This folder contains documents relating to Edison's giant crushing roll technology, which he developed as part of his magnetic ore separation project in the 1890s and subsequently licensed to mining companies. The documents for 1918 pertain to the expiration of Edison's principal patents, the concomitant end of royalties payable by the licensees, and sales of rolls from one company to another. The correspondents include William A. Hardy of the Legal Dept., Edison's personal business secretary Richard W. Kellow, Edison Portland Cement Co. president Walter S. Mallory, TAE Inc. financial executive Stephen B. Mambert, and engineer and former employee William H. Mason.

All of the documents have been selected.

Courtesy of Thomas Edison National Historical Park.