Bunsen
Achievements: Spectroscopy
Born: March 31, 1811; Göttingen, Westphalia [Germany]
Died: August 16, 1899; Heidelberg, Baden, Germany (Aged 88)
Field & Discipline: Science; Chemistry; Chemist
Language: German
Father: Christian Bunsen
Mother: ? Quensel
Siblings: Three elder brothers
Spouse: None
Children: None
Education: Gottingen Gymnasium; Holzminden Gymnasium, to 1828; University of Gottingen, 1828-30
Major Work: "Gasometrische Methoden" (1857)
Life & Times:
From 1830 to 1833, financed by a grant from the Hanoverian government, Bunsen travelled around Europe, meeting some of the leading chemists of the day and visiting many engineering works.
In 1831 he saw a new steam engine in a Kassel machinery factory, studied Christian Weiss's geognostic and mineralogic collections, met [met] Runge* (the discoverer of aniline), and worked in Heinrich Rose's laboratory. In 1832 he visited [visited] Liebig* in Giessen.
Then in September 1832 Bunsen travelled to Paris, where he worked in [worked with] Gay-Lussac's* laboratory and met many prominent scientists. From May to July 1833 he travelled to Vienna, where he toured several industrial plants.
In the autumn of 1833, Bunsen was appointed junior lecturer at the University of Gottingen, and in January 1836 succeeded [succeeded] Friedrich Wohler* as professor of chemistry at the Polytechnic Institute of Kassel. In October 1938 he became a professor of chemistry at the University of Marburg .
During these years Bunsen began his most significant work, on cacodyl derivatives, the unpleasant and highly toxic organic compounds of arsenic, obtaining the chloride, iodide, cyanide and fluoride by reacting concentrated acids with cacodyl oxide. Using vapor density techniques, Bunsen calculated the molecular formulae of these derivatives, and realized that the cacodyl radical, C[subscript 4]H[subscript 12]As[subscript 2] was preserved as an "unchangeable member" through the various reactions. His description of the structure of these compounds supported the controversial radical theory of organic compounds by Liebig, Justus and [supported theory of] Berzelius*.
During this period at Marburg, Bunsen also began industrial research, in particular involving the industrial production of cast iron in Germany and (in collaboration with the Scottish scientist [collaborated with] Lyon Playfair*) in Britain.
Between 1838 and 1846, Bunsen investigated the gases given off from blast furnaces, and discovered that in the German furnaces, which burned charcoal, over 50 percent of the heat of the fuel used was lost in the escaping gases during smelting, while the coal-burning British furnaces lost over 80 percent. He also discovered that valuable gaseous by-products, such as ammonia, were also lost, and that potassium cyanide was formed from potassium carbonate and atmospheric nitrogen at high temperatures.
Together with Playfair, Bunsen published these findings in a paper entitled "On the Gases Evolved from Iron Furnaces, With Reference to the Smelting of Iron" (1845), in which they suggested techniques that could recycle gases through the furnace, utilize the wasted heat and retrieve some of the escaping materials.
In 1846, Bunsen went on a three-month scientific expedition to Iceland, a year after the eruption of the volcano Hekla. During the trip Bunsen collected gases emitted from the volcanic openings and studied their action on volcanic rocks. His conclusion that volcanic rocks are mixtures, in varying proportions, of two extreme kinds of rock - one acidic and rich in silica (trachytic) and the other basic and less rich in silica (pyroxenic) - would prove important to the development of modern petrology.
In 1852 Bunsen was appointed professor of chemistry at the University of Heidelberg. He remained at Heidelberg for the next three decades, dedicating his life to teaching and research, and in 1857 he published his only book: 'Gasometry: Comprising the Leading Physical and Chemical Properties of Gases', a compilation of his extensive and accurate methods of gas analysis.
In the mid-1850s and 1860s he continued his research into metals, preparing sodium and aluminium from their molten chlorides, and isolating lithium and several alkaline earth metals - barium, calcium, and strontium - from their fused chlorides. He also (in collaboration with William Hillebrand and T.H. Norton) prepared the rare earth metals of the cerium group (cerium, lanthanum and didymium). Once he had obtained the specific heats, Bunsen was able to calculate the atomic weights of these elements and the formulae for their compounds.
During the late 1850s he also began working with the German chemist [worked closely with] Kirchhoff* to develop the [developed] spectroscope* fir use in in chemical analysis. During 1859-60, Bunsen and Kirchhoff realized that each element emits a light of characteristic wavelength and that, when colored flames of heated materials are placed in the path of an intense light source, they absorb light of the same wavelength that they usually emit, and produce characteristic “absorption spectra” (lines appearing at the frequency of the missing element).
In 1860-62, Bunsen discovered "new" lines in the spectra of minerals which represented the new alkali-group metal elements rubidium (which produced prominent red spectral lines) and caesium (which gives brilliant blue spectral lines).
The work by Bunsen and Kirchhoff opened the field of spectrum analysis and during the following years, using the same techniques, other researchers discovered several other new elements: [inspired] Crookes* discovered thallium in 1861; Ferdinand Reich and Hieronymous Richter discovered indium in 1863; inspired] Paul Emile Lecoq de Boisbaudran discovered gallium in 1875; Nilson discovered scandium in 1879; and [technique used by] Winkler* discovered germanium in 1886.
During the 1850s, probably in order to heat the materials for spectroscopic analysis, Bunsen's technician, Peter Desdega, appears to have developed the [introduced] Bunsen burner*, in which gas (originally coal gas, but any inflammable gas can be used) is released from a jet at the base of a chimney. At the base of the chimney a hole (or holes) are encircled by a movable collar (which also has holes), and thus rotation of the collar controls the amount of air admitted at the base of the chimney, while the air-gas mixture burns at the top. With the air holes closed, the gas burns with a luminous, sooty flame, but with the air holes open, the air-gas mixture burns with a hot, non-luminous flame, and makes a characteristic roaring sound.
Bunsen also invented the filter pump (1868) for washing precipitates, and the vapor - or steam - calorimeter (1887), which he used to measure the specific heats of platinum, glass, and water.
As well as for his many discoveries and inventions, Bunsen was also renowned as an outstanding teacher, training during his career a large number of important scientists, including [taught] Mendeleyev*, [taught] Kekule*, and [taught] Welsbach*.
Bunsen retired from the University of Heidelberg in 1889, and was eventually succeeded by the organic chemist [succeeded by] Curtius* in 1897.
Extra Connections: His work related to that of [work related to] Fischer* and [work related to] Caro*
[taught] Sprengel* worked in his lab.
Assessment: Pioneered the use of the spectroscope to analyse chemical compounds and discovered two new elements, rubidium and caesium.
Oneliner: Robert Bunsen, German chemist and inventor of Bunsen Burner.
Bibliography:
- Dictionary of Scientific Biography.
- Encyclopedia Britannica.
- Curtin, T., "Robert Wilhelm Bunsen", in Great Chemists (ed. E. Farber),
- New York, 575-81.