GPT on Question 21, Sep 28

In the 18th century, black powder was manufactured in specialized powder mills, often located away from towns because fires and explosions were common. The basic ingredients were saltpeter (potassium nitrate), charcoal, and sulfur, but producing consistent powder required several industrial stages:

• 1.Purifying the ingredients
  Saltpeter was refined by dissolving and recrystallizing it. Sulfur was cleaned of impurities, while charcoal was made from selected woods—such as willow, alder, or dogwood—heated with limited air.

• 2.Grinding and incorporating
  The ingredients were ground separately, then combined in water-powered mills using heavy wooden or stone wheels. The mixture was kept damp during much of this work to reduce airborne dust and accidental ignition. Thorough incorporation was essential for predictable performance.

• 3.Pressing
  The damp mixture was compressed into dense slabs or “press cake.” This made the ingredients remain closely mixed and produced stronger, more uniform powder.

• 4.Corning
  The cake was broken up and passed through sieves to create grains. This process, called corning, was a major improvement over earlier loose “serpentine” powder because grain size could be controlled.

• 5.Drying, glazing, and grading
  The grains were carefully dried, sometimes tumbled to smooth and harden their surfaces, and sorted by size. Coarser grades were used for cannon, finer grades for muskets and pistols, and very fine powder for priming flintlocks.

• 6.Packing and storage
  Finished powder was packed in wooden barrels and kept as dry as possible. Mill buildings were separated from one another, workers used non-sparking tools and clothing, and roofs or walls were sometimes designed to vent an explosion upward.

By the 18th century, powder making was therefore less a simple mixing operation than a hazardous, increasingly standardized industry involving chemical purification, water-powered machinery, pressing, granulation, and quality testing.