2019-01-092019-01-09MS 30 Gilliam Family Collection, Eva G. Farris Special Collections, W. Frank Steely Library, Northern Kentucky University.http://hdl.handle.net/11216/2571Postcard of a picture of the Salt Petre Vats with people standing on a walkway in Mammoth Cave, Ky.jpegen-USThis postcard is in the public domain, so this image may be freely used.Gilliam FamilyMammoth Cave (Ky.)Caves--Kentucky--Mammoth CaveImage, postcard