Frankenheim, Moritz Ludwig

(b. Brunswick, Germany, 29 June 1801; d. Deresden, Germany, 14 January 1869)

crystallogrpahy

Frankenheim attended the Gymnasium in Wolfenbüttel and Brunswick. In 1820 he began his university studies in Berlin with phiology but changed to mathematics and physics. In 1823 he received a doctorate for his dissertation. De theoria gasorum et vaporum He qualified as a university lecturer in 1826, also in Berlin. In 1827 he was appointed assistant professor at Breslau, where he became professor of physics in 1850; he held this position until 1866.

Frankenheim attended the gymnasium in Wolfenbuttel and Brunswick. In 1820 he began his university studies in Berlin with philology but changed to mathematics and physics. In 1823 he received a doctorate for his dissertation, De theoria gasorum et vaporum He qualified as a university lecturer in 1826, also in Belrin. In 1827 he was appointed assistant professor at Breaslau, where he became professor of physics in 1850; he held this position until 1866.

Frankenheim’s importance lies especially in the field of crystallography. In his work Die Lehre von der Köhäsion . . . (1835), he was the first to examine whether or not the geometrically possible types of crystal lattices agree in their symmetry relations with those actually observed in crystals. He showed that there could be only fifteen different “nodal” i.e. space latice, type configurations. Bravais, in his “Mémoires sur les systèmes formés par des points distributés régulièrment sur un plan ou dans l’espace” (1848), acknowledged Frankenheim’s achievement: “Frankenheim, in his beautiful researches in crystallogrphy, arrived at the same classification,” In 1856 he corrected himself: there could be only fourteen, because two of the proposed monoclinic subdivisions proved to be identical.

In his 1829 work De crystallorum cohaestione Frankenheim established that the hardness of crystals is always the same in the same cystallogrphic directions but varies with the direction through the crystal. He was also the first to investigate experimentally the influence of a crystal on oriented overgrowth from a crystal seed (epitaxy). In 1830 he investigated more exactly with the microscope the overgrowth of sodium carbonate on calcium carbonate that he had observed in his study of cohesion. In 1836 he grew potassium iodide on mica, a spectacular example of oriented overgrowth still used for demonstration. Frankenheim also introduced the concept of isodimorphism, which he derived from observations on sodium nitrate and potassium nitrate on the one hand and on calcite and aragonite on the other

Frankenheim devised an experiment that even today is a suitable lecture demonstration. Out of a drop of warm supersaturated potassium nitrate solu tion, a rhombohedral unstable modification precipitates out onto the microscope slide. With further cooling needlelike orthorhombic crystals form outward from the edge, and the rhombohedrons in the vicinity of the orthorhombic needles dissolve. If one of the needles is touched by a rhombohedron, the latter is very quickly transformed into an aggregate of rhombic crystals.

Frankenheim repeatedly took a position on the question of amorphous minerals in a polemic with the Munich mineralogis J. N. von Fuchs. In 1851 he held that these bodies were aggregates of many crystals of imperceptible dimensions. Much later the introduciton of X-ray investigation showed that this conception was correct in the case of a great many substances formerly considered amorphous.

AS early as 1860, Frankenheim used a new kind of polarizing microscope; the speciemen could be rotated so that the angles between two directions in the specimen, as well as its position relative to the orien tation of the Nicol prisms, could be exactly determined.

BIBLIOGRAPHY

I. Original Works. Frankenheim’s works include De theoria gasorum et vaporum (Berlin, 1823); De crystallorum cohaesione (vratisl, 1829); Die Lehre von der Kohäsion umfassend die Elastizität der Gase, die Elastizirtät und Kohärenz der flüssigen und festern körper und die Kristallkunde (Breslau, 1835); “Üeber die Verbindung verschiedenartiger Krystalle,” in Annalen der Physik, 37 (1836) 516–522 “System der Kristalle, ein Versuch,” in Nova acta Academiae Caesesarae Leopoldina Carolinae germanicae naturae curioso rum, Abt, II 19 (1842), 471–660; Krystallisation und Amorphie, in Journal fur praktische chemie, 54 (1851) 430–476; “Die Anordnung der Molekule im Kristalle,” in Annalen der physik, 97 (1856), 337–382; Entstehen und Wachsen der Kristalle, mikroskopische Beobachtungen ibid., 111 (1860), 37 ff; Zur Kristallkunde I. Charakiter istik der Kristalle (Leipzig, 1869), unfinished.

II. Secondary Literatirue. On Frankenheim and his work, see A. Bravais, “Mémoires sur les systèmes formés par des points distribués régulièrement sur un plan ou dans l’espace,” in journal de l’École polytechnique, 19 (1848) 1–28, presented to the Académie des Sciences on 11 Dec. 1848; it was translated by C. and E. Blasius as Abhandlung uber die System von regelmässig auf Ebene oder im Rauim verteilten punkten (Leipzig, 1897). See also P. Groth, Entwicklungsgeschichte der mineralogischen Wissenschaften (Berlin, 1926); and Poggendorff, I 792, and III 469

Carl W. Correns