Chemical Education Today
From Past Issues
Laboratory Balances—Perceptions from the Past by Kathryn R. Williams
A number of months ago, while paging through volume 17 (1940), I scribbled a note to myself about a likely topic for a future column. The memo, recently unearthed, gave only the necessary bibliographic data and the title, “Some Famous Balances” (1). I assumed the article reviewed the historical development of laboratory balances, but the author’s name, Ralph E. Oesper, should have been a clue. After reading a few paragraphs, I realized that this piece by the author of more than 100 JCE biographies did not focus on advances in beams, knife edges, and dampers but could pilot a hit TV series, “Balances of the Diligent and Famous”. The article contains vignettes about the balances used by 15 scientists—Henry Cavendish, Joseph Priestley, Antoine Lavoisier, Jöns Berzelius, John Dalton, and Justus Liebig, to name a few. Aside from the accompanying pictures of balances, the passages tell little about the balances per se. Instead, Oesper chose to emphasize the significant results obtained by the men who used the instruments: “Like religions, the natural sciences have relics, and among the relics pertaining to chemistry there are balances made famous either because of the men who used them or because these instruments played an important part in outstanding researches. … The purpose of this paper is not to trace the history of the analytical balance or its use by chemists, but rather to point out that a fairly good summary of the progress of chemistry can be obtained by emphasizing the arms rather than the man.” Throughout its history, the Journal has published scores of articles on various aspects of balances (2). Many pertain to mundane considerations such as buoyancy corrections, calibration of weights, and rest-point determinations. Only two other papers (3, 4) emphasize historical perspectives. Both provide more constructional details than the article by Oesper, but I did not find the descriptions particularly useful. Faculty wanting an overview of balance design for lectures or student reading assignments should definitely consult three comprehensive articles in Galen Ewing’s Topics in Chemical Instrumentation series. The contributions by Roland F. Hirsch from the late 1960s (5, 6) describe prima-
Figure 1. Sketch from an advertisement for Ivory. Originally printed in Harpers’ Magazine, 1883 (1).
rily lever-arm balances, including the fundamental physics, as well as clear explanations of both the single- and doublepan designs and the construction of key components. There are also sections on strain gauges and automatic balances. About a decade later, Ewing (7) added a discussion of electronic balances and a survey of commercial instruments available at the time. The advertisements for balances and related equipment that are interspersed throughout these articles are also interesting and provide much information. Compared to the trilogy from Topics…, Oesper’s paper provides little understanding of balance construction. Nor was continued on page 436
“As the usefulness and accuracy of chemistry depends entirely upon the determination of the weights of the ingredients and products before and after experiments, too much precision cannot be employed in this part of the subject; and, for this purpose, we must…have balances made with peculiar niceness by accurate workmen.” Antoine Lavoisier, “Elements of quoted in J. Chem. Educ. 1940, 17, 315. Figure 2. Lavoisier’s Large Balance (1, Fig. 4).
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Journal of Chemical Education • Vol. 78 No. 4 April 2001 • JChemEd.chem.wisc.edu
chemistry”;
Chemical Education Today
From Past Issues continued from page 434
I overly impressed with Oesper’s attempt to show the link between instrumentation advances and scientific progress. Nevertheless, from my 21st-century perspective, I found another message, which I’m sure the author appreciated as well. I refer to the notion of the balance as a personal device, to the oneness of an instrument and its user. We live in a world of mass-produced every- Figure 3. John Dalton’s balance, thing—from hamburg- made by Accum (1, Fig. 5). ers to computers (their moniker “PCs” notwithstanding). Oesper reminds us of a time when most laboratory apparatus was custom fabricated, when scientist and instrument worked together as partners. I now realize that Lavoisier, Liebig, Priestley, and other experimentalists of the 18th and 19th centuries perceived their balances much the same as musicians experience their strings and winds. I will henceforth conjure both images when I use the word “instrument”.
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“…the balance, that incomparable instrument, which gives permanence to every observation, dispels all ambiguity, establishes truth, detects error, and shows us that we are in the true path.” Justus Liebig, “Familiar letters on chemistry”; quoted in J. Chem. Educ. 1940, 17, 318.
Literature Cited 1. Oesper, R. E. J. Chem. Educ. 1940, 17, 312–323. 2. The online index found 101 hits with “balance” in the title field, although about one-half are concerned with equationbalancing or the proper balance of an instructional program. 3. Stock, J. T. J. Chem. Educ. 1968, 45, 254–257. 4. Stock, J. T. J. Chem. Educ. 1976, 53, 497–498. 5. Hirsch, R. F. J. Chem. Educ. 1967, 44, A1023–A1048. 6. Hirsch, R. F. J. Chem. Educ. 1968, 45, A7–A40. 7. Ewing, G. W. J. Chem. Educ. 1976, 53, A252–A299.
Kathryn R. Williams is in the Department of Chemistry, University of Florida, PO Box 117200, Gainesville, FL 326117200;
[email protected].
Journal of Chemical Education • Vol. 78 No. 4 April 2001 • JChemEd.chem.wisc.edu
