Smokeless powder
'Gunpowder' is a
pyrotechnic composition, an explosive mixture that burns rapidly, producing volumes of hot gas which can be used as a
propellant in
firearms and
fireworks.
Because of its slow decomposition rate and consequently low
brisance, gunpowder is classified as a
low explosive, that is, it produces a subsonic
deflagration wave rather than the supersonic
detonation wave produced by brisants, or
high explosives. The gases produced by burning gunpowder generate enough pressure to propel a bullet, but not enough to destroy the
barrel of a firearm. This makes gunpowder less suitable for shattering rock or fortifications, applications where high explosives such as
TNT are preferred.
Black powder
The term "black powder" was coined in the late
19th century to distinguish prior gunpowder formulations from the new
smokeless powders.
Black powder is a granular mixture of
★ a
nitrate—typically
saltpetre (KNO
3)—which supplies the reaction with oxygen
★
charcoal, which provides fuel for the reaction in the form of carbon (C)
★
sulfur (S), which is also a fuel, lowers the temperature of ignition and helps increase the speed of combustion
Saltpetre is the most important ingredient in terms of both bulk and function because the oxygen released by the combustion of saltpetre promotes the rapid burning of the other ingredients.
[Buchanan. "Editor's Introduction: Setting the Context", in .] To reduce the likelihood of accidental ignition by
static electricity, the granules of modern black powder are typically coated with
graphite, which prevents the build-up of electrostatic charge.
The current standard for black powder manufactured by
pyrotechnicians today is 75% potassium nitrate, 15% softwood charcoal and 10% sulfur; it appears to have been adopted as far back as 1780.
These ratios have varied over the centuries and can be altered somewhat depending on the purpose of the powder.
The burn rate of black powder can be changed by corning. Corning is a process which first compresses the fine black powder meal into blocks with a fixed density (1.7 g/cm³). The blocks are then broken up into granules. These granules are then sorted by size to give the various grades of black powder. In the
USA, standard grades of black powder run from the coarse Fg grade used in large bore rifles and small cannon though FFg (medium and smallbore rifles), FFFg (pistols), and FFFFg (smallbore, short pistols and priming
flintlocks). In the
United Kingdom, the gunpowder grains are categorised by mesh size: the BSS
sieve mesh size, being the largest mesh size on which no grains were retained. Recognised grain sizes are Gunpowder: 'G 7', 'G 20', 'G 40' and 'G 90'.
A simple, commonly cited,
chemical equation for the combustion of black powder is:
:2
KNO3 +
S + 3
C →
K2S +
N2 + 3
CO2
A more accurate, but still simplified, equation is:
[1]
:10
KNO3 + 3
S + 8
C → 2
K2CO3 + 3
K2SO4 + 6
CO2 + 5
N2
The products of burning do not follow any simple equation. One study's results showed it produced (in order of descending quantities): 55.91% solid products: potassium carbonate, potassium sulfate, potassium sulfide, sulfur, potassium nitrate, potassium thiocyanate, carbon, ammonium carbonate. 42.98% gaseous products: carbon dioxide, nitrogen, carbon monoxide, hydrogen sulfide, hydrogen, methane, 1.11% water. However, those products that contain hydrogen are probably contamination, due to the fact that none of reactants contain ''any'' hydrogen.
Black powder formulations where the nitrate used is sodium nitrate tend to be
hygroscopic, unlike black powders where the nitrate used is saltpetre. Because of this, black powder which uses saltpetre can be stored unsealed and remain viable for centuries provided no liquid
water is ever introduced;
muzzleloaders have been known to fire after hanging on a wall for decades in a loaded state, provided they remained dry. By contrast, powder which uses sodium nitrate, which is typically intended for blasting, must be sealed from moisture in the air to remain stable for long periods of time.
;Advantages of black powder
Smokeless powder requires precise loading of the charge to prevent damage due to overloading. With black powder, though such damage is still possible, loading can generally be carried out using volumetric measures rather than precise weight.
Generally, high explosives are preferred for shattering rock; however, because of its low
brisance, black powder causes fewer fractures and results in more usable stone compared to other explosives, making black powder useful for blasting monumental stone such as
granite and
marble.
Black powder is well suited for
blank rounds,
signal flares,
burst charges, and rescue-line launches.
Gunpowder can be used to make
fireworks by mixing with chemical compounds that produce the desired color.
;Disadvantages of black powder
Black powder has relatively low
energy density compared to modern smokeless powders and produces a thick
smoke that can impair aiming or reveal a shooter's position.
Combustion converts less than half the mass of black powder to gas; the rest ends up as a thick layer of
soot inside the barrel. In addition to being a nuisance, the residue from burnt black powder is
hygroscopic and an anhydrous
caustic substance. When moisture from the air is absorbed, the
potassium oxide or
sodium oxide turns into
hydroxide, which will corrode
wrought iron or
steel gun barrels. Black powder arms must be well cleaned both inside and out to remove the residue.
The
United States Department of Transportation has classified black powder as a "Class A High Explosive" for shipment because it ignites so easily, even though it is not a
high explosive at all. Complete manufactured devices containing black powder are usually classified as "Class C Firework", "Class C Model Rocket Engine", etc. for shipment because they are harder to ignite than loose powder.
Sulfur-free gunpowder
The development of
smokeless powders, such as
Cordite, in the late 19th century created the need for a spark-sensitive
priming charge, such as gunpowder. However, the sulfur content of traditional gunpowders caused
corrosion problems with Cordite Mk I and this led to the introduction of a range of sulfur-free gunpowders, of varying grain sizes.
They typically contain 70.5 parts of saltpetre and 29.5 parts of charcoal.
[ Like black powder, they were produced in different grain sizes. In United Kingdom, the finest grain was known as 'sulfur-free mealed powder' ('SMP'). Coarser grains were numbered as sulfur-free gunpowder (SFG n): 'SFG 12', 'SFG 20', 'SFG 40' and 'SFG 90', for example, where the number was a BSS sieve mesh size, being the largest mesh size on which no grains were retained.]
History
Main articles: History of gunpowder
Most sources credit the discovery of gunpowder to China alchemists in the 9th century searching for an elixir of immortality.[2] The discovery of gunpowder was probably the product of centuries of alchemical experimentation.[ Saltpetre was known to the Chinese by the mid-1st century AD and there is strong evidence of the use of saltpetre and sulfur in various largely medicine combinations.[3] A Chinese alchemical text from 492 noted that saltpeter gave off a purple flame when ignited, providing for the first time a practical and reliable means of distinguishing it from other inorganic salts, making it possible to evaluate and compare purification techniques.]
The first reference to gunpowder is probably a passage in the ''Zhenyuan miaodao yaolüe'', a Taoism text tentatively dated to the mid-800s:
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 earliest surviving recipes for gunpowder can be found in the Chinese military treatise ''Wujing zongyao''[ of 1044 AD, which contains three: two for use in incendiary bombs to be thrown by siege engines and one intended as fuel for poison smoke bombs.[4] The formulas in the ''Wujing zongyao'' range from 27 to 50 percent nitrate.[6] Experimenting with different levels of saltpetre content eventually produced bombs, grenades, and mines, in addition to giving fire-arrows a new lease on life.][ By the end of the 12th century, there were cast iron grenades filled with gunpowder formulations capable of bursting through their metal containers.[7] The 14th century ''Huolongjing'' contains gunpowder recipes with nitrate levels ranging from 12 to 91 percent, six of which approach the theoretical composition for maximal explosive force.]
In China, the 13th century saw the beginnings of rocketry[4][4] and the manufacture of the oldest gun still in existence,[[4] a descendant of the earlier fire-lance, a gunpowder-fueled flamethrower that could shoot shrapnel along with fire.]
In the 13th century contemporary documentation shows gunpowder beginning to spread from China to the rest of the world, starting with Europe[ argues—''contra'' the general notion that Arabic alchemy and chemistry did not know of saltpetre until the thirteenth century—that Arabs were purifying saltpetre by the eleventh.[12] Gunpowder arrived in India by the mid-1300s, but could have been introduced by the Mongols perhaps as early as the mid-1200s.]
The earliest extant written references to gunpowder in Europe are from the works of Roger Bacon. In Bacon's ''Epistola'', "''De Secretis Operibus Artis et Naturae et de Nullitate Magiae''," dated variously between 1248[ and 1257[4], he states:][. "frier Bacon, our countryman, mentions the compofition in exprefs terms, in his treatife De nullitate magiæ, publifhed at Oxford, in the year 1248."]
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.
Cannons forged in 1667 AD at the Fortín de La Galera,
Nueva Esparta, Venezuela.
The last part has been interpreted as an elaborate coded anagram for the quantities needed, but it may also be simply a garbled transcription of an illegible passage.
In the ''Opus Maior'' of 1267, Bacon describes firecrackers:
a child’s toy of sound and fire made in various parts of the world with powder of saltpeter, sulfur and charcoal of hazelwood.[4]
The ''Liber Ignium'', or ''Book of Fires'', attributed to Marcus Graecus, is a collection of incendiary recipes, including some gunpowder recipes. Partington dates the gunpowder recipes to approximately 1300.[4] One recipe for "flying fire" (''ingis volatilis'') involves saltpeter, sulfur, and colophonium, which, when inserted into a reed or hollow wood, "flies away suddenly and burns up everything." Another recipe, for artificial "thunder", specifies a mixture of one pound native sulfur, two pounds linden or willow charcoal, and six pounds of saltpeter.
Some of the gunpowder recipes in the ''De Mirabilibus Mundi'' of Albertus Magnus are identical to the recipes of the ''Liber Ignium'', and according to Partington, "may have been taken from that work, rather than conversely."[ Albertus Magnus died in 1280 AD.]
The introduction of smokeless powder in the late 19th century led to a contraction of the gunpowder industry.
Manufacture
Europe
Shot and gunpowder for military purposes were made by skilled military tradesmen, who later were called ''firemakers'', and who also were required to make fireworks for celebrations of victory or peace. During the Renaissance, two European schools of pyrotechnic thought emerged, one in Italy and the other at Nürnberg, Germany. The Italian school of pyrotechnics emphasized elaborate fireworks, and the German school stressed scientific advancement. Both schools added significantly to further development of pyrotechnics, and by the mid-17th century fireworks were used for entertainment on an unprecedented scale in Europe, being popular even at resorts and public gardens.["Fireworks," Microsoft Encarta Online Encyclopedia 2007 © 1997-2007 Microsoft Corporation. All Rights Reserved.]
By 1788, as a result of the reforms for which Lavoisier was mainly responsible, France had become self-sufficient in saltpeter, and its gunpowder had become both the best in Europe and inexpensive.[4]
United Kingdom
Gunpowder production in the United Kingdom appears to have started in the mid 13th century with the aim of supplying The Crown.[ Gunpowder was also being made or stored at other Royal castles, such as Portchester Castle and Edinburgh castle.]
By the early fourteenth century, according to N.J.G. Pounds's study ''The Medieval Castle in England and Wales,'' many English castles had been deserted and others were crumbling. Their military significance faded except on the borders. Gunpowder made smaller castles useless.[18]
Henry VIII was short of gunpowder when he invaded France in 1544 and England needed to import gunpowder via the port of Antwerp.
The English Civil War, 1642-1645, led to an expansion of the gunpowder industry, with the repeal of the Royal Patent in August 1641.
The Home Office removed gunpowder from its list of 'Permitted Explosives'; shortly afterwards, on 31 December 1931, Curtis & Harvey's Glynneath gunpowder factory at Pontneddfechan, in Wales, closed down, and it was demolished by fire in 1932.
The last remaining gunpowder mill at the Royal Gunpowder Factory, Waltham Abbey was damaged by a German parachute mine in 1941 and it never reopened.
This left the sole United Kingdom gunpowder factory at ICI Nobel's Ardeer site in Scotland; it too closed in October 1976.[ Since then gunpowder has been imported into the United Kingdom. In the late 1970s / early 1980s gunpowder was bought from eastern Europe; particularly from, what were then, the East Germany and Yugoslavia.]
The United States
Prior to the American Revolutionary War very little gunpowder was made in the United States; and, as a British Colony, most was imported from Britain.[ In October 1777 the British Parliament banned the importation of gunpowder into America.][ Gunpowder, however, was secretly obtained from France and the Netherlands.]
The first domestic supplies of gunpowder were made by E. I. du Pont de Nemours and Company.
Starting, initially, by reworking damaged gunpowder and refining saltpetre for the US Government they quickly moved into gunpowder manufacture.
In the United States, saltpetre was worked in the "nitre caves" of Kentucky at the beginning of the 19th century.[ Cannons and Gunpowder ]. Tourists at Mammoth Cave, KY to this day are shown the vast deposits of bat guano, as well as the historic machinery use in its extraction and conversion to usable saltpetre for gunpowder from Revolutionary times right up to World War I.
Manufacturing technology
For the most powerful black powder "meal" a wood charcoal is used. The best wood for the purpose is pacific willow, but others such as alder or buckthorn can be used.
The ingredients are mixed as thoroughly as possible. This is achieved using a ball mill with non-sparking grinding apparatus (e.g., bronze or lead), or similar device. Historically, a marble or limestone edge runner mill, running on a limestone bed was used in Great Britain; however, by the mid 19th century this had changed to either an iron shod stone wheel or a cast iron wheel running on an iron bed.[ The mix is sometimes dampened with alcohol or water during grinding to prevent accidental ignition.]
Around the late 14th century,[4] European powdermakers began adding liquid to the constituents of gunpowder to reduce dust and with it the risk of explosion. The powdermakers would then shape the resulting paste of moistened gunpowder—known as mill cake—into "corns," or granules, to dry. Not only did "corned" powder keep better because of its reduced surface area, gunners also found that it was more powerful and easier to load into guns. Before long, powdermakers standardized the process by forcing mill cake through sieves instead of corning powder by hand.
During the 18th century gunpowder factories became increasingly dependent on mechanical energy.[20]
See also
★ Ballistics
★ Elizabethton, Tennessee#American Revolution
★ Gunpowder Plot
★ Gunpowder warfare
★ Technology of the Song Dynasty
★ History of gunpowder
Notes
1. Flash! Bang! Whiz!, University of Denver
2. Bhattacharya (in ) acknowledges that "most sources credit the Chinese with the discovery of gunpowder" though he himself disagrees.
3. Buchanan. "Editor's Introduction: Setting the Context", in .
4.
5.
6.
7.
8.
9.
10.
11.
12. Potassium Nitrate in Arabic and Latin Sources
13.
14. A picture of this handwritten paragraph, taken from the Sloan MSS, held in the British Library is given on page one of Cocroft (2000)
15.
16.
17.
18. Ross, Charles. ''The Custom of the Castle: From Malory to Macbeth''. Berkeley: University of California Press, c1997. http://ark.cdlib.org/ark:/13030/ft3r29n8qn/ pp. 131-130.
19.
20. Frangsmyr, Tore, J. L. Heilbron, and Robin E. Rider, editors ''The Quantifying Spirit in the Eighteenth Century''. Berkeley: University of California Press, c1990. http://ark.cdlib.org/ark:/13030/ft6d5nb455/ p. 292.
References
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External links
★ Gun and Gunpowder
★ The Origins of Gunpowder
★ Cannons and Gunpowder
★ History of Science and Technology in Islam
★ Oare Gunpowder Works, Kent, UK
★ Royal Gunpowder Mills
★ Ulrich Bretschler's Gunpowder Chemistry page
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