Black powder is the original gunpowder and practically the only known propellant and explosive until the middle of the 19th century. It has largely been superseded by more efficient explosives such as smokeless powders and TNT.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 sulfur (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% gaseous 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% sulfur (by mass). 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 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 (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.

The formula for black powder was established in the 9th century,^[1] a byproduct of Taoist alchemical efforts to develop an elixir of immortality.^[2] A book dating from c. 850 CE called "Classified Essentials of the Mysterious Tao of the True Origin of Things" warns of one elixir, "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."^[3]

The impetus for the development of gunpowder weapons in China was increasing encroachment by tribes on its borders.^[4] The Wu jing zong yao (武经总要, "Collection of the Most Important Military Techniques") of 1044 CE contains three recipes for gunpowder: two for use in incendiary bombs to be thrown by siege engines and one intended as fuel for poison smoke bombs.^[5] Kelly posits that the Chinese began to use rockets in war in the middle of the 13th century.^[6] One early use of gunpowder as a weapon was the fire lance, a handheld flamethrower which could also be loaded with shrapnel; by the late 1200s the Chinese had developed these into the earliest guns.^[7] An account of a 1359 battle near Hangzhou records that both the Ming Chinese and Mongol sides were equipped with cannon.^[8] On archeology, the oldest cannon in China dates from 1298, as discovered recently with Chinese date inscribed 元大德二年 (1298) on the cannon. This is, however, similar to the bronze cannon of 1332, which also had its date inscription. 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.

In the 1270s, the Mongols conquered China and, with it, the technology of gunpowder. The use of cannons and rockets became a feature of East Asian warfare thereafter. 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.

Kelly dates the spread of gunpowder to the Arabs to the 13th century: "Around 1240 the Arabs acquired knowledge of saltpeter (“Chinese snow”) from the East, perhaps through India. They knew of gunpowder soon afterward. They also learned about fireworks (“Chinese flowers”) and rockets (“Chinese arrows”)."^[9] 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. Certainly by 1453, the Ottoman Turks were masters of gunpowder manufacture and the use of heavy gunpowder artilliery. The Turks were able to construct enormous cannon with a bore of 90cm firing a 320kg projectile a distance of over 1.6 kilometres.^{[citation needed]} It is widely recognized that it was 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 and reliable.

In Europe, the first written reference to gunpowder was set down by Roger Bacon c. 1267;^[10] Bacon had many contacts with Arab-ruled al-Andalus and it has been suggested that he learned about gunpowder from Arabic-speaking colleagues there. The first authenticated European reference to cannon is a record of them being exported from Ghent in 1313 ^{[citation needed]}.

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 soon replaced gunpowder in many applications.

One of the overlooked areas in the history of black powder is its use in civil engineering and mining. Until the invention of explosives, large rocks could only be broken up by hard labour, or heating with large fires followed by rapid quenching. The earliest surviving record for the use of gunpowder in mines comes from Hungary in 1627. It was introduced to Britain in 1638 by German miners, after which records are numerous. Until the invention of the safety fuse by William Bickford in 1831, the practice was extremely dangerous. Another reason for danger was the dense fumes given off and the risk of igniting flammable gas when used in coal mines.

The first time gunpowder was used on a large scale in civil engineering was in the construction of the Languedoc canal in Southern France. It was completed in 1681 and linked the Mediterranean sea with the Bay of Biscay with 240km of canal and 100 locks. Another noteworthy consumer of blackpowder was the Erie canal in New York, which was 585km long and took 8 years to complete starting in 1817. Canal construction led to a frenzy of activity among American gunpowder manufacturers.

Black powder was also extensively used in railway construction. At first tracks were limited to level ground, but later railways made extensive use of cuttings and tunnels. One 800-metre stretch of the notorious Box Tunnel on the Great Western Railway line between London and Bristol consumed a tonne of gunpowder per week for over two years. Over 100 lives were lost during construction of the 3.3km tunnel. The 12.9km long Mont Cenis Tunnel was completed in 13 years starting in 1857, but even with black powder progress was only 25cm a day until the invention of pneumatic drills sped up the work.

• Guns and Rifles of the World by Howard Blackmore ISBN 0-6703-5780-4
• The Big Bang: A history of Explosives by G I Brown ISBN 0-7509-1878-0
• Firearms : a global history to 1700 / by Chase, Kenneth Warren. ISBN 0-5218-2274-2
• The Chemistry of Powder & Explosives by Tenney L. Davis, ISBN 0-9130-2200-4
• Kelly, Jack (2004). Gunpowder: Alchemy, Bombards, & Pyrotechnics: The History of the Explosive that Changed the World. Basic Books. ISBN 0465037186.
• Needham, Joseph (2004). Science and Civilisation in China. Cambridge University Press. ISBN 0521087325.
• Partington, James Riddick (1998). A History of Greek Fire and Gunpowder. The Johns Hopkins University Press. ISBN 0801859549.

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

• Great Chinese encyclopedia - ancient gunpowder (in Chinese)
• Ulrich Bretscher's Blackpowder page
• Cannons: That diabolical instrument of war