Des Cloizeaux, Alfred-Louis-Olivier Legrand

(b. Beauvais, France, 17 October 1817; d. Paris, France, 6 May 1897)

mineralogy, crystallography.

Born of a family of the old bourgeoisie with a long tradition in the legal profession, Des Cloizeaux studied at the Lycée Charlemagne in Paris, where he came under the tutelage of Armand Lévy, a teacher of mathematics and mineralogy who instilled in him a fascination with minerals and crystals. Lévy encouraged Des Cloizeaux to attend the courses of Alexandre Brongniart at the Muséum d’Histoire Naturelle and those of Armand Dufrénoy at the École des Mines. Also through Lévy, Des Cloizeaux was introduced into Jean-Baptiste Biot’s laboratory at the Collège de France. It was through Biot’s influence that Des Cloizeaux was commissioned by the government in 1845 to travel to Iceland to study sources of Iceland spar. This voyage also enabled Des Cloizeaux to visit some British mineralogists (Robert Jameson, Thomas Thomson, and George Bellas Greenough, among others) and to inspect mineralogical collections in Scotland and England. In 1846 he returned to Iceland and joined there with members of a German-Danish expedition (including Bunsen and Wolfgang Sartorius von Waltershausen) in studying geysers and minerals. In succeeding years he traveled widely, especially in the Alpine regions, Scandinavia, and Baltic Russia.

In 1843 Des Cloizeaux had become a tutor at the École Centrale. He defended his thesis for the doctorate in 1857 at the Faculté des Sciences of Paris and was appointed professor in the École Normale Supérieure. In 1876 he was made professor of mineralogy at the Muséum in place of Delafosse, whom he had assisted at the Sorbonne since 1873; he taught at the Muséum until 1892. Des Cloizeaux was elected to the Académie des Sciences in 1869, replacing E. J. A. d’Archiac, having failed of election (to his considerable chagrin) in 1862, when Pasteur was chosen instead. In 1889 he served as president of the Academy.

Des Cloizeaux’s main achievements fall into two categories: his studies on the form of crystals, and his investigation of the optical properties of crystalline materials. While questions of morphology occupied him early in his career, after 1855 he devoted himself principally to optical problems in crystallography. In both categories his work was characterized by the broad interest of a naturalist attempting to relate the substance under investigation to its mode of origin.

Des Cloizeaux was able, in part through optical methods, to elucidate the interior structure of minerals that had already been subjected to thorough study (for example, quartz).¹ He set out ambitiously to produce a comprehensive work on the structure (but not in the modern sense) of minerals. The result, the Manuel de minéralogie, occupied him for thirty-five years but was never completed beyond two volumes. This project began simply as a plan to translate William Phillips’An Elementary Introduction to Mineralogy as extended by Henry James Brooke and William Hallowes Miller, but it grew into a text emphasizing Des Cloizeaux’s interest in crystallography and serving to establish the crystallographic notation invented by René-Just Haüy and augmented by Lévy.

The most original aspect of Des Cloizeaux’s work lies in the field of optical studies of crystals, which he took up in part through the influence of Henri de Sénarmont. He embarked on the gigantic task of determining the optical characters of all known crystals, and although this proved too large an undertaking for one man he did ascertain the optical properties of nearly 500 substances. He was among the first to perceive the great potential utility of the polarizing microscope for investigating minerals, and with improved polarizing microscopes of his own devising he developed techniques for the determination of significant optical characteristics in crystals (e.g., the angle of the optic axis and the dispersions of the optic axes, indicatrix, and bisectrices). His methods and determinations constituted a part of the foundation of petrology. Among his extensions of the knowledge of polarization in crystals was his demonstration of circular polarization in cinnabar and strychnine sulfate.²

Inquiring into the effects of heat on crystalline bodies, he found that prolonged heating beyond a certain temperature permanently alters the positions of the optic axes of certain crystals (notably the orthoclase minerals), thereby providing the geologist with a means of determining whether or not certain rocks have been subjected to high temperatures.³

Descloizite, a rare mineral consisting of basic lead and zinc vanadate, was named after Des Cloizeaux by his friend and collaborator Augustin-Alexis Damour.⁴

NOTES

1.Annales de chimie et de physique, 3rd ser., 45 (1855), 129–316;Mémoires présentés par divers savants à l’Académie des sciences. Sciences mathèmatiques et physiques, 15 (1858), 404–614.

2.Comptes rendus hebdomadaires des séances de l’Académie des sciences, 44 (1857), 876–878, 909–912; Annales de chimie et de physique, 3rd ser, 51 (1857), 361–367; Annalen der Physik und Chemie, 102 (1857), 471–474.

3.Comptes rendus, 53 (1861), 64–68; 55 (1862), 651–654; 62 (1866), 987–990; Annales de chimie et de physique, 3rd ser., 68 (1863),191–203; Annales des mines, 6th ser., 2 (1862), 327–328; Annalender Physik und Chemie, 119 (1863), 481–492: 129 (1866), 345–350; Bulletin de la Société géologique de France, 2nd ser., 20 (1862–1863), 41–47; Mémoires présentés par divers savants à l’Académie des sciences. Sciences mathématiques et physiques, 18 (1868), 511–732.

4.Annales de chimie et de physique, 3rd ser., 41 (1854), 72–78.

BIBLIOGRAPHY

I. Original Works. Des Cloizeaux’s major work is Manuel de minéralogie, 2 vols. in 3 parts (Paris, 1862–1893). Alfred Lacroix’s “Liste bibliographique des travaux de A. Des Cloizeaux,” in his Notice historique sur François-Sulpice Beudant et Alfred-Louis-Olivier Legrand Des Cloizeaux (Paris, 1930), pp. 91–101, is fairly complete. Des Cloizeaux’s own Notice sur les travaux minéralogiques et géologiques de M. Des Cloizeaux (Paris, 1869) provides annotations, some of them quite extensive, to a list of many of his publications.

II. Secondary Literature On Des Cloizeaux and his work, see Lacroix’s Notice, referred to above, also in Lacroix’s Figures de savants, 4 vols. (Paris, 1932–1938), I, 241–272. Contemporary biographical sources include Charles Barrois’s funeral speech in Bulletin de la Sociétégéologique de France, 25 (1897), 459–460; the eulogy by Adolphe Chatin, in Comptes rendus hebdomadaires des séances de l’Académie des sciences, 124 (1897), 983–984; an obituary by Lazarus Fletcher, in Proceedings of the Royal Society of London, 63 (1898), xxv–xxviii; and an anonymous sketch in L’année scientifique (1897), p. 409. Conrad Burri provides a recent assessment in “Alfred Des Cloizeaux 1817–1897, Ferdinand Fouqué 1828–1904, Auguste Michel–Lévy 1844–1911,” in Geschichte der Mikroskopie. Leben und Werk grosser Forscher, III, Hugo Freund and Alexander Berg, eds. (Frankfurt, 1966), 163–176.

Kenneth L. Taylor