Marc Delafontaine (March 31, 1837/1838, Céligny,

Switzerland ). Swiss law does not designate a ''capital'' as such, but the federal parliament and government are installed in Bern, while other federal institutions, such as the federal courts, are in other cities (Bellinzona, Lausanne, Luzern, Neuchâtel ...

–1911) was a

Swiss Swiss may refer to: * the adjectival form of Switzerland * Swiss people Places * Swiss, Missouri * Swiss, North Carolina *Swiss, West Virginia * Swiss, Wisconsin Other uses *Swiss-system tournament, in various games and sports *Swiss Internation ...

chemist A chemist (from Greek ''chēm(ía)'' alchemy; replacing ''chymist'' from Medieval Latin ''alchemist'') is a scientist trained in the study of chemistry. Chemists study the composition of matter and its properties. Chemists carefully describe th ...

and

spectroscopist Spectroscopy is the field of study that measures and interprets the electromagnetic spectra that result from the interaction between electromagnetic radiation and matter as a function of the wavelength or frequency of the radiation. Matter wav ...

who was involved in discovering and investigating some of the

rare earth elements The rare-earth elements (REE), also called the rare-earth metals or (in context) rare-earth oxides or sometimes the lanthanides (yttrium and scandium are usually included as rare earths), are a set of 17 nearly-indistinguishable lustrous silve ...

Career

Delafontaine studied with Jean Charles Galissard de Marignac at the

University of Geneva The University of Geneva (French: ''Université de Genève'') is a public research university located in Geneva, Switzerland. It was founded in 1559 by John Calvin as a theological seminary. It remained focused on theology until the 17th centu ...

. 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 (''City in a Garden''); I Will , image_map = , map_caption = Interactive Map of Chicago , coordinates = , coordinates_footnotes = , subdivision_type = Country , subdivision_name ...

at city high schools, and at a women's college. He also worked as analytical chemist with the Chicago Police Department.

Research

Holmium

In 1878, along with

Jacques-Louis Soret Jacques-Louis Soret (30 June 1827 – 13 May 1890) was a Swiss chemist and spectroscopist. He studied both spectroscopy and electrolysis. He held the chairs of chemistry (1873-1887) and medical physics (1887-1890) at the University of Genev ...

, Delafontaine first observed holmium spectroscopically. In 1879,

Per Teodor Cleve Per Teodor Cleve (10 February 1840 – 18 June 1905) was a Swedish chemist, biologist, mineralogist and oceanographer. He is best known for his discovery of the chemical elements holmium and thulium. Born in Stockholm in 1840, Cleve earned his B ...

chemically separated it from thulium and

erbium Erbium is a chemical element with the symbol Er and atomic number 68. A silvery-white solid metal when artificially isolated, natural erbium is always found in chemical combination with other elements. It is a lanthanide, a rare-earth element ...

. All three men are given credit for the element's discovery.

Yttrium, terbium and erbium

In 1843 Carl Gustaf Mosander discovered terbium and

as components of

yttria Yttrium oxide, also known as yttria, is Y2 O3. It is an air-stable, white solid substance. The thermal conductivity of yttrium oxide is 27 W/(m·K). Uses Phosphors Yttria is widely used to make Eu:YVO4 and Eu:Y2O3 phosphors that give the red ...

. However, this discovery was hotly contested. Spectroscopist

Nils Johan Berlin Nils Johan Berlin (Nils Johannes Berlin) (18 February 1812 – 27 December 1891) was a Swedish chemist and physician, who held various professorships at the University of Lund from 1843 to 1864. Berlin was the first chemist who took the initiativ ...

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. 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.

References

Notes

Swiss chemists 1837 births 1911 deaths Discoverers of chemical elements 19th-century Swiss people 19th-century chemists 20th-century Swiss people 20th-century chemists Holmium Rare earth scientists {{Chemist-stub