Editing Gunpowder (section)

== Components ==

Gunpowder is a granular mixture of:

* a [[nitrate]], typically potassium nitrate (KNO<sub>3</sub>), which supplies oxygen for the reaction;
* [[charcoal]], which provides carbon and other fuel for the reaction, simplified as carbon (C);
* [[sulfur]] (S), which, while also serving as a fuel, lowers the temperature required to ignite the mixture, thereby increasing the rate of [[combustion]].

Potassium nitrate is the most important ingredient in terms of both bulk and function because the combustion process releases oxygen from the potassium nitrate, promoting the rapid burning of the other ingredients.{{sfn|Buchanan|2006|p=4}} To reduce the likelihood of accidental ignition by [[static electricity]], the granules of modern gunpowder are typically coated with [[graphite]], which prevents the build-up of electrostatic charge.

Charcoal does not consist of pure carbon; rather, it consists of partially [[Pyrolysis|pyrolyzed]] [[cellulose]], in which the wood is not completely decomposed. [[Carbon]] differs from ordinary [[charcoal]]. Whereas charcoal's autoignition temperature is relatively low, carbon's is much greater. Thus, a gunpowder composition containing pure carbon would burn similarly to a match head, at best.<ref>[http://www.musketeer.ch/blackpowder/recipe.html Black Powder Recipes] {{Webarchive|url=https://archive.today/20120911093724/http://www.musketeer.ch/blackpowder/recipe.html |date=11 September 2012 }}, Ulrich Bretscher</ref>

The current standard composition for the gunpowder manufactured by pyrotechnicians was adopted as long ago as 1780. Proportions by weight are 75% potassium nitrate (known as saltpeter or saltpetre), 15% softwood charcoal, and 10% sulfur.<ref name = earl-2>{{Harvcolnb|Earl|1978|loc=Chapter 2: The Development of Gunpowder}}</ref> These ratios have varied over the centuries and by country, and can be altered somewhat depending on the purpose of the powder. For instance, power grades of black powder, unsuitable for use in firearms but adequate for blasting rock in quarrying operations, are called blasting powder rather than gunpowder with standard proportions of 70% nitrate, 14% charcoal, and 16% sulfur; blasting powder may be made with the cheaper [[sodium nitrate]] substituted for potassium nitrate and proportions may be as low as 40% nitrate, 30% charcoal, and 30% sulfur.<ref>{{cite book |first=Julian S. |last=Hatcher |title=Hatcher's Notebook |publisher=Military Service Publishing Company |date=1947 |chapter=Chapter XIII "Notes on Gunpowder" |pages=300–05}}</ref> In 1857, Lammot du Pont solved the main problem of using cheaper sodium nitrate formulations when he patented DuPont "B" blasting powder. After manufacturing grains from press-cake in the usual way, his process tumbled the powder with graphite dust for 12 hours. This formed a graphite coating on each grain that reduced its ability to absorb moisture.{{sfn|Kelly|2004|p=218}}

Neither the use of graphite nor sodium nitrate was new. Glossing gunpowder corns with graphite was already an accepted technique in 1839,<ref>{{cite journal|title=Some Account of Gunpowder|journal=The Saturday Magazine|date=January 1839|volume=422 |issue=supplement |pages=33–40}}</ref> and sodium nitrate-based blasting powder had been made in Peru for many years using the sodium nitrate mined at [[Tarapacá Province (Peru)|Tarapacá]] (now in Chile).<ref>{{cite journal|last1=Wisniak|first1=J. J.|last2=Garcés|first2=I.|title=The Rise and Fall of the Salitre (Sodium Nitrate) Industry|journal=Indian Journal of Chemical Technology|date=September 2001|pages=427–438}}</ref> Also, in 1846, two plants were built in south-west England to make blasting powder using this sodium nitrate.<ref>{{cite journal|last1=Ashford|first1=Bob|title=A New Interpretation of the Historical Data on the Gunpowder Industry in Devon and Cornwall|journal=J. Trevithick Soc.|date=2016|volume=43|pages=65–73}}</ref> The idea may well have been brought from Peru by Cornish miners returning home after completing their contracts. Another suggestion is that it was [[William Lobb]], the plant collector, who recognised the possibilities of sodium nitrate during his travels in South America. Lammot du Pont would have known about the use of graphite and probably also knew about the plants in south-west England. In his patent he was careful to state that his claim was for the combination of graphite with sodium nitrate-based powder, rather than for either of the two individual technologies.

French war powder in 1879 used the ratio 75% saltpeter, 12.5% charcoal, 12.5% sulfur. English war powder in 1879 used the ratio 75% saltpeter, 15% charcoal, 10% sulfur.<ref>{{cite book |title=Workshop Receipts |publisher=William Clowes and Son Limited |first=Ernest |last=Spon |date=1873}}</ref> The British Congreve rockets used 62.4% saltpeter, 23.2% charcoal and 14.4% sulfur, but the British Mark VII gunpowder was changed to 65% saltpeter, 20% charcoal and 15% sulfur.{{citation needed|date=March 2018}} The explanation for the wide variety in formulation relates to usage. Powder used for rocketry can use a slower burn rate since it accelerates the projectile for a much longer time—whereas powders for weapons such as flintlocks, cap-locks, or matchlocks need a higher burn rate to accelerate the projectile in a much shorter distance. Cannons usually used lower burn-rate powders, because most would burst with higher burn-rate powders.

=== Other compositions ===

Besides black powder, there are other historically important types of gunpowder. "Brown gunpowder" is cited as composed of 79% nitre, 3% sulfur, and 18% charcoal per 100 of dry powder, with about 2% moisture. [[brown powder|Prismatic Brown Powder]] is a large-grained product the [[Rottweil]] Company introduced in 1884 in Germany, which was adopted by the British Royal Navy shortly thereafter. The French navy adopted a fine, 3.1 millimeter, not prismatic grained product called ''Slow Burning Cocoa'' (SBC) or "cocoa powder". These brown powders reduced burning rate even further by using as little as 2 percent sulfur and using charcoal made from [[rye]] straw that had not been completely charred, hence the brown color.{{sfn|Kelly|2004|p=224}}

Lesmok powder was a product developed by DuPont in 1911,<ref>{{Cite web|url=http://cartridgecollectors.org/?page=glossary|title=A Cartridge Collector's Glossary - International Ammunition Association|website=cartridgecollectors.org}}</ref> one of several semi-smokeless products in the industry containing a mixture of black and nitrocellulose powder. It was sold to [[Winchester Repeating Arms Company|Winchester]] and others primarily for .22 and .32 small calibers. Its advantage was that it was believed at the time to be less corrosive than smokeless powders then in use.  It was not understood in the U.S. until the 1920s that the actual source of corrosion was the potassium chloride residue from potassium chlorate sensitized primers.  The bulkier black powder fouling better disperses primer residue.  Failure to mitigate primer corrosion by dispersion caused the false impression that nitrocellulose-based powder caused corrosion.<ref>{{cite book |first=Julian S. |last=Hatcher |title=Hatcher's Notebook |publisher=Stackpole Books |date=1962 |chapter=Chapter XIV, Gun Corrosion and Ammunition Developments |pages=346–49}}</ref> Lesmok had some of the bulk of black powder for dispersing primer residue, but somewhat less total bulk than straight black powder, thus requiring less frequent bore cleaning.<ref name=Wakeman/> It was last sold by Winchester in 1947.

=== Sulfur-free powders ===
[[File:Burst muzzle loader barrel.jpg|thumb|upright=1.25|Burst barrel of a muzzle loader pistol replica, which was loaded with nitrocellulose powder instead of black powder and could not withstand the higher pressures of the modern propellant]]

The development of smokeless powders, such as [[cordite]], in the late 19th century created the need for a spark-sensitive [[blasting cap|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.{{sfn|Cocroft|2000}} They typically contain 70.5% of saltpeter and 29.5% of charcoal.{{sfn|Cocroft|2000}} Like black powder, they were produced in different grain sizes. In the 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 represents the smallest BSS sieve mesh size, which retained no grains.

Sulfur's main role in gunpowder is to decrease the ignition temperature. A sample reaction for sulfur-free gunpowder would be:
:<chem>6 KNO3 + C7H4O -> 3 K2CO3 + 4 CO2 + 2 H2O + 3 N2</chem>

=== Smokeless powders ===

The term ''black powder'' was coined in the late 19th century, primarily in the United States, to distinguish prior gunpowder formulations from the new smokeless powders and semi-smokeless powders. Semi-smokeless powders featured bulk volume properties that approximated black powder, but had significantly reduced amounts of smoke and combustion products. Smokeless powder has different burning properties (pressure vs. time) and can generate higher pressures and work per gram. This can rupture older weapons designed for black powder. Smokeless powders ranged in color from brownish tan to yellow to white. Most of the bulk semi-smokeless powders ceased to be manufactured in the 1920s.<ref>{{Cite web|url=http://www.swissrifles.com/ammo/index.html|title=Swiss Handguns 1882|website=www.swissrifles.com}}</ref><ref name=Wakeman/><ref>{{cite web |url=http://www.ngpc.state.ne.us/nebland/articles/history/shotshells.asp |title=The History and Art of Shotshells |archive-url=https://web.archive.org/web/20071114215300/http://www.ngpc.state.ne.us/nebland/articles/history/shotshells.asp |archive-date=14 November 2007 |first=Jon |last=Farrar |work=Nebraskaland Magazine |publisher=Nebraska Game and Parks Commission}}</ref>