524

THE COLLIERY GUARDIAN

September 10, 1915.

CURRENT SCIENCE

A Makeshift Mine Ventilator.

A correspondent of the Practical Engineer describes
an ingenious way of sending air down a pit shaft
for ventilation. The shaft was about 12 ft. 6 in. in
diameter and 250 ft. deep, enough water being present
to keep a pair of Ilin, pumps going at four strokes per
minute, sending up water through 9 in. pump columns.
As the pump lifted the water the upper part of the
column was partly filled with water, displacing the air
to the extent of about 2^ cu. ft., and the bulk of the air
was sent to the bottom of the shaft by means of a return
air pipe, air valves being fitted at the head of the
column. Roughly, this meant that 16 cu. ft. was sent
down each minute, which was fully ample to keep a
good atmosphere to work in. The escape of water at
the water outlet lowered the water in the upper part of
the column, drawing air in through the lower valve.

Electrical Accidents : The Physiological Effect of High-
Tension Currents : Modern Methods of Resuscitation.

An article on the above subject by K. Alvensleben
appears in Gluckauf. The work of investigators into
the effects of electric currents on the animal bodyaie
not widely known. Some years back, Kratter demon-
strated that the danger to life does not increase with
the tension, and also that the repeated action of
otherwise harmless currents may prove fatal. Prevost
and Battelli went more thoroughly into the question,
taking into consideration the kind of current, frequency,
tension and current density, as well as duration of
contact. Experiments conducted on dogs showed that
static discharges are never fatal, so that shocks from
switched off cables are not dangerous to man, though
they may be unpleasant. Industrial currents, however,
are fatal within certain limits, but not above or below
same.

A tension of 5-10 volts produced only a temporary
increase in blood pressure, but 20-120 volts stopped the
heart’s action, though respiration continued for some
time; 240-600 volts caused death by stopping the
heart and breathing, whereas neither faculty was
permanently disturbed by 1,200 volts ; and above 2,400
volts the heart was unaffected and the respiration
could be fully restored by the usual methods of
resuscitation. Alternating current was employed, the
electrodes being inserted into the mouth and rectum.
Observations on the heart with the chest cavity opened
showed that below 600 volts the regularity of the beats
changed into convulsions of the walls of the heart, and
was not restored on the current being interrupted.
The supply of blood to the organs being stopped, death
resulted from that cause. This fluttering of the heart
was produced in dogs on the electrodes being applied
to both sides of the chest, and d-ath supervened in a
few seconds. On applying the electrodes to the
exposed heart, the fluttering was obtained with as low
as five volts.

This phenomenon ceased with tensions above 600 volts,
the heart stopping entirely, but resuming its regular
action when the contact did not exceed 5 seconds. With
a contact of 10 to 15 seconds the ventricles remained
motionless for some time. From his experiments with
other animals Battelli formed the conclusion that
fluttering cannot be set up in the human heart in the
above manner. He also ascertained that the determining
factor in the final result is the current density, and not
the tension, and Weiss has shown that the current
density in the organs themselves is the primary con-
sideration. His experiments were carried out on
anaesthetised dogs, with the electrodes applied to one
fore and one hind paw, alternating current of 4 ! periods
being used. With amperages of 0’035 and 0'038, at low
tension, the animal recovered quickly, whereas death
ensued with 0’116 ampere at 100 volts. On the other
hand, one subject stood six applications of 7 amperes at
4,600-2,700 volts, but succumbed on the density being
reduced to 0'45 ampere and the voltage to 110. Experi-
ments on another subject with 4,500 volts demonstrated
the predominating influence of the current density, for,
whilst 0 0425 ampere proved insufficient to produce
fluttering, death followed the application of 0'089 ampere
at the same tension.

The influence of the path taken by the current and of
the current density in the organs was also demonstrated
by this worker. With the electrodes applied to the top
of the head and under the chin, a density of 0'375
ampere at 1,080 volts merely crippled the respiration,
the heart not being in the path of the current; but on
transferring the second electrode to a hind paw death
resulted. A comparison of the effects of direct and
alternating. currect revealed the fact that, with the
former, four times as great a density is required to
produce the same result. On the other hand, the
incurable after-effects (lameness and paralysis) ascribed
by Weiss and Jellinek to the action of direct current,
are contrary to the result of experience in electrical
accidents, where these results have never been observed,
though wounds and death are not inf requently produced.
Persistent after-effects—general discomfort, insomnia
and heart troubles—occur, though rarely, after both
direct and alternating current. The fact that high-
tension currents are not always fatal has been demon-
strated in American electrocutions. At first a contact
of over a minute was found necessary, but the present
practice of starting with high tension and then lowering
the voltage produces immediate unconsciousness, death
supervening as the result of the fluttering effect. The
same thing has been noticed in electrical accidents,
many sufferers who have been seriously burned by the
action of high-tension currents having been saved by
immediate application of artificial respiration (working
the arms), which proved unavailing in other cases of
unconsciousness without other than merely slight
wounds, if any. The serious burns characteristic of

AND TECHNOLOGY.

high-tension accidents sometimes result in death only
after hours or days when some vital organ has been
affected.

Some authorities assume that functional disturbance
is the cause of death, whilst others regard it as
anatomical. Battelli, who holds the former view, claims
that if anatomical changes were produced, the rapid
recovery frequently observed, even in cases where
artificial respiration has to be resorted to, would be out
of the question. Post-mortem examination always
gives negative results, apart from the discovery of
burns, no discernible changes in the body having
occurred. For this reason it is impossible, up to the
present, to diagnose the cause of death as due to electric
shock, on the basis of post-mortem examination.

With regard to the best method of resuscitation after
electrical accidents, opinions are divided. In England
and America the Schafer method is employed, the
victim being laid face downward and pressure applied
to the chest at regular intervals. The Sylvester method,
practised in Germany, consists of laying the patient on
his back and producing artificial respiration by alter-
nately drawing the arms above the head and pressing
them down against the chest. This method is regarded
by prominent German workers as the only suitable one,
the other being physiologically incorrect.

Artificial respiration by working the arms to and fro
is considered preferable to mechanical devices. Where
several helpers are available, the Sylvester method
should always be employed. Even oxygen apparatus is
condemned in practice by many doctors, whereas others
look on oxygen as a cure-all. According to the author’s
experience, a distinction should be drawn between cases
of suffocation, hanging or drowning, and those of
electrical accidents. Whereas, in accidents of the
former kinds, oxygen apparatus has frequently proved
of value, these appliances have only been found to
resuscitate one victim of an electrical accident since
their introduction—namely, in Upper Silesia in 1911,
whilst in the Dortmund district alone 17 persons have
been restored to life by the aid of the Sylvester method
after electrical accidents in collieries. Where heart
fluttering is concerned, none of these methods is of any
avail.

Cereal Dust Explosions.

At a recent convention of the Fraternity of Operative
Millers of America, an address on the above subject
was delivered by David J. Price, engineer to the
Bureau of Chemistry, U.S. Department of Agriculture.
He says the study of cereal dust explosions has been
divided into two distinct sections, first the engineering
investigations which have to do with explosions of this
kind as they occur in the field, the circumstances and
conditions under which they occur, and the chemical
side of the problem, which includes the laboratory
experimental work. A total of 19 explosions that have
occurred during the past 10 years have been carefully
studied, 11 having taken place since this work began
in August 1913. In a large number of cases the cause
could not be definitely established. Eight explosions
were thought to have originated from sparks produced
in the machine during the grinding process, one was
attributed to production of static electricity, and in
the remaining 10 occurrences it was not possible to
establish a definite cause of the origin. In order to
definitely determine the relation of the sparks produced
by foreign matter and a suspended dust cloud, an
experimental mill has already been erected at Penn-
sylvania State College. It has already been found that
elevator dusts with as high as 16 per cent, of ash are
very inflammable and develop high pressures on ignition.

It has been found that sufficient static electricity could
be produced by friction of a very small pulley and belt
to readily ignite natural gas. It was learned at this
time that a milling company in the south, engaged in
grinding cotton-seed cake into meal, after experiencing
a series of explosions, had prevented a repetition of
previous occurrences, by grounding the grinding
machines, by means of a wiie connected to a rod driven
in the ground near by. The possibility of static
electricity as a source of cereal dust ignition was very
clearly established by an explosion in the dextrine
department of a starch factory in one of the Eastern
States in September 1914. The origin of the explosion
was traced to the production of static electricity by
friction of particles of dextrine on 80-mesh brass gauze
surrounding a revolving reel. This reel was only
revolving at the rate of 16 revolutions per minute at
the time of the explosion.

In this connection it is of interest to recall the
experiments recently made by Mr. Rudge, the results of
which he communicated to the Royal Society (C.G.
June 12, 1914). He found that if a cloud of dust is
blown against an insulated conductor (a wire for
instance) the wire becomes charged with electricity,
and under certain conditions may become so highly
charged as to give off sparks.

Mr. Price considers that the predominating factor
which determines the inflammability of a dust and the
action of a dust explosion has not been determined.

Since experiments have shown that the cereal dusts
will ignite and propagate a flame, it will be of interest
to consider the question of the amount of dust
necessary to propagate a flame. In some of the
experiments the dust was diffused in the proportion of
0'035 oz. per cubic foot of air space and high pressures
developed with the mixture. To obtain the same
proportion of dust and air, producing a mixture as
inflammable as used in these experiments, it would be
necessary to have only about 10 lb. of the dust in a
closed room 10 ft. X 30 ft. X 15 ft. Explosions have
been produced at the Pittsburg Testing Station of the
Bureau of Mines when there was only 0 032 oz. of coal

dust suspended in each cubic foot of air, or 1 lb. in
500 cubic feet. In order to produce combustion it
takes all of the oxygen in 1 cubic foot of air to
completely burn 0'123 oz. of the dust used. In France
ignition was obtained in one instance with as low a
weight as 0 023 oz. of coal dust per cubic foot, while at
the German Testing Station, ignitions have been
obtained when 0 04 oz. of coal dust was suspended in
1 cubic foot of air.

Preliminary experiments have shown that many
cereal dusts have relatively a lower ignition tempera-
ture and produce higher pressures than the coal dusts.
We might, therefore, conclude that the explosive limits
would be lower with cereal dusts than the figures given
for coal dust

THE GERMAN AND AUSTRIAN COAL
AND IRON TRADES.

We give below further extracts from German
periodicals that have reached us, showing the course of
the coal and iron trades in Germany and Austria :—

Compulsory Coal Syndicates .- Discussion in the Reichstag.

In the discussion of the proposed Compulsory Coal
Syndicate in the Reichstag on August 25, the Prussian
Minister of Commerce stated that the object in view
could not be achieved by fixing maximum prices, nor
(in reply to a suggestion) could the central government
undertake the task, which must be left to the central
authorities of the Federal States. He recommended
that the measures adopted should remain in force for
two years after the war. A Social Democrat expressed
the opinion that the Westphalian Coal Syndicate was a
national danger, and that the nationalisation of the
collieries was the only proper solution. He proposed
that the miners’ unions should be consulted in drawing
up the articles of association and on the questions of
the ironworks’ pits, export prices, import duties, and
the shutting down of pits. A Progressive deputy moved
that the carrying out of the Decree of July 12 should
be vested in the Realm Chancellor, who could be
empowered to depute his powers to the local central
authorities. He advocated the adoption of a resolution
(also supported by the Centre and Social Democrats)
that the control of syndicates and cartels was a matter
for the realm, and should be dealt with by the Ministry
of the Interior, and though it might be difficult to
arrange for this during the war, he felt certain it could
be accomplished afterwards. The Minister of Com-
merce consented to listen to the advice of the miners’
unions in connection with the fixing of prices and w’ages,
but could not agree that the carrying out of the Decree
should be left to the Realm Chancellor, the Federal
States alone having the necessary organisation. The
Progressive resolution was adopted, and also one of the
National Liberals to the effect that the Federal Council
should be asked to add to Article 5 of the Decree that
its operation should be suspended within two years at
latest from the conclusion of the war. The resolution
of the Progressive, Centre and Social Democrats was also
passed.

Coal Syndicate New Settling Prices.

The following new prices came into force on 1st inst.,
the old prices are given in parentheses :—Bituminous
coals : Through and through slack, 13 ink. (12 mk.) per
ton; through and through (25 per cent, large), 14-25 mk.
(13-25 mk.); mixed (40 per cent, large), 15 mk. (14 mk.):
best mixed (50 per cent, large), 15'50 mk. (14-50 mk.);
through and through smithy coal, 15 mk. (14 mk.);
mixed smithy coal, 15-50 mk. (14-50 mk.); large coal I.,
16'50mk. (15’50 mk.); II., 16mk. (15 mk.); III., 15’75
mk. (14-75 mk.); washed nuts I. and II., 17 mk.
(16 mk.); III., 16-75 mk. (15-75 mk.); IV., 16’25 mk.
(15-25 mk.); V., 15 mk. (14 mk.); washed small, 12-25
mk. (11’25 mk.); coking coal, 14'25 mk. (13 mk.). Gas
and gas flaming coals : Through and through slack, 12’75
mk. (11-75 mk.); open burning through and through,
14 mk. (13 mk.); gas flaming through and through, 14’75
mk. (13-75 mk.); producer coals, 15-25 mk. (14-25 mk.)’:
gas through and through, 14«75mk. (13’75 mk.); large
coal I., 16’50 mk. (15'50 mk.); II., 16 mk. (15 mk.):

111.,	15-75 mk. (14-75 mk.); washed nuts I. and

11.,	17 mk. (16 mk.); III., 16’75 mk. (15-75 mk.):
IV., 16-25 mk. (15-25 mk.); V., 15 mk. (14 mk.):
unwashed nuts I., 16’25 mk. (15*25 mk.); nuts
slack above 30 mm., 12’50 mk. (11’50 mk.); up to
30mm., 11-50mk. (10-50mk.); unwashed smalls, 9’75
mk. (8-75 mk.); washed small, 12-25 mk. (11’25 mk.).
Smithy coals : Through and through slack (10 per cent,
large), 13 mk. (12 mk.); through and through, with 25
per cent, large, 13-75 mk. (12’75 mk.); with 35 per cent,
large, 14’25 mk. (13'25 mk.); best mixed (50 per cent,
large), 15-50mk. (14-50 mk.); large, 16'25 mk. (15-25
mk.); washed nuts I. and II., 18-50 mk. (17’50 mk.):

111.,	17-25 mk. (16-25 mk.); IV., 16’25 mk. (15-25 mk.);
small, 11'25 mk. (10-25 mk.). Lean coals (Eastern dis-
trict) : Through and through slack (10 per cent, large),
12-25 mk. (11’25 mk.); through and through, with 25 per
cent, large, 13-75 mk. (13-25 mk.); with 35 per cent,
large, 14’25 mk. G3’25mk.); best mixed (50 per cent,
large), 15 mk. (14 mk.); large, 16-50 mk. (15-50 mk.):
nubbles, 17*50 mk. (16’50 mk.); washed nuts I. and II.,
19 mk. (18 mk.); III., 17-25 mk. (16-25 mk.); IV., 16-25
mk. (15’25 mk.); unwashed small, 9’75 mk. (8-75 mk.):
washed small, 10-75 mk. (9’75 mk.). Western dis-
trict : Through and through slack (10 per cent, large),
12 mk. (11 mk.); through and through, with 25 per cent,
large, 13'50 mk. (12-50ink.): with 35 per cent, large,
14 ink. (13 mk.); mixed (45 per cent, large), 14-75 mk.
(13-75 mk.); large, 17 mk. (16 mk.); washed anthracite,
nuts I., 21 mk. (20mk.); II., 25 mk. (24 mk.); III.
(house coals), 21-25 mk. (20’25 mk.): III. (steam), 16’75
mk. (15’75 mk.); -washed nuts IV. (8-15 min.), 14-50mk.
(13-50 mk.); unwashed small, 8-50 mk. (7-50 mk.):
washed fine (up to 7 per cent, ash), 10-25 mk. (9’25 mk.).