Improved Method of and Means for Obtaining Increased Safety in Shot Firing in Coal Mines, and in other Mines.
Year: 1898

page_text: Improved Method of and Means for Obtaining Increased Safety in
Shot Firing in Coal Mines, and in other Mines.
We, CHARLES HERBERT CURTIS, of the Firm of Curtis's & Harvey, 74, Lombard
Street, in the City of London, Gunpowder Manufacturers, DAVID JAMES METCALFE,
a Managing Director of John Hall & Son Limited, of 79, Cannon Street, in the
City of London, Gunpowder Manufacturers, and ALFRED COPLEY PEARCY, London
Manager of Hay, Merricks & Company Limited, of Roslin, Midlothian, Gunpowder
Manufacturers, do hereby declare the nature of this invention to be as follows:-
According to this invention suitable means are provided wholly or chiefly in
front of the gunpowder or other explosive blasting charge for extinguishing the
flame or incandescent particles of the said explosive charge and for lowering the
temperature of same, when fired for blasting purposes in localities such as a
dangerous coal or other mine. The explosive is combined in the cartridge with
the aforesaid means for exerting an extinguishing or cooling action when the
cartridge is fired so as to be readily available for transport, storing and immediate
application when wanted but so that the explosive and the flame extinguishing
means are not formed into a mixture but are kept separate or intact from each
other by a paper or other diaphragm or the like. Or the extinguishing and
cooling material may be used outside of the cartridge altogether either loose, in
a cartridge or in the form of a pellet. As suitable means for extinguishing the
flame we will name bi-carbonate of soda (NaHCO3) and oxalic acid (CHO)
either separately or together. These two substances are used either as part of the
above described cartridge or as a pellet or loose for the purpose of being used
either in the cartridge or otherwise for blasting gunpowder or other blasting
explosive.
and
or
The evolution of carbonic acid gas water vapour produced by the combustion
of the powder in the cartridge aids in the extinction of flame or sparks while also
exerting a cooling action. Although we have specially mentioned the two afore-
said materials we may also employ in the manner described other suitable materials
water vapour for the purpose
which cause the evolution of carbonic acid gas or
stated.
and

page_text: Improved Method of and Means for Obtaining Increased Safety in
Shot Firing in Coal Mines, and in other Mines.
CHARLES HERBERT CURTIS, of the Firm of Curtis's & Harvey, 74, Lombard
Street, in the City of London, Gunpowder Manufacturers, DAVID JAMES METCALFE,
a Managing Director of John Hall & Son Limited, of 79, Cannon Street, in the
City of London, Gunpowder Manufacturers, and ALFRED COPLEY PEARCY, London
Manager of Hay Merricks & Company Limited, of Roslin, Midlothian, Gunpowder
Manufacturers, do hereby declare the nature of this invention and in what manner
the same is to be performed, to be particularly described and ascertained in and
by the following statement;-
According to this invention suitable means are provided in front of the gun-
powder or other explosive blasting charge of a like kind not requiring detonation
for extinguishing the flame or incandescent particles of the said explosive charge
and otherwise lowering the temperature of the same when fired for blasting
purposes in localities such as dangerous coal or other mines.
In that modification of our invention which we consider most advantageous when
it can be used the explosive is combined in one cartridge with the aforesaid
means for exerting an extinguishing or cooling action when the cartridge is fired
so as to be readily available for transport storing and immediate application when
wanted but so that the explosive and the flame extinguishing means are not
formed into a mixture but are kept absolutely separate or intact from each other
by a paper or other diaphragm or the like.
If for any reason it is impracticable or undesirable to combine the explosive
charge and the cooler in one and the same cartridge the extinguishing and cooling
material may be used outside of the cartridge either loosely packed in a separate
cartridge or compacted into the form of a pellet.
As a suitable material to be used in any one of these ways for extinguishing the
flame ete. we have discovered the great utility of bicarbonate of soda Na HCO3.
We are aware it has been proposed to obtain the same safety object by utilising
the water of crystallisation contained in the ordinary crystallised carbonate of soda
commonly known as sola crystals or washing soda.
This material consists of carbonate of soda combined with a greater or lesser
amount of water of crystalli ation and it is the volatilization and otherwise cooling
action of this water on which relience ha en placed.
The material Lowever which we have di covered as being remarkably efficacious
for the effective accomplishment of the object in view is as previously stated the
bicarbonate of soda which consists of the anhydrous carbonate of soda (Na, CO₂)
combined with carlaric acid (H,CO). This material on being heated evolves
carbonic acid which immediately splits up into carbon di-oxide and water vapour.
Na CO
+
IT CO
The evolution of carbon dioxide and water vapour produced from the cooler by
the heat of the combustion of the explosive charge in the cartridge aids in extin-
guishing the flame and sparks and otherwise exerts a powerful and cooling action.
We de ire to explain that we have discovered that this material possesses in a
marked degree this cooling influence owing to its readily evolving at a moderate

page_text: temperature a large volume of carbon dioxide which has a special power of
extinguishing flame over other gases which are also nonsupporters of combustion
and is further aided in this direction by the water vapour.
There is however a further advantage obtained by the use of bicarbonate of
soda insomuch that although it splits up at a moderately-elevated temperature as
previously described it is perfectly stable at the ordinary temperature and is
therefore unchanged with long storage and always reliable.
It will be at once apparent that this material possesses advantages over the
normal carbonate of soda when combined with water as water of crystallisation
forming the crystallised earbonate of soda or soda crystals because in the first place
there is with the latter material no evolution of carbonic acid on being heated and
secondly because on being stored the water of crystallisation not only varies but
especially because it is efflorescent and owing to this instability the water of crystal-
lisation would pass to the explosive rendering it more or less useless.
This invention can be used in connection with the cartridge which forms the
subject of the Patent No. 232 granted in the year 1898.
From experience we find that one part of the cooling material by weight to two
parts by weight of the explosive is a good proportion but we do not restrict our-
selves to these proportions and either greater or lesser proportions may be used.
The cooling agent may be used in various forms. We however believe that it
is most efficient in a coarsely granulated form which leaves abundant interstitial
space and thus facilitates complete decomposition.
In order that the said invention so far as the same consists in the use of the
cartridge may be more fully understood we will describe the same by means of
the accompanying drawing.
Fig. 1 shews a drawing of the cartridge.
Fig. 2 is a drawing of the end piece through which the fuse passes.
Fig. 3 is a drawing of the diaphragm.
Fig. 4 is a sectional view of the same.
Fig. 5 is a sectional view of the cartridge.
A is the portion of the cartridge which contains the powder.
B is the disc or diaphragm constructed as shown in the form of a cardboard ring
supporting a membrane of muslin paper or other suitable separating material.
In place of a diaphragm constructed as shewn we might use a disc of paper or
other easily disrupted fabric supported and retained in place in any suitable
manner.
C, is the channel or passage for the reception of the fuse.
D), is the receptacle for the cooling material charged with bicarbonate of soda as
above mentioned in a coarsely granulated condition so as to leave a large proportion
of interstitial space.
E, is the end piece placed on the top of the cooling material to complete the
cartridge.
The cartridge may be made of paper or any other suitable material usually
employed for the purpose of making cartridges.
Having now particularly described and ascertained the nature of our invention
and in what manner the same is to be performed we declare that what we
claim is:-
1. The employment in connection with gunpowder or other blasting charges of
a like kind of a cooling agent for extinguishing flame and incandescent particles
consisting of bicarbonate of soda applied in the manner hereinbefore described.
2. A blasting cartridge charged with gunpowder or other explosive charge of
a like kind and with a cooling agent for extinguishing flame and incandescent
particles such cooling agent consisting of bicarbonate of soda preferably granulated
and placed in a separate compartment within the cartridge as herein before
described.
3. The employment in connection with gunpowder or other explosive blasting

page_text: charge of a like kind of a cooling agent for extinguishing flame and incandescent
particles such cooling agent consisting of bicarbonate of soda compacted into a
pellet as herein before described.
4. A blasting cartridge containing the materials herein before mentioned and
constructed and arranged as hereinbefore described and shown by the accom-
panying drawing.
Dated the 19th day of December 1898
THEO. MCKENNA,
Applicants' Agent, 17 & 18, Basinghall Street, London, E.C.