Saltpetre Mining
The term “petre cave” refers to the presence of calcium nitrate, in the soil of the cave. Nitre, put through a simple process, could be converted into potassium nitrate, or “saltpetre.” Saltpetre, combined with sulfur and charcoal, creates a good grade of black gunpowder.
The slaves began their work by hollowing out long logs of tulip poplar using "spoon-bit" augers. Many of these logs were hollowed out to make a pair of wooden pipelines extending over 1/3 of a mile. Square leaching vats were then built. They set up a collection of troughs below the vats and a pump tower in the center of the site. When everything was done, they set it into motion.They led oxen deep into the caves to gather cave soil. The soil was then put into the vats. Then, water was poured over the soil. The water would leech out the nitre and it would fall into the troughs. A slave would pump the nitre back to the surface, where others would transform the nitre into saltpetre crystals. Then, these saltpetre crystals would later be turned into gunpowder.
The slaves began their work by hollowing out long logs of tulip poplar using "spoon-bit" augers. Many of these logs were hollowed out to make a pair of wooden pipelines extending over 1/3 of a mile. Square leaching vats were then built. They set up a collection of troughs below the vats and a pump tower in the center of the site. When everything was done, they set it into motion.They led oxen deep into the caves to gather cave soil. The soil was then put into the vats. Then, water was poured over the soil. The water would leech out the nitre and it would fall into the troughs. A slave would pump the nitre back to the surface, where others would transform the nitre into saltpetre crystals. Then, these saltpetre crystals would later be turned into gunpowder.