World of Chemistry on Robert Wilhelm Eberhard Bunsen
Many people associate the word Bunsen with a gas burner used in school laboratories. Although generally known for his work on perfecting the Bunsen burner, which was actually an invention of Michael Faraday, Robert Bunsen's true claim to fame is spectroscopy. Along with Gustav Kirchhoff, Bunsen discovered the process of chemical analysis called spectroscopy.
The son of a university professor, Bunsen graduated from the Gymnasium at Holzminden in 1828. He began his graduate studies in chemistry, physics, and mathematics at the University of Gottingen in his hometown (the same school at which his father taught), earning his doctorate in 1830. Using grant money awarded by the Hanoverian government, Bunsen spent several years traveling in Europe, visiting Berlin, Bonn, Paris, and Vienna, and meeting with such prominent scientists as Joseph Louis Gay-Lussac, Henri-Victor Regnault (1810-1878), and Cesar Despretz (1798-1863). Upon his return Bunsen served on the academic staff of several universities before accepting a position at the University of Heidelberg in 1852, a post he held until his retirement in 1889.
Bunsen conducted scientific research throughout his career. He began in his late 20s, studying the properties of arsenic and the compounds that contained it, most of which were inorganic. During his research he found that hydrated ferric oxide made an effective antidote for arsenic poisoning. Some of Bunsen's experiments were quite dangerous: fires and explosions occurred frequently, and twice he nearly lost his life due to the inhalation of arsenic fumes. The last of these experiments was in 1843, when an explosion of cacodyl cyanide cost him the use of his right eye.
For the next several years Bunsen focused on understanding heated gases. He visited geysers and volcanoes as well as refineries and industrial furnaces. He published his only book,Gasometrische Methoden as a compilation of his gas research findings. Bunsen had become interested in the chemical properties of alkali metals, such as barium and sodium. In order to isolate these elements, he invented new types of galvanic and carbon-zinc batteries (many of which are still called Bunsen batteries). To properly analyze the elements, he constructed a very sensitive ice calorimeter, measuring the volume of melted ice, rather than its mass. Along the way, he invented scientific instruments such as an ice calorimeter and the Bunsen battery. Still, the behavior of inorganic compounds and their components remained his primary interest. He became curious about the effects of incandescence--heating an element until it glows or and studying the color of its light or flame. It was at this time that Bunsen met Gustav Kirchhoff, an instructor at Breslau. Kirchhoff was also interested in the information that could be obtained by analyzing the light emitted from certain elements. Recognizing a kindred spirit, Bunsen persuaded Kirchhoff to come to Gottingen so that they might work together.
Bunsen and Kirchhoff knew that the key to analyzing incandescent light was to view it through a spectroscope, a device that split the light into its component colors. (A prism is a very simple spectroscope.) In order to better see the spectral patterns, they first shone the light through a slit, reducing the light to a thin beam. When passed through a spectroscope, this beam revealed a series of colored lines called an emission spectrum . However, the spectra produced from Bunsen and Kirchhoff's initial experiments were tainted: light from the gas burner used to heat the specimens to incandescence would creep into the beam, skewing the spectrum. To maintain a pure incandescent light, Bunsen modified a gas burner which had as very hot yet nearly invisible flame. Using the Bunsen burner, the scientists' research yielded spectral patterns of remarkable clarity.
After only a few weeks, it became clear that each element was characterized by a specific emission spectrum, as individual as a fingerprint. It did not take long for Bunsen and Kirchhoff to catalog the spectral patterns of all the known elements. With knowledge of these spectra, a chemist could deduce the components of any unknown substance. Using this method, Bunsen and Kirchhoff discovered two new elements, cesium and rubidium.
Over the course of his career, Bunsen also invented a grease-spot photometer (used for measuring light), a process for mass-producing magnesium, a laboratory filter pump for washing precipitate samples, and a steam calorimeter.
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