Robert Wilhelm Bunsen

from Wikipedia, the free encyclopedia
Robert Bunsen
Memorial plaque for Robert Wilhelm Bunsen at his Heidelberg laboratory

Robert Wilhelm Eberhard Bunsen (born March 30, 1811 in Göttingen , † August 16, 1899 in Heidelberg ) was a German chemist . Together with Gustav Robert Kirchhoff, he developed spectral analysis , with the help of which chemical elements can be detected in a highly specific manner. He perfected the Bunsen burner named after him and invented the Bunsen element and the Bunsen photometer .


Robert Wilhelm Bunsen
Bunsen employee in Heidelberg in 1857

Early years

Robert Bunsen came as the youngest of four sons of the Göttingen literature professor and librarian Christian Bunsen , son of Philipp Christian Bunsen and his wife Auguste Friederike Bunsen born. Quensel (1775–1855), a daughter of Carl Quensel, British-Hanoverian major and syndic of the city of Goslar, and Melanie Heldberg, from a family of lawyers, were born.

Different information about Robert Bunsen's date of birth can be found in the literature. While Bunsen's baptism entry and a handwritten curriculum vitae refer to March 30, 1811, several reference works cite March 31 as the date of birth on which, according to his biographer Georg Lockemann, Bunsen also celebrated his birthday in later years. After completing school in Göttingen and graduating from high school in Holzminden , he studied natural sciences, especially chemistry and mathematics at the University of Göttingen . In 1830 he wrote a dissertation entirely in Latin on the then known hygrometers and received his doctorate in 1831 . From 1832 to 1833 he traveled through western Europe on a grant from the state government to further his education. During this time he met Friedlieb Ferdinand Runge , Justus Liebig in Gießen and Eilhard Mitscherlich in Berlin . He and his godfather's sons made each other unpopular at the Frankfurt Wachensturm .


After his return , Bunsen completed his habilitation in Göttingen in 1834 and began experimenting on the (in) solubility of metal salts of arsenic acid . His discovery of iron oxide hydrate is still used today as an antidote to arsenic poisoning . After the death of Friedrich Stromeyer (1835) and before the appointment of Friedrich Wöhler (1836), Bunsen took over the representation of the chair.


In 1836, Bunsen succeeded Friedrich Wöhler at the higher industrial school (polytechnic) in Kassel . Here he began researching the cacodyl compounds (tetramethyldiarsane As 2 (CH 3 ) 4 and its derivatives), injuring himself in his right eye as early as 1836 and becoming partially blind. In 1838 Bunsen undertook fundamental physical and chemical investigations of the processes taking place in the blast furnace (e.g. furnace gas ) in the ironworks located north of Kassel in Veckerhagen , which was then important .


In 1839 Bunsen was transferred to the University of Marburg , where he continued his work on kakodyl compounds and the development of gas analysis methods. His work brought him quick and wide recognition. In 1841, Bunsen developed a nitric acid-containing zinc-carbon battery (Bunsen element ), which was inexpensive and versatile.

When the Icelandic volcano Hekla erupted again in 1845 , the Danish government invited him to an expedition to Iceland , during which he a. a. was accompanied by Wolfgang Sartorius von Waltershausen and Carl Bergmann . After his cousin Robert Louis Karl Bunsen, personal physician of the Elector in Kassel, was able to convince the Elector Friedrich Wilhelm in 1846, he received six months' leave. The analysis of the gas and rock samples he had brought with him claimed him for the next six years, and he succeeded in developing the gas analysis into an exact procedure. Important students were in Marburg: Hermann Kolbe , Edward Frankland , John Tyndall , Heinrich Debus .


Robert Bunsen with Gustav Robert Kirchhoff, left in the picture

In 1850 Bunsen accepted a position at the University of Breslau . A new laboratory was built for him here, and it was here that he met the physicist Gustav Robert Kirchhoff . However , Bunsen taught in Breslau for only three semesters and then followed a call to Heidelberg.


Statue of Robert Bunsen, created by Hermann Volz , erected opposite the Palais Haus zum Riesen in Heidelberg

In 1852 Bunsen took over the chair from Leopold Gmelin at the Ruprecht-Karls-Universität . Here, too, Bunsen received a new laboratory and an official apartment. The laboratory was considered to be the most modern chemical laboratory in Germany.

In his experiments, Bunsen succeeded in extracting numerous metals such as chromium , magnesium , aluminum , manganese , sodium , barium , calcium and lithium in elemental form by means of the electrolysis of molten salts .

In his collaboration with Sir Henry Roscoe from 1852 on, the light-induced formation of hydrogen chloride from hydrogen and chlorine was investigated.

After seven years, Bunsen broke off his collaboration with Roscoe in 1859 and worked with Kirchhoff on the spectral analysis of chemical elements. With the help of spectroscopy, the characteristic spectral lines could be examined when chemical substances are heated in flames . For this purpose, Bunsen perfected a special gas burner, which had previously been invented by Michael Faraday and which was later to be given the name Bunsen.

During the spectral analysis of the mineral water of the newly developed Maxquelle in Dürkheim , Bunsen and Kirchhoff discovered the alkali metals cesium and rubidium in 1860/61 . Their studies also made it possible to explain the Fraunhofer lines and thus lay one of the most essential foundations for modern astronomy.

Bunsen taught well over 3000 students during his time in Heidelberg. He was supported by two or sometimes even three assistants. The “first assistant” helped directly in the lecture and in the laboratory. The “second assistant” looked after the beginners and helped them with their internship. The “third” has already been entrusted with special tasks.

A manuscript by his assistant for the preparation of the experiments and the writing on the blackboard for the lecture "Experimental Chemistry" appeared after 145 years in California. Inge König, a descendant of that assistant, handed the manuscript over to the Chemistry Faculty on the occasion of the Heidelberg University's 2004 annual celebration (today in the archive of the Bunsen Society ). The recorded periodic table comprised 60 elements at that time, before cesium and rubidium were added with pencil.

Bunsen did not offer any special training in organic chemistry, which has been criticized at times. However, he employed up to eight other lecturers who offered individual courses on organic and pharmaceutical chemistry, chemical technology, crystallography, forensic chemistry and the history of chemistry. Soldering tube exercises completed the offer. This wide range made the Heidelberg location attractive for students from other German and European countries and even from overseas.

In the old auditorium of Heidelberg University , Robert Wilhelm Bunsen was given a seat specially marked for him.

Important students were in Heidelberg: Konrad Beilstein , Emil Erlenmeyer , Henry Roscoe , Ludwig Carius , Lothar Meyer , Hans Landolt , Adolf Lieben , Adolf von Baeyer , Carl Graebe , Albert Ladenburg , Hermann Wichelhaus , Viktor Meyer , Hans Bunte , Carl Auer von Welsbach as well as August Kekulé and Leon Nikolajewitsch Schischkow (Léon Schischkoff).


Robert Wilhelm Bunsen's tomb in the Heidelberg Bergfriedhof , the tomb is in Department V

When Bunsen retired at the age of 78, he devoted himself to geology , which he had only pursued as a hobby until then.

Robert Wilhelm Bunsen died on August 16, 1899 at the age of 88 in Heidelberg. He was buried in the Heidelberg mountain cemetery. In his obituary, Roscoe said:

“As an investigator, he was great. As a teacher, even greater. As a man and friend, he was greatest. "

“He was great as a researcher. Even greater as a teacher. As a person and friend he was the greatest. "

Honors and memberships

Scientific work

In Göttingen, Bunsen carried out his first work on double and triple salts of cyanides .

In 1846, Bunsen received an invitation from the Danish government to accompany an expedition to Iceland. In Iceland he examines the Great Geyser. He finds hydrogen , hydrogen sulfide and carbon dioxide in the gases emitted . For the occurrence of hydrogen he finds the explanation of the splitting of hydrogen sulfide into sulfur and hydrogen. Bunsen investigated igneous rocks and feldspars from Iceland with regard to their chemical composition.

In Kassel he investigated organic arsenic compounds and the blast furnace process . During his first work on blast furnaces, Bunsen found that 75% of the calorific value of coal was not used. In England, in 1847, Bunsen and Lyon Playfair conducted investigations into English blast furnaces. He found that only 20% of the carbon monoxide was used for the reduction process and the majority escaped from the blast furnace unused. He made suggestions on how the heat could be better used. His investigations led to an improvement in the combustion technology and the use of generator gas in the blast furnace process. Between 1837 and 1843 he investigated the organic arsenic compound kakodyl (tetramethyldiarsane As 2 (CH 3 ) 4 ). The compound was very important at the time, as the molecular mass and the inorganic-organic nature of the compound could be verified by gas density measurement.

He developed iodometry into a quantitative method of determination.

Bunsen developed the Bunsen burner , which was initially operated with town gas and an admixture of oxygen. In the lower part of the flame cone he was able to reduce mineral salt samples (e.g. bismuth salt to elemental bismuth ), in the upper part of the flame the sample was oxidized (bismuth salt to white bismuth oxide).

Bunsen has also developed the first inexpensive power source for laboratory use, the Bunsen element based on zinc , carbon and nitric acid . The invention was based on preliminary work by Cooper (London) and Christian Friedrich Schönbein , who for the first time replaced platinum with inexpensive carbon in the zinc-platinum element. Bunsen improved the element through the preparation of the coal and the special arrangement. Until the discovery of the electrodynamic principle according to Werner von Siemens, the element was the most common element for generating electricity. With the electrolytic separation, Bunsen and co-workers were able to extract the elements magnesium , lithium , calcium and aluminum from the molten chlorides. In his laboratory, Carl Theodor Setterberg isolated the elements cesium and rubidium discovered by Bunsen and obtained the metals through fused- salt electrolysis.

His book Gasometric Methods , published in 1857, was significant . For example, methods for isolating gases in glass vessels, determining the constituents of gases, correcting Graham's theory on gas diffusion and the temperatures of flames were explained therein.

Other very important works by Bunsen concerned the investigation of the chemical effects of light . Bunsen split the light with a prism and studied the light effect of the split radiation on chemical reactions, plant growth and made calculations to change the light energy between the equator and the polar circle or for different altitudes.

William Henry Fox Talbot had already attempted spectral analysis around 1826 . In 1860, Bunsen and Gustav Robert Kirchhoff published their work on the applicability of spectral analysis . The spectroscope consisted of a prism with two lenses and an eyepiece in a wooden box. The prism split the uniform white light into a spectrum. If a salt sample was placed in a Bunsen burner flame (a candle flame did not produce good results), the spectroscope showed very characteristic color lines (emission spectra) for each element at certain points in the spectrum. With the spectroscope alkali and alkaline earth salts as well as indium , thallium and hydrogen could be detected.

With the spectral apparatus, Bunsen and Kirchhoff were able to discover two new chemical elements, which they then isolated: rubidium and cesium .

The detection of elements - even in the smallest traces - in a substance sample was now easily possible. The chemical composition of the stars could be investigated through the work of Kirchhoff on the basis of the absorption spectra.

In 1870 Bunsen published the description of his ice calorimeter . With the calorimeter, Bunsen was able to determine the specific heat capacity of substances. The investigations led to a more precise determination of the atomic weight of indium .

See also


  • Heinrich Debus:  Bunsen, Robert . In: Allgemeine Deutsche Biographie (ADB). Volume 47, Duncker & Humblot, Leipzig 1903, pp. 369-376.
  • Georg Lockemann:  Bunsen, Robert. In: New German Biography (NDB). Volume 3, Duncker & Humblot, Berlin 1957, ISBN 3-428-00184-2 , pp. 18-20 ( digitized version ).
  • Stephanie Brigitte Hoß-Hitzel: " Life is heavenly in Heidelberg" . Robert Wilhelm Bunsen and his correspondence. Dissertation at the University of Heidelberg in 2003. [Biography 1811–1899]
  • Christine Stock (Hrsg.): Robert Wilhelm Bunsen's correspondence before taking up the Heidelberg professorship (1852): critical edition . Wissenschaftliche Verlagsgesellschaft, Stuttgart 2007, ISBN 3-8047-2320-9
  • Heinrich Debus : Memories of Robert Wilhelm Bunsen and his scientific achievements: For students of the natural sciences, especially chemistry . Th. G. Fischer, Kassel 1901
  • Georg Lockemann : Robert Wilhelm Bunsen. Life picture of a German natural scientist . Scientific publishing company, Stuttgart 1949
  • Wilhelm Rothert : General Hanover Biography Volume 1: Hanoverian men and women since 1866 . Sponholtz, Hannover 1912, pp. 84-88
  • Dagmar Drüll: Heidelberger Gelehrtenlexikon 1803-1932 . Ed .: Rectorate of the Ruprecht-Karls-Universität-Heidelberg. Springer, Berlin / Heidelberg / Tokyo 2012, ISBN 978-3-642-70761-2 , 324 pp.
  • Susan G. Schacher: Bunsen, Robert . In: Charles Coulston Gillispie (Ed.): Dictionary of Scientific Biography . tape 2 : Hans Berger - Christoph Buys Ballot . Charles Scribner's Sons, New York 1970, p. 586-590 .

Web links

Commons : Robert Wilhelm Bunsen  - Collection of images, videos and audio files
Wikisource: Robert Wilhelm Bunsen  - Sources and full texts

Individual evidence

  1. Martin Quack : When was Robert Wilhelm Bunsen born? In: Bunsen magazine. 2/2011, pp. 56-57.
  2. ^ Robert (Roberto Guilielmo) Bunsen: Enumeratio ac descriptio Hygrometrorum quae inde a Saussurii temporibus proposita sunt . Commentatio praemio regio ornata. Vandenhoeck & Ruprecht, Göttingen 1830, OCLC 165981289 (Latin, 91 pages, Bunsen's dissertation as part of the collected essays online in the Internet Archive, online at the Munich Digitization Center of the Bavarian State Library BSB - list and description of the hygrometers that have been proposed since Saussure).
  3. Robert Bunsen: About the gaseous products of the court and their use as fuel . In: Johann Christian Poggendorff (Ed.): Annals of Physics and Chemistry . 122 (Pogg. Ann. 46), no. 2 . Johann Ambrosius Barth, Leipzig 1839, p. 193–227 , doi : 10.1002 / andp.18391220202 ( online at Gallica , Bibliothèque nationale de France).
  4. ^ A b Robert Bunsen: About a new construction of the galvanic column . In: Friedrich Wöhler, Justus Liebig (Ed.): Annals of Chemistry and Pharmacy . tape 38 , no. 3 . CF Winter, Heidelberg 1841, p. 311–313 , doi : 10.1002 / jlac.18410380307 ( online at the Internet Archive (in the collected works); online at the HathiTrust Digital Library - the work is dated May 14, 1841.).
  5. a b c Robert Bunsen: About the application of coal to voltaic batteries . In: Johann Christian Poggendorff (Ed.): Annals of Physics and Chemistry . 130 (Pogg. Ann. 54), no. 11 . Johann Ambrosius Barth, Leipzig 1841, p. 417-430 , doi : 10.1002 / andp.18411301109 ( online at Gallica , Bibliothèque nationale de France).
  6. ^ Philipps University of Marburg: Bunsen in Marburg
  7. a b c d Wolfgang U. Eckart , Klaus Huebner and Christine Nawa: Upswing of the natural sciences - Bunsen, Kirchhoff and Helmholtz , in: Heidelberg University, Leibniz Institute for Regional Geography, Peter Meusburger and Thomas Schuch, published on behalf of Rector Bernhard Eitel : Heidelberg University's Science Atlas , Bibliotheca Palatina, Knittlingen 2011, pp. 96–98; English translation: Wolfgang U. Eckart , Klaus Hübner, and Christine Nawa: The Rise of the Natural Sciences - Bunsen, Kirchhoff, and Helmholtz , in: Heidelberg University, Leibniz Institute for Regional Geography Leipzig, Peter Meusburger and Thomas Schuch (eds.) on behalf of Rector Bernhard Eitel : Wissenschaftsatlas of Heidelberg University , Bibliotheca Palatina, Knittlingen, 2012, pp. 96–98.
  8. Heidelberg University: Alte Aula 360 ° , accessed on July 10, 2017.
  9. Member entry of Robert Wilhelm Bunsen at the German Academy of Natural Scientists Leopoldina , accessed on June 14, 2017.
  10. ^ Directory of members since 1666: Letter B. Académie des sciences, accessed on September 29, 2019 (French).
  11. Holger Krahnke: The members of the Academy of Sciences in Göttingen 1751-2001 (= Treatises of the Academy of Sciences in Göttingen, Philological-Historical Class. Volume 3, Vol. 246 = Treatises of the Academy of Sciences in Göttingen, Mathematical-Physical Class. Episode 3, vol. 50). Vandenhoeck & Ruprecht, Göttingen 2001, ISBN 3-525-82516-1 , p. 53.
  12. ^ Fellows Directory. Biographical Index: Former RSE Fellows 1783–2002. Royal Society of Edinburgh, accessed October 13, 2019 .
  13. entry on Bunsen; Robert Wilhelm (1811-1899) in the Archives of the Royal Society , London
  14. full list of all past winners of the Copley Medal. In: The Royal Society Grants, Schemes & Awards> Premier medals and awards> Copley Medal. The Royal Society, accessed April 11, 2019 .
  15. ^ The Editors of Encyclopaedia Britannica: Copley Medal. In: Encyclopaedia Britannica, British scientific award. Retrieved April 11, 2019 .
  16. ^ Member History: Robert W. Bunsen. American Philosophical Society, accessed May 25, 2018 .
  17. The Order pour le merite for science and the arts . The members. Gebr. Mann-Verlag, Berlin 1975, Volume I, p. 246
  18. ^ Robert Wilhelm Bunsen. In: Members. Order Pour le mérite for Sciences and Arts, accessed on March 26, 2019 (admission to the Order on August 17, 1864.).
  19. Robert W. Bunsen. In: Member Directory> Deceased Members. National Academy of Sciences, accessed April 1, 2019 .
  20. Hans Körner: The Bavarian Maximilians Order for Science and Art and its members . In: Commission for Bavarian State History (Hrsg.): Journal for Bavarian State History (ZBLG) . tape 47 . CH Beck, Munich 1984, p. 299–398 , 323, 325, 372, 395 ( online at the Munich Digitization Center of the Bayerische Staatsbibliothek BSB - on p. 323 it says that Bunsen received the medal in 1861, but according to p. 372 and p. 395 it was in 1865) .
  21. Deceased members - Prof. Dr. Robert Bunsen. In: Scholars Community> Deceased. Bavarian Academy of Sciences, 2019, accessed April 7, 2019 .
  22. Robert Bunsen: About some peculiar compounds of double cyanure with ammonia . In: Johann Christian Poggendorff (Ed.): Annals of Physics and Chemistry . 110 (Pogg. Ann. 34), no. 1 . Johann Ambrosius Barth, Leipzig 1835, p. 131–147 , doi : 10.1002 / andp.18351100114 ( online at Gallica , Bibliothèque nationale de France).
  23. Robert Bunsen: Investigations on the double cyanure . In: Johann Christian Poggendorff (Ed.): Annals of Physics and Chemistry . 112 (Pogg. Ann. 36), no. 11 . Johann Ambrosius Barth, Leipzig 1835, p. 404–417 , doi : 10.1002 / andp.18351121108 ( online at Gallica , Bibliothèque nationale de France).
  24. Robert Bunsen: About the processes of volcanic rock formation in Iceland . In: Johann Christian Poggendorff (Ed.): Annals of Physics and Chemistry . 159 (Pogg. Ann. 83), no. 6 . Johann Ambrosius Barth, Leipzig 1851, p. 197–272 , doi : 10.1002 / andp.18511590602 ( online at Gallica , Bibliothèque nationale de France).
  25. ^ WP Doyle: Lyon Playfair (1818-1898). In: About Us> History> Professors> Lyon Playfair. The University of Edinburgh, accessed March 28, 2019 .
  26. ^ A b Robert Bunsen, Lyon Playfair: Investigations into the process of the English pig iron preparation . In: Otto Linné Erdmann, Richard Felix Marchand (Hrsg.): Journal for practical chemistry . tape 42 , no. 1 . Johann Ambrosius Barth, Leipzig 1847, p. 145–188, 257–275 and 385–400 , doi : 10.1002 / prac.18470420123 ( 1st part online , 2nd part online doi: 10.1002 / prac.18470420136 , 3rd part online , doi: 10.1002 / prac.18470420153 ) .
  27. Robert Bunsen: About a volumetric method of very general applicability . In: Friedrich Wöhler, Justus Liebig, Hermann Kopp (Hrsg.): Annalen der Chemie und Pharmacie . tape 86 , no. 3 . CF Winter, Heidelberg 1853, p. 265-291 , doi : 10.1002 / jlac.18530860302 ( online in the HathiTrust Digital Library).
  28. Bunsen's improved carbon battery and some experiments with the same . In: Annals of Physics and Chemistry . 136 (Pogg. Ann. 60), no. 11 , 1843, p. 402–405 , doi : 10.1002 / andp.18431361110 ( online at Gallica , Bibliothèque nationale de France).
  29. Robert Bunsen: Representation of magnesium by electrolytic means . In: Friedrich Wöhler, Justus Liebig, Hermann Kopp (Hrsg.): Annalen der Chemie und Pharmacie . tape 82 , no. 2 . CF Winter, Heidelberg 1852, p. 137–145 , doi : 10.1002 / jlac.18520820202 ( online in the Internet Archive).
  30. Robert Bunsen: Representation of the lithium . In: Friedrich Wöhler, Justus Liebig, Hermann Kopp (Hrsg.): Annalen der Chemie und Pharmacie . tape 94 , no. 1 . CF Winter, Leipzig and Heidelberg 1855, p. 107–111 , doi : 10.1002 / jlac.18550940112 ( online in the Internet Archive).
  31. Dr. Augustus Matthiessen: Electrolytic representation of the metals of the alkalis and earths . In: Friedrich Wöhler, Justus Liebig, Hermann Kopp (Hrsg.): Annalen der Chemie und Pharmacie . tape 93 , no. 3 . CF Winter, Heidelberg and Leipzig 1855, p. 277–286 , doi : 10.1002 / jlac.18550930302 ( online in the HathiTrust Digital Library - the work is dated December 16, 1854).
  32. Robert Bunsen: Note on the electrolytic extraction of earth and alkali metals . In: Johann Christian Poggendorff (Ed.): Annals of Physics and Chemistry . 168 (Pogg. Ann. 92), no. 8 . Johann Ambrosius Barth, Leipzig 1854, p. 648–651 , doi : 10.1002 / andp.18541680812 ( ).
  33. Carl Setterberg: About the representation of rubidium and cesium compounds and about the extraction of the metals themselves . In: Justus Liebig's Annals of Chemistry . tape 211 , no. 1 , 1882, p. 100-116 , doi : 10.1002 / jlac.18822110105 ( ).
  34. Robert Bunsen: gasometric methods . Verlag Friedrich Vieweg und Sohn, Braunschweig 1857, OCLC 4838029 ( limited preview in the Google book search, online at of the ETH Library - new edition 2006 as Ostwald's classic of the exact sciences Volume 296, ISBN 9783817132966 ).
  35. ^ Robert Bunsen, Henry Roscoe: Photochemical investigations . Second treatise. Measure the chemical effects of light. In: Johann Christian Poggendorff (Ed.): Annals of Physics and Chemistry . 176 (Pogg. Ann. 100), no. 1 . Johann Ambrosius Barth, Leipzig 1857, p. 43–88 , doi : 10.1002 / andp.18571760104 ( online at Gallica , Bibliothèque nationale de France.).
  36. ^ Robert Bunsen, Henry Roscoe: Photochemical investigations . Fourth treatise. Optical and chemical extinction of the rays. In: Johann Christian Poggendorff (Ed.): Annals of Physics and Chemistry . 177 (Pogg. Ann. 101), no. 6 . Johann Ambrosius Barth, Leipzig 1857, p. 235–263 , doi : 10.1002 / andp.18571770605 ( Gallica , Bibliothèque nationale de France).
  37. ^ Robert Bunsen, Henry Roscoe: Photochemical investigations . Fifth treatise. In: Johann Christian Poggendorff (Ed.): Annals of Physics and Chemistry . tape 184 , no. 10 . Johann Ambrosius Barth, Leipzig 1859, p. 193–273 , doi : 10.1002 / andp.18591841002 ( online at Gallica , Bibliothèque nationale de France).
  38. Jochen Hennig: The spectral apparatus Kirchhoffs and Bunsen . Deutsches Museum, publishing house for the history of natural sciences and technology, 2003
  39. G. Kirchhoff, Robert Bunsen: Chemical analysis through spectral observations . In: Johann Christian Poggendorff (Ed.): Annals of Physics and Chemistry . 186 (Pogg. Ann. 110), no. 6 . Johann Ambrosius Barth, Leipzig 1860, p. 161–189 , doi : 10.1002 / andp.18601860602 ( online at Gallica , Bibliothèque nationale de France, digital new edition , Heidelberg University 2008 - original work also in the Journal für Praktische Chemie, Volume 80, No. 1, doi: 10.1002 / prac.18600800151 ).
  40. Gustav Kirchhoff, Robert Bunsen: Chemical analysis through spectral observations . Second treatise. In: Johann Christian Poggendorff (Ed.): Annals of Physics and Chemistry . 189 (Pogg. Ann. 113), no. 7 . Johann Ambrosius Barth, Leipzig 1861, p. 337–381 , doi : 10.1002 / andp.18611890702 , bibcode : 1861AnP ... 189..337K ( online at Gallica , Bibliothèque nationale de France).
  41. ^ Robert Bunsen: Calorimetric investigations . In: Johann Christian Poggendorff (Ed.): Annals of Physics and Chemistry . 217 (Pogg. Ann. 141), no. 9 . Johann Ambrosius Barth, Leipzig 1870, p. 1–31 , doi : 10.1002 / andp.18702170903 ( online at Gallica , Bibliothèque nationale de France).