Arrien Johnsen

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Arrien Theodor Alwin Johnsen (born December 8, 1877 in Munkbrarup , † March 22, 1934 in Berlin ) was a German mineralogist .

Live and act

Arrien Johnsen was a son of Pastor Wilhelm Johnsen (1849-1914) from Husum . His mother Rosalie Mathilde, née Preuß (1849–1886), was the daughter of a lawyer from Neustadt bei Coburg . He had a grandfather named Joh. Carl Friedrich Johnsen, who lived in Munkbrarup and in whose house he was born. At the age of three he and his family moved to Neustadt bei Coburg. His father became a deacon there in 1881, pastor in 1891 and superintendent in 1910. He also worked in the Freystadt i. Lower Silesian. as rector and pastor of a seminar.

Arrien Johnsen attended a grammar school in Coburg . He then studied chemistry from 1897 to 1899, and later mineralogy at the University of Jena . He spent the summer semester of 1899 at the University of Göttingen . He then moved to the University of Königsberg , where in 1901 he became a Dr. phil. received his doctorate. He then worked at the mineralogical institute of the local university and received his habilitation there in 1904. In 1908 he moved to the University of Göttingen as a private lecturer. In 1909 he was appointed professor of mineralogy and general geology and director of the Mineralogical Institute at Kiel University . In 1920 he took over a chair at the University of Frankfurt am Main in the same position . In 1921 he followed a call from the University of Berlin as professor of mineralogy and petrography .

Johnsen had been married to Pauline Auguste Wandschneider (* 1889) from Kiel since 1913 .

Importance as a scientist

Inspired by his teacher Otto Mügge , Johnsen initially dealt with petrography, later he did research on crystallography. He worked mostly experimentally on the morphology and physics of crystals. He saw minerals not only as chemical compounds, but as natural bodies that had the property of reshaping themselves after the initial growth, to completely or partially destroy, but also to regenerate. With this he laid the foundation for the further development of mineralogy from a descriptive to an exact natural science.

Johnsen worked out a kinematic theory that described growth, shrinkage and crystal dress. In this he showed that abnormal mixed crystals have a two-phase character. This knowledge provided a basis for experiments on these difficult to understand processes and helped decisively to understand these processes.

Johnsen taught the mineralogists the mathematical background of the structural problem and understood by means of the geometric theory of crystal structures that the questions about crystal deformations, which had been understood as a continuum, could also be viewed as a three-dimensional periodic discontinuum. He also carried out X-ray geometrical research on the fine structure of crystals and, taking the geometry of crystals into account, developed a new symbolism of indicia for structural geometry. In addition, he described with a precise system which conditions must be met so that lattice and structure shifts can occur. This theory was important for understanding the motion processes of atoms.

The mineralogist also dealt with questions about the composition, color and appearance of gemstones. In addition, he was interested in work on minerogenesis, petrography and general geology, the research results of which he followed critically. He himself mostly proceeded analytically, but also knew how to summarize and synthesize knowledge. Johnsen dealt with methodological questions and the history of the natural sciences and tried to train young scientists in mineralogy as part of his teaching activities.

At Kiel University, Johnsen supported a newly established teaching collection. He established new laboratories, was able to achieve a higher budget for his institute and set up a position for a department head of paleontology and stratigraphy . He suggested setting up the Institute for Gemstone and Pearl Research in Berlin in 1928. The institute was attached to Johnsen's own and existed until 1955.

Memberships

Since 1922 Johnsen was a corresponding member of the Senckenberg Society for Natural Research and a full member of the Prussian Academy of Sciences . In 1924 he became a corresponding member of the Academy of Sciences in Göttingen . Until 1920 he was chairman of the Natural Science Association for Schleswig-Holstein and then became its honorary member.

From 1927 to 1930 Johnsen took over the chairmanship of the German Mineralogical Society and the editor of the journal “Progress of Mineralogy”. In 1920/21 he took over the rectorate of the University of Kiel.

literature

Web links

Individual evidence

  1. ↑ Holger Krahnke: The members of the Academy of Sciences in Göttingen 1751-2001 (= Treatises of the Academy of Sciences in Göttingen, Philological-Historical Class. Volume 3, Vol. 246 = Treatises of the Academy of Sciences in Göttingen, Mathematical-Physical Class. Episode 3, vol. 50). Vandenhoeck & Ruprecht, Göttingen 2001, ISBN 3-525-82516-1 , p. 125.
personal data
SURNAME Johnsen, Arrien
ALTERNATIVE NAMES Johnsen, Arrien Theodor Alwin
BRIEF DESCRIPTION German mineralogist
DATE OF BIRTH December 8, 1877
PLACE OF BIRTH Munkbrarup
DATE OF DEATH March 22, 1934
Place of death Berlin