Background

Jean Charles Galissard de Marignac was born on April 24, 1817, in Geneva, Switzerland. Descended from a distinguished Huguenot family, Marignac was the son of Jacob Galissard de Marignac, a judge and conseiller d’état and Suzanne Le Royer. His mother was the sister of the pharmacist and physiologist Augustin Le Royer, whose house and laboratory adjoining the Marignac home was a center of Genevan scientific life.

Education

In 1835, after education at the Académie de Genève, Marignac entered the École Polytechnique in Paris, where he attended the chemistry lectures of Le Royer’sformer pupil J. B. Dumas. From 1837 to 1839 he studied engineering and mineralogy at the École des mines. During 1840 Marignac traveled extensively through Europe, and for a short time, he studied the derivatives of naphthalene in Liegig’s laboratory at Giessen - his only research on organic chemistry.

Career

Through the influence of his teacher Dumas, Marignac spent six months during 1841 at the porcelain factory at Sèvres; but, eager for an academic career, in the same year he succeeded Benjamin Delaplanche in the chair of chemistry at the Académie de Genève, taking on, in addition, the chair of mineralogy in 1845. He resigned in 1878, five years after the Academy became the University of Geneva.

From 1846 to 1857 he was a joint editor of the Swiss journal Archives des sciences. He commanded great respect from his students and, with the aged Berzelius’ enthusiastic approval, worldwide renown for his analytical accuracy. Always modern in outlook, he supported the work on mass action of Guldberg and Waage; he switched to two-volume formulas (such as H2O) in 1858, and he attended the important Karlsruhe conference in 1860. In the French controversy over equivalent weight versus atomic weights in 1877, he gave statesmanlike support for the modern school.

Although Marignac completed a large amount of research on mineralogy (showing, for example, that silica should be represented by the formula SiO2, not SiO3, because of the isomorphism between fluorstannates and fluorsilicates) and physical chemistry (where he explored the thermal effects of adding variable concentrations of different solutions together, and the alteration of the specific heats of solutions with dilution), only his contributions to inorganic chemistry will be mentioned here. In this field, he accurately determined the atomic weights of nearly thirty elements and helped to unravel the tortuous chemistry of niobium and tantalum, the silicates, the tungstates, and the rare earths.

In 1842, inspired by a wave of criticism of Berzeliu’s atomic weights and by the plausibility of Prout’s hypothesis that atomic weights were whole-number multiples of that of hydrogen, Marignac determined the atomic weights of chlorine, potassium, and silver by various methods.

Marignac’s groundwork with the rare earths (in which he was frequently helped spectroscopically by his physicist colleague J. L. Soret) began in the 1840s with the separation of the three cerium oxides from cerite. In 1878 he showed, after exacting fractionations based on differing solubilities, that the erbia extracted from gadolinite contained a colorless earth, ytterbia, which he correctly supposed was an oxide of a new metal, ytterbium. His ytterbia was, in fact, impure, for L. F. Nilson was able to extract scandia from it in 1879, and in 1907 Urbain separated in into (neo)ytterbia and lutecia (now called lutetia). In 1880 Marignac isolated white and yellow oxides from samarskite, which he uncommittedly labeled Yα and Yβ (samaria). In 1886, at Boisbaudran’s request, he named the former gadolinia, and the element “gadolinium.”

Achievements

• Marignac is usually regarded as the discoverer of Ytterbium and gadolinium. In general, his separations were a strategic and indispensable part of chemistry success in understanding the elements of the rare-earth series. For his contribution to the development of science, he was awarded Davy Medal by the Royal Society of London. The third «Chemical Landmark» award in Switzerland went to Geneva: The «Uni Bastions» of the University of Geneva was awarded in honor of the chemist Jean-Charles Galissard de Marignac whose laboratory was located in this building.

Works

More photos

• book

  • Oeuvres completes publiees hors serie sous les auspices de la Societe de Physique et d'Histoire Naturelle de Geneve 1890

Religion

Marignac was born to a family that descended from Languedoc Hugenotes but he is not known to express any religious views.

Politics

There is no remaining information on the political views Marignac expressed.

Views

Although Marignac's experiments did not confirm “Pourt’s law” (as he termed it), he suggested in 1843 that the real multiple might possess only half the atomic weight of hydrogen - a suggestion not approved by Berzelius.

When, in 1860, Stas dismissed Prout’s law as an “illusion,” Marignac cautioned that deviations from the law of definite proportions might sometimes occur - a possibility suggested by an erroneous view of the composition of acids which he then held. More speculatively, he suggested that Prout’s law might be an “ideal” law (like Boyle’ law) which was subject to perturbing influences such that the weights of the sub-atomic particles of the primordial matter (from which ordinary chemical atoms were composed) did not add up to exactly the experimentally determined “atomic” weights. This daring speculation was revived in 1915 by W. D. Harkins and E. D. Wilson, and from it, the concept of the packing fraction was developed by F. W. Aston in 1920. Marignac was full of praise for Stas’s reply to his challenge in 1865, but unlike Stas, he was never able to accept that chance alone was the reason why atomic weights were so close to integers on the O = 16 scale (which he urged chemists to adopt in 1883). Unlike Crookes, Marignac did not speculate concerning the genesis of elements; although obviously sympathetic toward Crookes’s hypothesis of 1887, he found it wanting for its dubious arguments drawn from rare-earth separations and spectroscopy.

Membership

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  Royal Society , United Kingdom

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  Accademia dei Lincei , Italy

• 

  Now Berlin-Brandenburg Academy of Sciences and Humanities.

  Royal Prussian Academy of Sciences , Germany

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  American Academy of Arts and Sciences , United States

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  Royal Swedish Academy of Sciences , Sweden

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  Turin Academy of Sciences , Italy

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  Academy of Sciences Leopoldina , Germany

Personality

Marignac worked unassisted in a damp cellar laboratory for most of his life; and this, together with his reticence and modesty, helped to create the erroneous impression that he was a recluse.

Physical Characteristics: From 1884 on, chronic heart disease rendered Marignac a stoic but helpless invalid.

Connections

Jean Charles Galissard de Marignac married Marie Dominicé in 1845. They had five children, one of whom, Édouard, died while a student at the école Polytechnique.

Father:

Jacob Galissard de Marignac

Mother:

Suzanne Le Royer

Uncle:

Augustin Le Royer

Wife:

Marie Dominicé

Son:

Édouard Galissard de Marignac

mentor:

Jean-Baptiste Dumas

colleague:

Jean Stas

References

• Dictionary of Scientific Biography: Volumes 9 & 10
  1980