At last, the experiment you have all been waiting for. Purifying saltpetre.
As we all know, it is one of two critically important ingredients for gunpowder, the other being charcoal. The latter is easy enough to make, but saltpetre is a lot harder. The medieval folks at the Danish Mittelalter centre tried for several years before 2010 to make it and didn’t succeed. More recently, Haileigh Robertson has been working on a PhD related to gunpowder, and has made crude saltpetre at the centre, but there are major problems with the impurities, which render it of very low quality.
Saltpetre is a comparatively recent arrival in Europe. It was almost certainly imported from the middle east in the 12/13th centuries, and in the early 14th we have the evidence for its use in making gunpowder for cannon, but it was very expensive. However over the next century the price dropped greatly, making it much easier to buy and use, helping fuel the use of cannon and bombards, the latter having calibres of a foot and more and requiring several kilograms of blackpowder to fire.
Like anything else though, saltpetre needs to be pretty pure to be useful. So I thought I’d have a go at purifying it myself. Continue reading