This letter spells out the instrument maintenance and upgrades that the California Fruit Growers Exchange believe are included with the cost of developing the "glass electrode apparatus" (an early prototype of the Beckman pH meter).

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.