This notebook covers the period September-October 1891. All entries are by Edison. The book contains notes and drawings regarding the "blue bulb" phenomenon and the reduction of mercury vapor in incandescent lamps. There are also notes on various filament experiments, including entries, numbered 1-19, relating to the deposition of carbon and other compounds on the filaments. Edison's notations indicate that he was often assisted by an experimenter named "Joe," possibly John Joseph Force. The spine is labeled "122." The book contains 187 numbered pages.

Blank pages: 178-185.

Courtesy of Thomas Edison National Historical Park.