This notebook was used by Frank Detlef, Jr., during January-September 1920 as a daily record of analysis of electrolytes used in disc record plating. Detlef took samples and calculated specific gravity, acidity, and the amount of nickel, copper, iron, and aluminum. Inserted into the book are two notes by Edison regarding items to which he wanted Detlef to pay attention. Detlef refers to Edison\'s oversight at several points with phrases such as \"Mr. Edison says\"" or \""keep Mr. Edison informed.\"" There are also references to work by Ludwig F. (Louis) Ott, as well as some loose notes [not selected] in Ott\'s hand. The flyleaf is marked \""F. Detlef Book #2 - on Electrolyte Control for the Disc Record plating dept.\"" The pages are unnumbered. Approximately 125 pages have been used.

The entries from January have been selected as a representative sample. Several loose notes by Edison have also been selected."