This folder contains correspondence and other documents concerning the technical and commercial development of Edison's technologies for ore concentration. The documents relate primarily to Edison's collaboration with Henry B. Clifford, a mine and mill operator who employed longtime Edison associate James B. Ballantine as his engineer and experimenter. Among the other correspondents for 1913 are industrialist James Gaunt, chemical engineer Alcan Hirsch, journalist and diplomat Joaquin Mendez, longtime Edison associate William S. Perry, and the firm of Pilling & Crane. There are also references to Edison's earlier ore milling enterprises, including the New Jersey and Pennsylvania Concentrating Works, the Edison Ore Milling Co., Ltd., and the Dunderland Iron Ore Co., Ltd.

Approximately 80 percent of the documents have been selected. The unselected documents consist of letters of transmittal and unsolicited inquiries that received no substantive reply from Edison.