Geometrische Kristallograhie

Abstract

THE closing decade of the last century witnessed much progress made in the development of the geometrical theory of crystal structure, and we may now have confidence in the certainty of our knowledge regarding the possible types of crystalline symmetry. This advance has not been without marked influence on the methods of determining the physical properties of crystals. The old idea to consider a crystal as a solid bounded by plane faces, the relative positions of which harmonised with Hauy's law of rational intercepts, is giving way to the more logical principle that a crystal consists of a homogeneous arrangement of discrete particles in space. Indeed, as has been frequently pointed out, a theory which ignores the internal structure cannot avoid the difficulty presented by a peculiar case of pseudotrigonal symmetry. To the new school, which is typified most completely by Sch önflies's well-known treatise, the present work belongs.

Geometrische Kristallograhie.

By Ernst Sommerfeldt. Pp. x + 139; illustrated. (Leipzig: W. Engelmann, 1906.) Price 7s. net