Arnold Beckman invented his first pH meter in 1934 at the request of a chemist from the California citrus industry, who needed an accurate way to measure the acidity of his product. The resulting instrument kicked off rapid development not only of Beckman Instruments, Inc. but also of the electronic scientific instrument industry.
Beckman, Arnold O. “The Development of PH Instrumentation,” April 1950. Beckman Historical Collection, Box 19, Folder 20. Science History Institute. Philadelphia. https://digital.sciencehistory.org/works/z029p529v.