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 “acidimeter” with its glass electrode was renamed the Model G pH meter in 1937 and produced on a larger scale by Beckman’s company, National Technical Laboratories. This instrument kicked off the rapid development not only of NTL and Beckman Instruments, but also of the electronic scientific instrument industry.
“Operation and Maintenance of the Beckman Model G PH Meter,” n.d. Beckman Historical Collection, Box 18, Folder 27. Science History Institute. Philadelphia. https://digital.sciencehistory.org/works/0p096763c.