When Military Might Relied on Urine

A look at the chemistry behind the historical production of saltpeter from urine

17th century ancient flintlock musket with powder flask and led bullets on wooden deck.

Gunpowder has come to dominate battlefields since the 15th century (1400 to 1500). It is an explosive mixture of potassium nitrate (KNO₃), charcoal (C) and sulfur (S).

Gunpowder is made from 75% potassium nitrate, 15% charcoal and 10% sulfur

Charcoal and sulfur are relatively easy to obtain. The challenge is obtaining potassium nitrate, also known as saltpeter and niter, which historically made potassium nitrate an extremely important strategical resource. That is why this story will be all about potassium nitrate.

There are many accounts of historical saltpeter production. However, each time I read one of these accounts I was left scratching my head because the whole process seemed so utterly bizarre. I wrote this story for those, who like me, are curious about the science behind historical saltpeter production.