Jean Charles Galissard de Marignac
Encyclopedia
Jean Charles Galissard de Marignac (24 April 1817 – 15 April 1894) was a Swiss
chemist
whose work with atomic weight
s suggested the possibility of isotope
s and the packing fraction of nuclei
and whose study of the rare earth elements led to his discovery of ytterbium
in 1878 and codiscovery of gadolinium
in 1880.
, he was twenty-one years old when he began to attend the Ecole Polytechnique in Paris, and from 1837 to 1839 studied at the Ecole des Mines. Then, after a short time in Liebig's
laboratory at Gießen
, and in the Sèvres
porcelain factory, he became in 1841 professor of chemistry in the academy of Geneva. In 1845 he was appointed professor of mineralogy also, and held both chairs till 1878, when ill-health obliged him to resign. He died at Geneva.
Marignac's name is well known for the careful and exact determinations of atomic weights which he carried out for fifty-seven of the elements. In undertaking this work he had, like J. S. Stas
, the purpose of testing Prout's hypothesis
, but he remained more disposed than the Belgian chemist to consider the possibility that it may have some degree of validity. Throughout his life he paid great attention to the rare earths and the problem of separating and distinguishing them; in 1878 he extracted ytterbium from what was supposed to be pure erbia, and two years later found gadolinium and samarium
in the samarskite
earths.
In 1858 he pointed out the isomorphism
of the fluostannates and the fluosilicates, thus settling the then vexed question of the composition of silicic acid
; and subsequently he studied the fluorides of zirconium
, boron
, tungsten
, and other elements. He prepared silicotungstic acid, one of the first examples of the complex inorganic
acids. Marignac discovered that niobium
and tantalum
could be separated by fractional crystallization separation of potassium heptafluorotantalate
from potassium oxypentafluoroniobate monohydrate, a process which was used commercially until displaced by solvent extraction separation of the same fluorides starting in the 1950s.
In physical chemistry
he carried out extensive research on the nature and process of solution
s, investigating in particular the thermal effects produced by the dilution
of saline solutions
, the variation of the specific heat of saline solutions with temperature and concentration, and the phenomena of liquid diffusion.
Switzerland
Switzerland name of one of the Swiss cantons. ; ; ; or ), in its full name the Swiss Confederation , is a federal republic consisting of 26 cantons, with Bern as the seat of the federal authorities. The country is situated in Western Europe,Or Central Europe depending on the definition....
chemist
Chemistry
Chemistry is the science of matter, especially its chemical reactions, but also its composition, structure and properties. Chemistry is concerned with atoms and their interactions with other atoms, and particularly with the properties of chemical bonds....
whose work with atomic weight
Atomic weight
Atomic weight is a dimensionless physical quantity, the ratio of the average mass of atoms of an element to 1/12 of the mass of an atom of carbon-12...
s suggested the possibility of isotope
Isotope
Isotopes are variants of atoms of a particular chemical element, which have differing numbers of neutrons. Atoms of a particular element by definition must contain the same number of protons but may have a distinct number of neutrons which differs from atom to atom, without changing the designation...
s and the packing fraction of nuclei
Cell nucleus
In cell biology, the nucleus is a membrane-enclosed organelle found in eukaryotic cells. It contains most of the cell's genetic material, organized as multiple long linear DNA molecules in complex with a large variety of proteins, such as histones, to form chromosomes. The genes within these...
and whose study of the rare earth elements led to his discovery of ytterbium
Ytterbium
Ytterbium is a chemical element with the symbol Yb and atomic number 70. A soft silvery metallic element, ytterbium is a rare earth element of the lanthanide series and is found in the minerals gadolinite, monazite, and xenotime. The element is sometimes associated with yttrium or other related...
in 1878 and codiscovery of gadolinium
Gadolinium
Gadolinium is a chemical element with the symbol Gd and atomic number 64. It is a silvery-white, malleable and ductile rare-earth metal. It is found in nature only in combined form. Gadolinium was first detected spectroscopically in 1880 by de Marignac who separated its oxide and is credited with...
in 1880.
Life and work
Born in GenevaGeneva
Geneva In the national languages of Switzerland the city is known as Genf , Ginevra and Genevra is the second-most-populous city in Switzerland and is the most populous city of Romandie, the French-speaking part of Switzerland...
, he was twenty-one years old when he began to attend the Ecole Polytechnique in Paris, and from 1837 to 1839 studied at the Ecole des Mines. Then, after a short time in Liebig's
Justus von Liebig
Justus von Liebig was a German chemist who made major contributions to agricultural and biological chemistry, and worked on the organization of organic chemistry. As a professor, he devised the modern laboratory-oriented teaching method, and for such innovations, he is regarded as one of the...
laboratory at Gießen
Gießen
Gießen, also spelt Giessen is a town in the German federal state of Hesse, capital of both the district of Gießen and the administrative region of Gießen...
, and in the Sèvres
Sèvres
Sèvres is a commune in the southwestern suburbs of Paris, France. It is located from the centre of Paris.The town is known for its porcelain manufacture, the Manufacture nationale de Sèvres, making the famous Sèvres porcelain, as well as being the location of the International Bureau of Weights...
porcelain factory, he became in 1841 professor of chemistry in the academy of Geneva. In 1845 he was appointed professor of mineralogy also, and held both chairs till 1878, when ill-health obliged him to resign. He died at Geneva.
Marignac's name is well known for the careful and exact determinations of atomic weights which he carried out for fifty-seven of the elements. In undertaking this work he had, like J. S. Stas
Jean Stas
Jean Servais Stas was a Belgian analytical chemist.- Life and work :Stas was born in Leuven and trained initially as a physician. He later switched to chemistry and worked at the École Polytechnique in Paris under the direction of Jean-Baptiste Dumas...
, the purpose of testing Prout's hypothesis
Prout's hypothesis
Prout's hypothesis was an early 19th century attempt to explain the existence of the various chemical elements through a hypothesis regarding the internal structure of the atom...
, but he remained more disposed than the Belgian chemist to consider the possibility that it may have some degree of validity. Throughout his life he paid great attention to the rare earths and the problem of separating and distinguishing them; in 1878 he extracted ytterbium from what was supposed to be pure erbia, and two years later found gadolinium and samarium
Samarium
Samarium is a chemical element with the symbol Sm, atomic number 62 and atomic weight 150.36. It is a moderately hard silvery metal which readily oxidizes in air. Being a typical member of the lanthanide series, samarium usually assumes the oxidation state +3...
in the samarskite
Samarskite
Samarskite is a radioactive rare earth mineral series which includessamarskite- with formula: 22O8and samarskite- with formula 22O8 The formula for smarskite- is also given as: O4...
earths.
In 1858 he pointed out the isomorphism
Isomorphism
In abstract algebra, an isomorphism is a mapping between objects that shows a relationship between two properties or operations. If there exists an isomorphism between two structures, the two structures are said to be isomorphic. In a certain sense, isomorphic structures are...
of the fluostannates and the fluosilicates, thus settling the then vexed question of the composition of silicic acid
Silicic acid
Silicic acid is a general name for a family of chemical compounds of the element silicon, hydrogen, and oxygen, with the general formula [SiOx4-2x]n...
; and subsequently he studied the fluorides of zirconium
Zirconium
Zirconium is a chemical element with the symbol Zr and atomic number 40. The name of zirconium is taken from the mineral zircon. Its atomic mass is 91.224. It is a lustrous, grey-white, strong transition metal that resembles titanium...
, boron
Boron
Boron is the chemical element with atomic number 5 and the chemical symbol B. Boron is a metalloid. Because boron is not produced by stellar nucleosynthesis, it is a low-abundance element in both the solar system and the Earth's crust. However, boron is concentrated on Earth by the...
, tungsten
Tungsten
Tungsten , also known as wolfram , is a chemical element with the chemical symbol W and atomic number 74.A hard, rare metal under standard conditions when uncombined, tungsten is found naturally on Earth only in chemical compounds. It was identified as a new element in 1781, and first isolated as...
, and other elements. He prepared silicotungstic acid, one of the first examples of the complex inorganic
Inorganic chemistry
Inorganic chemistry is the branch of chemistry concerned with the properties and behavior of inorganic compounds. This field covers all chemical compounds except the myriad organic compounds , which are the subjects of organic chemistry...
acids. Marignac discovered that niobium
Niobium
Niobium or columbium , is a chemical element with the symbol Nb and atomic number 41. It's a soft, grey, ductile transition metal, which is often found in the pyrochlore mineral, the main commercial source for niobium, and columbite...
and tantalum
Tantalum
Tantalum is a chemical element with the symbol Ta and atomic number 73. Previously known as tantalium, the name comes from Tantalus, a character in Greek mythology. Tantalum is a rare, hard, blue-gray, lustrous transition metal that is highly corrosion resistant. It is part of the refractory...
could be separated by fractional crystallization separation of potassium heptafluorotantalate
Potassium heptafluorotantalate
Potassium heptafluorotantalate is an inorganic compound with the formula K2TaF7. This white, water-soluble solid is an intermediate in the purification of tantalum from its ores and is the precursor to the metal.-Structure:...
from potassium oxypentafluoroniobate monohydrate, a process which was used commercially until displaced by solvent extraction separation of the same fluorides starting in the 1950s.
In physical chemistry
Physical chemistry
Physical chemistry is the study of macroscopic, atomic, subatomic, and particulate phenomena in chemical systems in terms of physical laws and concepts...
he carried out extensive research on the nature and process of solution
Solution
In chemistry, a solution is a homogeneous mixture composed of only one phase. In such a mixture, a solute is dissolved in another substance, known as a solvent. The solvent does the dissolving.- Types of solutions :...
s, investigating in particular the thermal effects produced by the dilution
Enthalpy change of solution
The enthalpy of solution, enthalpy of dissolution, or heat of solution is the enthalpy change associated with the dissolution of a substance in a solvent at constant pressure resulting in infinite dilution....
of saline solutions
Salinity
Salinity is the saltiness or dissolved salt content of a body of water. It is a general term used to describe the levels of different salts such as sodium chloride, magnesium and calcium sulfates, and bicarbonates...
, the variation of the specific heat of saline solutions with temperature and concentration, and the phenomena of liquid diffusion.