[The first paragraph of this note covers all of the Unbound Notes and Drawings for Part I.]
The loose technical notes and drawings constituting this collection cover the years 1873-1878. They relate to a variety of subjects, including telegraphy, electric lighting and power, the electric pen and duplicating press, the telephone, and the phonograph. There are also documents pertaining to various other subjects, such as carbon rheostats, acoustic devices, the tasimeter, and the voltameter. The unbound notes and drawings are organized by year and within each year by subject. Undated notes and drawings, organized by subject, follow the dated material.
This folder contains 5 pages of notes, signed by Charles P. Edison and William Carman and dated September 2, 1878, regarding the development of an ink for the blind. A year earlier, Thomas Edison had hit upon the idea of using ink composed of arsenic acid to produce raised characters that a blind reader could feel. The notes in this folder relate to experiments to increase the effect of the arsenic acid by saturating the writing paper in various chemical compounds. Although the experiments in 1878 proved unsuccessful, Edison would periodically return to the idea of developing an ink for the blind. In 1914, for example, he made plans to work with Helen Keller on the project, but the war intervened before anything could be done. Courtesy of Thomas Edison National Historical Park.