Bunsen, Robert Wilhelm Eberhard

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Bunsen, Robert Wilhelm Eberhard

(b Göttingen, Germany, 31 March 1811; d. Heidelberg, Germany, 16 August 1899)


Bunsen was the youngest of four sons born to Christian Bunsen, chief librarian and professor of modern languages at the University of Göttingen. His ancestors on his father’s side had lived in Arolsen, where many of them held public office, frequently as master of the mint; his mother was the daughter of a British-Hanoverian officer named Quensel.

Bunsen began school in Göttingen but transferred to the Gymnasium at Holzminden, from which he graduated in 1828. Returning to Göttingen, Bunsen entered the university, where he studied chemistry physics, mineralogy, and mathematics. His chemistry teacher was Friedrich Stromeyer, who had discovered cadmium in 1817. Bunsen received his doctorate in 1830, presenting a thesis in physics: “Enumeratio ac descriptio hygrometrorum”.

Aided by a grant from the Hanoverian government, Bunsen toured Europe from 1830 to 1833, visiting factories, laboratories, and places of geologic interest. In May 1832, he saw a new steam engine in K. A. Henschel’s machinery factory in Kassel. Later that year, in Berlin, he studied Christian Weiss’s geognostic and mineralogic collections; met Freidlieb Runge, the discoverer of aniline, and Gustav Rose; and worked in Heinrich Rose’ laboratory. He visited Justus Liebig in Giessen and met Eilhard Mitcherlich in Bonn for a geological trip through the Eifel Plateau. In September 1832, Bunsen arrived in Paris. There he worked in Gay-Lussac’s laboratory and met such prominent scientists as Jules Reiset, Henri-Victor Regnault, Théophile Pelouze, and César Despretz. While in France, Bunsen visted the porcelain works at Sèvres. From May to July 1833, he traveled to Vienna, where he toured several industrial plants.

In the fall of 1833 Bunsen became Privatdozent at the University of Göttingen. He succeeded Friedrich Wöhler at the Polytechnic School in Kassel in January 1836. In October 1838 he was appointed professor extraordinarius of chemistry at the University of Marburg and became professor ordinarius four years later. Bunsen spent part of 1851 at Breslau, where he became acquainted with Gustav Kirchhoff, with whom he later did important research in spectroscopy. In 1852 he succeeded Leopold Gmelin at the University of Heidelberg. Although offered a position as Mitscherlich’s successor at the University of Berlin in 1863, Bunsen remained at Heidelberg until he retired in 1889, at the age of seventy-eight. A laboratory, constructed for him by the government of Baden, was completed in the summer of 1855; there Bunsen did his research and guided the work of numerous young men who became well-known scientists during the second half of the nineteenth century. Bunsen never married; his teaching and research consumed most of his time, and he traveled widely, either alone or with friends.

Bunsen was a most devoted teacher. He presented 100 hours of lectures during each of seventy-four semesters in a course entitled “Allgemeine Experimentalchemie”. The lectures, which changed little through the years, were concerned with inorganic chemistry; organic chemistry was excluded. Theoretical aspects were at a minimum: neither Avogadro’s hypothesis nor the periodic law of the elements–developed by his own students, Dmitri Mendeleev and Lothar Meyer–was mentioned. In his research, as in his teaching, Bunsen emphasized the experimental side of science. He enjoyed designing apparatus and, being a skilled glassblower, he frequently made his own glassware. He was also an expert crystallographer. Bunsen developed and improved several pieces of laboratory equipment, including the Bunsen burner, the Bunsen battery, an ice calorimeter, a vapor calorimeter, a filter pump, and a thermopile.

A man of wide scientific interests, Bunsen did some early research in organic chemistry but later abandoned this field and concentrated on inorganic chemistry. His most important work was the development of a variety of analytical techniques for the identification, separation, and measurement of inorganic substances., Throughout his life Bunsen gave much attention to geology. He was also interested in the application of experimental science to industrial problems.

His first research was on the insolubility of metal salts of arsenious acid, carried out in 1834. While involved in this work, Bunsen discovered that hydrated ferric oxide could be used as an antidote for arsenic poisoning. The ferric oxide is effective, he explained, because it combines with arsenic to form ferrous arsenite, a compound insoluble in both water and body fluids. This finding, still used today, was Bunsen’s only venture into physiological chemistry. In other early research, he analyzed a sample of allophane, an aluminum silicate, taken from a lignite bed near Bonn. In 1835 and 1836 Bunsen set forth the compositions and crystal measurements of a new series of double cyanides, showing, for example, that ammonium ferrocyanide and potassium ferrocyanide are isomorphous. He also discovered the double salt of ammonium ferrocyanide and ammonium chloride.

Bunsen’s only work in organic chemistry was an investigation of compounds of cacodyl, an arsenic-containing organic compound, the results of which appeared in five papers published between 1837 and 1842. In 1843, Bunsen lost the use of his right eye in an explosion of cacodyl cyanide. The first known cacodyl compound, alkarsine, had been prepared in 1760 by L. C. Cadet de Gassicourt, by distilling a mixture of dry arsenious oxide and potassium acetate. Alkarsine is a highly reactive, poisonous, spontaneously inflammable substance having heavy brown fumes and a nauseating odor. Its chemical composition was shown by Bunsen to be C4H12As2O, as Berzelius had suggested. Berzelius called the compound kakodyl oxide (from the Greek κακóδηs, “stinking”). Bunsen conducted a detailed study of cacodyl derivatives, obtaining the chloride, iodide, cyanide, and fluoride by reacting concentrated acids with the oxide. Using vapor density techniques, he determined the molecular formulas of the derivatives and realized that the cacodyl radical, C4H12As2, was preserved as an “unchangeable member” through the numerous reactions. This conclusion supported the radical theory of organic compounds advocated by Liebig and Berzelius. Bunsen put forth further evidence for the radical theory when he isolated the free radical by heating the chloride with zinc in an atmosphere of carbon dioxide. After presenting his papers, Bunsen withdrew from the controversy over the merits of the radical theory and turned to inorganic chemistry. It remained for his students, Adolph Kolbe and Edward Frankland, to show in 1853 that cacodyl compounds contain dimethylarsenic, As(CH3)2, and for Auguste Cahours and Jean Riche to demonstrate that free cacodyl is As2(CH3)4. Finally, in 1858 Adolph von Baeyer, another of Bunsen’s students, clarified the relationships among the members of the cacodyl series.

Between 1838 and 1846, Bunsen developed methods for the study of gases while he was investigating the industrial production of cast iron in Germany and, in collaboration with Lyon playfair, in England. He demonstrated the inefficiency of the process; in the charcoal-burning German furnaces, over 50 percent of the heat of the fuel used was lost in the escaping gases; worse, in the coal-burning English furnaces, over 80 percent was lost. Valuable by-products, such as ammonia, went unrealized and were among the gases lost to the atmosphere. Further, it was accidentally discovered that potassium cyanide was formed from potassium carbonate and atmospheric nitrogen at high temperatures. In an 1845 paper, “On the Gases Evolved From Iron Furnaces With Reference to the Smelting of Iron,” Bunsen and Playfair suggested techniques that could recycle gases through the furnace, thereby utilizing heat otherwise lost. They also dicussed ways by which valuable escaping materials could be retrieved

Bunsen compiled his research on the phenomena of gases into his only book, Gasometrische Methoden (1857). This work brought gas analysis to a level of accuracy and simplicity reached earlier by gravimetric and titrimetric techniques. Dividing the book into six parts. Bunsen presented methods of collecting, preserving, and measuring gases; techniques of eudiometric analysis; new processes for determining the specific gravities of gases; results of investigations on the absorption of gases in water and alcohol using asn absorptiometer he himself had devised; and results of experiments on gaseous diffusion and combustion. On the problem of gaseous absorption, Bunsen, assisted by several students, showed the experimental limits within which Henry’s law of pressures and Dalton’s law of partial pressures are valid.

Greatly interested in geology, Bunsen accompanied a scientific expedition to lceland in 1846, the year after the eruption of the volcano Hekla. The expedition, sponsored by the Danish government, lasted three and one-half months and included Sartorius von Waltershausen and Bergmen, both from Marburg, and Alfred DesCloizeaux, a French mineralogist. Bunsen collected gases emitted from the volcanic openings and studied the action of these gases on volcanic rocks. He performed extensive chemical analyses of eruptive rocks, insisting that instead of determining what minerals were in a rock, the chemical composition of the rock as a whole should be ascertained. Bunsen concluded that volcanic rocks are mixtures, in varying proportions, of two exteme kinds of rock; one kind acidic and rich in silica (trachytic). The other kind basic and less rich in silica (Pyroxenic). He thought that the formation of different kinds of rock could be traced to their differences in meltingpoint behavior under pressure. Although this explanation is no longer accepted, his observations contributed a great deal to the development of modern petrology. Bunsen also explored geysers, and at the Great Geyser made daring temperature measurements at several depths shortly before it erupted. He found that the temperature of water in the geyser tube, although high, did not reach the boiling point for a particular depth and corresponding pressure. He concluded that the driving force for eruption is supplied by steam that enters the tube under great presure from volcanic vents at the bottom. As the steam lifts the column of water, the effective pressure above the water is reduced. This change in the water’s depth results in a lowering of the boiling point and enables the already not water to boil.

Through the 1840’s and 1850’s Bunsen made a number of improvements in the galvanic battery. In 1841 he made a battery, known since as the Bunsen battery, with carbon, instead of the more expensive platinum or copper, as the negative pole. To prevent disintegration of the carbon pole by the nitric acid electrolyte, Bunsen treated the carbon, a mixture of coal and coke, with high heat. Forming a battery from forty-four subunits. Later, the made a battery with zinc and carbon plates in chromic acid. In 1852 Bunsen began to use electrochemical techniques to isolate pure metals in qauantities sufficient for determining their physical and chemical properties. He pressed magnesium into wire and used it as a light source in his subsequent photochemical experiments. Commercial manufacture of magnesium was also undertaken and the element came into general use as a brilliant illuminating agent.

In the mid-1850’s Bunsen prepared sodium and aluminium from their molten chlorided. With the assitance of Augustus Matthiessen, Bunsen isolated lithium and several alkaline earth metals-barium, calcium, and strontium-from their fused chlorides. Bunsen, with William hillebrand and T.H. Norton, prepared the rare earth metals of the cerium group-cerium, lanthanum, and didymium. To obtain the specific heats of these rare elements, Bunsen devised a sensitive ice calorimeter that measured the volume rather than the mass of the ice melted and requried only a small sample of the metal. From the specific heats, the atomic weights of these elements and the formulas of their compounds were calculated. Finally, the Bunsen battery made possible the electrolysis of a variety of organic compounds and the isolation of organic radicals by Kolbe and Frankland, who began their work under Bunsen’s direction in Marburg.

Between 1852 and 1862 Bunsen collaborated with Sir Henry Roscoe on photochemical research involving the chemical combination of equal volumes of hydrogen and chlorine when they were illuminated. For this experiment they altered a reaction vessel devised by John Draper in 1843. Bunsen and Roscoe found that for some time after the experiment started—a time they called the induction period—no reaction took place; then the reaction rate slowly increased until a constant rate, Proportional to the intensity of the light source used, was reached. The effect of the incident light was related to the wave- length and followed a law of inverse squares. Further, the illumination of chlorine alone before it entered the reaction chamber did not alter the length of the induction period. While variations of temperature within the range 18°–26° had little effect on the reaction, the presence of oxygen appeared to have a catalytic effect. Bunsen and Roscoe determined that the energy of the light radiated by the sun in one minute is equivalent to the energy needed for the conversion of 25 & 1012 cubic miles of a hydrogen-chlorine mixture into hydrogen chloride.

Bunsen developed his well-known burner during the 1850’s, building upon the inventions of Aimé Argand and Michael Faraday. The Bunsen burner, with its nonluminous flame, quickly supplanted the blowpipe flame in the dry tests of analytical chemistry. Bunsen used his burner to identify metals and their salts by their characteristic colored flames. Other experiments with the burner yielded data for melting points and rate of volatility of salts.

In the 1860’s Bunsen and Kirchhoff worked together to develop the field of spectroscopy. Kirchhoff realized in 1859 that when colored flames of heated materials, which usually give bright, sharp emission spectra, are placed in the path of an intense light source, they absorb light of the same wavelength that they otherwise emit, and produce characteristic absorption spectra. Bunsen saw that analyses of absorption spectra could be made in order to determine the composition of celestial and terrestrial matter. He further predicted that spectral analysis could aid in the discovery of new elements that might exist in too small quantities or be too similar to known elements to be identifiable by traditional chemical techniques. Spectral analysis led to Bunsen and Kirchhoff’s announcement in 1860 of a new alkali metal, cesium, detected in a few drops of the alkaline residue from an analysis of mineral water obtained from Durkheim. The element was named cesium (from the Latin caesius, “sky blue”) because of its brilliant blue spectral lines. Cesium salts had previously been mistaken for compounds of potassium. The following year the element rubidium (from the Latin rubidus, “darkred”)was detected from the spectrum of a few grains of the mineral lepidolite. By comparison, forty tons of mineral water were needed to yield 16.5 grams of cesium chloride and rubidium chloride that could be used in the chemical investigation of the compounds of these new elements. In 1862 Bunsen succeeded in isolating metallic rubidium by heating a mixture of the carbonate and charcoal. During the yeaars that followed, several other elements were identified by spectroscopic methods: thallium (Crookes, 1861), indium (Reich and Richter, 1863), gallium (Lecoq de Boisbaudran, 1875), scandium (Nilson, 1879), and germanium (Winkler, 1886).

Bunsen was concerned with a variety of additional analytic work. In 1853 he developed a technique for the volumetric determination of free iodine using sulfurous acid. In 1868 he worked out methods for separating the several metals—palladium, ruthenium, iridium, and rhodium—that remain in ores after the extraction of platinum; as part of this project Bunsen constructed a filter pump for washing precipitates. With the assistance of Victor Meyer, he conducted a government–sponsored study of the mineral water of Baden; results were published in 1871. He described the spark spectra of the rare earths in 1875. Late in his life Bunsen used a steam calorimeter that he had built to measure the specific heats of platinum, glass, and water.

Bunsen was honored by several European scientific societies. In 1842 he was elected a foreign member of the Chemical Society of London. He became a corresponding member of the Académie des Sciences in 1853, and a foreign member in 1882. He was named a foreign fellow of the Royal Society of London in 1858 and received its Copley Medal in 1860; Bunsen and Kirchhoff received the first Davy Medal in 1877. Finally, Bunsen’s scientific contributions to industry were recognized by the English Society of Arts, which awarded him the Albert Medal in 1898.


I. Original Works. Bunsen’s Writings include Gasometrische Methoden (Brunswick, 1857; enl. ed., 1877), trans. by Henry E. Roscoe as Gasometry; Comprising the Leading Physical and Chemical Properties of Gases (London, 1857); Photochemical Researches, 5 Pts. (London, 1858–1863), written with Henry E. Roscoe and pub. in German as Photochemische Untersuchungen (Leipzig, 1892); Chemische Analyse durch Spectralbeobachtungen (Vienna, 1860), written with Kirchhoff; and Gesammelte Abhandlungen, Wilhelm Ostwald and Ernst Bodenstein, eds., 3 vols. (Leipzig, 1904). Also of interest, all in Klassiker der exacten Wissenschaften, are Untersuchungen über die Kakodylreihe, Adolf von Baeyer, ed., no. 27; and Photo-chemische untersuchungen, W. Ostwald, ed., nos. 34, 38.

II. Secondary Literature. Works on Bunsen are Theodore Curtin’s article in Eduard Farber, Great Chemists (New York, 1961), pp. 575–581, a trans. from Journal für praktische Chemie (1900); O. Fuchs’s article in F. D. G. Bugge, Das Buch der grossen Chemiker, II (Berlin, 1930), 78–91; Georg Lockemann, Robert Wilhelm Bunsen. Lebensbild eines deutschen Forschers (Stuttgart, 1949); Ralph E. Oesper, “Robert Wilhelm Bunsen,” in Journal of Chemical Education, 4 (1927), 431–439; W. Ostwald’s article in Zeitschrift für Elektrochemie, 7 (1900), 608–618; J.R. Partington, A History of Chemistry, IV (London, 1964), 281–293;H. Rheinboldt, “Bunsens Vorlesung über allgemeine Experimentalchemie,” in Chymia, 3 (1950), 223–241; Henry E. Roscoe, “Bunsen Memorial Lecture” (delivered 29 Mar.1900), in Journal of the Chemical Society, 77, pt. I (1900), 513–554; and Bunseniana. Eine Sammlung von humoristischen Geschichten aus den Leben von Robert Bunsen (Heidelberg, 1904).

Susan G. Schacher

Bunsen, Robert Wilhelm Eberhard

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(b. Göttingen, Kingdom of Westphalia, 30 March 1811; d. Heidelberg, Germany, 26 August 1899)

chemistry, analytical chemistry, spectroscopy. For the original article on Bunsen see DSB, vol. 2.

Bunsen is best remembered for inventing and teaching methods that were crucial to the development of nineteenth-century analytical chemistry—above all those on gasometry, photochemical induction, and spectral analysis. Furthermore, he made important improvements in instrumental techniques and had a sincere interest in geological matters. A good description of these topics is given in the original DSB article, though some of the dates are incorrect. Drawing on subsequent research, some of the stations of Bunsen’s life and work are recapitulated. In addition, a fuller assessment of Bunsen’s interdisciplinary research practices and his involvement in political matters are provided.

Career Path. Bunsen was born into a Protestant bourgeois family from the middle of what is modern day Germany. His father, at once professor of physical geography, rhetoric, Spanish, and Italian and sub-librarian at the University of Göttingen, worked hard to feed his family. But raising four sons and funding their studies (the eldest son, Carl, died in an accident when he was seventeen years old) left the finances running low. Unlike his brothers, Bunsen studied not law but sciences and mathematics. Among his teachers were such prominent scientists as Friedrich Stromeyer, Johann Friedrich Blumenbach, Wilhelm Weber, Johann Friedrich Ludwig Hausmann, and Bernhard Friedrich Thibaut.

When only twenty years old, Bunsen received his doctor’s degree for a thesis originally written—and awarded— as an answer to the yearly announced Preisfrage (essay competition) of the philosophical faculty. His final exams

took place in September 1831. In May 1832 Bunsen departed on a fifteen-month grand tour through Germany, France, Switzerland, Tyrol, and Austria. Subsequently he started to work on ammonia cyano compounds for his Habilitation in January 1834. Together with the physician Arnold Adolph Berthold, he then began research on iron oxide as an antidote to arsenic acid, the first in a number of successful interdisciplinary projects. In April 1834 he took up a lectureship as a Privatdozent at the University of Göttingen. After Stromeyer’s death in August 1835, he took over the main lecture until Friedrich Wöhler succeeded him. In return, in April 1836 Bunsen followed Wöhler as teacher at the vocational school (Höhere Gewerbeschule) in Kassel. Here he began to work on organo-arsenic compounds and continued this work, despite a bad accident in November 1836 which damaged his right eye, after being appointed professor of chemistry in Marburg in 1839.

Due to his increasing scientific reputation, built above all on his new gasometrical methods, Bunsen received a full professorship in 1841. Early in his career he developed an ongoing interest in technical-analytical

questions, which was to play a significant role in linking his various research interests throughout his life.

In April 1851 Bunsen succeeded to Nikolaus Wolfgang Fischer’s chair in Breslau. There he lectured on organic chemistry for the last time. In later years, his teaching focused on inorganic chemistry. Select parts of organic chemistry, however, were implemented in his experimental teaching. In the fall of 1852 he moved to Heidelberg as professor at the philosophical faculty and as director of the chemical laboratory. At the same time he received the title of Hofrath. Main achievements of his career in Heidelberg were the photochemical research undertaken with Henry Enfield Roscoe from 1853 onward, and the scientific foundation of spectral analysis together with Gustav Robert Kirchhoff in 1859–1860.

While the scientific and technical significance of Bunsen’s work is generally accepted, the importance of interdisciplinary cooperation in it is frequently underestimated. Particularly the great inventions in photochemistry and spectroscopy would not have been possible, had he not been part of the well-developed experimental culture in Heidelberg at that time, the main features of which were the application of physical methods to chemical and physiological questions and the transfer of methods across disciplinary boundaries by means of scientific instruments.

Social Context. Subsequent research has shown that the emergence of this specific cultural setting was the result of both Baden’s successful science policy, and Bunsen’s own role in deliberately using academic employment policy for the creation of interdisciplinary networks. The nucleus of the Heidelberg network was built by Bunsen, Kirchhoff, Hermann von Helmholtz, Leo Königsberger, and, later on, Hermann Kopp. Their achievements, however, depended on the services and know-how of a group of assistants, instrument makers, mechanics and draftsmen, for example, the famous Munich instrument maker Carl August von Steinheil, who supplied the lenses for the first spectrometer, or Heidelberg’s university mechanic Peter Desaga, who provided Bunsen’s laboratory with the famous burners and whose company, later on, specialized in Bunsensche Apparate, or the almost anonymous painter Friedrich Veith, whose pencil drawings of instruments were used for publications.

Little is known about Bunsen’s political, and even less about his religious, position. But from his letters, from his actions and social relationships an antireactionary attitude can be inferred. Even though Bunsen played no active role in politics, Roscoe described him as a “staunch Liberal” (Roscoe, 1900, p. 552). While earlier research characterized Bunsen as apolitical, or, at best, hostile to Prussian politics, later research highlights his being part of a close network of liberal and politically active scholars such as Ludwig Häusser and Georg Gottfried Gervinus. Furthermore three of Bunsen’s cousins, Gustav, Georg, and Karl Bunsen were active in the Vormärz era.

Bunsen’s letters, especially those to his favorite pupil and friend Roscoe—in his later years a liberal member of Parliament for Manchester South—show him as a well-informed spectator of international politics who was well aware of the impact of political events upon university life and who knew how to interpret them for local purposes such as university politics. Thus it is by no means coincidental that Bunsen followed vocations from universities in more liberal states whenever the situation at his prior institution was worsening, a strategy that clearly demonstrates the close relationship between the careers of single scientists and science politics in the different territories of nineteenth-century Germany, which were competing for cultural excellence.


Important archival resources lie in the Deutsches Museum Munich, Germany (foremost letters to colleagues), and the Universitätsbibliothek Heidelberg, Germany (a part of his literary remains, and some pupils’ notes on Bunsen’s lectures).

Boberlin, Ursula. Photochemische Untersuchungen von R. Bunsen und H. Roscoe im Vergleich mit den Arbeiten J. W. Drapers und W. C. Wittwers. Die Anfänge der quantitativen Photochemie im 19. Jahrhundert. Berlin: Köster, 1993.

Borscheid, Peter. Naturwissenschaft, Staat und Industrie in Baden (1848–1914). Stuttgart: Klett, 1976.

HobHitzel, Stephanie Brigitte. “Es lebt sich himmlisch in Heidelberg.” Robert Wilhelm Bunsen und seine Korrespondenz. PhD diss., University of Heidelberg, 2003. Not in all aspects reliable.

James, Frank A. L. J. “Science as a Cultural Ornament: Bunsen, Kirchhoff and Helmholtz in Mid-Nineteenth-Century Baden.” Ambix 42 (1995): pt. 1, 1–9.

Jungnickel, Christa, and Russell McCormmach. “Kirchhoff and Helmholtz at Heidelberg: Relations of Physics to Chemistry and Physiology.” In Intellectual Mastery of Nature: Theoretical Physics from Ohm to Einstein. Volume 1: The Torch of Mathematics, 1800–1870, by Christa Jungnickel and Russell McCormmach. Chicago: University of Chicago Press, 1986.

Roscoe, Henry Enfield. The Life & Experiences of Sir Henry Enfield Roscoe, Written by Himself. London: Macmillan, 1906.

Roscoe, Henry Enfield. “Bunsen Memorial Lecture.” Journal of the Chemical Society 77 (1900): pt. 1, 513–554.

Stock, Christine. Robert Wilhelm Bunsens Korrespondenz vor dem Antritt der Heidelberger Professur (1852) – Kritische Edition. PhD diss., University of Marburg, 2005. (To be published by Wissenschaftliche Verlagsgesellschaft mbH, Stuttgart, series “Quellen und Studien zur Geschichte der Pharmazie,” in 2007.)

Tuchman, Arleen Marcia. Science, Medicine, and the State in Germany. The Case of Baden, 1815–1871. New York and Oxford: Oxford University Press, 1993.

Christine Nawa

Robert Wilhelm Bunsen

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Robert Wilhelm Bunsen

The German chemist and physicist Robert Wilhelm Bunsen (1811-1899) was one of the great experimental chemists and a pioneer of chemical spectroscopy.

Robert Bunsen was born on March 31, 1811, in the university town of Göttingen. His father was professor of linguistics and librarian at the university. Bunsen completed his advanced education at Göttingen, developing an extensive mastery of mathematics, physics, chemistry, and mineralogy. In later years, when his fame as an experimentalist was worldwide, Bunsen stated that "a chemist who is not a physicist is nothing."

With his strong practical bent and interest in the expanding industrial revolution, Bunsen studied blast furnace operations, the working of steam engines, and the physiochemical processes of the famed porcelain works at Sèvres. In later years his scientific discoveries contributed to the increased efficiency of some of these basic industries.

Bunsen established his reputation through his work in inorganic chemistry and his classical set of experiments in organic chemistry which involved the properties of the cacodyl series of compounds. These organic arsenic bodies were highly dangerous, and his work with them nearly cost Bunsen his life. A useful by-product of this research was his discovery of the antidote for arsenic poisoning.

In 1852 Bunsen succeeded Leopold Gmelin in Heidelberg. There he established his Institute of Chemistry, which soon attracted the most brilliant students from all over the world, including Edward Frankland, the developer of the theory of chemical valency, and Victor Meyer, the pioneer in the chemistry of benzene compounds.

A master craftsman, Bunsen developed many of the instruments for analytical chemistry, including the burner which bears his name but which had been used first in a primitive form by Michael Faraday. The ice calorimeter and many devices for gas analysis were the product of Bunsen's personal skill.

Bunsen contributed to the foundations of photochemistry in collaboration with H. E. Roscoe, determining the effect of light on the combining reactions of hydrogen and chlorine. This led Bunsen to the first effort to estimate the radiant energy of the sun.

The most fruitful collaboration of Bunsen was his work with Gustav Kirchhoff, the German physicist. By combining the Bunsen burner with the optical system pioneered by Joseph von Fraunhofer, the two scientists developed the science and art of spectroscopy. Since each chemical element rendered radiant by the heat source emitted a characteristic pattern of lines (spectrum), there had been developed the supreme instrument of chemical analysis. Bunsen and Kirchhoff soon discovered two hitherto-unknown elements, cesium and rubidium.

Further Reading

A good account of Bunsen appears in volume 4 of J. R. Partington, A History of Chemistry (1964). Eduard Farber, ed., Great Chemists (1961), contains a short biographical sketch. Henry M. Leicester and Herbert S. Klickstein, A Source Book in Chemistry, 1400-1900 (1952), includes a description of Bunsen's work. □

Bunsen, Robert Wilhelm

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Bunsen, Robert Wilhelm (1811–99) German chemist, professor at Heidelberg (1852–99). He did important work with organo-arsenic compounds and discovered an arsenic poisoning antidote and evolved a method of gas analysis. With Gustav Kirchhoff, he used spectroscopy to discover two new elements (caesium and rubidium). He invented various kinds of laboratory equipment, including the bunsen burner.

Robert Wilhelm Bunsen

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Robert Wilhelm Bunsen


German chemist who popularized and improved the bunsen burner, a small tabletop torch whose high-temperature, nonluminous flame was perfect for his pioneering spectroscopy experiments. It has since become standard laboratory equipment. Bunsen was the codiscoverer of two elements, cesium and rubidium. His other accomplishments included the development of an antidote to arsenic poisoning, an explanation for the action of geysers, and invention of the carbon-electrode battery, used for arc lights and electroplating.

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