   #copyright

Gunpowder

2007 Schools Wikipedia Selection. Related subjects: General Chemistry

   Smokeless powder
   Enlarge
   Smokeless powder

   Gunpowder, whether black powder or smokeless powder, is a substance
   that burns very rapidly, releasing gases that act as a propellant in
   firearms. Both forms of gunpowder are low explosives. As it burns, a
   subsonic deflagration wave is produced rather than the supersonic
   detonation wave which high explosives produce. As a result, pressures
   generated inside a gun are sufficient to propel a bullet, but not
   sufficient to destroy the barrel. At the same time, this makes
   gunpowder less suitable for shattering rock or fortifications,
   applications where high explosives are preferred.

History and origins

   A Mongol bomb thrown against a charging Japanese samurai during the
   Mongol Invasions of Japan, 1281.
   Enlarge
   A Mongol bomb thrown against a charging Japanese samurai during the
   Mongol Invasions of Japan, 1281.

   Gunpowder was invented in China and is considered one of the Four great
   inventions of ancient China.

   Gunpowder was the first known chemical explosive and propellant. The
   earliest record of gunpowder, a Chinese book from c. 850 AD called
   "Classified Essentials of the Mysterious Tao of the True Origin of
   Things," indicates that gunpowder was a byproduct of Taoist alchemical
   efforts to develop an elixir of immortality:

     Some have heated together sulfur, realgar and saltpeter with honey;
     smoke and flames result, so that their hands and faces have been
     burnt, and even the whole house where they were working burned down.

   The Chinese first used gunpowder in warfare in 904, as incendiary
   projectiles called "flying fires." Its use was soon expanded to
   explosive grenades hurled from catapults. The third step was to use
   gunpowder as a propellant. Its first such use was recorded in 1132 in
   experiments with mortars consisting of bamboo tubes. Mortars with metal
   tubes (made of iron or bronze) first appeared in the wars (1268-1279)
   between the Mongols and the Song Dynasty.

   Gunpowder spread to the Arabs in the 13th century.

   There is no direct record of how gunpowder came to be known in Europe.
   Most scholars believe that the knowledge spread west from China to the
   Middle East and then Europe, possibly via the Silk Road. Other
   historians believe that gunpowder was probably discovered independently
   by different cultures at different times, as James Partington writes in
   his History of Greek Fire and Gunpowder:

     Gunpowder is not, of course, an 'invention' in the modern sense, the
     product of a single time and place; no individual's name can be
     attached to it, nor can that of any single nation or region. Fire is
     one of the primordial forces of nature, and incendiary weapons have
     had a place in armies' toolkits for almost as long as civilized
     states have made war.

   In Europe, the first written mention of the composition of gunpowder in
   express terms was in Roger Bacon's "De nullitate magiæ" at Oxford in
   1216. In Bacon's "De Secretis Operibus Artis et Naturae" in 1248, he
   states: "We can, with saltpeter and other substances, compose
   artificially a fire that can be launched over long distances... By only
   using a very small quantity of this material much light can be created
   accompanied by a horrible fracas. It is possible with it to destroy a
   town or an army ... In order to produce this artificial lightning and
   thunder it is necessary to take saltpeter, sulfur, and Luru Vopo Vir
   Can Utriet." The last part is probably some sort of coded anagram for
   the quantities needed. In the "Opus Maior" he describes firecrackers
   around 1267: "a child’s toy of sound and fire made in various parts of
   the world with powder of saltpeter, sulphur and charcoal of hazelwood."
   The confusion of these two references have led to many widespread
   misunderstandings about Bacon and Gunpowder.

   The process of "corning" black powder was a further important
   improvement, and was developed in Europe probably during the late 14th
   century. Corning involves forcing damp powder through a sieve to form
   it into granules which harden when dry, preventing the component
   ingredients of gunpowder from separating over time, thus making it far
   more reliable and consistent. It also allowed for better ignition, as
   the granules allowed for air pockets in between granules.

Composition

   Black powder is a mixture of saltpeter (potassium nitrate or, less
   frequently, sodium nitrate), charcoal and sulfur with a ratio (by
   weight) of approximately 15:3:2 respectively. The ratio has changed
   over the centuries of its use, and can be altered somewhat depending on
   the purpose of the powder.

Characteristics and use

   Unlike smokeless propellants, it acts more like an explosive since its
   burn rate is not affected by pressure, but it is a very poor explosive
   because it has a very slow decomposition rate and therefore a very low
   brisance. This same property that makes it a poor explosive makes it
   useful as a propellant — the lack of brisance keeps the black powder
   from shattering the barrel, and directs the energy to propelling the
   bullet. Historically, potassium nitrate was extracted from manure by a
   process superficially similar to composting. " Nitre beds" took about a
   year to produce crystallized potassium nitrate. The main disadvantages
   of black powder are a relatively low energy density (compared to modern
   smokeless powders) and the extremely large quantities of soot left
   behind. During the combustion process, less than half of black powder
   is converted to gas. The rest ends up as a thick layer of soot inside
   the barrel and a dense cloud of white smoke. In addition to being a
   nuisance, the residue in the barrel is hydrophilic and an anhydrous
   caustic substance. When moisture from the air is absorbed, the
   potassium oxide or sodium oxide turn into hydroxides, which will
   corrode wrought iron or steel gun barrels. Black powder arms must be
   well cleaned inside and out after firing to remove the residue. The
   thick smoke of black powder is also a tactical disadvantage, as it can
   quickly become so opaque as to impair aiming.

   The size of the granules of powder and the confinement determine the
   burn rate of black powder. Finer grains result in greater surface area,
   which results in a faster burn. Tight confinement in the barrel causes
   a column of black powder to explode, which is the desired result. Not
   seating the bullet firmly against the powder column can result in a
   harmonic shockwave, which can create a dangerous over-pressure
   condition and damage the gun barrel. One of the advantages of black
   powder is that precise loading of the charge is not as vital as with
   smokeless powder firearms and is carried out using volumetric measures
   rather than precise weight. However, overloading causing damage to a
   gun and its shooter is still possible. The lack of pressure sensitivity
   means that the mass of the bullet makes little or no difference to the
   amount of powder used. A full charge of black powder seated by just a
   small wad of paper, with no bullet, will still burn just as quickly as
   if it had a full weight bullet in front of it. This makes black powder
   well suited for blank rounds, signal flares, and rescue line launches.
   Retrieved from " http://en.wikipedia.org/wiki/Gunpowder"
   This reference article is mainly selected from the English Wikipedia
   with only minor checks and changes (see www.wikipedia.org for details
   of authors and sources) and is available under the GNU Free
   Documentation License. See also our Disclaimer.
