Model 3 Ph Electrometer


A pH meter measures the acidity of aqueous solutions. The first modern example was designed in the 1930s by the chemist, Arnold Beckman. This one was made by Coleman Electric in the 1940s.

A paper label in the lid reads “Directions for Model 3 pH Electrometer.” The inscription on a metal label reads “INST No. 3305 / Model 3B / COLEMAN ELECTRIC CO., INC. / PAT. PEND. / MAYWOOD, ILL.” A metal tag on the front of the case reads “A GIFT FROM / WASHINGTON CHAPTER NO. 4 / WOMEN’S ORGANIZATION OF THE / NATIONAL ASSOCIATION OF RETAIL DRUGGISTS.”

The Coleman Electric Company of Maywood, Illinois, was formed by Edwin Dewitt Coleman in the 1930s, made “precision tools for the technologist” during World War II, and became Coleman Instruments in the 1940s. Coleman submitted his patent application for this instrument in January 1939

Ref: Edwin D. Coleman, “pH Measurement and Control Device,” U.S. Patent 2,311,976 (Feb. 23, 1943).

Location: Currently not on view

See more items in: Medicine and Science: Medicine


Exhibition Location:

Credit Line: George Washington University, School of Pharmacy

Data Source: National Museum of American History

Id Number: MG.M-11108Catalog Number: M-11108Accession Number: 259201

Object Name: Electrometer

Physical Description: metal (overall material)plastic (overall material)wood (overall material)


Record Id: nmah_722091

Our collection database is a work in progress. We may update this record based on further research and review. Learn more about our approach to sharing our collection online.

If you would like to know how you can use content on this page, see the Smithsonian's Terms of Use. If you need to request an image for publication or other use, please visit Rights and Reproductions.