Gemini on Question 21, Sep 19

In the 18th century, black powder (gunpowder) was the most important chemical commodity in the world. It was the lifeblood of empires, driving both military conquest and industrial mining.

By the 1700s, gunpowder manufacturing had evolved from a crude, dangerous mixing of dry chemicals into a highly industrialized, water-powered process. The standard formula had settled into roughly 75% saltpeter, 15% charcoal, and 10% sulfur.

Here is a step-by-step look at how black powder was historically manufactured in the 18th century.

1. Sourcing and Refining the Ingredients

The quality of black powder depended entirely on the purity of its three ingredients. Gathering and refining them was a massive industry in itself.

• •Saltpeter (Potassium Nitrate): This was the oxidizer, the most expensive ingredient, and the hardest to get. It was harvested from "niter beds." People would dig large pits and fill them with manure, rotting vegetables, straw, limestone, and human/animal urine. Over several months, bacteria would convert the ammonia into nitrates, which formed as a white crust on the soil. This crust was gathered, boiled in giant copper vats, filtered through wood ashes, and crystallized. By the late 18th century, Britain also began importing massive quantities of highly pure saltpeter from colonial India.
• •Charcoal: Charcoal acted as the fuel. Black powder required a very specific type of charcoal that burned quickly and evenly. Manufacturers used softwoods like willow, alder, buckthorn, or dogwood. The wood was stripped of its bark and baked in iron retorts (low-oxygen ovens) rather than open fires. This "pyrolysis" created highly uniform, carbon-rich charcoal.
• •Sulfur: Sulfur lowered the ignition temperature of the powder, allowing sparks from a flintlock to ignite it easily. It was generally mined in volcanic regions, most notably Sicily. It was purified by boiling it and skimming off the impurities, or by sublimation (turning it to gas and capturing the purified crystals).

2. Milling and Incorporation

The raw ingredients were ground into fine powders separately, but they could not simply be stirred together. They had to be mechanically pounded into one another so they were intimately mixed at a microscopic level.

In the 18th century, this was done using water-powered mills:

• •Stamp Mills: Early in the century, heavy wooden pestles (driven up and down by water wheels) pounded the mixture in wooden mortars.
• •Edge-Runner Mills: By the mid-to-late 18th century, the industry shifted to edge runners. These were two massive, vertical stone wheels (weighing several tons) that rolled in a circular stone trough.
• •The Wet Process: Milling was incredibly dangerous. To prevent friction from causing an explosion, water or alcohol was added to the powder to turn it into a damp paste.

3. Pressing

Early gunpowder was "serpentine" powder—just a loose dust. However, dust absorbed moisture from the air and separated during bumpy wagon transport (the heavier sulfur would sink to the bottom, ruining the powder).

To fix this, 18th-century powdermakers subjected the damp paste to immense pressure. Using massive wooden screw-presses, the paste was compressed into hard, slate-like cakes that were incredibly dense.

4. Corning (Granulation)

The solid cakes of powder were then broken down using wooden mallets. The broken pieces were forced through parchment or wire sieves to break the powder into uniform grains. This process was called corning.

Corning was the greatest leap forward in gunpowder technology. A charge made of uniform grains had microscopic air gaps between them. When ignited, the flame traveled instantly through the air gaps, igniting all the grains simultaneously and creating a violent, instantaneous explosion.

The powder was sifted into different sizes for different weapons:

• •Cannon powder: Large, coarse grains.
• •Musket powder: Medium grains.
• •Priming powder: Very fine, sand-like grains used in the flashpan of flintlock firearms.

5. Glazing

The newly corned grains had sharp edges, which would rub together during transport, creating explosive dust. To prevent this, the grains were poured into large wooden barrels and tumbled for hours. The friction rounded off the edges.

Sometimes a tiny amount of graphite was added during the tumbling. This gave the grains a shiny, slippery, black glaze that helped waterproof the powder and allowed it to pour smoothly down the barrel of a gun.

6. Drying and Packaging

The glazed powder was still slightly damp. It was taken to a drying house. Early in the century, it was dried in the sun, but this was unreliable in places like Britain or France. Later, they used "gloom stoves"—iron plates heated by a fire fed from the outside of a thick stone wall. The heat radiated through the wall into the drying room, keeping the open flame far away from the powder.

Finally, the finished powder was packed into airtight oak barrels, usually lined with copper or paper, ready for the military or mining companies.

Safety and Danger in the Mills

Gunpowder mills exploded with terrifying frequency. To mitigate the danger, 18th-century mills utilized strict safety protocols:

• •No iron tools: Workers used only tools made of copper, brass, bronze, or wood, as these metals do not spark when struck.
• •Clothing: Workers were forbidden from wearing clothing with metal buttons, and wore soft leather shoes (or went barefoot) to avoid scraping stones on the floor and creating sparks.
• •Blow-away Architecture: Powder mills were constructed with three thick stone walls and one flimsy wooden wall and roof facing a river. If the powder exploded, the blast would be directed outward over the water and upward, saving the expensive water wheel and the rest of the factory.