This letterbook covers the period April 1917-March 1918. Most of the correspondence is by Edison and William H. Meadowcroft. Included are items pertaining to Edison's benzol absorbing plants and other chemical manufacturing interests and to the commercial and technical development of his phonograph and storage battery. Also included are letters referring to war-related research, Edison's role as the president of the Naval Consulting Board, and his extended absence from the laboratory beginning in August 1917. Additional items concern members of Edison's family and the collection of books for his library. Among the correspondents are newspaper editor Arthur Brisbane, investors and longtime Edison associates Arthur I. Clymer and Theron I. Crane, industrialist Harvey S. Firestone, political cartoonist Rollin Kirby of the New York World, and representatives of Mitsui & Co.

The spine is stamped "Letters" and is labeled "Lab. Letter-Book 1917." The book contains 698 numbered pages and an index. Approximately 10 percent of the book has been selected.