Robert Bunsen

Robert Whilhelm Eberhard Bunsen was born on March 31, 1811 in Gottengen, Germany. His father, Christian Bunsen was the chief librarian and a professor at the University of Gottengen where Bunsen studied chemistry earning a PhD in 1831 at the age of nineteen. After finishing his doctorate Bunsen spent three years traveling through Europe, partially at the expense of the German government during which he studied a multitude of subjects. When he returned to Gottengen he served as a lecturer in chemistry. Beginning in 1836 he taught chemistry at the Polytechnic School of Cassel, and in 1839 he was appointed professor of chemistry at the University of Marburg where he remained until 1851. After a brief stint at the University of Breslau, in 1852 he became chair of chemistry at the University of Heidelberg, where he remained until retirement in 1889.

Bunsen's early research involved compounds of arsenic. He developed the use of iron oxide hydrate to precipitate arsenate which is still used to treat arsenate poisoning. He continued his studies of arsenic at the cost of almost poisoning himself and with the loss of an eye, injured by exploding glassware. One of his most lasting contribution to science was the invention of his eponymous burner. At the time chemists used oil and alcohol lamps as a source of flame. In 1854 Bunsen had gas piped into his laboratory and when none of burners available met his needs he developed his own, that produced a colorless flame, the intensity of which could be adjusted.

Using his new burner Bunsen tested different chemicals and observed different colors and was able to detect different elements based on the colors produced. Sometimes color produced by one element would mask another and he used colored glass to mask some elements. Not satisfied with this solution, he mentioned his problem to Gustav Kirchoff, a Russian physicist and using two parts from telescopes, a prism, and a cigar box with its inside covered in black the pair made a prototype spectroscope. Using their new spectroscope Bunsen and Kirchoff quickly were able to identify different elements by their spectra. In order to find undiscovered elements Bunsen had 40 tons of mineral water evaporated and he was able to identify for the first time the alkali metal elements cesium (from the Latin ceasium, sky blue, named for its blue spectral lines) and rubidium (from the Latin rubidius, or dark red, named for its red spectral lines). Today spectroscopes are widely used in chemical analysis.

Bunsen died on August 16, 1889 in Heidelberg.


References:

Fujinaka, Pam and Kerekes, Christina; "Robert Wilhelm Bunsen (1811-1899)"; retrieved from woodrow.org

Morris, Richard; Last Sorcerers: Path from Alchemy to the Periodic Table; Joseph Henry Press; 2003

Robert Whilhelm Bunsen NNDB profile

Robert Bunsen Wikipedia Entry

Vesto Slipher

Vesto Melvin Slipher was born on November 11, 1875 at a farm in Mulberry, Indiana. His younger brother Earl was also an astronomer. He graduated from high school in Frankfort, Indiana and taught briefly at a country school before going to the University of Indiana in Bloomington, Indiana starting in 1897. He earned his bachelors degree in astronomy and mechanics in 1901. He earned his masters in 1903 and his doctorate in 1909 with a dissertation on the spectrum of Mars. One of his professors, Wilbur Cogshall, recommended him to Percival Lowell and Lowell brought Slipher on as an assistant in 1901. Slipher remained at the observatory for fifty three years afterward. He became assistant director in 1915 and became acting director in 1916 with Lowell's death. He became director in 1926 and served there until his retirement in 1954.

Slipher's first project, at the direction of Lowell, writing from his Boston office, was mounting and using the new spectrograph on Lowell's 24-inch refracting telescope. Slipher used it to record the spectra of Mars, Jupiter, and Saturn. Using the spectra that Slipher produced the confirmed the visually known periods of the planets. Using spectra taken of Mars, he attempted to prove there was water in the Martian atmosphere and he attempted to find the rotational period of Venus. He then turned the telescope to the gas giants and determined that the rotational period of Uranus was 10.75 hrs (it was later determined to be 25 hrs.).

Slipher is remembered chiefly for the work that he did determining the velocity of what at the time where called spiral nebula. Today we know these spiral shaped clouds are galaxies, just like our Milky Way. Slipher determined that these spiral nebula were moving much faster (three times) the velocity of any object observed at that time. Edwin Hubble later used this data to show the universe was expanding and the farther an object was away from Earth, the faster it would be moving away. Slipher is also responsible for hiring Clyde Tombaugh and was responsible for overseeing the work involved in the discovery of Pluto.

Awards won by Slipher include the Bruce Medal (1935), the Lalande Prize (1919), a Gold Medal from the Royal Society (1932), the Henry Draper Prize from the National Academy of Sciences (1932) and a gold medal from the Paris Academy of Sciences (1919). Slipher also has a crater on the moon named after him. In addition to his scientific work Slipher was also active in the community of Flagstaff, Arizona, where he was one of the founders of  its first high school.

Slipher died on November 8, 1969, in Flagstaff, Arizona.


References:

Hoyt, Willliam Graves, "Vesto Melvin Slipher: 1875-1969"; National Academy Press, 1980

Trimble, Virginia; Williams, Thomas; Bracher, Katherine; Jarrell, Richard; Marche, Jordan; and Ragep, F. Jamil; "Vesto Slipher" in Biographical Encyclopedia of Astronomers; Springer; 2006

Vesto Sipher Wikipedia Entry

Eugene-Anatole Demarcay

Eugene-Anatole Demarcay was born in Paris France on January 1, 1852.  His grandfather, General Marc-Jean Demarcay, fought with Napoleon and played a role in the success of the Battle of Austerlitz.  Demarcay began attending the Ecole Polytechnique, then located in the Latin quarter of Paris, at age 18, first as a student and then as an assistant.  He studied under chemist Jean-Baptiste Dumas.  In his early 20s he gave up the academic life to make a tour of Algeria, Egypt and India to study the geology and culture of foreign lands.  After he returned to Paris he worked in the laboratory of August Cahours studying organic chemistry.  He moved on from organic chemistry, becoming interested in organo-metallic chemistry and then inorganic chemistry.  When experimenting with nitrogen sulfides his apparatus exploded, leaving him blind in one eye.

Damacay established a private laboratory in Paris where he became an expert reading the spectra of inorganic elements.  It was said that, he could read a spectra "like the score of an opera".  He built an spark spectrum instrument which allowed him to purify and study rare earth elements.  Rare earth elements are a group of metallic elements which include scandium, yttrium, and the entire lanthanide series of elements.  Despite their name they are relatively common (with the exception of promethium which is radioactive) but because of their geo-chemical properties they are not found in large, economically exploitable amounts.  Today China is the world leader in the production and export of these elements, which are used in the manufacture of electronics.

In 1898 when Marie and Pierre Curie isolated the radioactive element polonium, they saw that the sample from which it had been removed remained radioactive.  The Curies took their remaining radioactive sample to Demarcay for analysis.  Demarcay examined the spectra of the sample and determined that there was a spectral line unaccounted for and told the Curies there was an new element in their sample.  This spectral line was caused by radium in their sample, which the Curies were eventually able to isolate in 1902.

Demarcay is most famous for the discovery of the rare earth element europium.  In 1892 Paul Boisbaudran while working with a sample of the element samarium, which he had discovered, found a spectral line not accounted for.  Demarcay examined spectra of samples of samarium and gadolinium and proposed that there was an undiscovered element between them on the periodic table.  Using a crystallization technique of his own invention Demarcay was able to isolate the new element in 1902, which he named europium, after the continent of Eruope.

The date of his death in many references is incorrect.  Demarcay died on March 5, 1903.


References:

Daintith, John, editor; "Demarcay, Eugene Anatole (1854-1904)" in Biographical Dictionary of Scientists Third Edition; CRC Press, 2008

Marshall, John L. and Marshall, Virginia R.; "Discovery of the Elements: Europium-Eugene Demarcay"; The Hexagon; Summer 2003, p.19-21

Eugene-Anatole Demarcay Wikipedia Entry

Gerhard Herzberg

Gerhard Heinrich Friedrich Otto Julius Herzberg was born on December 25, 1904 in Hamburg, Germany.  His father was a businessman and worked for a small shipping company.  He died when Herzberg was still young.  After his father's death he lived briefly with his uncle in Frankfurt, but he did poorly in school and was homesick so he returned to live with his mother.  In Hamburg he attended the Realgymansium de Johanneums, where he had excellent teachers and developed an interest in astronomy and atomic physics.  He studied astronomy by reading textbooks from public libraries and with a friend made a crude telescope, but he was unable to pursue a career in astronomy for financial reasons.  With a fellowship from industrialist Hugo Stinnes he was able to attend the Technische Universtat Darmstadt, graduating with a Dr.Ing. in 1928.  After graduation he did postdoctoral work at Gottengen University and Bristol University under James Franck, Max Born and John Lennard-Jones.

After completing his postdoc he returned to Technishche Universtat Darmstadt as a pirvatdozant (lecturer).  In 1935 Herzberg was forced to flee Germany because of his Jewish wife, and he took a position as a guest lecturer at the University of Saskatchewan in Saskatoon, Saskatchewan, which was almost immediately made permanent. Herzberg remained at the University of Saskatchewan until 1945 when he became professor of spectroscopy at Yerkes Observatory at the University of Chicago, where he remained until 1948.  In 1948 he returned to Canada as the principal research officer and then director of the Division of Physics at the Canadian National Research Council.  In 1955 the Division of Physics of the Canadian National Research Council was split into two divisions, pure and applied physics and Herzberg remained president of the pure physics division.  In 1969 he was made distinguished scientist of the recombined Division of Physics of the Canadian National Research Council.

Herzberg's research dealt with spectroscopy and determining molecular geometries using spectroscopy.  From his doctoral thesis, on the spectrum of nitrogen gas, and throughout his career he determined spectra of various chemicals and from these data he was able to determine their geometry.  Because of Herzberg's work spectroscopy is a tool that chemists can use to determine the identity of a chemical.  Different molecules absorb and emit characteristic wavelengths of electromagnetic radiation determined by their structure.  Chemists use these characteristic absorbancies and emissions to determine the structure and identity of molecules.  At Yerkes Observatory Herzberg applied his knowledge of spectroscopy to determine the gasses present in planetary atmospheres.  He is author of the four volume Molecular Spectroscopy and Molecular Structure which has been called the spectroscopist's bible.  In 1971 Herzberg was awarded the Nobel Prize in chemistry for "his contributions to the knowledge of electronic structure and geometry of molecules, particularly free radicals".

Other honors won by Herzberg include election to the Canadian National Academy of Science in 1939 and the Royal Society of London in 1951.  Other awards won by Herzberg include the Willard Gibbs Award from the American Chemical Society, the Order of Canada, and the Royal Medal from the Royal Society of London.

Herzberg died on March 3, 1999 at the age of 94.


References:

Interview of Gerhard Herzberg by  Brenda J. Weinnwisser on February 28 and March 2, 1989, Niels Bohr Library and Archive, American Institute of Physics, aip.org.

Black, Harry; Canadian Scientists and Inventors: Biographies of People Who Made a Difference; Pembroke Publishers Ltd.; 1997

Devorkian, David; "Gerhard Herzberg, 1904-1999"; Bulletin of the American Astronomical Society; (2000)35:1669-1670

Gerhard Herzberg Nobel Biography

Gerhard Herzberg Wikipedia Entry