A Change of Symmetry with Temperature

DURING the course of an investigation into the effect of temperature on X-ray reflexion in crystals, some photographs were taken of basic beryllium acetate to see whether any of the diffuse reflexions observed by Charlesby, Finch and Wilman¹ with electron diffraction in organic crystals could be detected with X-rays. The photographs did not show with certainty any effect of the type looked for, but another effect was observed. At the time (1939), we did not think the matter of very great importance, but recently the results were shown here to Prof. W. T. Astbury, who suggested that they were of sufficient interest to deserve recording.