This advertisement for the Model W pH meter promotes its use in monitoring pH levels of wood pulp stock to ensure equipment works properly at the Bowaters Southern Paper Corporation.

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.