to answer a number of questions as to the position of
the dealers under the Order. Complaint was made by
speakers that some merchants had issued to their regular
customers the first requisition form with the merchant’s
name and address filled in, and the query was raised as
to whether this was permissible. It was considered to
be unfair to the smaller dealers and to the trade generally.
Mr. Mosley said such a practice was entirely wrong. The
forms should be sent blank, and if they were returned
incorrectly filled in, the merchant or dealer should make
no alteration, though he was quite entitled to advise the
consumer. The Merchants’ Section was working on the
soundest possible lines. There was no doubt that when
the Order got working the dealers would be much better
placed than they had been for some time. Merchants and
dealers who tried to get new customers would shortly
find not only that they had not enough coal to go round,
but that some official enquiry would be made into the
reasons why they, wanted more coal than formerly.