Background

François Ernest Mallard was born on February 4, 1833, in Châteauneuf-sur-cher, Centre, France. The son of a lawyer, he was brought up in St.-Amand-Montrond.

Education

François Ernest Mallard studied at a Collège in Bourges, the École Polytechnique, and the Paris School of Mines, from which he graduated in 1853 as ingénieur des mines. In 1888 he was awarded Doctor honoris causa from the University of Bologna.

Career

Mallard began his career as a geologist for the Corps des Mines but in 1859 was transferred to fill the chair of mineralogy at its École des Mineurs at Saint-Étienne. He continued his work for the Corps, first in geological mapping and after 1868 on problems of mining engineering. His work attracted favorable notice from G. A. Daubrée, professor of mineralogy at the École des Mines; and when Daubrée became director of the school in 1872, he chose Mallard to fill the vacated chair of mineralogy. The new post was a decisive change for mallard, involving a new concentration on more directly mineralogical problems, the area in which he found the greatest satisfaction and made his most important contributions. He continued as a member of investigative commissions in the Corps des Mines, for which he was promoted in 1867 to engineer first class and in 1886 to the inspector general. He was proposed, unsuccessfully, for several vacancies in the mineralogy section of the Académie des Sciences and finally was elected in 1890. In 1879 he was the second president of the Société minéralogique de France.

Mallard’s contributions in crystallography began in 1876, not long after he had assumed the chair of mineralogy at Paris. He took as his starting point the Études cristallographiques of Auguste Bravais, who had been a professor of physics there from 1845 to 1855. While Sohncke and later A. Schönflies were developing Bravais’s concept of a lattice of translationally equivalent points into a complete mathematical description of symmetry of crystals (the 230 space groups), Mallard independently developed other aspects of Bravais’s theories. This work had its notable beginning in the memoir Explication des phénomènes optiques anomaux, on optically “anomalous” crystals (that is, those crystals the morphology of which seems to be of greater symmetry than their optics), in which the powerful new polarizing microscope showed the importance of twinning in these “crystalline edifices” and of pseudosymmetry as an explanatory concept.

A summary of Mallard’s ideas was offered in a two-volume work with atlas entitled Traité de cristallographiegéométrique et physique, published in 1879 (geometrical crystallography, lattice theory, and morphology) and 1884 (crystal physics). Here, for the first time, the convoluted mathematical apparatus of Bravais was stripped away to reveal in a didactic but complete fashion the essential contributions of the lattice theory. Mallard recognized the way in which this theory corresponded to a special case of Haüy’s molécules intégrantes while admitting that the unsupportable remainder of Haüy’s theories of crystal structure had led to its being completely discredited by the German school of geometrical crystallographers. Wherever possible, he applied Bravais’ theory to an understanding of the wide range of physical properties of crystals that had been investigated in the thirty intervening years; and he found in a strict definition of homogeneity a common basis for both the lattice theory and the newer macroscopic description of physical properties of anisotropic crystals by characteristic ellipsoids. The detailed and generally favorable reviews of these volumes in Germany, where a divergent direction of theory had been followed since the time of C. S. Weiss, attests to their persuasive completeness.

A third volume of the Traité, in which Mallard planned to discuss isomorphism, polymorphism, twinning, pseudosymmetry, and crystal growth, was never completed. Some of his original work on these subjects was published separately. In this respect, his most important contribution was his theory of twins based on the continuation or pseudo-continuation of a lattice between the twinned crystals. Mallard’s development and extension of Bravais’s lattice theory, especially to the explanation of the importance of crystal faces (“law of Bravais”) and of twins, was further developed by observations and refined by Georges Friedel, who was Mallard’s student at the École des Mines; Friedel’s exposition on these subjects remained the definitive statement until very recent direct structural theories. On the other hand, Mallard’ theory of circular polarization in crystals as equivalent to a stack of thin, linearly polarized sheets has not stood the test of time.

Mallard also made notable scientific contributions in his capacity as a mining engineer. In 1878, soon after it was formed, he was appointed to an official commission investigating methods of preventing methane explosions in mines. A series of laboratory and field investigations in collaboration with H. Le Chatelier, then professor of general chemistry at the École des Mines, resulted in a series of joint papers on the design of safety lamps, on combustion temperature, on the velocity of flame propagation, and on the importance of mixtures of coal dust. They instituted the use of ammonium nitrate as an explosive; its low temperature of detonation made it safer (less likely to propagate in mixtures of air with gas or coal), and it has remained the preferred explosive to this day. Mallard continued his collaboration with Le Chatelier in experiments on the thermal properties of crystals.

Achievements

• François Ernest Mallard became Inspecteur General des Mines in 1886. He was elected the second president of the Mineralogical Society of France and was a member of the French Academy of Sciences in 1890. He received the Croix de chevalier in 1869 and became an officer of the Legion of Honour in 1888. The University of Bordeaux awarded him an honorary doctorate also in 1888. A key figure in the French school of crystallography and a bridge from Bravais to Friedel, Mallard was described as having “definitively displaced the center of gravity of crystallography that, thereafter, could not be cultivated as a descriptive science, but was elevated to the rank of rational science.”

Works

More photos

• book

  • Explication Des Phénomènes Optiques Anomaux Que Présentent Un Grand Nombre de Substances Cristallisées 1877
  • Géologie de la Creuse, Journal de Voyage d'Ernest Mallard, 1857-1880 1880
  • Traité de cristallographie géométrique et physique 1879

Religion

Mallard believed that a human was created by god.

Views

Mallard studied those crystals that appeared to have greater symmetry than their optical properties would indicate and which the important new polarizing microscope showed the importance of twinning in these "crystalline edifices." He introduced the concept of a pseudosymmetry as an explanation of such crystals.

Quotations: "Man has been created in the image of the Lord and therefore he is capable of penetrating by the power of his reason into the plans and thoughts of the Creator of all things, that must be his highest ambition here below."

Membership

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  French Academy of Sciences , France

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  French Society of Mineralogy and Crystallography , France

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  Geological Society of France , France

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  French Physical Society , France

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  Saint Petersburg Academy of Sciences , Russia

Personality

Mallard had great personal modesty but did not hesitate to put into print his thoughtful objections to publications of other scientists. He never wished to marry; he followed his vocations single-mindedly. Termier poignantly describes Mallard’s camaraderie with students during field excursions.

Connections

François Ernest Mallard was never married and had no children.

colleague:

Gabriel Auguste Daubrée

References

• Dictionary of Scientific Biography: Volumes 9 & 10
  1980