Phenomena Depending on the Change of Elastic Frequencies in Solid Bodies with Pressure

Shift with pressure of the residual rays of a crystal.—Born's theory of the constituent forces in heteropolar crystals is adopted. As a new conclusion of this theory a formula for the shift of frequencies of residual rays with pressure is deduced. The shift corresponding to a pressure of 10,000 atm. amounts approximately to 7μ in the case of NaCl (residual rays at 50μ).

Effect of pressure on the electrical conductivity of metals.—Qualitative conclusions are drawn with respect to the dependence of elastic frequencies on pressure in any crystal. This leads to a rational explanation (suggested at first by Grüneisen) for the effect of pressure on the specific electric conductivity of metals, this conductivity being in general increased by pressure. The relation of our results to those obtained by Grüneisen and Bridgman previously in a quite different way, is discussed.