 
GUNPOWDER.Gunpowder is a very intimate mixture of potassium nitrate (nitre), charcoal, and sulphur, and generally consists of the following proportions: Nitre, 75 parts; charcoal, 15 parts; sulphur, 10 parts. The following processes are used in its manufacture: (1) Mixing the ingredients; (2) incorporating or "milling"; (3) breaking down the mill-cake; (4) pressing; (5) granulating; (6) dusting; (7) glazing; (8) second dusting; (9) stoving or drying; (10) finishing. Good gunpowder should be composed of hard angular grains which do not soil the fingers, and should have a perfectly uniform dark-gray color. When new, it should be free from dust, and a gramme of it flashed on a copper or porcelain plate should leave no residue or foulness. It should give the required initial velocity to the projectile, and produce not more than the maximum strain upon the gun. When exposed to air of average dryness, it should not absorb more than 0.5 to 1.5 per cent of water. In damp air it absorbs more and deteriorates. Its exploding-point is 560° F. 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 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 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 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. RACK-A-ROCK.This powerful explosive, composed of a solid and a liquid ingredient, entirely inexplosive when separate, but easily and quickly combined, seems to present undoubted advantages for use in the military service. The solid is potassium chlorate, and the liquid is either "dead oil," or dead oil and bisulphide of carbon in equal volumes, or bisulphide of carbon with 3 per cent of carbon added, or mono-nitro-benzine. General Abbot considered the following the best: Potassium chlorate, 79 parts; mono-nitro-benzine, 21 parts. The potassium chlorate is put up in the form of a cartridge enclosed in a bag made of cotton or other suitable material. In preparing the charge for use the cartridges are placed in a wire frame, which is suspended from a spring-balance, and dipped in the liquid until a proportion of 3 to 4½ parts of solid to 1 part of liquid is shown by the balance; this requires from 3 to 6 seconds. Or, place the cartridges in a pan containing cells (each cartridge having a corresponding cell and cup) and then If the cartridges be kept, they appear to tend to increased sensibility to friction or percussion. GUNCOTTON.Compressed Guncotton.—Clippings and other waste from cotton-mills are thoroughly purified from oil and fatty matters by treatment with alkali and extraneous substances removed. The material is then opened up by a carding-machine and cut into suitable lengths. After thorough drying and when quite cold small quantities at a time are immersed in a cool mixture of 1 nitric acid (s. g. 1.52) and 3 sulphuric acid (s. g. 1.85). The excess of acid is then removed and the cotton carefully washed, reduced to pulp, purified, and compressed into given weights and shapes by a powerful hydraulic press, and weighs 60 lbs. per cubic foot. The disks or slabs can be cut into smaller sizes with a sharp saw or knife without danger, care being taken to press them between boards while so doing to prevent their falling to pieces. It has from 2 to 2½ times the strength of gunpowder for equal weights when the charges are well tamped, and 4 times the strength of gunpowder when the charges are untamped; it ignites at a lower temperature than gunpowder, as it may explode at 277° F. and must explode at 400° F.; it is comparatively insensible to shocks—caissons containing dry guncotton have been frequently inflamed by the penetration of a bullet from a military rifle, but never exploded, Wet guncotton is not easily ignited, burns up quietly in the open air, is not sensitive to friction; but if fired by a strongly charged percussion-cap it will explode with great violence. It does not deteriorate when wet and is then perfectly safe to handle. It is therefore stored in a wet state (as it cannot be exploded except by the detonation of other disks of dry guncotton); but it should not be exposed to a temperature that will freeze the water in the cakes, if possible. While frost has no effect on dry guncotton, it causes a mechanical disintegration of the wet compressed variety. In the field the slabs are carried wet; the disks dry and packed in hermetically sealed tins. These disks are used as primers, and have attached to them, when used, a fulminate fuze. To Fire Guncotton, the fuze is cut to the required length and inserted in the hollow end of the detonator, especial care being taken to push it down so as to rest on the quick-match; the tube is then slightly bent to prevent the fuze from being withdrawn. The small end of the detonator is then gently inserted into the primer (the dry disk) so as to fill the entire length of the hole in the latter. If it is loose, a piece of paper or grass must be wrapped round to make it fit tight. The primer must be placed in close contact with the charge to be fired. Care must be taken that no sparks from the fuze can fall on the charge, which might then burn instead of exploding. Bear in mind that a moist primer is certain to cause failure. The charge should be in close contact with the object to be demolished. Transportation.—The handling of high explosives should be done under the immediate supervision of persons thor On a steamer place the explosives in a well-ventilated place remote from the engine. On railways, if the weather be hot, there should be good ventilation and ice in the car, so placed that water cannot reach the explosives. In winter protect from freezing if possible. Packing in straw or sawdust may be useful. Under no circumstances should cases of fuzes be in the same car, or in the vicinity of the explosive. The packages of guncotton should not be exposed to the sun—cover with paulins, put under shade-trees. Storage.—At military posts, in ordinary service magazines over which are erected light wooden roofs, so as to insure a draught during hot weather. The usual precautions against fire and for storage of ordinary powder must be taken; and neither fuzes, caps, nor detonators of any kind should ever be allowed in the magazine containing the explosives. Dry guncotton should not be stored in the same magazine with wet guncotton. Before being placed in the magazine the boxes should be given a coat of paint or shellac, to protect them from moisture. They should also be placed on skids and the space between the skids partially filled with sawdust, to absorb any exuding nitro-glycerine. If any powder should be spilled on the floor, or nitro-glycerine exude and be absorbed by the sawdust, it should be removed at once and When guncotton is received, pour into each package enough water to cover it, or otherwise immerse it. Let the water remain for 15 minutes; then pour it off and hermetically close the box. This should be done every three months. Packages of guncotton stained brown or yellow, giving off nitric fumes, or showing other signs of decomposition, should be removed and immersed in water. If decomposition be far advanced, they should be removed to a safe place and burned. WHERE AND HOW TO PLACE CHARGES.Masonry or Brick Arch.—Attack the haunches of the arch or the piers. In bridges of a single arch the haunches are the best points, two trenches being dug across the width of the roadway down to the back of the arch. When there is no time for this, the charge should be placed along the crown of the arch. With guncotton untamped use ¾T2 × B; if tamped with a depth of earth equal to the thickness of the arch, use ?T2 × B. With gunpowder, if over crown of arch, use 3/2T2 × B; if behind haunch, ?T2 × B. In the former case use tamping if possible equal to the thickness of the arch, and in the latter case equal to twice the thickness. The quantity of powder obtained by these rules should be divided into two or more charges placed across the arch. When the bridge consists of a series of arches, and the piers are short and thick, the haunches should be attacked by the rules given in table on next page. If the piers be high and thin, it is better to place the charges against them, as the fall of one pier will involve RULES FOR CALCULATING CHARGES FOR HASTY DEMOLITIONS BY GUNCOTTON OR GUNPOWDER.Charges are in lbs.; B and T are in feet; t is in inches. B is length of breach to be made; T or t is thickness of object to be demolished. Gunpowder is assumed to be roughly tamped with sand-bags, guncotton untamped. If the guncotton is tamped, the charges may be reduced one half. Charges of guncotton must be equal in length to the breach which is to be made.
In the presence of an enemy increase above charges 50% to allow for contingencies. House with Moderately Thick Walls.—Attack portions of walls between the windows, the charges being tamped, and inside the house if possible. Otherwise place outside, or one or two large charges inside untamped. To demolish a building, a sufficient height of wall must be brought down to insure the arches over the doors and windows falling. The length of breach must be equal to this height. With very thick walls cut grooves. To Cut Down Trees.—Place charge in an auger-hole bored horizontally into the tree at desired height. If tree be 1½ to 2 feet in diameter, use two holes. With a little care they can be bored so as to meet in the centre, in which case one detonator will suffice to fire the charge; with plenty of detonators it may be better to fire one hole first and then a second hole in the uninjured part of the tree, and so on. The tree may be made to fall in any required direction by attaching a rope to the upper branches, and taking the strain on it before firing. The guncotton may be hung around the tree, but this often fails with trees over 12 inches in diameter. A hole may be dug under the roots. Dig down by the side of the tree and then horizontally under the bottom close to the wood, the hole being just large enough for the cartridge. The rules for felling trees apply to timbers of wooden bridges, the uprights of the piers being the best point to attack. To Blow Down a Stockade 12" × 12".—Use 3 lbs. of guncotton per running foot. The slabs should be threaded together, so as to be in contact, and hung or laid against the timbers at the required level. If gunpowder be used, a charge of 80 lbs. should be To Demolish a Gate.—Fifty pounds of guncotton hung against the gate by a nail or pickaxe or laid on the ground will suffice. The charge of gunpowder should be 200 lbs., covered with sand-bags if possible. Destruction of Iron Bridges.—Place charge on lower girders near an abutment, and at a point where the thickness of the plates is least. If sections are uniform throughout the length of the bridge, place charge at centre of a span between two piers. When the bridge plate is entirely of iron, place charge on top of beams. Destruction of Railroad Tracks.—To destroy heavy iron rails, a charge of six 2-ounce disks (including primer) should be used. To Destroy a Tunnel.—The crown of the arch or the side-walls should be attacked. The points selected should be some distance inside the tunnel. To Destroy Field-and Siege-guns.—Detonate 1½ lbs. of guncotton on the outside near the muzzle. In heavier wrought-iron guns detonate 4 lbs. in the bottom of the bore, tamping with sand. Heavy cast-iron guns can be burst by firing 1 lb. of guncotton in the same position and tamping with sand. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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