May 19, 1916.

THE COLLIERY GUARDIAN

957

CHANCE ACETYLENE SAFETY LAMP.*

By H. M. Chance.

The acetylene lamp is readily extinguished by con-
cussion. As the generation of gas is continuous,
re-ignition, if only provided by an uncertain hand-
operated device might be delayed till a violent explosive
mixture was formed in the lamp. The gauze might
pass the flame of the resultant explosion, and thus a
gaseous atmosphere surrounding it might be ignited.
It was only the successful provision for instant re-light-
ing which made it possible to retain all the great
advantages of an acetylene safety lamp without the
introduction of any of its dangers.

All flame safety lamps employ a wire gauze, perforated
metal or other equivalent means for preventing the
passage of flame from the combustible gases inside the
lamp to an inflammable or explosive atmosphere sur-
rounding it.

In recent years the principal object sought has been
the development of a safety lamp that will give more
light than those in common use. The best results so
far attained, in lamps that have come into general
notice and use, have been obtained from oil or benzene
burning lamps of the bohneted Mueseler and Marsaut
types, which have a glass shield surmounted by a gauze
that is surrounded by a protective metal bonnet.

The illumination obtained from such lamps has
ranged from 0’6 to 1’2 candle-power for lamps of the
Marsaut bottom air feed type, and from 0’5 to 1’3
candle-power for lamps of the Mueseler nou-reflector
type, down to from 0’15 to 0-2 candle-power for stan-
dard Davy lamps. The miners’ electric cap or hand
portable lamps in use give about 0’50 mean horizontal
candle-power.

In many mines the open acetylene lamp has almost
entirely displaced the open oil torch, and has furnished
the miner with light at « cost equal to or materially less,
light for light, than that of an oil torch. "Where high
grade oil is required, the cost of the acetylene light is
much less than that of the open oil lamp. If in com-
paring the relative costs of these two methods of
lighting we take into account the illuminating candle-
power furnished by oil and by acetylene, we
find that under practically all conditions the
light produced from acetylene is much cheaper
than that obtained by the use of oil.

Many attempts have been made to use
acetylene in safety lamps, and a number of
acetylene safety lamps of different types have
been manufactured and offered for sale, but
none of them has come into general use. The
obstacle to the use of such lamps is that they
fail to meet requirements which are essential
to safety.

Effect of Concussion.

An acetylene lamp, or any lamp burning a
combustible gas which is supplied to the burner
under a very low pressure—a few inches of
water gauge, or an ounce or two pressure per
square inch—is easily extinguished by a shock
or concussion such as that produced by blast-
ing. Whenever the atmospheric pressure
external to the lamp becomes greater than the
pressure of the acetylene or other combustible
gas, the flow of acetylene through the burner
tip immediately ceases, and the flame is
extinguished. If this rise in pressure is caused
by' a pressure wave from the concussion of a
shot in blasting, the flame is instantly extin-
guished, but the jet of acetylene is immediately
re-established, for such pressure waves travel
at high velocity, and the duration of this increase in
pressure at any place is but a small fraction of a second.

With an open light, the miner can re-light bis lamp,
but if his light is a safety lamp, and locked, ho cannot
open it, and he must return the lamp to some lighting
station underground or at the surface, where a lamp
tender is on duty to perform this service.

The only way of avoiding this annoyance and danger
is to equip the lamp with some form of re-lighter; and
this has been done in some types by the use of a strip
of paper with phosphorus patches, similar to many
pocket cigar lighters, or by the use of an “ Auer-metal ”
re-lighter. As neither of these is automatic, and as some
seconds or minutes may elapse after the lamp is extin-
guished before the miner finds it or attempts to operate
the re-lighter, the 'acetylene that has passed through the
burner while the lamp was extinguished has had time to
form an explosive mixture filling the interior of the
lamp. Under such conditions the miner, in operating
the re-lighter, will fire this combustible mixture, and
produce an explosion that may wreck the lamp or may
force flame through the lamp gauze and ignite any explo-
sive or combustible atmosphere surrounding it.

Instantaneous Self-Igniter.

To overcome this difficulty, the re-lighter must
re-light the gas jet immediately after it has been extin-
guished, that is, as soon as acetylene again commences
to flow through the burner. The re-lighting device
must therefore work automatically and instantaneously.

In the Chance acetylene safety lamp this end has
been attained by placing a refractory substance, capable
of absorbing and retaining heat, adjacent to the flame
of the lamp, but not in contact with it, and of such
dimensions and shape as will ensure the heating of this
substance, mainly by heat radiated from the flame, to
a temperature higher than the temperature necessary to
ignite acetylene.

.The re-igniter shown at A in the figures is a flattened,
serpentine coil of “ Nichrome ” wire, an alloy of nickel
and chromium. It is placed between the flames of the
burner, which may be furnished with two or any desired
number of jets.

* Coal Age.

The action of this re-igniter is positive and certain.
The lamp has been subjected to test by placing it within
30 ft. of holes for raising bottom, heavily charged with
dynamite. These shots extinguished all other lamps at
much greater distances. It put out the acetylene lamp
also, but the latter was instantaneously re-ignited. The
re-igniter remains red-hot as long as the lamp burns,
that is, as long as the carbide charge is generating
acetylene, and will always instantaneously re-ignite the
flame when it is extinguished by shock, jar, or
concussion.

It is important to so locate the re-igniter that it will
not be in contact with the flame, because the latter
will be chilled by the contact, and its temperature will
be lowered, its luminosity reduced, and a deposit of
carbon will form upon the re-igniter, which will quickly
grow to a mass of considerable size. Any such accre-
tion will still further reduce the temperature and
luminosity of the flame. Carbon so deposited upon the
re-igniter will become detached, and may clog up the
burners or become deposited on the glass shield or upon
the wire gauze.

Specifications for a Practical Re-Igniter.

As a result of experiments, certain conditions have
been clearly established as necessary to success. The
most important of these is that the re-igniter must not
be in contact with the flame. Another essential require-
ment is that the re-igniter must be operative, whether
the flame of the lamp be high or low. It is essential
that it should be rugged enough to withstand ordinary
shocks and jars, and it must not quickly deteriorate or
become weak or brittle from oxidation or any other
cause.

In practice the lamp will be cleaned, charged with
carbide and water, lighted, assembled, and locked in
the lamp house by the lampman, and handed to the
miner lighted and ready for use and capable of burning
at its rated capacity for a full shift of, say, nine or
10 hours. It will be practically impossible to extin-
guish the lamp by ordinary shocks, jarring, swinging at
high angles from the vertical, by the concussions caused
by shot-firing, or by draughts in going through doors,
or while travelling along airways or roadways.

Chance Burner Fitted to Wolf Lamp.

It can be turned down for gas testing, and for this
purpose is more sensitive than a Davy or other oil lamp,
and it can be extinguished by turning off the water and
gas should the miner at any time find it necessary to
extinguish it because of the presence of firedamp in
dangerous quantity. When so extinguished, it will, of
course, be necessary to return it to the lamp tender,
either at the surface or at re-lighting stations maintained
underground for this purpose.

The lamps shown in the figures are of the two-jet
burner type, and will give from 3-0 to 4-5 standard
English sperm candle-power. Some flame safety lamps
are said to produce 1-75 candle-power using kerosene,
but this illumination is obtained by means of a reflector.
It will be readily understood that if resort be had to the
use of a reflecting device, a concentrated light of 6 or 7
candle-power can be obtained from this acetylene lamp.

Efficiency when the Lamp Glass is Smoked.

The candle-power of lamps is greatly affected by the
condition of the glass. Oil lamp glasses soon get sooted
and greasy, and the effective light is thus greatly
reduced. If the factor of absorption of light by a glass
shield be taken at 0-5 candle-power—that is, the light
lost by the dirty condition of the glass—a benzine lamp
of 10 candle-power is reduced to 1-0—0-5 candle-power,
or 0-5 candle-power in actual service, and the loss of
this quantity of light has been ascertained in many
lamps in underground use.

If the same high loss is experienced in the acetylene
safety lamp—a quite unlikely condition, as this type
of lamp does not often make much soot—then the effec-
tive light from a 3 candle-power acetylene lamp will be
3-0 — 0'5 candle-power, or 2-5 candle-power, and the
ratio of the benzine to the acetylene lamp illumination
is as 0-5 is to 2-5, or as 1 is to 5, instead of the ratio
of 1 is to 3 with the glasses clean. The lower percen-
tage of light lost from dirty glasses will thus be an
important factor in comparing the relative illumination
obtained with oil and acetylene lamps.

It is common to find the gauze of the oil-burning
safety lamp badly sooted, and hence unsafe, after a
few hours burning. The acetylene safety lamp can
often be used for days without the gauzes needing to be

cleaned, and with a relatively small accumulation of
dirt on the inside of the glass.

The oil-burning safety lamp is extinguished in atmo-
spheres containing 16 to 18 per cent, oxygen, while the
acetylene lamp can burn in air containing as little as
14 per cent., and men can exist in an atmosphere con-
taining less than 12 per cent., and, in some cases, if
there is only 10 per cent, of free oxygen. Hence the
acetylene safety lamp may be used in atmospheres
extinctive to oil lamps, and will also detect firedamp in
atmospheres that are so low in oxygen, due to the pre-
sence of this inflammable gas, that they will actually
extinguish the oil-burning safety lamp.

The advantages which may be claimed for this type
of lamp may be briefly and conservatively stated as
follows :—

(1)	Illumination.—The illumination is from three' to
six times that of any oil or electric safety lamp now in
use, and will (a) enable the miner to make a better
inspection of the roof, props, etc., and keep his work-
ing place safer and in better condition for economic
and efficient work; (b) aid him to clean the coal from
the slate in a much better manner than is now possible,
thus saving a large economic loss now suffered in many
safety lamp mines; (c) enable him to increase his output
owing to increased efficiency in mining and loading the
coal; (d) improve his working conditions by reducing
the eye strain resulting from the deficient illumination
supplied by the oil and electric safety lamps now used.

(2)	Re-Lighting Properties.—The re-ignition is abso-
lutely automatic and instantaneous in action. It
cannot cause interior explosion in the lamp. Some of
the advantages that will follow its use are : (a) In case
of a colliery disaster, such as an explosion of dust or
gas, the lamp will instantly re-light itself. The miner
will thus have a much better chance to make his escape
before the afterdamp reaches him. (b) Re-ignition is
provided without the accompanying danger of wreck-
ing the lamp by internal explosion and the risk of the
firing of an explosive atmosphere, as is the experience
when using manually operated re-igniters with benzine
safety lamps, (c) Increase in atmospheric pressure due
to blasting or falls of roof has no effect on the efficiency
of the lamp, the re-igniter automatically re-lighting the
lamp after any such disturbance may have extinguished
it. (d) The acetylene lamp cannot be extinguished by
jarring or overturning, as is the case with oil-burning
lamps, and if laid on its side the flame burns centrally
in the lamp gauze with little danger of overheating
and breaking the glass, an accident quite likely to occur
in oil-burning safety lamps.

The lamp shown is a German Wolf acetylene
safety lamp of 12 hours burning capacity, which has
been converted to operate under the system described
by the addition of the automatic re-igniter, marked A
in the figure.

PROPOSED FRENCH LEGISLATION ON
PRE-WAR CONTRACTS.

A Bill was recently introduced in the Chamber of
Deputies by M. Faillot, to deal with the question of
pre-war contracts, and was referred to the Committee
on Commerce and Industry.

Article 1 proposes that sales or contracts of a com-
mercial nature entered into prior to August 1, 1914, and
relating to deliveries of products or merchandise over a
term, may be cancelled, with or without indemnity, on
the application of either party, provided that, as a result
of the state of war, the execution of the agreement would
entail expenses or losses that the parties could not
reasonably foresee at the time the contract was made.
The contract may also be suspended for a certain time
by the courts, on the application of one of the parties.

Article 2 sets forth that the second party (respondent)
may ask for the contract to be modified, instead of being
cancelled or suspended. The tribunal may then decide
what increased price or modification in terms is
equitable—without power to impose same—and, if these
modifications be refused, the party who refuses will get
nothing more than simple cancellation of the contract,
without any claim to indemnification. Consent to the
proposed modification must be signified in writing
within a week, or cancellation will ensue.

In Article 3, parties who have come to a mutual
arrangement, voluntarily or under legislation anterior to
the present Bill, will still have the right of submitting
their contracts to the tribunal.

Article 4 provides for an amicable settlement of appli-
cations under the Bill, before the president of the
tribunal, in default of which the proceedings will be
held in accordance with Articles 405 et seq. of the Civil
Code, and 414 et seq. (commercial cases) of the same
Code. The time for lodging appeals shall be reduced to
10 days. No registration fees shall be charged on the
contracts or other documents produced in the pro-
ceedings.

Article 5 limits the duration of the Bill to one year
after the cessation of hostilities.

The Kentucky River Power Company is putting up a large
new central power station, which will be one of the largest in
the State, and will be capable of developing enough power to
supply the city of Hazard with beat and light, and operate
the machinery and do the hauling for the 14 mines in the dis-
trict. The equipment comprises two 2,000 horse-power steam
turbines, two 500 horse-power boilers with automatic stokers,
and generators that will produce up to 33,000 volts of elec-
tricity. The transmission system is designed to carry power
a distance of 45 miles.

Grimsby Coal Exports. — Returns for the week ended
May 12 show that the coal export from Grimsby consisted
of the following :—Foreign—To Dieppe, 389; Dunkirk, 467 ;
Esbjerg, 1.018; Gothenburg. 1,511; Rouen, 1,985; and
Treport, 217 tons; total, 5,587 tons foreign, against 9,190
tons foreign during the corresponding week of last year.