Handbook for Light Artillery

by A. B. Dyer

DYNAMITE.

Dynamite is composed of a particularly porous siliceous earth (Keiselguhr) impregnated with about 70 or 75 per cent of nitro-glycerine. True dynamite resembles in appearance moist brown sugar. It takes fire at 350° F., and freezes.

MATERIALS IN USE FOR BLASTING.

Cartridges.—The regular sizes are from four to eight inches long and from three fourths of an inch to two inches in diameter. They are furnished to order of any required size, packed in boxes containing 25 or 50 pounds, the layers of cartridges being separated by sawdust. To use a small cartridge in a large hole, slit it on the side and press it down into the drill-hole with a wooden tamping-rod. Cartridges may be readily cut into desired lengths. In tamping powder or explosives always use a wooden rammer, never an iron or steel bar.

Caps.—The regular cap or exploder is employed. It consists of a hollow copper cylinder about ¼ inch in diameter and from one to two inches long, and contains 15 to 20 per cent or more of fulminate of mercury mixed with other ingredients into a cement, which fills the closed end of the cap.

Fuzes.—The double-tape fuze is the best. Single-tape fuze may be used when the ground is only a little wet.

Nippers and Pincers.—For cutting the fuze, and after it is inserted in the cap for squeezing the cap tightly around the fuze.

Funnel.—Used in charging with loose powder.

DRILL-HOLES.

As a general rule drill-holes and charges for dynamite should be comparatively small. In heavy work the holes should be large in size and less in number, and the amount of dynamite should be in proportion to the work done.

Charging with Cartridges.—The charge must fit and fill the bottom of the bore, and be packed solid. Take a cartridge as nearly as possible of the same size as the bore, and cut it into sections of about twice or three times the diameter. With a hard-wood 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. If the cartridge is smaller than the hole, slit it lengthwise. Metallic rammers must not be used.

Priming.—Cut off squarely the end of the fuze and thrust it into the cap up to the fulminate. If the fuze is too large, scrape it down, and if too small wind it with paper. Then clamp the cap to the fuze with the nippers, being careful not to disturb the fulminate in the cap. If for a wet hole, smear the junction of the fuze and the cap with bar-soap or the like, to make it water-tight. Now open the end of the cartridge, and with a pointed stick make a hole in the explosive and insert the cap (with the fuze attached) the full length of the cap, and press the explosive firmly about the cap. Next gather the cartridge-paper about the fuze and tie it there strongly with a string, so that the cap cannot be withdrawn from the explosive. Cut off so much of the cartridge as is not needed, and the primer is complete. Thus prepared, place it in the drill-hole and press it with a wooden rod into contact with the charge.

Tamping.—This is of great importance. Always tamp if you can, and with the best materials and in the strongest manner. In deep and down holes water is good. A shallow tamp of water amounts to very little. A shallow tamp of sand or clay is better. In driving and packing the tamp next to the primer be careful not to explode the cap; the first handful of tamp should always be pressed down gently. In fissures or artificial cracks surround the charge with mud, clay, sand, or water, if possible.

Explosion of Blast.—In most cases it is better not to cut off the required length of fuze until the hole is tamped. Then cut off at a safe length and fire by igniting with a match or fuzee. If it misses fire, be careful in taking out the tamping not to approach nearer the cap than within two or three inches; then put in another cartridge and fire it. Never pick out the charge. After inserting the primer it is well to put a ball of newspaper or some substance readily recognized on top of it and then the tamping. If then the tamping has to be removed, warning will be given on approaching the primer.

To Insure Explosion.—The dynamite must not be frozen; the fuze must be good and kept in the cap; the cap must be dry and not withdrawn from the explosive.

Frozen Dynamite.—Dynamite freezes more easily than water, becomes hard and cannot be properly loaded into bore-holes, and is more difficult of explosion. Keep it where it will not freeze if possible.

It must not be thawed by a fire, but by hot water in an apparatus like a common glue-pot, the dynamite being in the inner vessel and hot (not boiling) water in the outer. Eissler states that there is but one safe way of thawing it, which is to keep it in a kitchen or other room at summer heat, and away from the fire, until it is soft. It is then ready for use.

Precautions.—Never attempt to thaw frozen dynamite by roasting, toasting, or baking it. Never put it in heated vessels, or in boilers, or before fires or heated metals. It must not be thawed or heated rapidly.

Never put a cap into a charge or primer until you are ready to use it. After it is made never let a primer leave your hands until it is in the hole. Keep the caps away from the dynamite. Never let them come near each other except when used.

Never allow smoking or other fire near the powder or explosive, as it burns rapidly, and especially when loose, and may fire caps incautiously left near by, and thus bring on an explosion.

Never use a metallic rammer.

Do not get nitro-glycerine on your fingers. It will be absorbed by the skin and give you a headache. Invariably prepare your primer at a distance from your explosive.