- circa 1980
The name of this pH meter model refers to its expanded measurement scale.
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…
- Creator Beckman Instruments, inc.
- Photographer Armstrong & Hess
- Subject Hydrogen-ion concentration--Measurement--Instruments, Scientific apparatus and instruments, and Beckman Instruments, inc.