This folder contains documents relating to Edison's search for platinum to be used in his lamp filament. In the spring of 1879 Edison sent out a circular to the various mining regions, particularly in the West, requesting information about mines and asking for ore samples. Most of the replies were of a very routine nature, with correspondents providing information about mines, prospectors, and mine operators or sending samples of ores to be assayed by Edison's laboratory.
Edison also sent two agents, Frank McLaughlin and William E. Hidden, to locate potential sources of platinum in the western United States and Canada and in the southeastern states. There are numerous letters from McLaughlin and Hidden relating to their searches, as well as some items relating to their expenses. Other correspondents include author and editor Caroline Jenkins Harris of Wilmington, North Carolina, who offered assistance in the platinum search.
Approximately 50 percent of the documents have been selected. The selected items bear extensive marginal comments, many of them in Edison's hand, which indicate the interest that he took in these matters. Letters with no marginal notes or with routine marginalia (such as a request for additional information) have not been selected. Courtesy of Thomas Edison National Historical Park.