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Heyrovský, Jaroslav

Heyrovský, Jaroslav

(b. Prague, Czechoslovakia, 20 December 1890; d. Prague, 27 March 1967)

electrochemistry.

Heyrovský studied mathematics, physics, and chemistry in the Czech section of the Prague university (then called Charles-Ferdinand University), which he entered in 1909. There he was especially influenced by the physicists František Zāviška and Bohumil (Gottlieb) Kučera and by the chemist Bohumil Brauner, who had studied in Manchester under Roscoe and was well known for his work on rare earths. Perhaps the example of Brauner and the fame of Sir William Ramsay influenced Heyrovský to continue his studies in England. He entered University College, London, in 1910, and received the B.Sc. in 1913. It was an unusual step, since at that time most Czech graduate students tended to complete their education in Germany, France, or Switzerland. Attracted to electrochemistry, a subject close to the heart of F. G. Donnan, who had succeeded Ramsay, Heyrovský began a Ph.D. thesis on the electrochemical properties of aluminum.

World War I began while Heyrovsky was on holiday in Prague, and he was prevented from returning to London. After working for a short time in one of the chemical laboratories of Charles-Ferdinand University, in 1915 Heyrovský was drafted into the Austro-Hungarian army and spent the war years as a dispensing chemist and roentgenologist in a military hospital. This occupation apparently did not take up all his time and Heyrovský was still able to pursue his research interests; in the autumn of 1918 he submitted his Ph.D. thesis on the electroaffinity of aluminum.

After the war Heyrovský became an assistant to Brauner and continued to work on the chemistry of aluminum. His habilitation thesis, which qualified him in 1920 to become a docent in physical chemistry, dealt with the constitution and acidity of aluminic acid. There papers summarizing his work on the electrochemical properties of aluminum (1920) brought him the D.Sc. from the University of London a year later.1 Heyrovský academic rise in Czechoslovakia was swift; in 1924 he became extraordinary professor and director of the newly established Institute of Physical Chemistry; and four years later he was appointed full professor in physical chemistry at Charles University.

Shortly after the German occupation of Prague in 1939, Czech universities were closed and their institutes and laboratories taken over by professors from German institutions. The holder of the chair in physical chemistry at the German University in Prague was J. Böhm, a former co-worker with Haber and Hevesy, “a unique character and highly qualified scientist.” 2 of mixed Czech-German parentage (his mother was Czech), he had no sympathies with Nazism and made it possible for Heyrovský to keep up with research during the occupation. Although misinterpreted by some, the actions and behavior of both scholars were honorable—in contrast with the overwhelming majority of Germans, who had to leave Czechoslovakia after World War II, Böhm remained in the country and in 1953 was elected corresponding member of the reorganized Academy of Sciences.

The reorganization of the Academy of Sciences (1952) was the culmination of a series of changes in the scientific life of Czechoslovakia which also brought about the establishment of a Central Polarographic Institute in 1950, with Heyrovský as its head. Later incorporated into the Academy of Sciences, it has been called the J. Heyrovský Institute of Polarography since 1964. Heyrovský received many honors both at home and abroad: he was the first Czech to win the Nobel Prize, awarded him in 1959 for his discovery of polarography. In 1965 he was elected a foreign member of the Royal Society.

Polarography was discovered when Heyrovský unified two somewhat disparate lines of investigation that related the principles of electrocapillarity to the measurement of electrode potentials. The historical connections of polarography with electrocapillarity date from the investigations of G. Lippmann, who set up (1873)3 an electrochemical cell of which the polarizable electrode consisted of a mercury meniscus in a capillary; the nonpolarizable electrode was a large mercury pool at the bottom of the cell. Lippmann proceeded to examine surface tension alterations of the mercury meniscus under the influence of polarization. Its changes in elevation (proportional to the changes in surface tension), plotted against applied voltage (equal to the potential of the polarizable electrode), result in a curve, known as the electricdouble-layer conception, the peak of the curve denotes the potential at which the mercury surface is uncharged.

This “static” approach to electrocapillary phenomena was followed by another method developed by Kučera (1903).4 Instead of following the movements of the meniscus in the capillary, he weighed the mercury dropping from the capillary because the drop’s weight is directly proportional to the surface tension. Because it involved a continuous renewal of the mercury surface, this approach was described as “dynamic.” In certain cases, such as dilute electrolyte solutions, Kučera obtained parabolic curves with a secondary maximum. These anomalies did not occur with the static method, and Kučera was unable to elucidate them.

As professor of physics at the Czech university, Kučera examined Heyrovský for his doctorate. Following the examination, at Kučera’s suggestion, Heyrovský undertook a systematic study of the anomalous behavior of electrocapillary curves, in the course of which his experimental and theoretical knowledge of electrochemistry became very useful. Heyrovský noticed that the addition of reducible cations to the solution caused an inflection in the electrocapillary curves at potentials close to the decomposition voltages of the cations. Instead of the rather unrewarding weighing of mercury drops at different potentials, he began to measure the current between the dropping mercury electrode and the large mercury pool which served as a reference electrode. In due course he created, in polarography, a novel method for the study of electrochemical processes.

It has been asserted that Heyrovský owed the idea of the dropping electrode to Donnan, who suggested work on the electropotential of aluminum to the young scientist. The position of aluminum in the table of electropotentials was uncertain because the metal, coated with an oxide film, did not yield reproducible measurements. In his paper on the subject (1920) Heyrovský showed that he was aware of the difficulties and, following previous attempts, decided to use amalgamated aluminum as a reversible electrode. The main problem was to devise a method to prevent the evolution of hydrogen.

Whether or not Donnan originally porposed the use of amalgam flowing out of a capillary, Heyrovský did not report on such a technique in his paper on the aluminum electrode. In fact, he adopted a type of dropping electrode. employed previously by G. N. Lewis and his co-workers. Heyrovský became acquainted with the work of the American chemists on the determination of potentials of alkaline metals, published in the Journal of the American Chemical Society between 1910 and 1915. The significance of this work lay in the success of the American chemists in measuring the ptentials of alkaline metals by means of alkali amalgam electrodes. In their experiments, the the Americans had set up a special apparatus for the preparation and preservation of the dilute amalgam with theamalgam surface at the end of a capilary servi8ng as an electrode. At first they found that the sodium amalgam surface, when placed in the sodium hydroxide, evolved considerable hydrogen. But when the amalgam surface was repeatedly renewed by allowing one or two drops of amalgam to flow out at the end of the capillary, “the surface remained clear of hydrogen for ten to twenty minutes, and showed a constant and perfectly reproducible potential within 0.1 millivolt.”5 Heyrovský was impressed by this work, done at the laboratory of physical chemistry of the Massachusetts Institute of Technology, and wrote:

The high overvoltage of hydrogen on a mercury surface makes it possible for a dilute amalgam of a very negative metal to behave as a reversible electrode, because the evolution of hydrogen is almost entirely prevented. Lewis... has been able to dtermine the electrolytic potentials of alkali metals using dilute amalgms, and the same method has been adopted here for aluminum.6

Heyrovský’s inclinations toward electrochemistry and his recent experience in this field transformed the study of electrocapillarity into polarography by 1921. After measuring with a galvanometer currents passing through the cell to which potentiometrically different voltages were applied, Heyrovský observed that the current-voltage curves obtained with the dropping mercury electrode represented qualitative and quantitative relationships characteristic for the solution undergoing electrolysis. As the applied voltage become greater, the current increased not continuously but in steps, reaching limiting values corresponding to the different cations or other reducible groups in the solution. On plotting the values for voltage and current, he obtained usually S-shaped curves in which the position of the polarographic curve or wave (voltage) indicated the qualitative composition of the solution and the height of the curve (current) determined its contents quantitatively.

Heyrovský reported his findings for the first time in 1922, writing in Czech; a year later he published them in English,7 From then on, he remained in the van of experimenters with the dropping mercury electrode. He said in his Nobel lecture:

The reason why I keep some 38 years to the electrochemical researches with the dropping mercury electrode is its exquisite property as electrode material. Its physical condition of dropping as well as the chemical changes during the passage of the electric current are well defined, and the phenomena displayed at the dropping mercury electrode proceed with strict reproducibility. Owing to the latter property the processes at the electrode can be exactly expressed mathematically. 8

Heyrovský never tired of emphasizing that the advantages of the dropping mercury electrode depended on the considerations that the surface of mercury was renewed and that the large overvoltage on the mercury electrode prevented hydrogen deposition. Highly reproducible results are obtained with a very small amount of solution because the mean current depends only on the applied potential and is independent of time and of the direction of the polarizing voltage.

The term “polarography” was not coined until 1925. In that year Heyrovský and his co-worker Masuzo Shikata (later professor at Kyoto) published a description of an instrument which they called a “polarograph.”9 It automatically registered the current-voltage curves or “polarograms” on a cylinder covered with photographic paper and connected to a Kohlrausch drum (originally rotated by means of a phonograph motor). It was one of the earliest automated laboratory instruments, and the first Polarograph cost only about £3 to build. The mechanic at the institute was prepared to supply a Polarograph the production of a polarogram often took over an hour, but the novel arrangement reduced it to fifteen to twenty minutes. It is noteworthy that with the very first instrument a high sensitivity could be achieved showing depolarizers in a concentration of 10-5 gram molecules per liter. According to Heyrovský, some of the later developments in the construction, although producing more complex instruments, did not make them necessarily more accurate or easier to understand.

In the early 1920’s electrochemistry was not considered one of the fields offering promising new openings for research. In retrospect, it is now recognized that the polarographic investigations initiated by Heyrovský gave a new impetus to the study of electrode processes. During the first two decades or so of the twentieth century Heyrovský and a small but steadily growing band of enthusiastic pupils concentrated on the theoretical foundations of polarography, which eventually led to a more precise understanding of the polarogram.

The nature of the limiting current—that is, the current which, after reaching a maximum value, remains unaffected by an increase in voltage—was considered in some detail. Heyrovský distinguished between the migration and diffusion sides of the current resulting from the electrolysis of the solution using a dropping mercury electrode. The relationship between the migration and diffusion components of the limiting current were defined and the importance of the latter in practical polarography was explained, resulting in the working out of an equation by D. Ilkovič (1934) linking in a linear relationship the diffusion current and the concentration of the depolarizer, which is the substance reduced or oxidized at the dropping electrode.10 Heyrovský and Ilkovič (1935) also worked out an equation for the cathodic wave which threw light on the inflection point on the wave (half-wave point) and demonstrated the importance of the corresponding potential (half-wave potential) as a constant in polarography.11 Besides diffusion-controlled currents other types, such as adsorption currents, were observed and studied by Rudolf Brdička, Heyrovský’s most distinguished pupil. It was shown that the depolarizer or some other component in the solution, when adsorbed by the dropping mercury electrode, could cause changes in polarographic currents.

An important step in theoretical polarography occurred after the recognition of the existence of kinetic currents—polarographic currents governed by the rate of the chemical reactions taking place near the electrode. The theory of kinetic currents began to be worked out in the early 1940’s by Brdička and K. Wiesner.12 Heyrovský’s persistent interest in the problem of hydrogen overvoltage led him to propose a mechanism for the reduction of hydrogen ions at the dropping mercury electrode, based on the classical electrochemical theroy of reversible electrode potentials and the classical kinetic theory of rate reactions.13 He believed that the overvoltage was due to slow formation of hydrogen molecules and to an interaction of water at the electrode interface. He visualized the formation of hydrogen molecules in the three steps

assuming that step (2) indicated the rate-determining reaction. Heyrovský’s interpretation of the hydrogen overvoltage contributed to the understanding of catalytic, hydrogen currents. These polarographic currents, observed in the presence of substances which act as catalysts, are connected with the accelerated evolution of hydrogen. Bridčka’s discovery (1933) that proteins containing SH groups exhibit catalytic activities accompanied by hydrogen evolution demonstrated an interesting example of a catalytic current and was developed as a polarographic test with blood sera of pathological origin (taken from tumors, for instance).14

By 1938 the first attempts were made in polarography to use a cathode-ray oscilloscope instead of a galvanometer. The voltage of the ordinary alternating-current supply was applied to the dropping mercury electrode, and changes of its potential were followed on the oscilloscope. But Heyrovský, who began to use this method in the early 1940’s15 and since then had studied it intensively, concluded that it was neessary to distinguish between the situation in which “thee oscilloscope merely replaces the galvanometer and brings no fundamental change in the polarograpghic instrumentation”16 and oscillofraphic polarography proper, involving methods “in which the electrode in polarized by an alternating voltage or current or by single voltage or current sweeps and for which the resulting curves are followed by means of an oscilloscope.”17 No doubt, what impressed Heyrovský about oscillographic polarography was that it reduced the time of recording the curve to fractions of seconds, a much more rapid arrangement than the ordinary polarographic method and about equally accurate. It was in the course of his studies on oscillopolarography that he found it useful to employ the streaming mercury electrode in order to obtain a steady oscillogram.

It may perhaps be useful to restate Heyrovský’s definition of polarography:

... Polarography is the science of studying the processes occurring arround the dropping-mercury electrode. It includes not only the study of current-voltage curves, but also of other relationships, such as the current-time curves for single drops, potential-time curves, electrocapillary phenomena and the streaming of electrolytes, and the streaming of electrolytes, and its tools include besides the polarograph, the microscope, the string galvanometer and even the cathoderay oscillograph.18

He adhered to the view that polarography was basically “restricted to the mercury capillary electrodes.”19

Heyrovský devoted much attention to investigations of polarographic current-voltage curves which under certain circumstances show so-called maxima of the first kind, that is, a sharp increase of current above the limiting value, followed by a sudden fall to the normal magnitude.20 This phenomenon relates to the anomalous electrocapillary curves which Kučera asked the young Heyrovský to investigate, It is curious that the problem which catalyzed the rise of polarography is as yet not completely resolved.21

Not until about ten years after the first publications did the scientific community outside Czechoslovakia take notice of polarography. In 1933 Heyrovský lectured at Berkeley and other American universities as Carnegie visiting professor. A year later he had the opportunity to acquaint a Russian audience with his work when he was invited to attend the Mendeleev centenary in Leningrad. The earliest translation from Czech of Heyrovský’s first book on the use of polarography (1933) appeared four years later in Russian. According to Heyrovský, the major breakthrough occurred when the German analyst Wilhelm Böttger, editor of the compendium Physikalische Methoden der analytischen Chemie, asked him to write on polarography for volume II, published in 1936. In 1941 Heyrovský brought out his account of the subject in German, and in the United States there appeared a series of articles by O. H. Müller in Journal of Chemical Education and a book by I. M. Kolthoff and J. J. Lingane which long remained the major source of systematic information on polarography for English-speaking readers.22

Since then interest in polarography has deepened and widened because of its extensive uses not only in electrochemical and other research but also in industrial and hospital laboratories. It has been said that polarography belongs to the “top five” analytical methods, which indicates that its international recognition derives primarily from its use in analytical practice. Certainly it was the novelty of the technique and its speed which made polarography “one of the most important methods of contemporary chemical analysis,”23 as was pointed out in the presentation speech by A. Ölander, a member of the Nobel Committee for chemistry; clearly it was the primary reason for the award of the Nobel Prize to Heyrovský. Yet Heyrovský, who was always just as concerned with the electrochemical aspects as with the analytical ramifications of polarography, took pains to refute suggestions that it was merely a somewhat better analytical procedure. Indeed, he explicitly touched upon this point in his Nobel lecture, saying:

We meet often with the opinion that polarography did not bring anything new into chemistry except an improvement of analytical methods. That is decidedly not so, since in the study of reductions or oxidations many otherwise inaccessible physico-chemical constants are determinable. Polarography helps the investigation of chemical structure of organic and lately even inorganic compounds... .Although the analytical application of polarography is highly advanced at present, the field of its utilization in basic chemical problems begins to open.24

Even a short biographical sketch of Heyrovský would be incomplete if it were limited to the bare outline of his contribution to electrochemistry and analytical chemistry. A consideration of his life and work reveals features interesting from the point of a more general history of science. Both the Royal Society and the Nature obituaries found Heyrovský unique in that during an active working life of about forty years he concentrated on the elaboration of his original discovery and remained the acknowledged leader in a continuously expanding and changing area of science. In 1959, before an audience gathered in Prague to pay homage to him as the recipient of the Nobel Prize, Heyrovský admitted the high personal cost he had paid for the award. For years he spent every free moment, including long weekends, in the laboratories and gradually gave up his manysided interests in science, literature, music, and sports. But however great his individual devotion to polarography may have been, it could not by itself account for the widespread success of that science. It is true that from the start Heyrovský did not doubt the theoretical and practical significance of his discovery, and he decided to pursue systematically the subject of the dropping mercury electrode. At a relatively early stage he was joined by a group of investigators who recognized his undisputable, although not restraining, authority and formed the nucleus of a school of polarography whose influence eventually became worldwide.

Although not particularly keen on administration, Heyrovský early recognized that growth of scientific knowledge could not be separated from its dissemination, which had to be organized. In 1928 he investigated the publication of papers by Czech chemists and found that during the ten years of Czechoslovakia’s existence as an independent state they published 163 times abroad and 235 times at home. It should be added that a considerable number of these papers appeared in both Czech and another language. The survey reinforced the position of Emil Votoček, professor of chemistry at the Czech Technical University of Prague and widely known for his researches in carbohydrate chemistry, who had proposed the founding of a Czechoslovak chemical journal for original papers written in either French or English. With the aid of the ministry of education and the patronage of the Royal Bohemian Society Science of the patronage of the Royal Bohemian Society of Sciences (founded 1769–1771), Collection of Czechoslovak Chemical Communications made its first appearance in 1929 under the editorship of Heyrovský and Votoček, who also remained the publishers of the Anglo-French journal until 1947. Votoček, a gifted linguist, became responsible for the French and Heyrovský concentrated on the English section, which frequently meant that they also served as translators. Their high standards led to the Collection attaining international recognition. It is still flourishing, now published in German and Russian as well.

The early volumes contained many of the significant contributions to polarography by Heyrovský and his school, thus constituting an important source for the history of polarography. From the beginning it was envisioned that the journal would include a bibliography of all Czechoslovak chemical publications. In 1938 Heyrovský embarked on producing from time to time, at first in the journal and then separately, bibliographies on polarography. He persevered for years in this ambitious program, aided by J. Klumpar, O. H. Müller, J. Hrbek, J. E. S. Han, and lately above all by his wife, Marie Heyrovská, who chose to remain anonymous. Heyrovský’s farsightedness insured that few other fields could compete with polarography in having from the beginning continuous and good bibliographies.

Among Czech scientists Heyrovský became second only to Purkyně. Born into a national group which spoke a language understood by practically no scientist outside the Czech community, they both became promoters of Czech science but in different ways. The activities of Purkyně in the nineteenth century and Heyrovský in the twentieth century reflected two sides of a problem which scientists belonging to small national groups or countries perennially have to face. Purkyně, who became internationally recognized on the basis of his work written in German and Latin, believed passionately that science interpreted in the national language was an indispensable part of national culture. For this reason, throughout his working life he devoted much time and energy to the creation of Czech scientific terms, to the foundation of Czech scientific periodicals—in short, to the establishment of a Czech scientific culture. A hundred years later Heyrovský was determined to demonstrate the maturity of his country’s chemical science to the international scientific community. A more convincing proof than Heyrovský’s own contribution could hardly have been supplied.

NOTES

1. “The Electroaffinity of Aluminium. Part I. The Ionisation and Hydrolysis of Aluminium Chloride,” in Journal of the Chemical Society (Transactions), 117 , no. 1 (1920), 11–26; “Part II. The Aluminium Electrode,” ibid., pp. 27–36; “Part III. The Acidity and Constitution of Aluminic Acid,” ibid., no. 2 (1920), pp. 1013–1025.

2. J. D. Cockcroft, “George de Hevesy,” in Biographical Memoirs of Fellows of the Royal Society, 13 (1967), 141.

3. G. Lippmann, “Beziehungen zwischen den capillaren und elektrischen Erscheinungen,” in Poggendorff’s Annalen der Physik und Chemie, 149 (1873), 546–561.

4. G. Kučera, “Zur Oberflächenspannung von polarisiertem Quecksilber,” in Annalen der Physik, 11 (1903), 529–560, 698–725, extract from his Habilitationsschrift (Leipzig, 1903).

5. G. N. Lewis and C. A. Kraus, “The Potential of Sodium Chloride,” in Journal of the American Chemical Society, 32 (1910), 1462.

6.Journal of the Chemical Society (Transactions), 117 , no. 1 (1920), 30.

7. “Elektrolysa se rtuťovou kapkovou kathodou,” in Chemické Listy, 16 (1922), 256–264; “Electrolysis With a Dropping Mercury Cathode. Part I. Deposition of Alkali and Alkaline Earth Metals,” in Philosophical Magazine, 45 (1923), 303–314.

8. “The Trends of Polarography,” in Nobel Lectures Chemistry 1942–1962 (Amsterdam-London-New York, 1964), p. 564.

9. “Researches With the Dropping Mercury Cathode, Part II. The Polarograph,” in Recueil des travaux chimiques des Pays-Bas, 44 (1925), 496–498, written with M. Shikata.

10. D. Ilkovič “Polarographic Studies With the Dropping Mercury Kathode. Part XLIV. The Dependence of Limiting Currents on the Diffusion Constant, on the Rate of Dropping and on the Size of Drops,” in Collection of Czechoslovak Chemical Communications, 6 (1934), 498–513.

11. “Polarographic Studies With the Dropping Mercury Electrode. Part II. The Absolute Determination of Reduction and Depolarization Potentials,” ibid., 7 (1935), 198–214.

12. K. Wiesner, “Über durch Wasserstoffatome katalysierte Depolarisationsvorgänge an der tropfenden Quecksilberelektrode,” in Zeitschrift für Elektrochemie, 49 (1943), 164–166; R. Brdička and K. Wiesner, “Polarographische Bestimmung der Geschwindigkeitskonstante für die Oxydation von Ferrohäm und anderen Ferronkonplexen durch H2 O2,” in Naturwissenschaften, 31 (1943), 247.

13. “Polarographic Studies With the Dropping Mercury Kathode. Part LXIX. The Hydrogen Overpotential in Light and Heavy Water,” in Collection of Czechoslovak Chemical Communications, 9 (1937), 273–301; “The Electrodeposition of Hydrogen and Deuterium at the Dropping Mercury Cathode,” in Chemical Reviews, 24 (1939), 125–134; Principles of Polarography (Prague-London, 1966), p. 235, written with J. Küta.

14. See R. Brdička, M. Březina, and V. Kalous, “Polarography of Proteins and Its Analytical Aspects,” in Talanta, 12 (1965), 1149–1162.

15. “Oszillographische Polarographie,” in Zeitschrift für physikalische Chemie, Abt. A. 193 (1944), 77–96, written with J. Forejt; Oszillographische Polarographie mit Wechselstrom (Berlin, 1960), written with R. Kalvoda.

16. Heyrovský and Küta, Principles of Polarography, p. 498.

17.Ibid., p. 499.

18. “The Development of Polarographic Analysis,” in Analyst, 81 (1956), 189.

19.Ibid.

20. “Betrachtungen über polarographische Maxima I. Art,” in Zeitschrift für physikalische Chemie (Leipzig) (July 1958 [separately published]), pp. 7–27.

21. Heyrovský and Küta, Principles of Polarography, pp. 429–450.

22.Polarographie, theoretische Grundlage, praktische Ausführung mit Anwendungen der Elektrolyse mit der tropfenden Queckilberelektrode (Vienna, 1941); O. H. Müller, “The Polarographic Method of Analysis,” in Journal of Chemical Education, 18 (1941), 65–72, 111–115, 172–177, 227–234, 320–329, also published as a book with the same title (Easton, Pa., 1941); I. M. Kolthoff and J. J. Lingane, Polarography (New york, 1941).

23.Nobel Lectures Chemistry, 1942–1962 p. 563.

24.Ibid., pp. 582–583.

BIBLIOGRAPHY

Some of Heyrovskýs publications are mentioned in the notes; a full bibliography is in Biographical Memoirs of Fellows of the Royal Society, 13 (1967), 182–191.

Understandably, no critical account of Heyrovskýs life and work exists as yet. An obiturary in Czech is by R. Brdička, in Chemické Listy, 61 (1967), 573–580; two in English are by J. A. V. Butler and P. Zuman, in Biographical Memoirs of Fellows of the Royal Society, 13 (1967), 167–182; and R. Belcher, in Nature, 214 (1967), 953. Much the same material has been covered in p. Zuman and P. J. E. Elving, “Jaroslav Heyrovský: Nobel Laureate,” in Journal of Chemical Education, 37 (1960), 572, repr. in Aaron J. Ihde and William F. Kieffer, Selected Readings in the History of Chemistry (Easton, Pa., 1965), pp. 104–109. Marie Heyrovská, “Polarographic Literature,” and other contributions by eminent experts to the Heyrovský Festschrift, Progress in Polarography, P. Zuman and I. M. Kolthoff, eds., 2 vols (New York-London, 1962), contain much useful historical information.

MikulÁŠ Teich

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Heyrovský, Jaroslav

Heyrovský, Jaroslav


CZECH PHYSICAL CHEMIST
18901967

Jaroslav Heyrovský was born on November 20, 1890, in Prague (then part of the Austro-Hungarian Empire), where he also died on March 27, 1967. He began studying chemistry and physics at Prague University in 1909. Between 1910 and 1914 he studied at University College in London under William Ramsay and Frederick G. Donnan, where he earned a B.Sc. degree in 1913. Following war service in a military hospital during World War I, he earned a Ph.D. degree in Prague in 1918 and a D.Sc. degree in London in 1921. In 1922 Heyrovský was promoted to full professor and head of the Institute of Physical Chemistry at Charles University (in Prague); and in 1950 he became director of the Polarographic Institute of the Czechoslovak Academy of Sciences.

Heyrovský was the discoverer of polarography and the inventor of the polarograph, an instrument that analyzes the composition of solutions electrochemically. His discovery of polarography was a culmination of the work of other scientists in electrochemistry. Other scientists' investigations of electrolysis had demonstrated the dependence of the intensity of a current flowing through a saline solution on the voltage applied to electrodes immersed in the solution. They found that at certain voltages, currents began to flow and metals were deposited on the electrodes.

The second line of research that led to polarography was the investigation of the interface tension between mercury and saline solutions. Gabriel Lippmann (18451921) found that increasing the voltage applied to mercury in contact with a surrounding saline solution changed the mercury's surface tension in a characteristic manner, which he was able to represent as a parabolic curve called an electrocapillary parabola. Professor Bohumil Kucčera (18741921), Heyrovský's teacher in Prague, made a similar investigation, for which he used a mercury-dropping electrode. The electrode consisted of a capillary tube from which mercury dripped into the solution. Kucčera witnessed deviations in the shapes of the curves as he varied the voltages, and proposed that Heyrovský investigate the phenomenon.

Heyrovský in effect combined the investigations of electrolysis and electrocapillary parabolas. In 1922 Heyrovský constructed an electrical circuit whose voltage from a battery was applied through a Kohlrausch drum to a mercury-dropping electrode immersed in a saline solution. The electrical potential of this electrode was then changed incrementally from 0 to 2 volts. A layer of mercury on the bottom of the vessel served as the second electrode. A mirror galvanometer would then detect a current flowing through this circuit, and the values of current intensity would be plotted point by point (by hand) as a function of the applied voltage. As the dissolved ions reacted electrochemically with the mercury-dropping electrode, curves with characteristic steps (polarographic waves) at certain voltage values were obtained. The identity of the ion present in the solution was determined by the voltage (expressed in electrochemical potential) at half of the height of the polarographic wave (so-called half-wave potential). The intensity of the current, represented in the graph as the height of the polarographic wave, was found to be directly proportional to the concentration of the ion.

Heyrovský's method, later called polarography, became an excellent analytical tool because it yielded qualitative and quantitative analyses of a solution in a single experiment. With Masuzo Shikata (18951964), Heyrovský constructed the first polarograph, an instrument equipped with an electromotor that moved the Kohlrausch drum in accord with photographic paper rotating in a cylindrical cassette. It allowed the potential of the mercury-dropping

electrode to change continuously. Light from the mirror galvanometer entered the cassette through a narrow slit (requiring these experiments to be performed in darkness). A continuous polarographic curve appeared upon the development of the photographic paper.

The polarograph was the first fully automatic instrument used in chemistry. For decades polarography was the only precise method for the analysis of inorganic and organic compounds in solution. Polarographic analyses of human blood serum served as a tool for diagnosing cancer during the 1940s and 1950s. Modern polarographs equipped with computers use advanced techniques such as oscillopolarography and square-wave polarography. In 1959 Heyrovský was awarded the Nobel Prize in chemistry "for his discovery and development of the polarographic method of analysis."

see also Analytical Chemistry; Electrochemistry.

Vladimir Karpenko

Bibliography

Butler, John A. V., and Zuman, Petr (1967). "Jaroslav Heyrovský (18901967)." In Biographical Memoirs of Fellows of the Royal Society, Vol. 13. London: Royal Society.

Heyrovský, Jaroslav (1941). Polarographie. Vienna: Springer Verlag.

Heyrovský, Jaroslav, and Kůta, Jaroslav (1965). Principles of Polarography. Prague: Publishing House of the Czechoslovak Academy of Sciences.

Ihde, Aaron J. (1984). The Development of Modern Chemistry. New York: Dover.

Internet Resources

Nobel e-Museum. "The Nobel Prize in Chemistry, 1959." Available from <http://www.nobel.se/chemistry/laureates/1959/>.

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"Heyrovský, Jaroslav." Chemistry: Foundations and Applications. . Encyclopedia.com. 22 Jun. 2017 <http://www.encyclopedia.com>.

"Heyrovský, Jaroslav." Chemistry: Foundations and Applications. . Encyclopedia.com. (June 22, 2017). http://www.encyclopedia.com/science/news-wires-white-papers-and-books/heyrovsky-jaroslav

"Heyrovský, Jaroslav." Chemistry: Foundations and Applications. . Retrieved June 22, 2017 from Encyclopedia.com: http://www.encyclopedia.com/science/news-wires-white-papers-and-books/heyrovsky-jaroslav