This undated notebook was used by Edison, probably during June 1911. The entries report on the evaluation of various chemicals from E. De HaŽn of Hanover, Germany, for use in making phonograph records. Individual entries note the melting points, hardness or viscosity, character of crystallization, and sometimes the price of the compounds being tested. The inside back cover contains some rough calculations by an unidentified employee. Inserted into the book is an unrelated memorandum from Peter Christensen to Edison regarding an electrolyte produced in June 1911. The pages are unnumbered. Only 12 pages have been used. Courtesy of Thomas Edison National Historical Park.