GPT on Question 21, Sep 15

In the 18th century, black powder was generally made in specialized powder mills from three ingredients: refined saltpeter (potassium nitrate), charcoal, and sulfur. The broad process was:

• 1.Refining saltpeter: Crude nitrate—often recovered from soil, manure-rich deposits, or imported sources—was dissolved, filtered, and recrystallized to improve purity.
• 2.Making charcoal: Selected woods such as willow, alder, or dogwood were heated with limited air. Charcoal quality strongly affected the powder’s performance.
• 3.Preparing sulfur: Sulfur was purified and reduced to a fine material.
• 4.Incorporation: The ingredients were first processed separately, then combined while damp in stamp mills or heavy wheel mills. Water reduced dust and helped limit accidental ignition.
• 5.Pressing: The damp mixture was compressed into dense slabs or “press cake.”
• 6.Corning: The cake was broken into grains and screened into different sizes. Grain size was chosen for applications such as muskets, cannon, pistols, or priming.
• 7.Glazing and drying: Grains were tumbled to smooth and strengthen them, sometimes with a small amount of graphite, then carefully dried and packed.

This “corned” powder was more consistent and less prone to separating during transport than older loose or “serpentine” powder. Manufacture was extremely hazardous: mills were commonly divided into separate, widely spaced buildings, with limited quantities handled in each and lightweight walls or roofs intended to vent explosions. Exact formulations and practices varied by country, mill, and intended use.