edited by JOHN H. WOTlZ
Southern Illinois University Carbondale, Illinois62901
The Development of the pH Meter D. S. Tarbell a n d A. T. Tarbell Vanderbilt Uniuersity Nashuille, TN 37235 The H~ckman1111meter drsigned hy l h . A. 0. Reckman in 1Y:i.l hrr:~ldedthe Instrumental Riwoltltim, which had profound effects on the nature of chemical and biochemical research. It also led to the development of the Beckman D U spectroph~~tomrter and tu many suhsrquent instruments of ftmtlamenral injpurtnnce in current reiearrh.'l'hcstory nt'the design " of the n~ meter is not readilv accessible. and it is important enough in the history of chemical instrumentation to deserve wider circulation. Arnold 0.Beckmann (h. 1900, B.S., M.S. Illinois, 1922, 1923, Ph.D., Caltech, 1928) had been influenced hy Carl S. Marvel to attend Illinois. He became sensitized to alkylmercury compounds a t Illinois and transferred to Caltech, where he took his PhD with R. G. Dickinson in 1928. He stayed a t Caltech, where he took his PhD with R. G. Dickinson in 1928. He stayed a t Caltech as assistant professor and expected to make his career in academic work. In 1934, however, he was a~oroached hv an Illinois classmate. Dr. Glen J o s e. ~ .hwho , was .. working for the California Fruit Growers Exchange on products from lemons. He was measurina the DH of lemon iuice treated with sulfur dioxide; indicaiors and the hydrogen electrode could not he used, and he was using a glass electrode combined with a sensitive galvanometer, both of which frequently broke. The forerunner of the glass electrode was described by Helmholtz in his famous Faraday Lecture of 1881' and was developed notably by MacInnes and Dole.2 The glass electrodes they used were very thin, and even then the resistance was so high that a sensitive device for measuring current was required. Beckman realized that a thicker and more rugged glass electrode must he used; this would have a higher resistance and would require a different current measuring device. He designed and built an electronic amplifer in his spare time and used it in a new instrument for Joseph. A few months later, Joseph asked him to make another "acidity meter" for him, because the first one was in constant use by other people. This ~~
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suggested to Beckman that there might he a considerable market for his instruments. After talking with leading analytical chemists a t the September 1935 ACS meeting in San Francisco. Beckman visited eight or ten of the eastern scientific supply houses. The m ~ s enomraging r estimntc he gut uns that GO0 instruments, suon called " ~ l m~ter;", l miaht t,i, s.ld in ten years. Actually several hundred thousand f; these instruments have been sold. Beckman started his pH meter manufacture in a 9-ft portion of a garage in East Pasadena, which he rented from the Caltech instrument maker for $5 a month, with two Caltech graduates working part time as employees. They soon moved to larger auarters a t $50 ner month. and in 1936. the first full year i f saies, 444 pH meters were sold. By 1939, nearly 2000 had been sold. and Beckman reluctantlv resiened from Caltech to devote full time to the company,then called National Technical Laboratories. The company soon built its own. quarters on Mission Street in South Pasadena and expansion continued. Beckman found the problems of business fascinating, as well as the technical problems. For example, a chemist in a sugar plant, where the glass electrodes were exposed to hot alkaline solutions, found that the glass dissolved under these conditions. This reauired research on . oro~erties of "elass.. and . over the years hundreds of thousands of samples of glass have been made by the Beckman group to obtain electrodes resistant to alkali, usable in high concentrations of sodium ion, with sufficiently low electrical resistance and with other desirahle properties. Glass electrodes have been developed sturdy enough ground to measure the pH of the . to he stuck into the . soil. The amplifying circuit that Beckman had designed for the pH meter was suitable for measuring the small currents in photo cells. Beckman and his staff designed the DU ultraviolet oneration. The instrument could be used for quantitative determinations, and this aspect was particularly important, because a t the time. around 1940, vitamin A and D concentrates were being widely used and the spectrophotometric assay for vitamin content was far more rapid than animal assays: The D U instruments became workhorses in chemical and biochemical laboratories, and many thousand were sold. Impruvements mere introduced mnttnually ttntil the I ) II line was discontinued in 1976.'
Volume 57, Number 2,February 1980 1 133
Beckman Instruments. Inc.. the name a d o ~ t e din 1940, developed a large number of other instruments, including some for use in World War 11; these played a large role in the Instrumental Revolution and made the company a mnltimillion dollar husiness. Dr. Reckman became a civic leader, was for many years Chairman of the Trustees of Caltech, and was a loyal benefactor of the Institute. The whole enterprise developed by logical steps from the request to design a sturdy instrument to measure the acidity of lemon juice. Acknowledgment
We are indebted to the Centennial Fund of Vanderbilt Universitv for travel funds and to Dr. Arnold 0.Beckman for his kind hospitality and a fascinating interview. 'Helmholtz, H., J Chem Sue., 39,277 (18811; later work hy Haher,
F.. and Klernenslewiez. 2.. Z, fur Pkvs. Chem.. 67.385 (19091. '2~aclnness,D. A., and ~ d e M., : ~ . ~ ~ m~ ch kr r. ni .~ o c . ,52,29'(1930); Ind. En$. ('hem., Anal. Ed.. 1,57 (19291. :'Sources: interview with Dr. Heckman, taped by D. S. T., March 15, 1978; Beckman, A. O., Newcornen Society, Puhlieation, 1032 (1976). 'The history of the D U instruments is described in detail by Reckman, A. 0.. Gallaway, W. S., Kaye, W., and Ulrich, W. F., Anal. Chem., 49, A280 (1977).
134 / Journal of Chemical Education
