~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ` ` ` CHiNA Explo-File #1 ` ` ` ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Introduction ------------ Well folks here is the first file in the explosive series from CHiNA. Written by the newest CHiNA member Mr. X If you have any questions, comments or you just wanna bitch - then please leave us a message on any of our nodes. PROPERTIES OF EXPLOSIVES ======================== Definition ---------- An explosive is a material, either a pure single substance or a mixture of substances, which is capable of producing an explosion by its own energy. It seems unnecessary to define an explosion, for everyone knows what it is - a loud noise and the sudden going away of things from the place where they have been. Sometimes it may only be the air in the neighborhood of the material or the gas from the explosion which goes away. Our simple definition makes mention of the one single attribute which all explosives possess. It will be necessary to add other ideas to it if we wish to describe the explosive properties of any particular substance. For example, it is not proper to define an explosive as a substance, or a mixture of substances, which is capable of undergoing a sudden transformation with the production of heat and gas. The production of heat alone by the inherent energy of the substance which produces it will be enough to constitute the substance an explosive. Cuprous acetylide explodes by decomposing into copper and carbon and heat, no gas whatsoever, but the sudden heat causes a sudden expansion of the air in the neighborhood, and the result is an unequivocal explosion. All explosive substances produce heat; nearly all of them produce gas. The change is invariably accompanied by the liberation of energy. The products of the explosion represent a lower energy level than did the explosive before it had produced the explosion. Explosives commonly require some some stimulus, like a blow or spark, to provoke them to liberate their energy, that is, to undergo the change which produces the explosion, but the stimulus which "sets off" the explosive does not contribute to the energy of the explosion. The various stimuli to which explosives respond and the manners of their responses in producing explosions provide a convenient basis for the classification of these interesting materials. Since we understand an explosive material to be one which is capable of producing and explosion by its own energy, we have opened the way to a consideration of diverse possibilities. An explosive perfectly capable of producing an explosion may liberate its energy without producing one. Black powder, for example, may burn in the open air. An explosion may occur without an explosive, that is, without any material which contains intrinsically the energy needed to produce the explosion. A steam boiler may explode because of the heat energy which has been put into the water which it contains. But the energy is not intrinsic to water, and water is not an explosive. Also, we have explosives which do not themselves explode. The explosions consist in the sudden ruptures of the containers which confine them, as happens in a Chinese firecracker. Fire, traveling along the fuse (note the spelling) reaches the black powder - mixture of potassium nitrate, sulfur, and charcoal - which is wrapped tightly within many layers of paper; the powder burns rapidly and produces gas. It burns very rapidly, for the heat, resulting from the burning of the first portion cannot get away, but raises the temperature of the next portion of powder, and a rise of temperature of 10 degrees C. more than doubles the velocity of a chemical reaction. The temperature mounts rapidly; gas is produced suddenly; an explosion ensues. The powder burns; the cracker explodes. And in still other cases we have materials which make themselves explode. The molecules undergo such a sudden transformation with the liberation of heat, or of heat and gas, that the effect is an explosion. Classification Of Explosives ---------------------------- I. Propellants - or low explosives are combustible materials, containing within themselves all oxygen needful for their combustion, which burn but do not explode, and function by producing gas which produces an explosion. Examples: black powder, smokeless powder. Explosives of this class differ widely among themselves in the rate at which they deliver their energy. There are slow powders and fast powders for different uses. The kick of a shotgun is quite different from the persistent push against the shoulder of a high- powered military rifle in which a slower-burning and more powerful powder is used. II. Primary Explosives - or initiators explode or detonate when they are heated or subjected to shock. They do not burn; sometimes they do not even contain the elements necessary for combustion. The materials themselves explode, and the explosion results whether they are confined or not. They differ considerably in their sensitivity to heat, in the amount of heat which they give off, and in their brisance, that is, in the shock which they produce when they explode. Not all of them are brisant enough to initiate the explosion of a high explosive. Examples: mercury fulminate, lead azide, the lead salts of picric acid and trinitroresorcinol, m-nitrophenyldiazonium perchlorate, tetracene, nitrogen sulfide, copper acetylide, fulminating gold, nitrosoguanidine, mixtures of potassium chlorate with red phosphorus or with various other substances, the tartarates and oxalates of mercury and silver. III. High Explosives - detonate under the influence of the shock of the explosion of a suitable primary explosive. The do not function by burning; in fact, not all of them are combustible, but most of them can be ignited by a flame and in small amount generally burn tranquilly and can be extinguished easily. If heated to a high temperature by external heat or by their own combustion, they sometimes explode. They differ from primary explosives in not being readily by heat or by shock, and generally in being more brisant and powerful. They exert a mechanical effect upon whatever is near them when they explode, whether they are confined or not. Examples: dynamite, trinitrotoluene, tetryl, picric acid, nitrocellulose, nitroglycerin, liquid oxygen mixed with wood pulp, fuming nitric acid mixed with nitrobenzene, compressed acetylene and cyanogen, ammonium nitrate and perchlorate, nitroguanidine. It is evident that we cannot describe a substance by saying that it is "very explosive". We must specify whether it is sensitive to fire and to shock, whether it is really powerful or merely brisant, or both, whether it is fast or slow. Likewise in further topics, we must distinguish carefully between sensitivity, stability, and reactivity. A substance may be extremely reactive chemically but perfectly stable in the absence of anything with which it might react. A substance may be exploded readily by a slight shock, but it may be stable if left to itself. Another may require the shock of a powerful detonator to make it explode but may be subject to spontaneous decomposition. The three classes of explosive materials overlap somewhat, for the behavior of a number of them is determined by the nature of the stimuli to which they are subjected and by the manner in which they are used. Black powder has probably never been known, even in the hideous explosions which have sometimes occurred at black powder mills, to do anything but burn. Smokeless powder which is made from colloided nitrocellulose, especially if it exists in a state of fine subdivision, is a vigorous high explosive and may detonate by means of a sufficiently powerful initiator. In the gun it is lighted by a flame and functions as a propellant. Nitroglycerin, trinitrotoluene, nitroguanidine, and other high explosives are used in admixture with nitrocellulose in smokeless powders. Fulminate of mercury if compressed very strongly becomes "dead pressed" and loses its power to detonate from flame, but retains its power to burn, and will detonate from the shock of the explosion of less highly compressed mercury fulminate. Lead azide, however, always explodes from shock, from fire, and from friction. Some of the properties characteristic of explosives may be demonstrated safely by experiment. A sample of commercial black powder of moderately fine granulation say FFF, may be poured out in a narrow train, 6 inches or a foot long, on a sheet of asbestos paper or a wooden board. When one end of the train is ignited, the whole of it appears to burn at one time, for the flame travels along it faster than the eye can follow. Commercial black powder is an extremely intimate mixture; the rate of its burning is evidence of the effect of intimacy of contact upon the rate of a chemical reaction. The same materials mixed together as intimately as it is possible to mix them in the laboratory, will burn much more slowly. Six parts by weight of potassium nitrate, one of sulfur (roll brimstone), and one of soft wood (willow) charcoal are powdered separately and passed through a silk bolting-cloth. They are then mixed, ground together in a mortar, and again passed through the cloth; and this process is repeated. The resulting mixture, made into a train, burns fairly rapidly but by no means in a single flash. The experiment is most convincing if a train of commercial black powder leads into a train of this laboratory powder, and the black powder is ignited by means of a piece of 'black match' leading from one end of the train and extending beyond the edge of the surface on which the powder is placed. The black match may be ignited easily by a flame, whereas black powder on a flat surface is often surprisingly difficult to light. Black match may be made conveniently by twisting three or four strands of fine soft cotton twine together, impregnating the resulting cord with a paste made by moistening meal powder (Corning mill dust, the most finely divided and intimately incorporated black powder which it is possible to procure. Lacking this, black sporting powder may be ground up in small portions at a time in a porcelain mortar.) with water, wiping off the excess of the paste, and drying while the cord is stretched over a frame. A slower-burning black match may be made from the laboratory powder described above, and is satisfactory for experiments with explosives. The effect of temperature on the rate of a chemical reaction may be demonstrated strikingly by introducing a 12-inch length of black match into a 10-inch glass or paper tube (which need not fit tightly); when the match is ignited, it burns in the open air at a moderate rate, but, as soon as the fire reaches the point where the tube prevents the escape of heat, the flame darts through the tube almost instantaneously, and the gases generally shoot the burning match out of the tube. Cuprous acetylide of which only a small quantity may be prepared safely at one time, is procured by bubbling acetylene into an ammoniacal solution of cuprous chloride. It precipitates as a brick-red powder. The powder is collected on a small filter paper and washed with water. About 0.1 gram of the material, still moist, is transferred to a small iron crucible - the rest being destroyed by dissolving in dilute nitric acid - and the crucible is placed on a triangle over a small flame. As soon as the material has dried out, it explodes, with a loud report, causing a dent in the bottom of the crucible. A 4-inch filter paper is folded as if for filtration, about a gram of FFF black powder is introduced, a 3-inch piece of black match is inserted, and the paper is twisted in such a manner as to hold the powder together in one place in contact with one end of the match. The black match is lighted and the package is dropped, conveniently, into an empty pail. The powder burns with a hissing sound, but there is no explosion for the powder was not really confined. The same experiment with about 1 gram of potassium picrate gives a loud explosion. All metallic picrates are primary explosives, those of the alkali metals being the least violent. Potassium picrate may be prepared by dissolving potassium carbonate in a convenient amount of water, warming almost to boiling, adding picric acid in small portions at a time as long as it dissolves with effervescence, cooling the solution, and collecting the crystals and drying them by exposing to air. For safety's sake, quantities of more than a few grams ought to be kept under water, in which the substance is only slightly soluble at normal temperatures. About a gram of trinitrotoluene or of picric acid is heated in a porcelain crucible. The substance first melts and gives off combustible vapors which burn when a flame is applied but go out when the flame is removed. A small quantity of trinitrotoluene, say 0.1 gram, may actually be sublimed if heated cautiously in a test tube. If heated quickly and strongly, it decomposes or explodes mildly with a "zishing" sound and with the liberation of soot. One gram of powdered picric acid and as much by volume of litharge (PbO) are mixed carefully on a piece of paper by turning the powders over upon themselves (not by stirring). The mixture is then poured in a small heap in the center of a clean iron sand-bath dish. This is set upon a tripod, a lighted burner is placed beneath it, and the operator retires to a distance. As soon as the picric acid melts, the material explodes with an astonishing report. The dish is badly dented or possibly punctured. A Complete Round Of Ammunition ------------------------------ The manner in which explosives of all three classes are brought into use will be made clearer by a consideration of the things which happen when a round of H.E. (high-explosive) ammunition is fired. O OOOOOOOOOOOOOOOOOOOOOOOOOOOOO O xx wwwwwwwwwwwwwwwwwwwwww OOODD O xx wwwwwwwwwwwwwwwwwwwwwww GGGGGGGGGGGGGGGGGGGGGGGGGGGGG O xx wwwwwwwwwwwwwwwwwwwwwwww yyyyyyyyyyyyyyyyyyyyyyyyyyyGG O xx wwwwwwwwwwwwwwwwwwwwwwww yyyyyyyyyyyyyyyyyyyyyyyyyyyyyRR = xx wwwwwwwwwwwwwwwwwwwwwwww yyyyyyyyyyyyyyyyyyyyyysssssdpRRF O xx wwwwwwwwwwwwwwwwwwwwwwww yyyyyyyyyyyyyyyyyyyyyyyyyyyyyRR O xx wwwwwwwwwwwwwwwwwwwwwwww yyyyyyyyyyyyyyyyyyyyyyyyyyyGG O xx wwwwwwwwwwwwwwwwwwwwwww GGGGGGGGGGGGGGGGGGGGGGGGGGGGG O xx wwwwwwwwwwwwwwwwwwwwww OOODD OOOOOOOOOOOOOOOOOOOOOOOOOOOOOO O Legend: O - Brass Casing D - Driving Band d - Detonator = - Primer G - Steel Shell p - Black Powder x - Igniter y - Bursting Charge R - Time-Train Rings w - Propelling Charge s - Booster F - Fuze The brass cartridge case, the steel case with its copper driving band and the fuze screwed into its nose are represented diagramatically above. Note the spelling of fuze: a fuze is a device for initiating the explosion of high- explosive shells or of bombs, shrapnel, mines, grenades, etc.; a fuse is a device for communicating fire. In cases where the shell is expected to penetrate armor plate or other obstruction, and not to explode until after it has penetrated its target, the nose of the shell is pointed and of solid steel, and the fuze is screwed into the base of the shell - a base-detonating fuze. The fuze which we here wish to discuss is a point combination fuze, point because it is at the nose of the shell, and combination because it is designed to explode the shell either after a definite interval of flight or immediately on impact with the target. The impact of the firing pin or trigger upon the primer cap in the base of the cartridge case produces fire, a quick small spurt of flame which sets fire to the black powder which is also within the primer. This sets fire to the power, or in the case of bagged charges, to the igniter - and this produces a a large hot flame which sweeps out into the chamber of the gun or cartridge, sweeps around the grains of smokeless powder, and sets fire to them all over their surface. In a typical case the primer cap contains a mixture of mercury fulminate with antimony sulfide and potassium chlorate. The fulminate explodes when the mixture is crushed; it produces fire, and the other ingredients of the composition maintain the fire for a short interval. The igniter bag in our diagram is a silk bag containing black powder which takes fire readily and burns rapidly. The igniter and the bag containing the smokeless powder are made from silk because silk either burns or goes out - and leaves no smoldering residue in the barrel of the gun after the shot has been fired. For different guns and among different nations the igniters are designed in a variety of ways, many of which are described in the books which deal with guns, gunnery, and ammunition. Sometimes the igniter powder is contained in an integral part of the cartridge case. For small arms, no igniter is needed; the primer ignites the propellant. For large guns, no cartridge case is used, the projectile and the propelling charge are loaded from the breech, the igniter bag being sewed or tied to the base end of the bag which contains the powder, and the primer being fitted in a hole in the breech-block by which the gun is closed. Written by : Mr. X Sysop of The Forbidden Passage (713) 774-0449 1200/2400 Here goes.. A big hello to Software Surgeon, Barimor, The Maestro, Monalisa Overdrive The Viper, The Conflict, Montresor and all the boys in 408. Also if you don't already know.. the new number for The Celestial Woodlands is 817-754-2999 Same wonderful Celestial Treeman!