## The Three Ingredients
Eighteenth-century powder was made from saltpeter (potassium nitrate), charcoal, and sulfur, in a ratio that by then had largely standardized around 75:15:10 by weight — though military establishments each had their own preferred proportions, and powder for mining or fowling differed from cannon powder.
**Saltpeter** was the bottleneck and the strategic commodity. It came from two kinds of sources:
- *Imported crude niter*, above all from Bengal, where nitrate-rich soils were leached and crystallized locally. The British East India Company's control of this trade was a major reason for British powder supremacy, and Company ships carried saltpeter as profitable ballast.
- *Domestic "niter beds" and scavenging.* Nitrifying bacteria produce nitrates in manure-rich earth, so saltpeter men collected soil from stables, dovecotes, cellars, and byres, or maintained purpose-built beds of dung, straw, and earth watered with urine over several years. The earth was washed with water, and the liquor boiled down and crystallized, then recrystallized repeatedly with additives to remove deliquescent calcium and magnesium salts that would spoil the powder.
In France this was organized under the *Régie des Poudres et Salpêtres*, created in 1775, with Antoine Lavoisier among its four administrators. Lavoisier systematized refining, ran prize competitions for better methods, and raised French powder to arguably the best in Europe. The saltpeter collectors' legal right to dig up private cellars was deeply resented — a genuine grievance in the run-up to 1789.
**Sulfur** came overwhelmingly from Sicilian volcanic deposits, purified by melting and distillation into "roll brimstone" or sublimed "flowers of sulfur."
**Charcoal** was made from soft, low-ash woods — willow, alder, and especially buckthorn (dogwood). Over the 18th century, open pit-burning gave way to charring in closed iron cylinders or retorts, which gave far more consistent results and was an important quality improvement.
## The Milling Process
Powder mills were water-powered industrial sites, typically strung along rivers in dispersed clusters of small buildings.
1. **Separate preparation** — each ingredient ground and sieved on its own.
2. **Incorporation** — the critical step, since black powder is a mechanical mixture rather than a compound, and performance depends on intimacy of mixing. Older *stamp mills* (rows of wooden stamps pounding mixtures in mortars) were gradually replaced during the century by *edge-runner* or *incorporating mills*: two heavy stone or iron wheels rotating on a circular bed. The charge was kept damp throughout, which both suppressed ignition and helped the saltpeter penetrate the charcoal.
3. **Pressing** — the "mill cake" was pressed into hard, dense slabs, which raised the powder's density and hence its power.
4. **Corning** — the cake was broken and sieved into graded grains: coarse for cannon, medium for muskets, fine for priming and pistols. Grain size controlled burn rate.
5. **Glazing** — late in the century, tumbling grains in rotating barrels (sometimes with graphite) rounded them, reduced dust, improved flow, and made the powder less hygroscopic.
6. **Drying and packing** — in heated stove houses or in the sun, then dusted and barreled.
## Proof and Quality Control
Powder was tested with the *éprouvette*, a small mortar that threw a standard ball or lifted a weighted lid a measured distance. Cruder tests included burning a small heap on paper to check for residue and scorching. Lavoisier's circle pushed toward more quantitative standards, including density measurement.
## Organization and Risk
Production was usually a state monopoly or tightly licensed. Britain relied on private mills in Kent and Essex — Faversham, Dartford, Oare — with the Crown buying the Faversham works in 1759 and Waltham Abbey in 1787, the latter modernized under William Congreve. The American colonies were almost entirely dependent on imports; during the Revolution the great majority of powder came from France and the Netherlands through the Caribbean, while committees of safety printed saltpeter-making pamphlets to encourage domestic supply. Éleuthère Irénée du Pont, who had trained under Lavoisier, founded his Brandywine mills in 1802 explicitly to fix American powder quality.
The work was genuinely lethal. Mills were built with light roofs and heavy blast walls or earthen berms to direct explosions upward, buildings were widely spaced, and workers wore leather or felt shoes without nails and used wooden or bronze tools. Even so, catastrophic explosions were routine — the 1781 Faversham blast is one of many well-documented disasters — and powder villages tended to be close-knit communities living with constant risk.
## Why It Mattered
The 18th century didn't invent black powder, but it industrialized and standardized it: consistent retort charcoal, reliable saltpeter refining, dense pressed and glazed grains, and graded granulation together produced powder substantially more powerful and uniform than 17th-century equivalents. That consistency is part of what made the era's artillery science, and figures like Gribeauval, possible.