Marc Delafontaine
{{Short description|Swiss chemist (1838–1911)}}
{{Hatnote|For the Canadian comic creator, see Delaf.}}
{{Infobox scientist
| name = Marc Delafontaine
| image = Marc Delafontaine.jpg
| birth_date = March 31, 1837 or 1838
| birth_place = Céligny, Switzerland
| death_date = May 21, 1911
| death_place = Chicago, Illinois, USA
| resting_place = Forest Home Cemetery (Forest Park)
| residence =
| nationality = Swiss
| field =
| work_institutions = University of Geneva
| alma_mater = University of Geneva
|doctoral_advisor =
| awards =
|known_for = holmium
}}
Marc Delafontaine (March 31, 1837/1838, Céligny, Switzerland{{efn|name="b"}}–1911{{efn|name="d"}}) was a Swiss chemist and spectroscopist who was involved in discovering and investigating some of the rare earth elements.
Career
Delafontaine studied with Jean Charles Galissard de Marignac at the University of Geneva. He also worked at the University of Geneva.
Delafontaine moved to the United States of America, arriving in New York in 1870, and later becoming a naturalized citizen.
He taught in Chicago, Illinois at city high schools, and at a women's college.
He also worked as an analytical chemist with the
Research
=Holmium=
In 1878, along with Jacques-Louis Soret, Delafontaine first observed holmium spectroscopically.{{Cite journal |last=Thornton |first=Brett F. |last2=Burdette |first2=Shawn C. |date=20 May 2015 |title=Homely holmium |journal=Nature Chemistry |volume=7 |issue=6 |pages=532 |bibcode=2015NatCh...7..532T |doi=10.1038/nchem.2264 |pmid=25991534 |doi-access=free}} In 1879, Per Teodor Cleve chemically separated it from thulium and erbium. All three men are given credit for the element's discovery.{{Cite book |last=Fontani |first=Marco |title=The Lost Elements: The Periodic Table's Shadow Side |last2=Costa |first2=Mariagrazia |last3=Orna |first3=Mary Virginia |publisher=Oxford University Press |year=2014 |isbn=9780199383344 |pages=119–125}}
=Yttrium, terbium and erbium=
In 1843, Carl Gustaf Mosander discovered terbium and erbium as components of yttria.{{Cite book |last=Tansjö |first=Levi |url=https://books.google.com/books?id=EFzuCAAAQBAJ&q=Mosander |title=Episodes from the History of the Rare Earth Elements |date=December 6, 2012 |publisher=Springer Science & Business Media |isbn=9789400902879 |editor-last=Evans |editor-first=C. H. |pages=38–55 |chapter=Carl Gustaf Mosander and His Research on Rare Earths}}{{rp|38}}{{Cite book |last=Weeks |first=Mary Elvira |url=https://archive.org/details/discoveryoftheel002045mbp |title=The discovery of the elements |date=1956 |publisher=Journal of Chemical Education |edition=6th |location=Easton, PA}}{{rp|701}}{{Cite journal |last=Weeks, Mary Elvira |author-link=Mary Elvira Weeks |year=1932 |title=The discovery of the elements: XVI. The rare earth elements |journal=Journal of Chemical Education |volume=9 |issue=10 |pages=1751–1773 |bibcode=1932JChEd...9.1751W |doi=10.1021/ed009p1751}}{{Cite book |last=Marshall |first=James L. |title=Science history : a traveler's guide |last2=Marshall |first2=Virginia R. |date=October 31, 2014 |publisher=ACS Symposium Series |isbn=9780841230200 |volume=1179 |pages=209–257 |chapter=Northern Scandinavia: An Elemental Treasure Trove |doi=10.1021/bk-2014-1179.ch011}}
However, this discovery was hotly contested. Spectroscopist Nils Johan Berlin denied that the two elements existed, failing to confirm the existence of "erbia" and suggesting that its name be applied to "terbia".
In 1864, Marc Delafontaine used optical spectroscopy to conclusively prove that yttrium, terbium, and erbium were separate elements.{{Cite book |last=Friend |first=John Newton |url=https://books.google.com/books?id=CwxDAAAAIAAJ&pg=PA223 |title=A Text-book of Inorganic Chemistry |date=1917 |publisher=Griffin & Company |isbn=9781130017649 |volume=4 |pages=221–223}} Ironically, however, the confusion that had been introduced between the names continued. Mosander's proposed names were switched, giving the amethyst compound the name "erbium" oxide and the yellow substance the name "terbium" oxide, instead of the other way around as originally proposed.{{Cite journal |last=Holden |first=Norman E. |date=2001-06-29 |title=History of the Origin of the Chemical Elements and Their Discoverers |url=https://www.osti.gov/servlets/purl/789650 |location=Upton, New York |publisher=Brookhaven National Laboratory (BNL)}}{{Cite book |last=Krishnamurthy |first=Nagaiyar |url=https://books.google.com/books?id=F0Bte_XhzoAC&pg=PA5 |title=Extractive metallurgy of rare earths |date=December 16, 2015 |publisher=CRC Press |isbn=9781466576346 |edition=2nd |pages=5–7}}
References
{{Reflist}}
Notes
{{notelist|refs=
{{efn|name=b|Fontani op. cit. p. 125 states that Poggendorff's Biographisch-Literarisches Handwörterbuch, Verlag von Johan Ambrosius Barth, Leipzig, 1898, p. 344 gives his birthyear as 1838, while Mary Elvira Weeks Discovery of the Elements, 7. ed., Journal of Chemical Education: Easton, Pennsylvania, 1968, p. 677 says it is 1837.}}
{{efn|name=d|Fontani op. cit. p. 125 says that no documents exist to report his death but it is assumed Delafontaine passed away in 1911.}}
}}
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{{DEFAULTSORT:Delafontaine, Marc}}
Category:Discoverers of chemical elements
Category:19th-century Swiss chemists
Category:20th-century Swiss people
Category:20th-century Swiss chemists
Category:Rare earth scientists
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