Bunsen , Robert Wilhelm

(1811–1899) German chemist

Bunsen, the son of a professor of linguistics, gained his doctorate at the university in his native city of Göttingen (1830) with a thesis on hygrometers. After an extensive scientific tour in Europe, he became a lecturer at Göttingen in 1834. He was professor of chemistry at Kassel (1836), Marburg (1841), and Heidelberg (1852–89).

Bunsen carried out one great series of researches in organic chemistry, Studies in the Cacodyl Series (1837–42), after which he abandoned organic for analytical and inorganic chemistry. During his research on the highly toxic cacodyl compound he lost one eye in an explosion and twice nearly killed himself through arsenic poisoning. He prepared various derivatives of cacodyl (tetramethylarsine, (CH₃)₂As₂(CH₃)₂), including the chloride, iodide, fluoride, and cyanide, and his work was eagerly welcomed by Jöns Berzelius as confirmation of his theory that organic chemistry mirrored inorganic, the ‘radical theory’.

Bunsen was a great experimentalist, an expert in gas analysis and glass blowing, and a pioneer of photochemistry and spectroscopy. He also worked in electrochemistry, devising an improved version of the Grove cell. At Heidelberg he used his new cell to produce metals by electrodeposition. The classic paper Chemical Analysis through Observation of the Spectrum (1860) by Bunsen and Gustav Kirchhoff ushered in the era of chemical spectroscopy. The spectroscope was an extremely sensitive analytical instrument. With it Bunsen discovered two new elements: rubidium and cesium.

The famous Bunsen burner was introduced by him in 1855, although a similar burner, used by Michael Faraday, did exist before Bunsen and the regulating collar was a later refinement. He greatly refined gas analysis and wrote a standard treatise on the subject, Gasometrische Methoden (1857, Methods in Gas Measurement).

Bunsen was a great teacher and at Heidelberg he became a legend. Chemists who came to study with him included Adolph Kolbe, Edward Frankland, Victor and Lothar Meyer, Friedrich Beilstein, and Johann Baeyer.