Borrowing from Industry - ACS Symposium Series (ACS Publications)

Chapter 31

Borrowing from Industry

Downloaded by UNIV OF CALIFORNIA SAN DIEGO on April 5, 2016 | http://pubs.acs.org Publication Date: January 1, 1989 | doi: 10.1021/bk-1989-0390.ch031

Edgar Fahs Smith's Rotating Anode and Double-Cup Mercury Cathode Lisa M a e Robinson Department of Natural Science, Michigan State University, East Lansing, M I 48824 From 1890 to 1910, Edgar Fahs Smith and his students at the University of Pennsylvania brought electrolysis into standard analytical practice by developing two new techniques designed to make electrolytic separation easier and faster. They pioneered the development of several electrochemical analytical techniques, the best known of which are the rotating anode and the double-cup mercury cathode. In 1903, Smith and his doctoral student, Franz Frederick Exner developed a rotating anode expressly for industrial analytical practice that greatly reduced the time needed for analysis. The next year, Smith and another doctoral student, Joel Henry Hildebrand, created a double-cup mercury cathode by explicitly borrowing the basic operating principle of Dow Chemical Company's Castner-Kellner electrolytic cell. These inventions illustrate the interrelationship between industrial and academic science in the early twentieth century that produced a flow of ideas and methods in both directions. The research of Edgar Fahs Smith and his students at the University of Pennsylvania represents an attempt to bring electrolysis into standard analytical practice and to revolutionize mineralogy. From 1890 until 1910, Smith and his students developed two new electrolytic analytical techniques, the rotating anode and the double-cup mercury cathode that gave a simpler and faster electrolysis with a more complete separation. Smith and his students published a total of twenty-six papers exploring the uses of these techniques, which Smith further promoted through his widely-used textbook, Electrochemical Analysis. (1-2) Edgar Fahs Smith (1854-1928) had been trained at the University of Göttingen under Friedrich Wöhler in both mineralogy and 0097-6156/89/0390-0458$06.00/0 © 1989 American Chemical Society

Stock and Orna; Electrochemistry, Past and Present ACS Symposium Series; American Chemical Society: Washington, DC, 1989.


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Rotating Anode and Double-Cup Mercury Cathode

analytical chemistry. Smith believed that electrolysis would prove to be particularly useful in the analysis of minerals, claiming in 1909 that the day is coming when we shall analyze a great many minerals in the electrolytic way. If you ask me how we are going to do it, I do not know, but we are going ahead and shall try to do it. What the method will be no one knows, but something will come. (3) Smith was confident that he and his students could provide the methods necessary to take mineral chemistry in a new direction. However, mineral chemists turned to other techniques and derived their inspiration mainly from geology, not chemistry. Smith's electroanalytical techniques did find an appreciative audience among industrial chemists concerned with the electrolytic production of heavy chemicals, especially chlorine. Ironically, this was the one group of chemists that Smith had no interest in reaching, for he despised their interest in profit from scientific research. (4-5) An examination of Smith's electrochemical research reveals some interesting facets of the relation between academic research and industry. First, it shows that even very academically-oriented research can be useful to the improvement of industrial processes. Second, we see that academic research is not totally isolated from industrial developments and industry can provide valuable models for academic research. Finally, Smith's work reveals that research has unintended and perhaps unwanted influences on academic science. However much Smith wanted to revolutionize mineralogy or analytical chemistry, chemists would use Smith's techniques in ways he never intended or imagined. Electrolysis began to acquire importance in analytical chemistry in the last quarter of the 19th century. The first American study was done in 1864 by Oliver Wolcott Gibbs, who investigated the electrolytic determination of copper and nickel and described methods for electrolytically analyzing silver, bismuth, lead, and manganese. Although others later claimed prior use of electricity for analytical purposes, most chemists (including Edgar Fahs Smith) saw Gibbs as the father of American electrochemistry. (6) The Rotating Anode Smith's first contribution to the development of electroanalytical techniques was the rotating anode. Smith became interested in the idea of anode rotation in 1901 while attempting the separation of molybdenum from tungsten. He could not obtain a satisfactory separation because a tungsten oxide that contaminated the molybdenum always formed during electrolysis . Smith tried rotating the anode to agitate the solution, thereby preventing local reactions around the anode from interfering with the precipitation of the molybdenum. He devised his own agitating apparatus, but did not publish this research at the time. (7-9)


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During the next two years, Smith and Franz Frederick Exner (1868-1950), one of his doctoral students, refined the rotating anode for use in the separation of molybdenum from tungsten. They found that its rotation at high speed allowed the application of a more intense current and a higher voltage. The more intense current caused a more rapid precipitation of metals, greatly reducing the time needed for electrolytic precipitation. They tried this new technique on the precipitation of copper, silver and mercury with great success. The reduction of analysis time was the most important, although unintended, result of Smith and Exner's research. Electrolytic precipitation using the old methods usually took from three to twelve hours, and Smith regularly applied electric current to solutions for the entire night. The rotating anode with its more powerful current accomplished complete electrolytic separations in ten to twenty minutes, a significant reduction indeed. Exner was very keen on seeing electrolytic methods replace traditional volumetric and gravimetric methods of analysis in industry and believed that the rotating anode would be a breakthrough in industrial analytical practice. In his doctoral dissertation, he stressed the importance of analytical speed for industry, speed that could be best obtained through electroanalysis. The time factor is a most important one to the technical man, and has no doubt made many slow to exchange their old and tried methods for the new, on the ground that the advantages of the change were not sufficiently pronounced. This investigation, it is believed, will be sufficient to convince the hitherto most skeptical, concerning the advantages of electrolytic analysis, as far as the time factor is concerned. (10) Exner's dissertation, which appeared in part in the Journal of the American Chemical Society in 1903, was the first publication on the rotating anode. Using a strong current with an anode rotating at high speed, Exner investigated the effect on the precipitation of various metals. He successfully precipitated copper, nickel, zinc, bismuth, mercury, cobalt, cadmium, iron, lead, molybdenum, tin, antimony, gold, and silver. His attempted precipitations of arsenic and manganese were unsuccessful. (11) Exner's anode (Figure 1), made by the Electrochemische Werkstatte of Darmstadt, Germany, consisted of a flat platinum spiral two inches in diameter. It could rotate from 300 to 1700 revolutions per minute, although Exner found that 600 to 700 revolutions per minute worked for most precipitations. His critical design problem was maintaining constant contact between the anode and solution. As the flat spiral anode whirled the electrolyte against the side of the dish, the solution formed a vortex. The bottom of this funnel often dipped below the anode, losing contact with it, and thereby increasing the solution's resistance. Exner solved this problem by bending the anode into a


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Figure 1. The rotating anode used by Exner and Smith. (Reproduced with permission from the Edgar Fahs Smith Memorial Collection, Van Pelt Library, University of Pennsylvania.)



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bowl shape, so that as the funnel formed, the anode remained in contact with it. He also found that this anode shape stirred the solution more effectively and completely, thereby further aiding electrolysis. The next year, in 1904, Smith himself published a paper on possible uses for the rotating anode. In it he presented the work of George H. West, an undergraduate student, and Lily Gavit Kollock, a doctoral candidate. West successfully used the rotating anode to precipitate nickel, while Kollock produced pure cobalt. Smith also mentioned Exner's thesis on the precipitation of various metals, as well as the dissertations of two other graduate students. He concluded that the rotating anode would be most effectively used in conjunction with the mercury cathode and referred readers to his recent paper on this device. (12-16) The Mercury Cathode Smith first published his experiments with the mercury cathode in September 1903 in the Journal of the American Chemical Society. He reported various attempts at the electrolytic separation of various metallic sulfates, nitrates, and halides. Smith used the best available mercury cathode that consisted of a beaker of mercury into which extended a hollow, carbon-tipped glass tube, also full of mercury. A copper wire inserted into the beaker's mercury through the glass tube and connected to the battery's negative electrode made the mercury into a cathode. A thin platinum wire inserted through the wall of the beaker served as the anode. Smith found this arrangement unsatisfactory for two reasons. First, the mercury in the beaker was difficult to dry and required repeated washing with ether and alcohol to remove all traces of water. Second, some of the metal electrolyte usually precipitated on the platinum anode, which then had to be weighed along with the mercury. (17-18) During the course of these experiments, William H. Howard, an undergraduate student in Smith's laboratory, devised a new mercury cathode (Figure 2) that solved the problem of weighing the mercury. Howard's cathode was a small beaker of mercury penetrated at the bottom by a thin platinum wire that connected the mercury with a copper disk underneath the beaker. Another wire connected the disk to a battery's negative electrode, making the mercury into a cathode. Since the platinum wire was imbedded into the beaker, any precipitant adhering to it would be weighed along with the mercury. However, accurate atomic weight determination still required repeated washing and drying of the amalgam. (19) Three years later Joel Henry Hildebrand (1881-1983), one of Smith's doctoral students, developed an improved configuration for the mercury cathode during the course of his dissertation research. Hildebrand's thesis attempted the simultaneous electrolytic determination of both components of various electrolytes, especially sodium chloride. He pointed out that little work had been done previously on the electrolysis of salts or anions. Smith's preliminary study in 1903 of simultaneous



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Figure 2. The mercury cathode used by Smith in 1903. (Reproduced with permission from the Edgar Fahs Smith Memorial Collection, Van Pelt Library, University of Pennsylvania.)



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electrolysis used a stationary silver anode and a mercury cathode like the one developed by William Howard. In 1905, James Renwick Withrow, also Smith's student, completed his doctoral thesis on the simultaneous precipitation of gold halides and used a similar mercury cathode with a rotating anode. Hildebrand proposed to use an improved mercury cathode, which he called the double-cup, with a rotating anode. (20-22) The electrolysis of salt (sodium chloride) was also the object of continued interest by the electrochemical industry. The Dow Chemical Company, for example, had a long-standing interest in the electrolysis of salt, and they began an extensive, in-house research campaign in 1908 in order to produce sodium hydroxide (caustic soda) and chlorine. Hildebrand's dissertation was not overtly directed towards industrial problems, but his successful electrolytic separation of common salt legitimated such an industrial research campaign by showing that such an electrolytic separation was possible. Hildebrand's academic research provided Dow with new ideas for their industrial research. (23) Hildebrand's thesis is also a case where developments in industry provided ideas and models for academic research. Hildebrand based his double-cup mercury cathode on the Castner-Kellner process for the industrial production of caustic soda. This process, which has been called the "most elegant electrolytic process ever invented," was patented in 1894 by Hamilton Castner, an American analytical chemist. By 1902, Castner had increased its efficiency to 90 percent. The heart of the process was Castner's "rocking" mercury cell. The cell had two chambers through which mercury moved back and forth, continuously removed metallic sodium from the decomposing chamber, thus preventing the recombination of the sodium and chlorine. (24) Hildebrand's double-cup mercury cathode employed two of Castner's innovations, the continuous removal of the product and the use of two electrolytic chambers or cells. Hildebrand's cathode consisted of a bottomless beaker resting on a thin, Y-shaped glass rod that supported the beaker slightly above the bottom of a larger glass dish. Three rubber stoppers fitted between the dish and the beaker kept the beaker securely in position. A thin layer of mercury filled the bottom of the dish, while the arrangement of the bottomless beaker formed two sections for the mercury, which were connected sufficiently to permit passage of current and ions, yet were separate enough to prevent recombination of ions. The solution to be electrolyzed was put into the inner compartment and distilled water covered the mercury in the outer compartment. As the cations slowly moved into the outer compartment, they dissolved in the mercury of the inner compartment. The anions remained behind in the inner compartment and therefore did not recombine with the cations. A platinum wire dipped into the outer compartment connected the mercury to the battery. After completing the electrolysis, the entire contents of the dish (and beaker) were poured off for separation, washing, drying, and weighing. (25)



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Hildebrand combined his new mercury cathode with the rotating anode developed by Smith and Exner the previous year. This anode spun freely in the electrolytic solution in the inner compartment. The next year (1907), Thomas Potter McCutcheon, Jr. used both the rotating anode and the double-cup mercury cathode (Figure 3) in his doctoral thesis on electroanalysis. McCutcheon slightly modified the rotating anode by using a wire mesh at the bottom of the spinning rod, rather than a wire coil. He also modified the double-cup cathode by resting the inner beaker on a triangular glass rod for greater stability. (26) Hildebrand's and McCutcheon's dissertations marked the apex of development for the rotating anode and the double-cup mercury cathode. Smith and his students continued to used these techniques for three more years until Smith became Provost of the University of Pennsylvania in 1910. The responsibilities of this office caused Smith to cut back the time he spent on his scientific research and limit the number of graduate students he trained. Consequently, with the advent of Smith's new administrative duties, the rotating anode and double-cup mercury cathode ceased to be objects of active research. Conclusion While the rotating anode and the double-cup mercury cathode were useful analytical techniques and enjoyed a brief popularity with analytical chemists, they did not find an enduring audience. Analytical chemists retained their reliance on chemical means of separation and essentially forgot their brief fascination with electrolysis. Neither did Smith succeed in revolutionizing mineralogy, which again relied more on gravimetric and volumetric methods of analysis. While those physical chemists interested in describing the behavior of ions in solutions used electrolytic techniques, Smith himself deplored their use of mathematical models. Indeed, Smith's most promising student, Joel Henry Hildebrand, left Smith and the University of Pennsylvania amid much bitterness in order to pursue the study of solution theory. The group that most appreciated Smith's work were industrial chemists concerned with the electrolytic production of heavy chemicals. Ironically, this was the one group of chemists that Smith had absolutely no interest in reaching, for he despised their concern with profits. (27-29) The development of the rotating anode and the double-cup mercury cathode reveals the complex interaction between academic science and chemical industry. At first glance, we see that the research of Smith and his students furthered knowledge about electrolytic separation, knowledge that was greatly needed by the growing electrochemicals industry. But a closer examination of this research reveals three ways in which these academic chemists borrowed from their industrial cousins. The search for speed in electrolytic separations was fueled by the importance of time for industrial analyses. Smith and Exner developed the rotating anode, in part, because they wished to see electrolytic techniques adopted


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Figure 3. The double-cup mercury cathode developed by Thomas McCutcheon in 1907. (Reproduced with permission from the Edgar Fahs Smith Memorial Collection, Van Pell Library, University of Pennsylvania.)



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by industrial chemists. Another borrowed concern was the choice of problem. Smith and Hildebrand chose to investigate the electrolysis of salt, again in part, because it was a pressing problem for electrochemical producers. Finally, Smith and Hildebrand borrowed directly from industry when they used the Castner-Kellner cell as a model with which to redesign their mercury cathode. The development of the rotating anode and the double-cup mercury cathode reminds us that industrial science is not merely a parasite of academic science, consuming useful ideas to feed profits. Rather, it also provides possible directions for academic research and valuable methods to facilitate that research. Acknowledgments I would like to thank P. Thomas Carroll, John Servos, Anthony Stranges, Jeffrey Sturchio, and Arnold Thackray for their comments on this paper. Literature Cited 1. 2. 3. 4.

5. 6. 7. 8. 9. 10.

11. 12. 13.

14.

15. 16.

Smith, E. F. Electrochemical Analysis [6 editions]; Philadelphia, 1890-1918. Robinson, L. M. "The Electrochemical School of Edgar Fahs Smith" Ph.D. Thesis, University of Pennsylvania, 1986. Smith, E. F. Trans. Am. Electrochem. Soc. 1909, 16, 65-77; quote on p 76. Smith,. E. F. "Address at Franklin and Marshall College on the occasion of the Dedication of a Science Hall" (manuscript, 1907) in the Edgar Fahs Smith Memorial Collection, University of Pennsylvania (hereafter referred to as EFSC). Easton, W.; Ross, S. Letters in The John Harrison Letter [March 1906] in EFSC. Ihde, A. The Development of Modern Chemistry: Dover: New York, 1984; pp 292-293. Smith, E. F. Electrochemical Analysis: Philadelphia, 1918; pp 40-41. Von Klobukow, J. Prakt. Chem. 1886, 33, 473. Von Klobukow, J. Prakt. Chem. 1873, 40, 121. Exner, F. F. "The Rapid Precipitation of Metals in the Electrolytic Way" Ph.D. Thesis, University of Pennsylvania, 1903; p 1. Exner, F. F. J. Am. Chem. Soc. 1903, 25, 896-907. Smith. E. F. J. Am. Chem. Soc. 1904, 26, 1595-1615. Ashbrook, D. S. "Electrolytic Separations Possible with a Rotating Anode" Ph.D. Thesis, University of Pennsylvania, 1904. Ingham, L. H. "The Use of a Rotating Anode in the Electrolytic Estimation of Zinc and of Nitric Acid" Ph.D. Thesis, University of Pennsylvania, 1904. Kollock, L. G. "Electrolytic Determinations and Separations" Ph.D. Thesis, University of Pennsylvania, 1899. Smith, E. F. Electrochemical Analysis: Philadelphia, 1918; pp 40-63.


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21. 22.

23. 24.

25.

26. 27. 28. 29.

ELECTROCHEMISTRY, PAST AND PRESENT Smith, E. F. J. Am. Chem. Soc. 1903, 25, 883-96. Drown and McKenna, J. Anal. Appl. Chem. 1891, 5, 627. Smith, Electrochemical Analysis: 1918; pp 63-71. Hildebrand, J. H. "The Determination of Anions in the Electrolytic Way" Ph.D. Thesis, University of Pennsylvania, 1906. Smith, E. F. J. Am. Chem. Soc. 1903, 25, 890. Withrow, J. R. "The Electrolytic Precipitation of Gold with a Rotating Anode and the Rapid Analysis of Halide" Ph.D. Thesis, University of Pennsylvania, 1905. Campbell, M; Hatton, H. Herbert H. Dow: Pioneer in Creative Chemistry: Appleton-Century-Crofts: New York, 1951; pp 89-101. Trescott, M. M. The Rise of American Electrochemical Industry. 1870-1910: Greenwood Press: Westport, CT, 1981; p 448. Hildebrand, J. H. "The Determination of Anions in the Electrolytic Way" Ph.D. Thesis, University of Pennsylvania, 1906. McCutcheon, Jr., T. P. "New Results in Electro-Analysis" Ph.D. Thesis, University of Pennsylvania, 1907. Hildebrand, J. H. Perspectives in Biology and Medicine Autumn 1972, 16, 93-95. Browne, C. A. "Reminiscences of Edgar Fahs Smith" manuscript, 1926, p 53 in EFSC. Smith, E. F. "Address at Franklin and Marshall College on the occasion of the Dedication of a Science Hall" manuscript, 1907 in EFSC.

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Borrowing from Industry - ACS Symposium Series (ACS Publications)

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