Georg von Hevesy

Hungarian chemist

• Born: August 1, 1885
• Birthplace: Budapest, Hungary
• Died: July 5, 1966
• Place of death: Freiburg im Breisgau, West Germany (now in Germany)

Hevesy pioneered the use of radioactive isotopes to study chemical processes. For this work, he was awarded the Nobel Prize in Chemistry in 1944 and the Atoms for Peace Award in 1959. He is also known for his discovery in 1923 of the element hafnium.

Early Life

Georg von Hevesy (GAY-ohrg fuhn HEH-vesh-ee) was born in Budapest, Hungary, into a family of wealthy Jewish industrialists and landowners. He was educated at a Roman Catholic school in Budapest and was expected to enter one of the professions. The young Hevesy decided to become a scientist instead. He was enrolled in the Technical High School in Berlin with the aim of becoming a chemical engineer, but his studies there were cut short when he contracted pneumonia in 1905 and had to move to Freiburg, Germany, for the milder climate.

At the University of Freiburg, Hevesy studied chemistry and physics. In 1908, under the direction of Georg Meyer, he completed his doctorate there on the interaction of metallic sodium with molten sodium hydroxide. Because of his family’s wealth, Hevesy was free to pursue postdoctoral studies wherever he wished. He traveled first to Switzerland to study the chemistry of molten salts with Richard Lorenz and then to the Karlsruhe laboratories of Fritz Haber, where he investigated the emission of electrons during the oxidation of sodium-potassium alloys.

In 1911, on Haber’s advice, Hevesy went to Manchester to study the technique of radioactive measurement that had been developed by Ernest Rutherford. It was a decisive move for him, not only because his research at Manchester would form the basis for the work that many years later would earn for him the Nobel Prize but also because there he met and became lifelong friends with Niels Bohr.

Much of the research in physics and chemistry at this time was concerned with the phenomenon of naturally occurring radioactivity. Rutherford set Hevesy the task of chemically separating radioactive radium D, with which Rutherford was interested in experimenting, from lead. Hevesy worked on the problem for two years without success. It is now known that chemical separation is impossible because radium D is an isotope of lead. Turning his apparent failure to advantage, Hevesy used this very property of radium D that it is inseparable from lead to label lead and thus to indicate its presence by measuring the radioactivity imparted to it by its isotope, radium D.

Hevesy returned to Hungary in 1912 and spent the next year traveling between Budapest and Vienna to collaborate with Friedrich Paneth at the Institute of Radium Research. Paneth had also been trying, unsuccessfully, to separate radium D from lead. Hevesy proposed to Paneth that they use radium D not only to label lead but also to trace it through a series of chemical reactions. Hevesy had been quick to realize the significance of the fact that radioactive atoms behave chemically and physically like their stable counterparts, but with the important difference that they can be traced, or tracked, by measuring the radiation they emit. Using radium D and a Geiger counter, the two men successfully applied the tracer method to the investigation of the solubility of lead chromate in water at various temperatures.

Hevesy had planned to return to England to study with Henry Moseley, who was then working in X-ray spectroscopy at the University of Oxford, but World War II erupted, and he returned instead to Vienna. He continued his research with Paneth on the tracer method, applying it to the study of the physicochemical properties of heavy metals and their inorganic salts. Judged unfit for military service because of his frail health, Hevesy spent the war as a supervisor in an electrochemical plant. After the war, in 1919, he received a one-year appointment to lecture on experimental physics at the University of Budapest, but the revolution in Hungary left his financial and professional future in that country uncertain, and within the year he decided to emigrate.

Life’s Work

Bohr had invited Hevesy to Copenhagen to work at Bohr’s newly established Institute of Theoretical Physics. Hevesy’s tenure there, from 1920 to 1926, was to be one of the most creative periods of his career. Bohr was then working on explaining the periodic table of elements. Based on his theories of atomic structure and the X-ray studies of Moseley, he had identified six elements that had not yet been discovered. It was generally assumed that the element corresponding to atomic number 72 was chemically similar to the rare earth elements. Bohr thought otherwise. He suggested to Hevesy that he look for the undiscovered element 72 in the ores of metallic zirconium. Hevesy accepted Bohr’s challenge with the help of Dirk Coster, an expert in X-ray spectroscopy. In 1923, while investigating zirconium minerals using X rays, the two men discovered the new element, which they called hafnium, for Hafnia, the Latin name for Copenhagen. Hafnium is a lustrous, silvery metal, whose chemical properties are almost identical to those of zirconium. Hevesy proceeded to successfully separate hafnium from zirconium and conducted extensive investigations on the chemical nature of the new element. He lectured widely on the subject and wrote numerous papers, as well as a book, Das Element Hafnium (1927).

It was generally expected that Hevesy and Coster would be awarded the Nobel Prize for their work, but several British as well as French chemists also laid claim to the discovery of element 72. The controversy that followed confused the issue to the extent that the Nobel Committee was unable to agree on honoring Hevesy and Coster, although the two men were eventually recognized as the legitimate discoverers of element 72.

During this time, Hevesy returned to the use of radioactive isotopes as tracers, which he now applied to the field of botany. In 1923, using a radioactive isotope of lead, he traced the absorption and distribution of lead in bean plants. In the same year, his book on radioactivity, Lehrbuch der Radioaktivität (1923; A Manual of Radioactivity , 1926), which he wrote with Paneth, was published. The following year, Hevesy used the tracer method to study the circulation in animals of bismuth, then being used to treat syphilis, and lead salts, which were of interest in cancer therapy.

In 1926, Hevesy left Copenhagen to accept the chair of physical chemistry at the University of Freiburg. He had married Ria Riis in Denmark in the fall of 1924, and their first of four children had been born. The position in Freiburg, which Hevesy held for eight years, offered him economic security and prestige, although apparently not the inspiration that had produced the remarkable achievements of the previous years. Hevesy did very little work on radioactive indicators during this time. Instead, he concentrated on studying the occurrence of various chemical elements in rocks and meteorites using quantitative X-ray analyses. His book Chemical Analysis by X Rays and Its Applications (1932) was published several years later.

In the early 1930’s, Hevesy began experimenting again with his radioactive tracer technique, applying it more widely to biological studies. Until this time, his biological research had been limited because the heavy metals he had to work with, such as lead, were extremely toxic to biological organisms. This changed in 1931 with Harold C. Urey’s discovery of deuterium, an isotope of hydrogen. Using deuterium, Hevesy was able to measure the rate of exchange of hydrogen in animals as well as the elimination of water from and the total water content of the human body.

In July, 1934, in response to the growing threat of Nazism, Hevesy resigned his position at Freiburg and, again at Bohr’s invitation, returned to Copenhagen to work at the Institute of Theoretical Physics. His stay there, which was to be an extremely productive one, lasted from 1935 to 1943. In 1933, Enrico Fermi had discovered that radioactive isotopes could be formed by bombarding a stable element with neutrons. This discovery, which made it possible to produce radioactive isotopes for the common elements artificially, was to broaden significantly the scope of Hevesy’s research. The production in 1934 of an unstable isotope of phosphorus made it possible for him to investigate phosphorous metabolism in animals. Hevesy also used the isotope to trace the movement of phosphorus in the human body. His work revealed that the formation of the bones is a dynamic process and that the mineral constituents of the skeleton are constantly renewed, a finding that challenged the prevailing views. This was perhaps the single most important discovery Hevesy was to make using the tracer method. Hevesy also experimented on the soft tissues of the body, which he showed were likewise dynamic in nature, and went on to study the life span of the red and white blood cells as well as the biochemistry of nucleic acids. His research received the intellectual support of Bohr, the financial support of the Rockefeller Foundation, and eventually the acclaim of the scientific and medical research communities.

In 1943, Hevesy was forced to flee German-occupied Denmark. He sought asylum in Sweden, where he became a professor at the Institute of Organic Chemistry at the University of Stockholm. While there, he was awarded the 1943 Nobel Prize in Chemistry for his discovery and development of radioactive tracing. Along with the prize, Hevesy accepted Swedish citizenship.

For some time after World War II, Hevesy traveled between Stockholm and Copenhagen, where he continued to work on the movement of radioactive isotopes in living material. As his health began to fail, he confined his research efforts to Stockholm, primarily focusing on the effect of X rays on biochemical processes in animals. While gradually cutting back on his experimental work, Hevesy continued to be a prolific writer. During this time, he wrote his classic book on the use of radioisotopes as tracers, entitled Radioactive Indicators: Their Application in Biochemistry, Animal Physiology, and Pathology (1948). In 1959, Hevesy received the Atoms for Peace Award for the medical application of radioisotopes. The award was presented to him by Dag Hammarskjöld, secretary-general of the United Nations. In 1962, Hevesy published a two-volume collection of what he considered to be his most important papers, entitled Adventures in Radioisotope Research: The Collected Papers of George Hevesy .

Bohr, Hevesy’s closest friend and greatest source of inspiration, died in the fall of 1962. Shortly thereafter, Hevesy was diagnosed as having lung cancer. His condition quickly deteriorated, and he was moved to a clinic in Freiburg, where he died on July 5, 1966, at the age of eighty.

Significance

Hevesy’s genius is perhaps best exemplified in the way he turned failure into success. His inability to separate radium D from lead led to his discovery of radioactive labeling and the development of the use of radioactive isotopes as tracers. Though his discovery, first made in Manchester and applied in Vienna in 1912, did not receive much attention at the time, Hevesy continued to develop and expand the technique over the next several decades, applying it not only to problems in chemistry but also to physics, biology, and medicine. In time, Hevesy’s tracer method was recognized as one of the most important research tools of modern science. It has been used to study the nocturnal activity of bats, the assimilation of carbon dioxide and water by green plants, the fixation of iodine by the human thyroid gland, and the physiological fate of medicines and poisons. In industry, the tracer method is used to test the wear and corrosion of mechanical components and even to monitor and control the entire operation of an industrial plant. Perhaps the greatest impact of Hevesy’s pioneering work has been in the field of medicine, where radioactive isotopes are used in the diagnosis and treatment of diseases. Radioisotopes are now routinely used in cancer research and detection, most notably in the scanning techniques used to locate tumors in the brain.

Bibliography

Cockcroft, John D. “George de Hevesy.” Biographical Memoirs of Fellows of the Royal Society 13 (1967): 125-166. Based almost entirely on the extensive notes that Hevesy turned over to Cockcroft shortly before his death, this article is, in effect, an autobiographical account by Hevesy of his own life and work. It is filled with personal insights, political observations, and affectionate, often amusing anecdotes about Hevesy’s associates and friends. Includes a six-page bibliography of Hevesy’s scientific work.

Hevesy, George de. “A Scientific Career.” Perspectives in Biology and Medicine 1 (1958): 345-365. An autobiographical essay by Hevesy for the layperson. Contains reminiscences of some of Hevesy’s distinguished colleagues and contemporaries, including Rutherford, Bohr, Moseley, Albert Einstein, and Marie Curie, as well as a discussion of the controversy surrounding the discovery of the element hafnium.

Larsson, Ulf, ed. Cultures of Creativity: The Centennial Exhibition of the Nobel Prize. Canton, Mass.: Science History, 2001. This history of the Nobel Prize includes a biography of Hevesy.

Levi, Hilde. George de Hevesy: Life and Work. Bristol, England: Adam Hilger, 1985. A short biography of Hevesy written by his assistant in Copenhagen from 1934 to 1943. Based on Hevesy’s letters, notes, and manuscripts, the book focuses on the personal aspects of Hevesy’s life. His scientific achievements are viewed in the context of his family background and early training as well as the times in which he lived. The book includes photographs, a list of references, a glossary, an index of names, and a complete bibliography of Hevesy’s considerable output.

‗‗‗‗‗‗‗. “George de Hevesy: 1 August 1855-July 1966.” Nuclear Physics 98 (1967): 1-24. A tribute to Hevesy written shortly after his death. The essay gives a clear and concise summary of Hevesy’s scientific work and its impact on modern science as well as a short biographical sketch. Includes a bibliography of Hevesy’s papers and books.

‗‗‗‗‗‗‗. “George Hevesy and His Concept of Radioactive Indicators In Retrospect.” European Journal of Nuclear Medicine 1 (1976): 3-10. Originally presented at the University of Copenhagen as the Georg von Hevesy Memorial Lecture, this essay traces the development of Hevesy’s major contributions to science over a twenty-year period. Describes in some detail, and with photographs, the scientific instrumentation, such as the early Geiger counters, that made it possible for Hevesy and his coworkers to carry out their experiments using radioisotopes as tracers.

Myers, William G. “Georg Charles de Hevesy: The Father of Nuclear Medicine.” Journal of Nuclear Medicine 20 (1979): 590-594. Given as the first Hevesy Nuclear Pioneer Lecture in 1979 by the historian of the Society of Nuclear Medicine, this address acknowledges Hevesy as the founder of nuclear medicine and pays tribute to his discovery of the tracer method of analysis and its application to the field of biomedicine.

Spence, R. “George Charles de Hevesy.” Chemistry in Britain 3 (1967): 527-532. A chronological and complete overview of Hevesy’s work. The essay is an abridged version of a lecture given in Hevesy’s honor. Includes photographs of Hevesy, Bohr, Rutherford, and Moseley.