When Arnold Beckman, a professor of analytical chemistry at the California Institute of Technology, was asked to devise a way to measure acidity in citrus fruit, the resulting “acidometer” revolutionized chemical instrumentation. The innovative features of the pH meter, including its use of integrated electronic technology and all-in-one design, were the basis for subsequent modern instrumentation developed by Beckman and his company.

The plaque commemorating the development reads:

Arnold O. Beckman developed the first commercially successful electronic pH meter while a member of the faculty of the California Institute of Technology. This rugged and portable "acidimeter," which had all necessary components housed in a single unit, allowed scientists to measure acidity accurately and rapidly. It immediately met an important need of the California citrus industry: how to measure the pH of lemon juice. The innovative features of the pH meter, including an early use of integrated electronic technology, were the basis for subsequent modern instrumentation developed by Beckman and Beckman Instruments.