This notebook was used by Edison in April 1919 for experiments with electromotograph cylinders and chemically treated papers. Included is a list of substances tried as molded cylinders in an electromotograph (chalk) telephone, along with notes on the relative sensitivity of various recording papers. The entries in this book relate to those in N-19-04-23.2 and also to one of the 1919 entries in N-08-02-13 (Thomas A. Edison Papers: A Selective Microfilm Edition, Part IV (1899-1910)). The front cover is marked "Scientific Experiments April 20 1919." The pages are unnumbered. Only 9 pages have been used. Courtesy of Thomas Edison National Historical Park.