Robert Bunsen

Lore & Background

Robert Bunsen was born in Göttingen, Germany, on March 30, 1811, the youngest of four sons of the university's chief librarian. He studied chemistry, mineralogy, and mathematics at Göttingen, earning his PhD in 1831, then traveled through France, Germany, and Austria, meeting scientists such as Justus von Liebig. He began his academic career as a lecturer at Göttingen in 1833, where he studied arsenic compounds and discovered iron oxide hydrate as an antidote for arsenic poisoning.

Bunsen later taught at the Polytechnic School of Kassel and the University of Marburg, where he worked on cacodyl derivatives, nearly dying from arsenic poisoning and losing sight in his right eye from an explosion. In 1841 he created the Bunsen cell battery, and in 1852 he succeeded Leopold Gmelin at Heidelberg. There he used electrolysis to produce pure metals and collaborated with Henry Enfield Roscoe on photochemistry. With Gustav Kirchhoff, he developed the spectroscope and discovered caesium in 1860 and rubidium in 1861.

Bunsen retired in 1889 at age 78, shifting his work to geology and mineralogy. He died in Heidelberg on August 16, 1899, at age 88. He never married and never took out a patent. The crater Bunsen on the Moon was named after him in 1964.

Reader's Guide

Robert Bunsen's significance lies in his foundational contributions to spectrum analysis, which enabled the discovery of two new elements, caesium and rubidium, and established a method for identifying elements by their spectral lines. His collaboration with Gustav Kirchhoff led to the development of the spectroscope, a tool that revolutionized analytical chemistry and astrophysics. The Bunsen burner, perfected with Peter Desaga, became a ubiquitous laboratory device, providing a clean, hot flame for heating and sterilization. Bunsen also advanced photochemistry through the reciprocity law with Henry Enfield Roscoe, and his work on arsenic compounds produced an effective antidote. His legacy is commemorated by the Bunsen–Kirchhoff Award for spectroscopy and the lunar crater Bunsen. As a teacher, he was devoted to his students and avoided theoretical disputes, preferring practical laboratory work. He never patented his inventions, reflecting a commitment to open scientific progress.

Did You Know?

• Bunsen discovered caesium in 1860 and rubidium in 1861 with physicist Gustav Kirchhoff.
• He developed the Bunsen burner with his laboratory assistant Peter Desaga.
• Bunsen almost died from arsenic poisoning and lost sight in his right eye from a cacodyl explosion.
• He was one of the first recipients of the Davy Medal in 1877, together with Gustav Kirchhoff.

Academic Journey and Scientific Breadth

Robert Wilhelm Eberhard Bunsen entered the world on March 30, 1811, in Göttingen, as the youngest of four sons born to the university's chief librarian and a professor of modern philology. His early schooling in Holzminden gave way to matriculation at Göttingen in 1828, where he absorbed chemistry from Friedrich Stromeyer, mineralogy from Hausmann, and mathematics from the legendary Carl Friedrich Gauss. A doctorate followed in 1831, and the two years of travel that came next—through France, Germany, and Austria—connected him with Friedlieb Runge, Justus von Liebig, and Eilhard Mitscherlich, broadening his scientific horizons considerably. His academic postings then carried him from a Göttingen lectureship in 1833, through Kassel and Marburg, to Breslau and finally Heidelberg in 1852, where he would remain for the rest of his career. Along the way his research spanned an astonishing range: gas-analytical methods, photochemistry, organic arsenic chemistry, and the development of the Bunsen cell battery, which substituted a carbon electrode for the costly platinum one used in Grove's earlier electrochemical design. His work on cacodyl derivatives, though nearly fatal to him, proved a crucial step toward the radical theory of organic compounds.

The Spectral Discoveries

The summer of 1859 marked a turning point when Gustav Kirchhoff proposed that Bunsen attempt to form prismatic spectra from the characteristic colors emitted by heated elements. By October, the pair had built a prototype spectroscope, refining Joseph von Fraunhofer's 1814 design, and immediately identified the unique spectral signatures of sodium, lithium, and potassium. Bunsen then undertook painstaking purification of samples to demonstrate that only highly pure substances produced truly distinct emission lines. The breakthrough came when he noticed unfamiliar blue spectral lines in mineral water drawn from Dürkheim—a signature that no known element could explain. Suspecting an undiscovered substance, Bunsen distilled forty tons of that water over an extended period, ultimately isolating just seventeen grams of a new metal in the spring of 1860. He christened it caesium, from the Latin word for deep blue. The following year, using a comparable procedure, he identified rubidium. These discoveries, made in close partnership with Kirchhoff and supported by the clean, hot flame of the Bunsen burner that he and his assistant Peter Desaga had perfected by 1855, established spectrum analysis as a rigorous new discipline.

Enduring Legacy and Recognition

Few pieces of laboratory equipment are as universally recognized as the Bunsen burner, yet its origins trace to a practical problem: the need for a hotter, cleaner flame suitable for spectroscopic observation. Bunsen and Desaga's design, finalized around 1855, drew on earlier models but delivered a performance that made it indispensable, and it remains a standard fixture in chemistry labs worldwide. His scientific contributions earned him a remarkable string of honors. In 1860 he received honorary membership in the Manchester Literary and Philosophical Society and was elected a foreign member of the Royal Swedish Academy of Sciences; two years later the American Philosophical Society admitted him as a member. In 1877, Bunsen and Kirchhoff became the very first recipients of the Davy Medal, awarded specifically for their researches and discoveries in spectrum analysis. A modern prize, the Bunsen–Kirchhoff Award, continues to honor excellence in that field. His 1833 discovery that iron oxide hydrate serves as a precipitating agent for arsenous acid compounds still stands as the most effective antidote to arsenic poisoning. In 1964, a lunar crater was named Bunsen, extending his name into the cosmos.

Character and the Final Chapter

Bunsen's colleagues and students remembered him less for his titles than for his temperament. He was a devoted teacher who inspired fierce loyalty in return, yet he deliberately kept his distance from the caustic theoretical debates that animated his era, preferring the quiet solitude of the laboratory bench. As a matter of personal principle, he never filed a patent, and he never married. Those who knew him described a vivid chemical character with a sharp sense of humor, and his name is surrounded by a rich collection of amusing anecdotes. His dedication to dangerous work came at a personal cost: he nearly perished from arsenic poisoning, and a cacodyl explosion permanently robbed him of sight in his right eye. When he retired from his Heidelberg professorship in 1889 at the age of seventy-eight, he redirected his energies toward geology and mineralogy, interests he had cultivated throughout his career. He lived another decade, passing away in Heidelberg on August 16, 1899, at the age of eighty-eight, leaving behind a body of work that touched chemistry, physics, and medicine in equal measure.

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