A Military Dictionary and Gazetteer. Thomas Wilhelm
with hydrogen. It may be sulphur or any substance having a great affinity for oxygen. Organic substances containing carbon and hydrogen are frequently used. In the chemical reaction the carbon is oxidized to carbonic acid and the hydrogen to water with the evolution of great heat.
The oxidizing substances ordinarily used are the nitrates and chlorates. Mixtures containing nitrates are the most stable, since the nitrate is comparatively slow to give up its oxygen. The chlorate mixtures are sensitive to friction and percussion, and explode with great quickness. Many of them are unsafe to handle. A new mode of preparing chlorate mixtures has been suggested which avoids this danger. A combustible liquid is used, being absorbed in cakes or lumps of potassium or other chlorate.
Detonating explosives are chemical compounds. Among them are chloride and iodide of nitrogen. Both are dangerous, violent explosives of which no practical use has been made.
The fulminates are salts of fulminic acid. The fulminate of mercury is the one in common use. See Fulminates.
The nitro-substitution compounds form a large class, comprising the most important of the higher explosives. They are all formed by the action of nitric acid on organic substances containing oxygen, carbon, and hydrogen. This action is to replace hydrogen (H) in the organic substance by hyponitric acid (NO2) (in the acid), equivalent for equivalent. Sulphuric acid is generally mixed with the nitric, though it plays no direct part in the reaction, being used to absorb the water formed and prevent the dilution of the nitric acid.
Nitro-glycerine, the most powerful explosive in common use, is formed by the action of the acids on glycerine. See Nitro-glycerine.
Nitro-starch and nitro-mannite are analogous substances, formed by the action of the acids on starch and sugar.
Gun-cotton is produced by the action of the acids on cotton-wool—a form of cellulose. See Gun-cotton.
There are varieties of all these compounds produced, by the substitution of different numbers of equivalents of hyponitric acid, but the names are specially given to the most highly nitrated forms.
Picric acid, the salts of which form the well-known picrates, is made by the action of the acids on carbolic acid.
To heighten the effect of the lower forms of nitro-substitution compounds they are usually mixed with an oxidizing agent, such as nitrate or chlorate, which supplies the deficient oxygen. This is exemplified in Schultz’s wood powder (which see), and Reeve’s gun felt.
The picrates are similarly treated. Ammonium picrate mixed with nitre forms Abel’s picric powder (Burgess’s powder). This has been used as a bursting charge for shells.
Mixtures of two high explosives have also been used, as in glyoxiline, invented by Prof. Abel, which is gun-cotton saturated with nitro-glycerine.
Explosive effect depends upon three elements—1st, the volume of the gases produced taken at a standard temperature; 2d, the heat evolved in the chemical reaction; 3d, the time consumed in the development of the gases. Explosive effect is directly proportional to the first two of these elements, and inversely proportional to the third. According to Bertholet, nitro-glycerine gives out twice as much heat and three and a half times as much gas as an equal weight of gunpowder, but this gives no idea of their relative explosive effects, as the element of time in the detonating explosives is so short that it cannot be calculated. So nearly is this element absent that we may consider these explosions as almost perfect Impulsive Forces. To secure ballistic effect requires the gradual application of force. When motion is imparted to a body the inertia developed is inversely proportional to the time consumed in imparting it. This resistance to motion becomes enormously great when the detonating explosives are used. For this reason their ballistic effect is small. The force which should give the projectile motion is expended in producing molecular changes in both projectile and gun. The same quality, however, fits them especially for blasting and torpedoes, where shattering effect is desirable.
Express Rifle. A modern sporting rifle of great killing power, used in hunting large or dangerous animals. They were first introduced in England, and have become celebrated in the hands of African travelers and explorers. The principle consists in using large charges of powder and a light bullet, which gives a very high initial velocity and a trajectory practically a right line for 150 or 200 yards, hence the term “Express.” To increase the killing power of the bullet it is made of pure lead and has a hollow point. Upon striking game the bullet spreads outwardly, giving a fearful death-wound. Moreover, for specially ugly game a small explosive cartridge can be dropped into the cavity in the point, making it an explosive bullet. (See Bullets, Express.) In England a caliber as large as .57 is used for some Express rifles. In the United States a caliber of .45 or .50 is considered sufficient.
Expugn. To conquer; to take by assault.
Expugnable. Capable of being expugned, forced or conquered.
Expugnation. The act of taking by assault; conquest.
Expugner. One who expugns or conquers.
Extend. A term peculiarly applicable to light infantry movements, when the files are frequently loosened, and the front of the line extended for the purpose of skirmishing. When the divisions of a column are made to occupy a greater space of ground, they are said to extend their front.
Exterior Crest. The crest of the exterior slope of a parapet.
Exterior Form of Cannon. See Ordnance, Exterior Form.
Exterior Side. In fortification, is the side of the polygon, upon which a front of fortification is formed.
Exterior Slope. In fortification, is the slope given to the outside of a parapet. It is found by experience that earth of common quality will naturally acquire a slope of 45°, even when battered by cannon. This inclination is therefore given to the slope.
External Injuries to Cannon. See Injuries to Cannon.
Extortion. Under the modern laws of war, honorable men no longer permit the use of any violence against prisoners in order to extort information or to punish them for having given false information.
Extrados (Fr.). The exterior surface of a regular arch, used in the construction of powder-magazines.
Extraordinaries of the Army. In the English service, the allowances to troops beyond the gross pay in the pay office, come under this head. Such are the expenses for barracks, marches, encampments, staff, etc.
Extraordinarii. In the ancient Roman army, a select body of men consisting of the third part of the foreign cavalry and a fifth of the infantry. These were carefully separated from the other forces borrowed from the confederate states, in order to prevent any treacherous coalition between them. From among the extraordinarii a more choice body of men were drawn, under the name of ablecti. See Ablecti.
Eylau, or Eilau. Usually called Prussian Eylau, a town in the government of Königsberg, celebrated for the battle fought here between Napoleon and the allies—Russians and Prussians—under Bennigsen, February 8, 1807. The French force amounted to about 80,000, and the allies numbered 58,000, but were superior in artillery. The French claimed the victory, chiefly because the allied forces, unable to recruit their strength, were ordered to retreat from the field on the night of the battle, and to retire upon Königsberg. The loss of the allies is estimated at about 20,000, while that of the French must have been considerably greater.
F.