DYNAMITE OR GIANT POWDER
Is made by mixing nitroglycerine infusorial earth. It is an ungrained powder, of a greyish brown color, resembling moist sawdust in appearance. Insoluble in water, it is not affected by time or exposure to air and moisture. It congeals at about 42 degrees Fahrenheit. In the open air or in ordinary packing it burns without exploding. Its combustion produces carbonic acid, carbonic oxide, hyponitrous acid and water. When heated above 212 degrees (the boiling point of water) it throws off noxious fumes and becomes weakened and finally destroyed.
It should, therefore, be kept in some place having a temperature between these extremes.
When frozen it can be thawed by being kept for a time in this proper temperature. It is perfectly safe to thaw the powder by placing the cartridges in an open vessel and the vessel then placed in hot water. When it becomes soft it is ready for use, and its strength unimpaired. As it freezes very slowly, no inconvenient haste is required in its application.
Unlike gunpowder, its explosion is instantaneous. The entire mass of powder explodes as if it were a single grain. This quality in connection with its extraordinary evolution of gases, causes its explosive effect to be especially great in solid substances. Its explosion produces carbonic acid, nitrogen and water.
There are three methods of exploding it: lst.--By a violent explosion either in or into it. 2nd.--By confining it in a very strong and tight vessel, and setting it on fire, or heating the vessel sufficiently. 3rd.--By a percussive shock so intense as to produce heat and violence equivalent to an explosion. Practically it cannot be exploded by accident. Fire alone will not explode it, nor heat in any form. Nor will any amount of mere weight upon it or simple pressure of any kind explode it. It cannot be exploded by any of the ordinary movements, accidents or incidents which attend its handling, transportation or use. The pressing it into cartridges, or ramming it into the bore-holes, with a wooden rod however hard, throwing it about, or even the crushing or violence of overturning wagons or collisions of cars will never explode it. The burning or flashing of gun-powder, unconfined, is not sufficient.
When set on fire while under confinement in some tight and strong vessel, the burning of the powder produces gases, which, finding no escape, at length cause a pressure so great as to produce, with the heat of the burning, an explosion of the unburnt powder.
A vessel of the strongest tin has not the requisite strength; it, like paper cartridges, ordinary packing boxes, barrels, casks, &c., will be burst asunder by the gases before the pressure is sufficient to cause explosion.
Cartridges.--Except in special eases it is better to use the powder in the form of cartridges. It is more economical in both time and powder; and the explosion is more certain.
Fuse.--Ordinary fuse may be used, but, to make sure of a discharge in all cases, and to keep the powder from being burned by fire from a leaky fuse, the best fuse is recommended, and of a size to fit the caps precisely.
Caps are manufactured for the special purpose of exploding giant powder. They are more heavily charged with fulminate than ordinary ones, and corresponding care should be taken in their handling and use. A pair of cutting nippers, with their edges blunted, may be used in securing the caps tightly and firmly to the fuse.
Drill-holes, Charges, &c.--As to the diameter and depth of holes, and where they should be made, and the direction they should take, and also as to the quantity of powder to be used, and many other matters, no definite or arbitrary rules can be laid down for blasting with any explosive. As a general rule, the drill-holes and charges for giant powder can be, and should be, comparatively small. Experience has proved that ¾ inch octagon steel, with 3½ pound hammers, used by single hand drillers, are best adapted to use the powder to the greatest advantage. Holes one inch in diameter are abundantly large for all ordinary heavy work; for light work, correspondingly smaller ones should be made. The quantity of powder should not only be proportionate to the resistance, but the hole should be proportionate to the powder. As, by reason of its quickness, giant powder in bore-holes is nearly as effectual without tamping as with it, it can be exploded with great advantage without any tamping at all, in natural fissure and artificial cracks. It is, therefore, urged that advantage be taken of this extraordinary quality as often as practicable.
Charging.--The charge must fit and fill the bottom of the bore, and be packed solid. This is an essential pre-requisite to an effective blast. The only way to secure it is this: Take a cartridge as nearly as possible of the same size as the bore, and cut it into sections from one to two inches long. With a hardwood rammer, as large as will run freely in the hole, press these sections into the bore-hole one by one, with sufficient force, until each section is driven to the bottom and expanded laterally, so as to fill the hole solidly in every direction. Any sized cartridge may be used, provided it is thus put in. In wet holes, the sections should be rolled in additional paper, and the ends rolled to prevent the powder from getting mixed with water. Metallic rammers must not be used.
Firing the Charge.--The modes of exploding the charges are various. After the cap is put on the end of the fuse, and, with a pair of nippers, pressed firmly round the edge into the fuse, some grease, soap or wax should be rubbed round the upper end of the cap to make the same air and water tight. Now insert the fuse into the bore-hole until the cap rests on the charge, then take a small piece of cartridge, about three-quarters of an inch, push it down with the ramrod and press it round the cap so that the latter is inserted in the powder to about half its whole length, but never deeper, because, if part of the fuse were in the powder above, the cap would be burnt up without exploding. Another way of exploding the powder is to cut off about an inch in length of the cartridge, smaller in dimension than the borehole, press into this piece of so-called "priming cartridge" the cap, after it is well fastened to the fuse, and with a string tie both together to prevent the cap from being withdrawn, then let this priming cartridge down the bore-hole until it rests on the charge, and fire the fuse.
The stronger grades of giant powder frequently do not require any tamping, and wherever water tamping can be used, as for instance in all downward holes, it should be applied. It excludes every particle of air, and forms a solid column on the charge.
In case the blast misses fire, put in another primer.
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Last Modified: 2000-09-01
Originally Printed by: The Citizen Publishing Company
The information contained on this site is not provided for the purpose of factual
representation. Instead, it is provided in an historical context. Every effort has
been made to ensure that this information represents the actual content
of the published Nova Scotia Department of Mines annual reports.
Nevertheless, no warranties are provided in any respect.
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