This letterbook covers the period September 1881-June 1887. Many of the letters are by Sherburne B. Eaton, general manager of the Edison Ore Milling Co., Ltd. There is also correspondence by Samuel Insull and William H. Meadowcroft. Much of Eaton's correspondence is in the hand of Meadowcroft, acting as Eaton's secretary. The letters relate primarily to the company's project to separate iron ore from black sand at Quonocontaug, Rhode Island. Other letters pertain to the dismantling and disposition of equipment following the cessation of operations in 1883. There are also replies to inquiries about ore separation processes. Among the recipients are John O. Beebe, W. H. Cheesman, and M. R. Conley. The front cover is labeled "The Edison Ore Milling Company, Limited." The book contains 497 numbered pages and an index. Pages 340-497 are blank. Approximately 25 percent of the documents have been selected. Courtesy of Thomas Edison National Historical Park.