"On the banks of the Merrimack and the Gasconade are found numerous caves, which yield an earth impregnated largely with nitre, which is procured from it by lixiviation. On the head of Current's river are also found several caves from which nitre is procured, the principal of which is Ashley's cave, or Cave Creek, about eighty miles south-west of Potosi. This is one of those stupendous and extensive caverns, that cannot be viewed without exciting our wonder and astonishment, which is increased by beholding those complete works for the manufacture of nitre, situated in its interior

"The native nitrate of potash is found in beautiful white crystals, investing the fissures of the limestone rock which forms the walls of this cave; and several of those in its vicinity exhibit the same phenomenon." - -Schoolcraft, on the Lead Mines of Missouri