Improvement in the Manufacture of Gunpowder and Blasting Cartridges.
Year: 1899

page_text: Date of Application, 25th Mar., 1899
Complete Specification Left, 3rd Aug., 1899-Accepted, 30th Sept., 1899
Improvement in the Manufacture of Gunpowder and Blasting
Cartridges.
We, CHARLES HERBERT CURTIS, CLEMENT LEIGH WATSON SMITII, DAVID JAMES
METCALFE, and ALFRED COPLEY PEARCY, all of 3, Gracechurch Street, London,
and ANDREW FULLER HARGREAVES, of Roslin, Midlothian, Gunpowder Manu-
facturers, do hereby declare the nature of this invention to be as follows:-
This invention relates to an improvement in the manufacture of gunpowder
ordinarily so called and of blasting cartridges made from gunpowder whereby
the use of this explosive is rendered safe for use in dangerous coal and other
mines without fear of ignition or explosion of dust or gas.
The superiority of ordinary blasting powder for coal getting as compared with
higher explosives has long been admitted owing to its comparatively slow and
consequently spreading action, but its use has been curtailed in gaseous and
fiery mines because of its liability to cause disaster by reason of the heat or
flames evolved. For some time we have given considerable attention to this
subject and came to the conclusion that if the heat of combustion or explosion
of the charge could be utilized for the evolution of a flame destroying gas such
as C.O, or the resolution of a solid into a liquid or gaseous form the gunpowder
could be rendered safe and we applied this principle in our Patents No. 232 of
1898 8756 of 1898 and 12404 of 1898.
We have found that potassium nitrate commonly called salt petre can be used
in place of oxalate of ammonia or bicarbonate of soda or bi-carbonate of potash
as the cooling agent in a cartridge constructed in the manner described in the
Specification of our said Patent No. 232 of 1898 but the additional potassium
nitrate used as a cooler is not an explosive and does not appreciably add to the
strength of the gunpowder.
We have also found that the cooling charge of potassium nitrate may be added
to the explosive itself either in a granular form added to the powder already
manufactured or incorporated with the powder in the process of manufacture.
When the excess of potassium nitrate is incorporated with the powder the addition
of the cooler is very simply affected in the course of manufacture by merely
altering the proportions of the constituents of the powder.
In carrying out our invention by the last described method we make a gun.
powder consisting of the ordinary ingredients but in which the potassium nitrate
must be in not less proportion than 83% of the whole weight. This increase in
the proportion of potassium nitrate necessitates a reduction in the proportion
of charcoal and sulphur which enter as constituents into the gunpowder. We
find that it is desirable to diminish the proportion of sulphur more than that
of charcoal. For example we may reduce the sulphur to as low a proportion
as 1% of the total weight of the gunpowder or less or even omit it in some
forms of our new powder with a good result. The balance, whatever it may
be, will consist of charcoal and when the amount of sulphur is reduced or omitted

page_text: it is, we find, advantageous to use rather the less highly than the more highly
carbonized forms of charcoal. It is not however necessary to select any particular
form of charcoal. We use the kinds usually employed in the manufacture of
gunpowder.
The manufacture of our improved blasting powder is conducted in the ordinary
way of manufacturing gunpowder and substantially the resulting difference in
the composition of the powder is that it contains potassium nitrate in considerable
excess. The excess of potassium nitrate serves not only by its absorption of
heat to reduce the temperature of the gases produced by the explosion but also
by providing an excess of oxygen in the cartridge to promote the complete oxida-
tion of the products of the combustion and to prevent the liberation of inflamma-
ble gases such as heated carbon non-oxide and also to avoid the formation of the
inflammable form of potassium sulphide.
Our improved blasting powder can not only be used in the ordinary meal
or granular form but it has the great advantage of being safe and available for
use in gaseous and fiery mines when compressed into pellets.
THEO. MCKENNA,
17 & 18, Basinghall Street, London, E.C.,
Applicant's Agent.
Improvements in the Manufacture of Gunpowder and Blasting
Cartridges:
We, CHARLES HERBERT CURTIS, CLEMENT LEIGH WATSON SMITH, DAVID JAMES
METCALFE, and ALFRED COPLEY PEARCY, all of 3, Gracechurch Street, London,
and ANDREW FULLER HARGREAVES, of Roslin, Midlothian, Gunpowder Manu-
facturers, 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:-
The invention relates to an improvement in the manufacture of gunpowder
ordinarily so called and of blasting cartridges made from gunpowder whereby
the use of this explosive is rendered safe for use in dangerous coal and other
mines without fear of ignition or explosion of dust or gas.
The superiority of ordinary blasting powder for coal getting as compared with
higher explosives has long been admitted owing to its comparatively slow and
consequently spreading action, but its use has been curtailed in gaseous and
fiery mines because of its liability to cause disaster by reason of the heat or
flames evolved. For some time we have given considerable attention to this
subject and have come to the conclusion that if the heat of combustion or explosion
of the charge could be utilized for the evolution of a flame destroying gas such
as CO, or the resolution of a solid into a liquid or gascous form the gunpowder
could be rendered safe and we applied this principle in our Patents No. 232 of
1898, 6756 of 1898 and 12404 of 1898. We have found that potassium nitrate
commonly called saltpetre can be used in place of oxalate of ainmonia or bicar-
bonate of soda or bicarbonate of potash as the cooling agent in a cartridge con-
structed in the manner described in the Specification of our said Patent No. 232
of 1898 but the additional potassium nitrate used as a cooler is not an explosive
and does not appreciably add to the strength of the gunpowder.
We have also found that the cooling charge of potassium nitrate may be in-
corporated with the powder in the process of manufacture. When the excess of
potassium nitrate is so incorporated the addition of the cooler is very simply

page_text: effected in the course of manufacture by merely altering the proportions of the
constituents of the powder.
In carrying out our invention by the last described method we make a gun-
powder consisting of the ordinary ingredients but in which the potassium nitrate
must be in not less proportion than 83% of the whole weight. This increase in
the proportion of potassium nitrate necessitates a reduction in the proportion
of charcoal and sulphur which enter as constituents into the gunpowder. We
find that it is desirable to diminish the proportion of sulphur rather than that
of charcoal. For example we may reduce the sulphur to as low a proportion
as 1% of the total weight of the gunpowder or less or even omit it in some
forms of our new powder with a good result. The balance whatever it may
amount to will consist of charcoal and we employ for this purpose any of the
kinds of charcoal usually employed in the manufacture of gunpowder selecting
the particular kind to be used in the manufacture of any particular powder for
technical reasons such as are well understood.
The manufacture of our improved blasting powder is conducted in the ordinary
way of manufacturing gunpowder and substantially the resulting difference in
the composition of the powder is that it contains potassium nitrate in considerable
excess. The excess of potassium nitrate serves not only by its absorption of
heat to reduce the temperature of the gases produced by the explosion but also
by providing an excess of oxygen in the cartridge to promote the complete oxida-
tion of the products of the combustion and to prevent the liberation of inflamma-
ble gases such as heated carbon non-oxide and also to avoid the formation of the
inflammable form of potassium sulphide.
The excess of potassium nitrate is ascertained by calculating its proportion
to the actual carbon present in the charcoal and is represented by the balance left
over after providing sufficient oxygen fully to oxidise the carbon.
As the charcoal in our powder is made from wood and carbonised as fully as
that for ordinary gunpowder, there is but a very moderate amount of volatile
matter evolved from it on being heated. What oxygen and hydrogen are present
are nearly (though not absolutely) in the proportion in which they exist in
water and it is not necessary therefore to draw on the oxygen of the saltpetre or
other extraneous sources for oxidation purposes beyond what is necessary fully
to oxidise the carbon and therefore, as stated above, the excess of potassium
nitrate acts as a cooling agent and prevents any stray particle of carbon from
escaping either wholly or partially unoxidised.
It is impracticable to use a charcoal containing the highest percentage of
carbon attainable because owing to its hardness and therefore excessively slow
combustibility such a charcoal is not suited to the manufacture of our blasting
gunpowder. Subject however to this we use a charcoal which, whilst being
readily combustible, contains only a moderate amount of volatile matter.
If any considerable quantity of inflammable hydro carbons were present (and
especially any free hydrogen as is the case with some carbonaceous materials)
it would have a tendency to produce one or other or both of the following effects.
That is to say, it would reduce the available excess of saltpetre or it would
be evolved on the explosion unchanged, and on coming into contact with the
atmospheric oxygen in a highly heated condition would instantly burst into
flame. In any case it would be a source of danger tending in the one event
to diminish the quantity of saltpetre available for cooling and in the other event
generating flame, or both these evils may be produced. We therefore make
choice of our charcoal with a view to these among other considerations and whilst
selecting any particular charcoal upon general technical grounds we are careful
not to employ any such variety as yields upon combustion any considerable
quantity of inflammable vapour. It is therefore, according to our experience,
a sound general rule to avoid such forms of charcoal as yield more than about
22% to 25% of volatile matter when strongly heated in a current of coal
FOR
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hydrogen

page_text: Our improved blasting powder can not only be used in the ordinary meal
or granular form but it has the great advantage of being safe and available for
use in gaseous and fiery mines when compressed into pellets.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed we declare that what
we claim is:-
1. A blasting powder compounded as herein specified in which an excess of
saltpetre calculated to be not less than is herein before mentioned in proportion
to the carbon present is incorporated in the manufacture of the gunpowder with
a suitable charcoal substantially as hereinbefore described.
2. A blasting powder compounded as herein specified in which an excess of
saltpetre calculated to be not less than is hereinbefore mentioned in proportion
to the carbon present is incorporated in the manufacture of the gunpowder with
a suitable charcoal and a small proportion of sulphur substantially as herein-
before described.
3. The use in a cartridge constructed in the manner described in the Specifica-
tion of our said Patent No. 232 of 1898 of potassium nitrate as the cooling agent
in place of oxalate of ammonia as hereinbefore described.
11 12
1
1000
18
THEO. MCKENNA,
17 & 18, Basinghall Street, London, E.C.,
THEO. MCKENNA,
17 & 18, Basinghall Street, London, E.C.,
Agent.