Compressibility of Crystals

Abstract

IN NATURE of Mar. 23, 1929, p. 448, N. Rashevsky calls into question the experimentally determined values for the compressibility coefficient. He points out that there is good evidence that sub-microscopic cracks depress the true tensile strength of materials to small values, and suggests that these cracks may likewise lead to compressibility coefficients much greater than the true coefficients, which in fact may be zero. In an attempt to estimate the volume of these cracks, he concludes that possibly several per cent of the volume of crystals is void. Since the total volume change over a range of 10,000 atmospheres is ordinarily only a few per cent, he reasons that “it is not impossible that practically the whole change of the volume is due to the decrease of the size of the cracks”.