Short answers, pulled from the story.
Gunpowder was first invented in the year 808 when a Taoist alchemist mixed sulfur and saltpeter with birthwort herb. This accidental explosion marked the first known reference to what we now call gunpowder.
The Song dynasty court official Zeng Gongliang recorded the earliest chemical formula for gunpowder in his book Wujing Zongyao in 1044. His text described mixtures containing petrochemicals, garlic, and honey alongside the core ingredients.
Gunpowder consists of three main ingredients: sulfur, charcoal, and potassium nitrate. Sulfur acts as fuel but also lowers the ignition temperature required to start the reaction while charcoal provides carbon and other fuels for combustion. Potassium nitrate serves as the oxidizer that supplies oxygen for the process.
European manufacturers improved gunpowder quality by adding liquid during the grinding process to form a moist paste known as mill cake. In 1857, Lammot du Pont patented a method to coat powder grains with graphite dust to reduce moisture absorption.
The last remaining gunpowder mill at Waltham Abbey closed in October 1976. The Home Office removed gunpowder from its list of permitted explosives shortly after World War I ended.