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Gunpowder

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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.

Historians of gunpowder, such as Joseph Needham, sometimes use the word gunpowder to refer not only to the explosive defined at the top of this article, but to previous concoctions of combustible material mixed with saltpetre. The definition of gunpowder used in this history is that given at the top of this article, namely, black powder or smokeless powder. Previous saltpetre explosives, including those made from the ancient Chinese recipes, which were less powerful than gunpowder, are here referred to as saltpetre explosives. Of course, gunpowder itself is also a saltpetre explosive.

Saltpetre explosives were the first known chemical explosives and propellants.[1] The facilitation of combustion by addition of saltpetre was discovered very early in China. An early record of saltpetre combustion comes from a Chinese Han era book "The Kinship of the Three" compiled in A.D. 142 by Wei Boyang, where he recorded experiments in which a set of ingredients were said to "fly and dance" in a violent reaction. By A.D. 300, Ge Hong, an alchemist of the Jin dynasty conclusively recorded the chemical reactions caused when saltpetre, redwood and charcoal were heated together in his book "Book of the Master of the Preservations of Solidarity".[2] Another early record of saltpetre mixtures, a Chinese book from c. 850 A.D. called "Classified Essentials of the Mysterious Tao of the True Origin of Things," indicates that saltpetre-aided combustion was an unintended byproduct of Taoist alchemical efforts to develop an elixir of immortality:[3]

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.[4]

The Chinese used saltpetre explosives in warfare in 904 A.D., as incendiary projectiles called "flying fires." (These were invented during the Tang Dynasty and were originally used for fireworks.) The use of saltpetre explosives was soon expanded to explosive grenades hurled from catapults. The third step was to use these mixtures as propellants. The 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.[5]

Saltpetre combustion techniques spread to the Arabs in the 13th century.[6]

There is no direct record of how gunpowder itself was invented, or how it came to be known in Europe and Asia. Most scholars believe that saltpetre explosives developed into an early form of gunpowder in China, and that this technology spread west from China to the Middle East and then Europe, possibly via the Silk Road.[7][8][9] 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.

The first written record of the composition of actual gunpowder, from anywhere in the world, was in Roger Bacon's "De nullitate magiæ" at Oxford in 1234.[10] 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 1200:

"a child’s toy of sound and fire made in various parts of the world with powder of saltpeter, sulphur and charcoal of hazelwood."[11]

The first Chinese recipe for true gunpowder given by Needham is from 1628, almost four hundred year's after Roger Bacon's book.[12] It comes from a book called the Wu Pei Chih, which lists all the gunpowder recipes from the 1606 Ping Lu, but includes exactly one new mixture, for "lead bullet gunpowder" (chhien chhung huo yao), composed of 40 oz. of saltpetre, 6 oz. of sluphur, and 6-8 oz. of charcoal. As Needham observes, "The explosive is used here as a charge of black powder."[13]

The process of "corning" black powder was a further important improvement, and was developed in Europe probably during the late 14th century.[14] 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 more powerful and faster ignition, since the spaces between the particles allowed for oxygen necessary for speedy combustion.

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. 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. It could also be mined from caves with high concentrations of potassium nitrate.

Characteristics and use

Gunpowder is not classified as a high 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 a gun barrel, and directs the energy to propelling the bullet.

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 granule 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, damage to a gun and its shooter due to overloading 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.

Additionally, the low brisance of black powder made it useful when blasting monumental stone such as granite and marble. Black powder caused fewer fractures when compared to other explosives, with the result that more of the quarried stone could be used. Gunpowder is used to make fireworks. They do this by mixing it with other chemical elements that produce color

Notes

  1. ^ Needham, Joseph (2004). Science and Civilisation in China. Cambridge University Press. p. 74. ISBN 0-521-08732-5.
  2. ^ Liang, Jieming (2006). Chinese Siege Warfare: Mechanical Artillery & Siege Weapons of Antiquity, pp. Appendix C VII
  3. ^ Kelly, Jack (2004). Gunpowder: Alchemy, Bombards, & Pyrotechnics: The History of the Explosive that Changed the World. Basic Books. p. 3. ISBN 0-465-03718-6.
  4. ^ Kelly 2004:4
  5. ^ Gernet, Jacques (1996). A History of Chinese Civilisation. Cambridge University Press. ISBN 0-521-49781-7.
  6. ^ Kelly 2004:22 'Around 1240 the Arabs acquired knowledge of saltpeter (“Chinese snow”) from the East, perhaps through India. They also learned about fireworks (“Chinese flowers”) and rockets (“Chinese arrows”).'
  7. ^ Brown, G. I. (1998). The Big Bang: A History of Explosives. Sutton Publishing. ISBN 0-7509-1878-0.
  8. ^ Gernet 1996
  9. ^ Kelly 2004
  10. ^ "Gunpowder". Encyclopedia Britannica. London. 1771. frier Bacon, our countryman, mentions the compofition in exprefs terms, in his treatife De nullitate magiæ, publifhed at Oxford, in the year 1216.
  11. ^ Kelly 2004:25
  12. ^ Needham, Joseph (2004). Science and Civilisation in China. Vol. 7. Cambridge University Press. p. 345. ISBN 0-521-08732-5.
  13. ^ Needham, Joseph (2004). Science and Civilisation in China. Vol. 7. Cambridge University Press. p. 345. ISBN 0-521-08732-5.
  14. ^ Kelly 2004:60–61

References

  • Ebrey, Patricia Buckley (1999). The Cambridge Illustrated History of China. Cambridge University Press. ISBN 0-521-66991-X.
  • Partington, James Riddick (1998). A History of Greek Fire and Gunpowder. The Johns Hopkins University Press. ISBN 0-8018-5954-9.
  • Liang, Jieming (2006). Chinese Siege Warfare: Mechanical Artillery & Siege Weapons of Antiquity. ISBN 981-05-5380-3.

See also

Look up gunpowder in Wiktionary, the free dictionary.

External links

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