pH Meter

pH Meter

Usage conditions apply
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).
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metal (overall material)
plastic (overall material)
wood (overall material)
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Medicine and Science: Medicine
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National Museum of American History
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