August 16, 1918.

THE COLLIERY GUARDIAN.

339

had conducted in boring a hole into a seam of coal and
then hermetically sealing it, one got an enormous
pressure, up to 450 lb. When, however, one released
the pipe from the hole, the hole did not continue to
give off such a pressure as was indicated in the paper.

Mr. Atkinson said he thought that they probably
struck a fissure in the coal, connected with considerable
services of gas.

Mr. C. C. Leach remarked that the great difficulty
at Harton was to get the holes made gas-tight.

The Chairman asked Mr. Atkinson it he did not
think the gas was generated in the coal seams and
filled into the post and other strata.

Mr. Atkinson replied that it was not quite certain,;
but he thought that was the most probable. They did
get natural gas where there was no coal seam; but still
he thought that, on the whole, probably the firedamp
was from the coal seam, but in a long period of time it
must have disseminated itself through the whole of the
strata. Going down a wet sinking pit, one could hear
the sides hissing all the way down. He thought it was
quite a fallacy to suppose that firedamp was confined to
coal seams, but that was a fallacy that seemed to be
very generally held.

Mr. Parrington said there was no doubt that gas
was contained in the soft shales, as well as in the coal
seams. What they called ‘‘surfeit” in coal was caused
by gas, he took it, which enabled the hewer to work to
the best advantage. The Hutton seam at Wearmouth
Colliery was very gassy, and, when a man was hewing
there, the gas threw off the coal with considerable noise
and force—the consequence being that it made very
small coal. Many years ago it was desirable to get as
large coal as possible, and the speaker conceived the
idea of “ winding ” the coal, i.e., draining the gas out of
it by driving in the soft cover on the top. W hen they
got that place entered in the soft shale on the top of the
coal, it was just as soft as the coal itself, and behaved
in exactly the same way. The gas threw off great
shives of the shale, just as it had thrown off great sbives
of the coal.

Mr. Atkinson suggested that that might have been
due to the pressure of the strata above.

A Member asked if it was not a fact that oil and gas
came off from strata not necessarily associated with
seams of coal at all. He remembered, when he travelled
through Pittsburg years ag<\ that they had to go
through the coal measuies to get into the gassy strata.

The Chairman asked if they did not think that,
where there was a water-bearing stiata, when they got
to t the bottom of that strata, they met with gas
immediately at the same pressure as the static pressure
of the water.

Mr. Atkinson replied that Mr. A. L. Steavenson had
suggested that the pressure of gas would be equal to
that of a column of water. The speaker did not know
whether that was true, but he thought it was likely.

The Chairman said that in the Durham coal field
one frequently met with blowers of gas from the clay,
right above the coal measures altogether, in strata
through which one would think the gas could not pass.
At Hutton Henry, for instance, there were some pipes
put in through the wading when the pit was opened
out a second time to vent off the gas, and at any time
one could light the gas at these pipes. He supposed
that would be marsh gas.

Mr. Atkinson .- Probably firedamp from the coal
measures below. There were several places in the
county of Durham in which, under similar circum-
stances, one could light the gas at any time.

The meeting then ended.

Mr. Arnold Lupton.

A special meeting was held to consider a resolution,
that, in consequence of his conviction und^r the Defence
of the Realm Act, Mr. Arnold Lupton should be expelled
from the institute and his name erased from the list
of members.

The Chairman (Col. Frank Coulson) explained that
Mr. Lupton had been given the opportunity of resigning
but had taken no steps in the matter.

Without discussion, the council’s resolution was
agreed to, nem. con.

THE BY-PRODUCTS TRADE.

Tar Products.—In the London market this week pitch
is from 55s. to 58s. 6d., and the advance is shared by
provincial quotations. East Coast prices have risen from
32s. to 35s. f.o.b. The Liverpool quotation, 31s. to 31s. 6d.,
and west coast figure, 30s. to 31s. f.a.s. also indicate the
upward trend, despite the oft-mentioned difficulties of
transport. The position of affairs from now onwards is
rather in favour of holders, and the result probably
will be seen in a further advance in some of the pro-
vincial prices. Tar remains steady, but rather feature-
less. Crude realises 32s. to 35s. per ton in London, 27s.
to 29s. Midlands, and 28s. to 30s. north, all ex works.
In bulk it is 4d. per gallon. Benzol, another controlled
by-product, is noticeable, chiefly for the view which the
trade takes concerning the control price. The figure is
far from being satisfactory. Solvent naphtha is dull, and
not much change in tone is likely yet awhile. Crude
naphtha is not plentiful just now, but the price is un-
altered. Crude carbolic continues firm at late rates, and
supplies at those figures are far from plentiful. Crystals
command a good figure. Crude naphthalene has been going
well. Toluol, cresylic and some of the other by-products
hardly call for particular notice this week, inasmuch as
the market has a great deal of sameness just now, and
the unchanged quotations do not invite comment.

Sulphate of Ammonia.—In London and the provinces
the output meets with a really good demand, and forward
business is well booked at scheduled figures.

Derby Miners’ Example.—In the Derbyshire coal field
miners are responding well to the Prime Minister’s appeal.
Absenteeism has shown a marked decline, and an appeal
is to be made by the Derbyshire miners’ council on
Saturday to their 50,000 members to maintain an unbroken
front. The miners have set a fine example by only
taking sufficient of their house allowance of coal to meet
their bare necessities.

CURRENT SCIENCE

Liquid Oxygen Explosives.

Le Genie Civil describes some recent German devel-
opments in the use of liquid air for blasting. The
Sprengluft Gesellschaft m.b.H, manufactures plants
capable of supplying 22 lb. of rectified liquid oxygen
(“oxyliquite”) per hour, at a net cost of less than
Id. per lb. The liquid oxygen is stored in a modified
form of Dewar flask, usually of brass or thin steel,
the jacket space being filled with charcoal, which
absorbs any small amount of gas escaping through the
pores of the metal. In utilising the liquid oxygen for
blasting, lampblack has been found the most satisfac-
tory combustible material. Cartridge cases of card-
board are filled with the lampblack, and then immersed
for some time in a tank containing the liquid oxygen,
so that they become thoroughly impregnated just
before use. They are usually fired by a small primer,
preferably ignited by electricity. Oxyliquite is stated
to be very efficient for mining work on account of
its brisant properties, but is less suitable for quarry
work. It is considered safer than the explosives
generally used, since the cartridge is only explosive
for ten minutes after the time of saturation with the
liquid oxygen. This fact, however, makes it necessary
to instal a liquid oxygen plant near the scene of
operations.

Slip of Belts on Pulleys.

W. F. Schaphorst (American Gas Engineering
Journal) has investigated the question of slip of belt,
and the distance slipped, or travelled over, in rubbing
contact in a given time. He distinguishes creep from
slip proper, and calculates for the former. A 4 ft.
pulley, for example, rotates at the rate of 250 revolu-
tions a minute. Its belt does not slip, but the creep is
2 per cent. It runs ten hours a day during 300 work-
ing days in the year. Calculation shows that the
periphery of the pulley travels 3,141-6 ft. a minute.
Two per cent, of this, the creep of the belt, is about
63 ft. a minute. This amounts to 2,140 miles in the
year. Two thousand one hundred and forty miles of
rubbing, even on a smooth surface, is considerable. If
there is any slip on the pulley in addition to the
creep the result will be the more serious. It must be
remembered that a given point on the contact-side
of the belt is not in touch with the pulleys all the time.,
During each complete trip of the belt round the pulleys
the given point is in contact with one pulley for a short
time, during which there is a rubbing action to some
extent. Then the given point is not in contact with
anything until it reaches the next pulley, when it
again rubs. The greater the distance between the
shafts, then, the less the yearly slip or creep of the
point. A short belt, on the contrary, is subject to
greater wear because the point comes more frequently
in contact with the pulleys. The writer gives a for-
mula for computing the slip plus the creep of a point,
account being taken of the radii of the pulleys and
the distance apart of the shaft centres.

German, Lignite-Electric Generating Station.

Before the war the Allgemeine Elektricitats Gesell-
schaft put down at Bitterfeld, close to important lig-
nite deposits, a large electric generating station, the
power of which was to reach 140,000 h.p. The current
was to be transmitted to Berlin. When the war
broke out (Elektroindustrie, abstracted in Engineer-
ing') the State purchased the current and utilised it
in large electro-chemical works which were rapidly put
down. It was stated that the A.E.G. sold the current
at the rate of 0-9 pf. (0T08d.) per kilowatt-hour; the
statement was also made that power stations which
utilised lignite could generate current as cheaply as
the Swiss hydro-electric plants. It was found later,
however, that for the concern to pay, the current
should be sold at 1-5 pf. (0-18d.) per kilowatt-hour, at
the switchboard; and although the State works later
increased the price they paid for current, the A.E.G.
were'the losers.

Owing to the heavy outlay incurred by the con-
struction of this generating station, the A.E.G. com-
pany was obliged last spring to increase its capital,
and the director stated at the general meeting that
the hopes which had been placed upon a power station
utilising lignite as fuel did not all come true, adding
that the experience gained at Bitterfeld showed that
for the electro-chemical industry the required current
should be obtained from hydro-electric power stations.

It appears that, notwithstanding the improved me-
chanical appliances used for extracting the lignite, a
large amount of labour was necessary. The removal,
first, of a layer of earth about 12 ft. in thickness
appeared to be a particularly costly undertaking. The
maintenance of the large boilers also leads to a heavy
outlay. It is doubtful whether the current can be
obtained at a price below 1 pf. (0-12d.) per kilowatt-
h ' r. S'* ce "he Bitterfeld plant of the A.E.G. sold
to the State the greater part of the current generated
(a total of 300,000,000 kw.hours last year), it was to
be expected that the State should finally purchase
the plant, and this has recently been done. The
price of the station was about 28,000,000 mk., that
of the land and lignite deposits 6,000,000 mk., whilst
that of the mining installations was also about
6,000,000 mk. The State now works the station in
the form of a company with share capital.

Fractional Separation of Benzene.

In a paper read before the annual general meeting
of the Society of Chemical Industry, Messrs.
T. Howard Butler, Ph.D., M.Sc., and F. J. W.
Popham dealt with some of the factors that make for
efficiency in working commercial apparatus for the
fractional separation of benzene, toluene and xylenes.

Efficient column is essential, and may be attained
by any means so long as intimate contact with vapour
and refluxing liquid is obtained.

dephlegmation plays a most important part in good
fractionation. By careful regulation of the tempera-
ture’of the water in the dephlegmator, it is possible
to increase very materially the efficiency of any plant.

AND TECHNOLOGY.

This is due largely, no doubt, to the fact that by this
means a larger quantity of condensed liquid is return-
ing down the column, thus affording better contact
between vapour and liquid. In regulating any plant,
it is advisable to work as much as possible by altering
the flow of water in the dephlegmator in preference to
regulating the steam supply to the coil in the still.

Constant steam pressure must be maintained, other-
wise regulation of temperature of still contents is
almost impossible. A valve to reduce the pressure of
the steam to the minimum usually obtained at any
time is a material help in this direction.

A steam pressure sufficiently high to enable the
toluene to be distilled off should be available, other-
wise a partial vacuum must be put on the plant, which
is never so effective. The xylenes may well be distilled
over by means of live steam, but even then high pres-
sure steam is preferable.

Should the coils in the still leak even to a very
small extent, the separation will be entirely upset, and
under these conditions it is often impossible to obtain
pure products.

Efficient water supply to dephlegmator requires
careful supervision. A works supplied with hard water
will soon lose efficiency owing to the fact that the
dephlegmator becomes badly scaled; in these cases a
water-softening plant is necessary.

In plants put up in the open the columns must be
protected against wind and rain, otherwise irregu-
larity in speed of running will result.

CARBONISATION AT LOW TEMPERATURES.

In France, the Societe des Mines de Blanzy, among
other companies, is engaged in researches into th©
utilisation of bituminous coal with a view to recover-
ing the by-products obtained by distillation. In 1916
this company sent over here to the Chiswick Labora-
tory 20 tons of coal to be treated by a special dis-
tillation process. The experiment, however, was not
successful, as the coal became transformed into a kind
of coke which choked up the distillation apparatus.
In 1917 the company started a series of tests on bitu-
minous coal, containing 30 per cent, of volatiles, at
its own laboratory. The temperature of distillation
was gradually raised to between 600 and 700 degs.
Cent., and the resulting products were very similar
to those obtained by the distillation of crude petro-
leum or of bituminous shales. The spirit distilling
at 90 to 120 degs. Cent, (and forming a possible sub-
stitute for petrol) has a density of 1’792, as compared
with 0-650 to 0-700. Similarly, the burning oil /frac-
tions have a density of 0’850 to 0’900, instead of 0-800
for the same oils obtained from petroleum; whilst
the density of the heavy oils is 0-960 to 1’000 instead
of 0-880 to 0-930. The spirit obtained from the low
temperature distillation of Blanzy coal has not the
same properties as the benzol from the high tempera-
ture distillation of coal during the coking process,
benzol having the density 0-900 and freezing at a
temperature of 0 deg., whereas the spirit in question
does not freeze. On the other hand, the heavy oils—
from which lubricating oils can be extracted—contain a
certain amount of paraffin, but no naphthalene or
anthracene. The viscosity of these oils is comparable
with those obtained by the distillation of bituminous
shales.

The average results secured at the laboratory with
the Blanzy coal are as follow, the figures representing
parts per 1,000 parts of the pure coal: —

Spirit distilling over between 90 and 160

degs. .............................. 10

Lamp oils ...	...	...	...	”0

Phenols ...	...	...	...	...	5-6

Motor and lubricating oils...............25-30

Paraffin ................................. 1-2

Pitch (suitable for briquetting) ....... 40-45

The residue after distillation still contains about
8 per cent, of volatiles, and could very well serve as
industrial or domestic fuel.

These experiments, on being repeated on the large
scale in a tubular cast iron retort, furnished similar
results, except that the total yield was decidedly
smaller, apparently by reason of defects in the plant.

The Societe de Blanzy is continuing its interesting
experiments with the object of finding an industrial
solution of the ^problem of the low temperature dis-
tillation of coal, in view of the great advantages that
would accrue from the installation of gas engine plants
at the pit head, and from the provision of an ample
supply of residual fuel for domestic purposes.

THE TIN-PLATE TRADE.

Liverpool.

There is plenty of enquiry, but not very much actual
business going through the merchants’ hands, largely
owing to the fact that works are heavily booked up for
several weeks to come, and are not anxious to sell forward.
A big order for IC 28 by 20 cokes was distributed amongst
various makers the other day for Allied account, and the
full official maximum price was paid. The official figure
to-day stands at 33s. 7|d. per ba«is box for cokes, net cash,
f.o.t at works, and sellers will not entertain any new
business at anything below this. Wasters of all kinds are
in good request—28 by 20 being exceedingly scarce. Terne-
plates are also in good demand at top prices.

An explosion of blasting gelignite occurred at Dalkeith
Collieries on August 8. Three men were overcome by
fumes, and two died before they could be rescued. One
workman who tried to rescue them was also overcome.

The Fuel and Light Committee for the Rotherham rural
area have passed a resolution protesting against the Fuel
and Lighting Order in its present form,, and expressing
the opinion that it was a waste of time, labour and
expense, and that it would not have the effect upon the
country it was intended to have,