This undated notebook was probably used during February 1910 and was annotated at least once after that date. All entries are by Edison, and many entries were later marked "Ent[ered]" and copied by him into the undated notebook, N-19-04-20.1. Included are a log of storage battery cell tests and extensive notes regarding the chemical reactions involved in the discharge and charge of cells. Inserted into the book are loose notes by Edison and a one-page entry by Walter E. Holland, dated February 1910, regarding the cell tests. The front cover is marked "Iron" and is labeled "Iron Book." The pages are unnumbered. Approximately 60 pages have been used.