This notebook was used by Edison in April 1919. The entries relate to the preparation of iron mix for use in the negative electrode pockets of storage batteries; the mix was made from pure iron and 3 percent yellow mercuric oxide. Included are experiments performed on red iron oxide identified as "giving us trouble at factory." Other experiments involve the iron sulphate used in the production of that iron oxide. Also included are reminders to direct "Miller" (probably Edison's brother-in-law John V. Miller, manager of the Edison Chemical Works) to perform tasks or collect information, along with a list of matters to investigate further. One entry summarizes the results from storage battery tests recorded "from old books," one of which was N-19-04-20.1. The front cover is labeled "Very Important," "Iron Mix Experiments," and "April 22 1919." The pages are unnumbered. Only 18 pages have been used. Courtesy of Thomas Edison National Historical Park.