Georg Brandt

Georg Brandt was born on July 21, 1694 in Riddarhyttan, Sweden. His father, Jurgen Brandt, was a metalworker and an apothecary. Growing up he assisted his father with his metalwork projects and he became interested in it. Brandt attended Uppsala University and worked for the council of mines. In 1721 he traveled to Leiden where he worked in the laboratory of Herman Boerhaave for three years. There he studied chemistry and medicine. He earned a medical doctorate from the University of Rheims in 1726. When he returned home to Sweden he was made the director of laboratory of the Council of Mines. Brandt was named warden of the Royal Mint in 1730. He became an associate member of the council of mines in 1747 and a full member in 1750.

Brandt's research involved investigating metals. He coined the term semi-metals to describe elements that have both metal and non-metal characteristics. These elements are now called metalloids. Metaloids are the elements in the region between metal and non-metal elements on the periodic table (see here) In 1733 he investigated arsenic and its compounds. In 1735 he postulated that the blue color in an ore known as smalt was due to an unknown metal or semi-metal. In 1742 he was able to isolate this unknown blue metal which he named cobalt, taking the name from the old Teutonic word kobold meaning demon. Cobalt is atomic number 27 and is represented by the chemical symbol Co.

Brandt's later research involved using hot acid solutions to dissolve gold. Brandt's later publications dealt with criticism of the alchemical belief that other "base" metals could be transformed into gold. It has been said that he did more than any other chemist to clarify that transmutation of other metals into gold was impossible and that claims of alchemists that they could create gold from other metals were false.

Brandt died on April 29, 1768 in Stockholm, Sweden of prostate cancer.


References:

Morris, Richard; The Last Sorcerers; Joseph Henry Press; 2003

"Brandt, Georg" in Complete Dictionary of Scientific Biography; Charles Scribner's Sons; 2008

Georg Brandt Wikipedia Entry

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

Edwin Mattison McMillan

Edwin Mattison McMillan was born on September 17, 1907 in Redondo Beach, California.  His father Edwin McMillan was a physician.  As a child McMillan was always building gadgets and living in Pasadena, California he was able to attend lectures and get to know the physicists at the nearby California Institute of Technology.  After high school he attended the California Institute of Technology studying physics and chemistry and earning his B.Sc. in 1928 and his M.Sc. one year later.  He earned his Ph.D. at Princeton University in 1932.  His thesis described the behavior of a beam of hydrogen chloride molecules in a non-homogeneous electric field.

After earning his Ph.D., McMillan won a National Research Council fellowship.  At the invitation of Ernest Lawrence he went to the University of California at Berkley where he worked in Lawrence's Berkley Radiation Laboratory.  He became a an instructor in the physics department at Berkeley in 1935, assistant professor in 1936, associate professor in 1941, and professor in 1946.  During the World War II MacMillan worked at the Massachusetts Institute of Technology developing radar, at the U.S. Navy Radar and Sonar Laboratory in San Diego California working on sonar, and he worked on the Manhattan Project in Los Alamos, New Mexico.  He returned to Berkley after the war and with the death of Lawrence in 1958 he became director of the Berkley Radiation Laboratory, later renamed after Lawrence.  He remained director until his retirement in 1973.

McMillan is most remembered for his work in creating the first transuranic elements.  Working at Berkley he used the newly invented cyclotron to bombard uranium with neutrons and deuterium to create neptunium and plutonium.  These elements (atomic numbers 93 and 94) were the first elements created with more protons than uranium, which was thought to have the highest possible number.  Like uranium these elements are subject to radioactive decay.  McMillan and Glenn Seaborg, who finished MacMillan's work when he left Berkley to go to M.I.T., were awarded the Nobel Prize in Chemistry in 1951 for "their discoveries in the chemistry of transuranium elements".  McMillan also used the cyclotron to create other non-naturally occurring radioactive elements including oxygen-18 and beryllium-10.

Other honors won by MacMillan include election to the National Academy of Science in 1947 (he served as its chairman from 1968 to 1971), the Atoms for Peace award in 1963, shared with Vladimir Veksler, for the creation of the synchrotron, and the National Medal of Science in 1990. 

McMillan died on September 7, 1991.


References:

Jackson, David J. and Panofsky, W.K.H.; "Edwin Mattison McMillan: 1907-1991"; Biographical Memoirs Vol. 69; National Academy Press; 1996

Edwin McMillan Nobel Biography

Edwin McMillan Wikipedia Entry