Black powder is a type of gunpowder invented in the 9th century and was practically the only known propellant and explosive until the middle of the 19th century. It has been superseded by more efficient explosives such as smokeless powders and TNT. It is still manufactured today but primarily for use in fireworks, model rocket engines, and reproductions of muzzleloading weapons.

Black powder consists of the granular ingredients sulphur (S), charcoal (provides carbon to the reaction) and saltpetre (saltpetre, potassium nitrate, KNO₃; provides oxygen to the reaction).

A simple, commonly cited, chemical equation for the combustion of black powder is:

2 KNO₃ + S + 3C → K₂S + N₂ + 3CO₂

A more accurate, but still simplified[1], equation is

10 KNO₃ + 3S + 8C → 2K₂CO₃ + 3K₂SO₄ + 6 CO₂ + 5N₂

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% gasseous products: Carbon dioxide, Nitrogen, Carbon monoxide, Hydrogen sulfide, Hydrogen, Methane. 1.11% water

The optimum proportions for gunpowder are: 74.64% saltpetre, 13.51% charcoal, and 11.85% sulphur (by weight). The current standard for black powder manufactured by pyrotechnicians today is 75% potassium nitrate, 15% softwood charcoal and 10% sulfur.

For the most powerful black powder "meal" a wood charcoal is used. The best wood for the purpose is buckthorn, but others such as balsa or willow can be used. The ingredients are mixed as thoroughly as possible. This is achieved using a ball mill with non-sparking grinding apparatus (lead), or similar device.

Black powder is also corned to change its burn rate. 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. 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). Very coarse black powder was used in mining before the development of nitroglycerine and dynamite.

Black powder is classified as a low explosive, that is, it deflagrates (burns) rapidly. High explosives detonate at a rate approximately 10 times faster than the burning of black powder.

Although black powder is not a high explosive, the United States Department of Transportation classifies it as a "Class A High Explosive" for shipment because it is so easily ignited. Highly destructive explosions at fireworks manufacturing plants are rather common events, especially in Asia. 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 the loose powder.

Gunpowder was invented in China in the 9th century during the late Tang dynasty (618 - 907 CE). The invention appears to have been made accidentally, by Taoist alchemists seeking the elixir of immortality, or possibly as a fire starter for the easy ignition of tinder by sparks. The first references to gunpowder appear as warnings in alchemy texts not to mix certain materials together. However these early mixtures contain large amounts of incombustible material (one recipe even included human semen) and are pyrotechnic in nature rather than trully explosive. By the 11th century, gunpowder began to be used for military purposes in China in the form of rockets and explosive bombs fired from catapults. The first reference to missile throwing weapons appears in 1259 when bamboo or copper tubes were used to launch baked clay bullets or shrapnel consisting of pebbles and small stones at the enemy. This type of weapon was primarily a nuisance, rather than a danger on the battlefield. Many early mixtures of Chinese gunpowder contained toxic substances such as mercury and arsenic compounds, and could be considered an early form of chemical warfare. The oldest metal cannon in China dates from 1323.

From China, the military use of gunpowder appears to have spread to the rest of the world. It was used by the Mongols (1279 - 1368) against the Russians and was mentioned in a European manuscript by Roger Bacon in 1248. Bacon had many contacts with Arab-ruled Al-Andalus and it is likely his formulas originated there. There are Spanish references to the use of "Truenos" ("Thunderers") in Al-Andalus as early as 1248, but it is more likely these were bombs hurled by catapult, or rockets rather than cannon. The first authenticated European reference to cannon is a record of them being exported from Ghent in 1313. By the mid 14th century, early cannon are mentioned extensively both in Europe and in China. It was the Europeans (or possibly the Arabs) who realized that only three ingredients were necessary for effective gunpowder, and who realized the importance of potassium nitrate in increasing the power of the mixture enough to make cannon effective.

The origins of gunpowder and cannon remains controversial as most of the Chinese written sources are 17th century revisions of earlier texts. Chinese firearms failed to develop beyond the most primitive stage until after contact with European traders. Japanese sources state that hand held firearms were completely unknown (or forgotten) before the Portuguese landed (or rather were shipwrecked) at Tanegashima in 1543. The military adventurism of the Mongols (1279 - 1368) seems to have been the impetus for the development of gunpowder weapons in China, but at the time older forms of siege equipment such as the trebuchet still dominated. Cannon and rockets were extensively used in the Mongol conquests of the 13th and 14th centuries and were a feature of East Asian warfare afterwards. The low, thick city walls of Beijing (started in 1406) for example, were specifically designed to withstand a gunpowder artillery attack, and the Ming dynasty(1368-1644) moved the capital from Nanjing to Beijing in 1421 specifically because the hills around Nanjing were good locations for invaders to place artillery.

The early use of gunpowder in the Arab world is complex and sometimes confusing in nature, mainly because of changes in the meaning of words. The Arab alchemists were well aquainted with saltpetre (which they called "Chinese Snow"), and as previously noted Roger Bacon may have learned about gunpowder through his Arabic speaking colleagues in Al-Andalus. Certainly by 1453, the Ottoman Turks were masters of gunpowder manufacture and the use of heavy gunpowder artilliery

The 15th through 17th century saw widespread development in gunpowder technology mainly in Europe. Advances in metallurgy led to portable weapons and the development of hand-held firearms such as muskets. Cannon technology in Europe gradually outpaced that of China and these technological improvements transferred back to China through Jesuit missionaries who were put in charge of cannon manufacture by the late Ming and early Qing emperors.

The latter half of the 19th Century saw the invention of nitroglycerin, nitrocellulose and smokeless powders which rapidly led to the replacement of gunpowder in many applications.

• Meal powder
• Green mix
• Smokeless powder
• Early modern warfare
• Gonne

• Gunpowder: Alchemy, Bombards, & Pyrotechnics by Jack Kelly, Basic Books, ISBN 0-465-03718-6.
• A History of Greek Fire and Gunpowder by J.R. Partington ISBN 0801859549
• Guns and Rifles of the World by Howard Blackmore ISBN 0670357804
• The Chemistry of Powder & Explosives by Tenney L. Davis, ISBN-0913022-00-4
• Firearms : a global history to 1700 / by Chase, Kenneth Warren. ISBN-0521822742

• Ulrich Bretscher's Blackpowder page
• Cannons: That diabolical instrument of war