Human history and the art of war was forever changed with the invention of firearms. Gunpowder made it happen. The availability, or lack of, gunpowder often meant the winning or loss of a battle. In American history this was most important early in the War of Independence. At the Siege of Boston, the Colonials were able to trap the British forces on the then peninsula of Boston, and eventually to force the British to retreat to Halifax in Nova Scotia, Canada. It was the first great battle of the Revolution, and allowed the Americans the self confidence to pursue the war and eventually gain independence. But, at one point during the nearly 11 month siege, each of the Colonial troops were down to their last 1/2 pound of gun powder. Had the British known the sorry state of supplies they surely would have attacked and won the day, and perhaps have ended the revolution before it had barely begun. Fortunately, as the Colonials became better prepared for war, supplies of gunpowder became more available.
Gun powder is composed of salt peter (potassium nitrate), charcoal and sulfur. When gun powder was first produced there was no science to explain why it worked. People just knew that mixing its parts together produced a powder that exploded. Because there was no chemical understanding, the recipes for its production varied widely, and was especially dependent on the quality of it parts, most particularly the quality of the salt peter.
Sulfur and charcoal are easy, they can be dug or produced in abundance. Salt peter is another matter. It is produced by the mixing together and rotting of plant material, manure, and urine for a period of usually six months. Salt peter (niter) crystals precipitated out of this mixture and were then gathered, then refined. Or, salt peter can be gathered from certain caves, most commonly located in Tennessee, Virginia, Kentucky and Alabama. Dirt from the caves was dug and placed in large wood troughs, then water was poured over the dirt to extract out the salt peter or niter.
But the key part of the production of the salt peter was to mix it with water and cook it in kettles to further refine it. Without the kettles, it couldn’t be refined enough to make effective, reliable gun powder. Without the kettles, the American Revolution, the War of 1812 and the Civil War may have had very different outcomes.
Shortly after the Civil War the chemical industry became much more sophisticated and much better explosives were developed. And the once so important kettles were no longer needed. There are very few left, with most long forgotten or consumed in the scrap metal drives of the World Wars.
There are several still in caves located within National Parks in the South. The DuPont Chemical Co. has two kettles (used by the DuPont’s in the early days of their company) which are displayed at their museum on their original manufacturing grounds. And there is one of these now very rare, and once so important, kettles at this museum.