pH Meter


A pH meter measures the acidity of aqueous solutions. When asked about a meter suitable for testing citrus fruit, Arnold Beckman, a young chemist at the California Institute of Technology, designed one with glass electrodes, and introduced a prototype at the American Chemical Society meeting in 1935. Most instrument dealers were deterred by the cost (about $195), but with encouragement from Arthur H. Thomas, in Philadelphia, Beckman established the National Technical Laboratories in Pasadena, and began production. The firm became Arnold O. Beckman, Inc. in the 1940s, and later Beckman Instruments, Inc.

This example came from the National Bureau of Standards. The inscription on a metal tag reads “A. Beckman Instrument Patents Issued and Pending Serial No. 5956 Model G Manufactured in U.S.A. by National Technical Laboratories – South Pasadena, Calif.” The Model G was introduced in 1937.

Maker: National Technical Laboratories

Location: Currently not on view

See more items in: Medicine and Science: Chemistry


Exhibition Location:

Credit Line: Transfer from Excess Property, National Bureau of Standards

Data Source: National Museum of American History

Id Number: CH.326627Catalog Number: 326627Accession Number: 261654

Object Name: pH Meter

Measurements: battery 3: 2 3/4 in x 4 in x 7/8 in; 6.985 cm x 10.16 cm x 2.2225 cmbox: 28 cm x 28.5 cm x 21.5 cm; 11 in x 11 1/4 in x 8 7/16 inbattery 1: 4 in x 2 5/8 in x 2 5/8 in; 10.16 cm x 6.6675 cm x 6.6675 cmoverall in box: 11 1/2 in x 11 1/4 in x 8 1/4 in; 29.21 cm x 28.575 cm x 20.955 cm


Record Id: nmah_2500

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