Gunpowder

• 1. Introduction

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  Gunpowder began not as a weapon but as a quest for immortality. Chinese alchemists, mixing sulfur, realgar, and saltpeter with honey, watched smoke and flames erupt. Their hands and faces were burnt, and even the whole house where they were working burned down. This warning, recorded in a Daoist text known as the Zhenyuan miaodao yaolüe, captures the strange birth of the earliest known chemical explosive. The substance they stumbled upon mixes sulfur, charcoal, and potassium nitrate. The Chinese gave it a fitting name: huoyao, meaning fire medicine. How did a recipe sought by Taoists chasing the elixir of life become a propellant for firearms across the world? Why does this powder burn rather than detonate, and why did that distinction matter for centuries of warfare? And how did knowledge of it travel so fast across Eurasia when paper, the compass, and printing took centuries to follow the same road?

• 2. Fire Medicine

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  Saltpeter was known to the Chinese by the mid-1st century AD, drawn primarily from the provinces of Sichuan, Shanxi, and Shandong. A Chinese alchemical text dated 492 noted that saltpeter burnt with a purple flame. That purple flash gave alchemists a reliable means of telling it apart from other inorganic salts, letting them judge their purification techniques. The earliest Latin accounts of saltpeter purification are dated only after 1200, leaving China centuries ahead. The first confirmed reference to gunpowder appears in the 9th century during the Tang dynasty, in a formula contained in the Taishang Shengzu Jindan Mijue in 808. That formula called for six parts sulfur to six parts saltpeter to one part birthwort herb. Gunpowder had originally been produced for medicinal purposes, and the idea outlasted the alchemists. People ate it expecting to cure digestive ailments, inhaled it for respiratory disorders, and rubbed it onto rashes or burns. The leap from a medicine cabinet to a battlefield was neither obvious nor quick.

• 3. Deflagrate Not Detonate

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  Gunpowder is classified as a low explosive, and that single fact shapes everything it can and cannot do. It deflagrates, burning at subsonic speeds, while high explosives detonate and produce a supersonic shockwave. Ignition behind a projectile builds enough pressure to force the shot from the muzzle at high speed, but usually not enough to rupture the gun barrel. That gentleness is the whole point of a propellant: no operator wants a blast that shatters the weapon in their hands. Combustion converts less than half the mass of gunpowder to gas, and most of it becomes particulate matter. Some is ejected, wasting propelling power, fouling the air, and giving away a soldier's position with smoke. The rest settles as a thick layer of soot inside the barrel. That residue contains potassium oxide or sodium oxide, which is hygroscopic and forms hydroxides upon absorbing moisture, corroding wrought iron or steel barrels. For this reason, gunpowder arms require thorough and regular cleaning. The same low brisance that makes it a poor rock-breaker makes it ideal for blasting fragile slate or monumental stone like granite and marble, because it causes fewer fractures and yields more usable stone.

• 4. From Fire Lance To Cannon

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  By 1083 the Song court was producing hundreds of thousands of fire arrows for their garrisons. The first recorded military use of gunpowder dates to 904, in the form of incendiary projectiles. Bombs and the first proto-guns, called fire lances, rose to prominence during the 12th century in the Jin-Song Wars. Fire lances were first recorded at the Siege of De'an in 1132, used by Song forces against the Jin. The weapon then evolved through a remarkable sequence of experiments. By 1257 some fire lances were firing wads of bullets. In the late 13th century metal fire lances became eruptors, proto-cannons firing co-viative projectiles mixed in with the propellant rather than seated over it with a wad. By 1287 at the latest these had become true guns, the hand cannon, complete with a metal barrel, touch hole, and gunpowder chamber. The military potential was not always so obvious. The earliest chemical formula for gunpowder appeared in the 11th-century Song text Wujing Zongyao, written by Zeng Gongliang between 1040 and 1044. Its mixtures contained at most 50% saltpeter, not enough to explode, producing an incendiary instead. Written by a court bureaucrat, the book left little trace on the wars of its own century. Physical proof of these weapons endures: explosive bombs were recovered from a shipwreck off the shore of Japan dated to 1281, during the Mongol invasions.

• 5. Chinese Snow

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  Hasan al-Rammah, a Syrian writer, called saltpeter Chinese snow, fireworks Chinese flowers, and rockets Chinese arrows. Those names betrayed where his knowledge came from. The Muslims acquired knowledge of gunpowder sometime between 1240 and 1280, after the Mongols introduced it during their invasion of Persia and Mesopotamia. In Persia, saltpeter was known as Chinese salt. Al-Rammah included 107 gunpowder recipes in The Book of Military Horsemanship and Ingenious War Devices, 22 of which are for rockets. The median of 17 of these rocket compositions runs to 75% nitrates, 9.06% sulphur, and 15.94% charcoal, nearly identical to the modern ideal recipe. His text also described the earliest torpedo, called the egg which moves itself and burns. Two iron sheets were fastened together and tightened with felt, then filled with gunpowder, metal filings, two rods, and a large rocket for propulsion. By the illustration, it was meant to glide across the water. Identifying the first true cannon in this region is fraught, because Arabic texts used the same word, naft, for both gunpowder and the older incendiary naphtha. Shihab al-Din Abu al-Abbas al-Qalqashandi described a metal cannon firing an iron ball between 1365 and 1376, while the musket appeared in the Ottoman Empire by 1465.

• 6. Europe And The Petermen

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  Roger Bacon, the English philosopher, wrote the earliest Western accounts of gunpowder in 1267, in texts called Opus Majus and Opus Tertium. In England, gunpowder was being made at the Tower of London in 1346, and by 1515 three King's gunpowder makers worked there. In late 14th century Europe, makers improved the powder by corning, drying it into small clumps for better combustion and consistency. The story of European powder is also a story of saltpeter and the lengths states went to secure it. For hundreds of years France relied on saltpetremen with royal warrants, the droit de fouille or right to dig. These men could seize nitrous soil and demolish the walls of barnyards without compensation, driving farmers and whole villages to bribe them to leave their buildings alone. In 1774, when Louis XVI ascended to the throne of France at the age of 20, he found the country was not self-sufficient in gunpowder. A Gunpowder Administration was created and the lawyer Antoine Lavoisier was appointed to head it. Lavoisier launched a crash program, revised and later eliminated the droit de fouille, and established pricing that drew private investment. In only a year France had gunpowder to export, and a chief beneficiary of that surplus was the American Revolution. By 1788 the powder from mills such as Essonne outside Paris had become the best in the world.

• 7. Mysorean Rockets

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  Hyder Ali and his son Tipu Sultan unleashed the Mysorean rockets against their British opponents, defeating them on various occasions during the Second Anglo-Mysore War. From the founding of the Sultanate of Mysore by Hyder Ali, French military officers trained the Mysore Army, and Hyder Ali and Tipu Sultan were the first in India to introduce modern cannons and muskets, and the first to dress their soldiers in official uniforms. Those rockets left a lasting mark abroad: they inspired the development of the Congreve rocket, which the British widely used during the Napoleonic Wars and the War of 1812. Gunpowder had reached India through the Mongol invasions, and India became a great supplier as well as a user. The Mughal emperor Akbar mass-produced matchlocks for the Mughal Army and is personally known to have shot a leading Rajput commander during the Siege of Chittorgarh. His descendant Shah Jahan introduced more advanced matchlocks combining Ottoman and Mughal designs. The province of Gujarat supplied Europe with saltpeter during the 17th century, while the Dutch, French, Portuguese, and English used Chhapra as a center of saltpeter refining.

• 8. The Powdermaker's Craft

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  The current standard recipe used by pyrotechnicians was adopted as long ago as 1780: 75% potassium nitrate, 15% softwood charcoal, and 10% sulfur. These ratios shifted across centuries and countries depending on purpose. Blasting powder for quarrying might run 70% nitrate, 14% charcoal, and 16% sulfur, or fall as low as 40% nitrate with cheaper sodium nitrate substituted in. The original European powder of the 15th century, known as Serpentine, was ground together with a mortar and pestle, perhaps for 24 hours, into a fine flour. Serpentine had a fatal flaw: vibration during transport could separate the components again, forcing remixing in the field, where the dust was a major hazard. Corning solved this. In late 14th century Europe and China, makers added liquid during grinding, then shaped the damp paste into corn-sized grains, each providing its own air space for rapid combustion. This corned gunpowder proved from 30% to 300% more powerful. One example records that 34 pounds of serpentine was needed to shoot a 47 pound ball, but only 18 pounds of corned powder did the same work. Power has its limits, though. Gunpowder releases 3 megajoules per kilogram, less than the 4.7 of TNT, which is why heavy projectiles demand large amounts of it. That low energy density, alongside corrosion and smoke, is exactly what later inventions would attack.

  On the 31st of December 1931, the former Curtis and Harvey's Glynneath gunpowder factory at Pontneddfechan in Wales closed down, and the factory was demolished by fire in 1932. The introduction of smokeless powder in the late 19th century had begun a long contraction of the gunpowder industry. After World War I, most British gunpowder manufacturers merged into a single firm, Explosives Trades Limited, which became Nobel Industries Limited and in 1926 a founding member of Imperial Chemical Industries. The last remaining mill at the Royal Gunpowder Factory, Waltham Abbey was damaged by a German parachute mine in 1941 and never reopened. ICI Nobel's Roslin factory closed in 1954, leaving the Ardeer site in Scotland as the only factory in Great Britain producing gunpowder until its gunpowder area closed in October 1976. Even as it faded from war, the powder kept turning up in surprising places. After the Battle of Aspern-Essling in 1809, Dominique-Jean Larrey, surgeon of the Napoleonic Army, lacking salt, seasoned a horse meat bouillon for the wounded with gunpowder. British sailors used it for traumatic tattooing when ink ran out, pricking the skin and rubbing the powder into the wound. Christiaan Huygens experimented with it in 1673 in an early attempt to build a gunpowder engine, and starting in 1967 the Los Angeles artist Ed Ruscha began using gunpowder as a medium for works on paper.