Humboldt State University

Robert A. Paselk Scientific Instrument Museum

Early North Coast Scientific Instruments

c. 1850 – c. 1950

Richard Paselk, Curator

Laboratory Instruments for Health and Industry

In the late 19th century instruments began to play a significant role in commercial, food and medical laboratories. Two of the most common and important instruments are featured: the Duboscq Colorimeter and the Beckman Model G pH Meter.

Introduced in 1868, the Duboscq Colorimeter measures concentrations of colored substances in solution by comparison to known (standard) solutions. Dubosc colorimeters were essential tools in industrial and scientific laboratories by the early 20th century. They were critical for blood and urine chemistry in hospital and clinical laboratories. Electronic colorimeters such as the Spectronic 20 displaced them in the mid to late 20th century. Our example was used at the old St. Joseph Hospital. The Sisters of Saint Joseph expanded their ministry to health care with the 1918 flu epidemic. The people of Eureka asked them to continue their successful new mission by reopening a closed hospital. St. Joseph Hospital was established as a result in 1920.

Arnold Beckman invented the modern pH meter at Caltech in 1934 in response to the need for a convenient, accurate way to measure the pH of lemon juice in the California citrus industry.

"Arnold Beckman's instrument for measuring pH was revolutionary in two senses. First, the amplifier itself was an electronic innovation-compact, robust, and (because of its two-vacuum-tube design) highly sensitive to even the smallest of electrical currents. … Second, his idea of building an integrated chemical instrument around the amplifier was equally new. Now a scientist could purchase a precision instrument and start making quick, simple, and reliable measurements. The frustrations of assembly, then measurement, then mathematical calculation all vanished. With the disarmingly simple-looking box Beckman designed, the chemist had only to prepare and position his sample, then read "pH 3.7" off a dial. Not only had the chores disappeared, but the instrument itself required of its users no special expertise in either electrochemistry or electronics: The expertise was in the box." *

The Beckman Model G pH Meter on display is essentially identical to Beckman’s original commercial design of 1935. It was used at Leslie Foods in Oakland, CA.

image icon

Duboscq Colorimeter

image icon

Model G pH Meter


*Thackray, Arnold and Minor Myers, jr. Arnold O. Beckman: One Hundred Years of Excellence. Chemical Heritage Foundation, Philadelphia (2000) p 130.

Museum Home

 HSTC icon
HSTC (1921-34)
HSC 35-53 icon
HSC (1935-1953)
HSC 54-73 icon
HSC (1954-1973)

© R. Paselk

Last modified 228 January 2014