1076

THE COLLIERY GUARDIAN.

November 22,. 1918.

portion in the same manner, commencing at the bottom
end, this relative distance between the working faces
being maintained throughout. All debris and empties,
in this case, pass down the centre brow and the full
tubs of coal are pulled up each of the side brows. The
bottom end of each of the three brows is levelled up
with debris to make a level road from the lower to the
upper face.

Improving on Old Methods.

There is still plenty of room for improvements, both
in the engineering side of mining and in such under-
ground work as main road making and supporting,

Fig. 4.—Auxiliary Haulage Systsm. Extended

Tigntanlng
Thoel.

EVERY 15 TO 20 YDS.

tunnelling, and in haulaging arrangements and appli-
ances ; and while it is to be hoped that all mining will
for ever keep “ safety first” as its motto, it may also be
hoped that there will be found enterprising men who
will dare to forsake old methods when there is at least
a fair chance to improve on those old methods.

In mining, just as in general education, travel
improves and broadens one’s mind. However small the
colliery or works visited, one can usually find something
worth noting—the best things with a view to adopting,
or even improving upon to suit our own circumstances,

Section through the two working faces.

Fig. 5.

umimuitiiimmii:

wnnumtl

initnpL

o

Fig. 6.

Figs. 5 and 6.—Working Thick Seam with
Single-track Haulage.

and the worst things in order to prevent us making the
same mistake in similar circumstances. It would
prove beneficial to all concerned if a regular system
of visiting were instituted to apply to the higher
officials of all our collieries (say, the manager and the
under manager to visit one other colliery per month);
and on such occasions not the least among the many
matters which would be of interest to them would be
the different methods of working seams.

Releasing Miners from the Forces.—The Coal Controller
intimates that the statements appearing in a number of
newspapers to the effect that a further 100,000 miners are
being released from the Forces are incorrect. Steps are
being taken to release a further number of miners from
the Forces, both at home and overseas, and the numbers
will depend on the military situation from time to time.

Irish Coal Prospects.—There is no likelihood of the
Irish coal supplies being extended at the expense of other
parts of the United Kingdom. The whole Irish output
is being used up as it is produced, and it should shortly
be increased considerably. The railway to the Wolfhill
mines has been completed, and the work of completing the
railway between Castlecomer collieries and the main line
at Kilkenny is being got on with as rapidly as possible.
The sidings at Gracefield and Modubeagh mines are being
completed. Ireland will therefore have some portion of an
extended supply before the rigours of winter.

THE MOTOR FUEL PROBLEM.*

By W. R. Ormandy, D.Sc.

Of the solid fuels suitable for motor work, the use
of coal, particularly of the bituminous type, is asso-
ciated with many difficulties, and though the internal
combustion engine of the future may be driven by
gas generated from solid fuel in a producer, the
difficulty associated with the use of bituminous coal
iu gas producers has hitherto prevented this type
from becoming popular even for the stationary suction
or other gas-producer plant, and for the portable
engine these difficulties are greatly enhanced. Even
for use as a generator of heat for steam raising m
motor tractors bituminous coal has many drawbacks.
The last word has probably not been said regarding
steam driven motors. The inventor of the Clarkson
steam motor ’bus has directed his ingenuity to the
production of a coke-fired boiler, and, it is believed,
with every prospect of success. It "would not appear
that even for heavy motor vehicles the steam engine
and boiler would oust the internal combustion engine.
If the price of fuel for the internal combustion engine
becomes excessive, the steam motor may have a new
lease of life, but this will be accompanied by an
entire revolution in the existing trade. On the other
hand, for small stationary engines and heavy motor
vehicles, and possibly for motor boats, there would
seem to be at any rate a prospect of success for the
internal combustion efigine driven by some form of
suction gas; but to genei ate such gas a solid fuel
free from tarry constituents must be employed, owing
to the difficulty introduced in washing the gas.

As regards charcoal, ordinary wood charcoal is
expensive, and, owing to its bulk, inconvenient to
store; but charcoal produced from the woody lignites
found in Ireland would seem ideal for the purpose
in view, and it is not impossible that some form
of compressed peat charcoal should prove of value in
this respect.

Gaseous Fuels.

Ordinary coal gas works efficiently in high-speed
engines, and it has become quite customary to use
town’s gas for running motor engines on the bench,
whilst it has been found that 250 cu. ft. of normal
town’s gas are equivalent to a gallon of petrol. The
development of this utilisation of town’s gas is de-
pendent upon the discovery of some suitable container
capable of holding the gas under a considerable
pressure so that the volume and weight of the
container shall not be unreasonable. The use of
coal gas necessitates practically no change in the
existing engine, and the fact that England possesses
a more widely distributed coal gas manufacture than
any other country in the world points to the ad-
visability of developing the pressure gas container at
the earliest moment. The Government have recog-
nised the importance of this matter, and have a Com-
mittee which is doing valuable work upon the subject,
under the chairmanship of Sir Bo verton Redwood.

Liquid Fuels.

The paraffin series of liquid fuels can be divided
into three groups. First, the more volatile portion
known under the general name of petrol, used in
high-speed internal combustion engines; second, what
is generally known as paraffin oil, such as is used
for illuminating purposes, employed in marine motors,
and, generally speaking, where wide and sudden varia-
tions of speeds are not constantly required ; and,
third, solar or fuel oil, being the fraction boiling at
a higher temperature than paraffin, used in Diesel
or semi-Diesel engines, and, as the name implies, as
liquid fuel for steam raising.

Substitutes for Petrol.

The most important of these is undoubtedly the
volatile fuel. Of the home-produced materials which
can serve as an alternative to petrol, the coal tar
distillates must first receive consideration. That
benzol can be used in the ordinary motor car with
trifling alterations has been demonstrated beyond all
question.

From Coke Ovens.—During the distillation of coal
in the coke oven certain volatile products are evolved
which, in the case of by-product ovens, contain from
1J to 3J gallons of liquid fuel from each ton of coal
carbonised. Owing to the Government demands for
these volatile liquids, most by-product coke ovens have
the necessary plant for their recovery.

From Gas Works.-—When coal is distilled in the
smaller retorts employed in the manufacture of coal
gas, the resulting coal tar yields on subsequent frac-
tionation a small proportion of volatile liquids, and
a much larger proportion of oils. The enormous war
requirements for benzol and toluol have led to plant
being installed at most of the large gas works for the
recovery of these particular volatile liquids, and any-
thing from one to two gallons per ton of coal carbon-
ised may be recovered in this wise.. As probably only
the Government officials have accurate information
as to the total amount of benzol which is produced
by the washing of coal gas, it is impossible to give
more than a rough estimate as to the amount of volatile
liquid coal tar distillates produced in this country per
year, but it may be assumed that, under post-war con-
ditions, something approaching 50,000,000 gallons per
annum will be available for all purposes. One-half to
two-thirds of this will be produced in approximately
9,000 coke ovens now in operation. If the projected
central electric power stations come into being, these
may receive their energy in the form of gas made
in by-product recovery producer plants, in which case
they would add something to the fuel supply, but
very much less than if the same amount of fuel were
coked or converted into coal gas along the ordinary
lines.

Shale Oil.—The bituminous shales yield sulphate of
ammonia and a range of liquid products running from
a volatile spirit to a heavy lubricating oil. Compared
to the home requirements, the total yield is at present

* From a paper read before the Institution of Petroleum
Technologists on November 19.

comparatively small, but there are immense deposits
running from Norfolk down to Dorsetshire which are
practically untouched. It is true that these more
southern shales are badly contaminated with sulphur
compounds, but there is no reason to believe that the
problems involved in obtaining a marketable product
are insuperable. Better and fuller utilisation of all
such available oil shale deposits, and the working up
of low-grade cannel and coals, must receive a degree
of attention in the future which they have escaped
in the past. Any product required to displace petrol
must be capable of production in very large quan cities,
and within a certain range of prices. These two
requirements limit the field of possibility, and, with
the exception of products produced from the distilla-
tion of coal and shale, the only substitute which has
hitherto warranted serious consideration is alcohol.

Alcohol as a Motor Fuel.

Prior to the war there existed thousands of alcohol
engines on the Continent for the most part employed
in agricultural work. These were chiefly stationary
engines, designed with a long stroke and a high com-
pression, and provided with means for heating the fuel
or the air supply for starting purposes. The thermal
efficiency of these engines is so much higher than that
of petrol engines that the fuel consumption per brake
horse-power hour is practically equal in the two cases,
though the heat value of the alcohol is net quite two-
thirds that of the same weight of petroh Moreover,
experience has proved that there is no special corro-
sion arising from the production of acid products, as
to which such a cry has been made.

The problem which meets us in this country is the
provision of motor fuel which shall be applicable to
the hundreds of thousands of existing motors, and it
is undoubted that alcohol cannot be thus employed
without some admixture. There is a home production
of approximately 50,000,000 gallons per annum of
coal tar distillates. This motor benzol will mix with
alcohol in any proportion, and experiments have
shown that one part of benzol mixed with two parts
of alcohol can be employed in existing engines without
any alteration whatever beyond arranging for the
better heating of the air supply to the carburetter,
and possibly a slightly larger jet. Such admixture
not only shows a higher thermal efficiency than either
constituent alone, but an engine provided with such
admixture runs more smoothly than if petrol were
employed. If 100,900,000 gallons of alcohol per annum
were available, this, mixed with the 50,000,000 gallons
of benzol, would provide us with an amount of fuel
which would go far towards meeting immediate re-
quirements. Should the demand for this mixed fuel
increase at a rate, so great that the supply of benzol
became inadequate, we have a ready means available
of supplementing it by the production of an ethyl
ether by a simple industrial operation from the
alcohol itself.

Benzol Supply.

With regard to the possibility of an increase in the
supply of benzol, the number of coke ovens employed
is dependent upon the country’s production of pig
iron. Prior to the war the German production of
coke was about three times that of this country.
During the ten years prior to the outbreak of the war
the German output of coke increased from 12,000,000
tons to 32,000,000 tons, and in the same period the
English production remained practically stationary.
In the post-war period it may be hoped that this
state of affairs will no longer obtain, but it must be
recognised that coke-oven benzol, in the eyes of the
steel world, is a very minute by-product, and that
no variation in its price will have any appreciable
influence upon the amount manufactured. As regards
gas works, it is certain that the utilisation of coal
gas in industrial and heating operations will con-
tinuously grow, and in so far as this is the case there
will be an increased output of motor benzol. It is,
however, to the better utilisation of hitherto neglected
low-grade cannel and other coals that one must look
for additional outputs.

The more the position is looked into, the more com-
plex are seen to be the relations which obtain. The
production of benzol from the coke oven is primarily
dependent on the growth of the iron and steel
industry, and whether the coke ovens installed shall
put down benzol recovery plant depends upon the
market value of the product, for there is a price below
which it does not pay to extract. Similarly, the
utilisation of low-grade fuel depends upon the market
for power, and the relative amounts and values of
the sulphate of ammonia and other volatile products
obtained therefrom. The production of alcohol is very
frequently bound up with complex agricultural ques-
tions, such as the relation of crop rotation, the carry-
ing of stock, and the value of residuals. Whether
the gas works will continue to extract benzol and
toluol from the town’s gas depends to some extent
upon the value of the extracted fuel, but also upon
legislation dealing with the nature of the gas which
the companies are to be allowed to sell. The incan-
descent mantle has so revolutionised lighting that
it would appear that the time has come when gas
should be sold upon its heating value rather than
upon a candle power basis. If this heating value is
not set at too high a figure, and the candle power
restriction is removed, the gas works will be readier
to continue to strip the benzol. The utilisation of
vertical retorts working at a high temperature, with
simultaneous steaming of the retorts, will lead to an
increased production of volatile fuel. This will
resemble paraffin rather than the aromatic compounds.
Though this will introduce new problems for the tar
distiller and the refiner, the fuel produced will be
in every way applicable to the motor industry.

Distribution.

The specific gravity of petrol has been increasing
for a number of years. Tn the early days when carbu-
retters were somewhat primitive, a 0*680 to 0*690 fuel
was essential. The increased demand has led to the
necessity on the part of the petrol producers to cut
at a higher temperature, giving a larger yield of liquid