Bernal, J. D. (1901-1971), an Irish physicist, pioneered in the analysis of biological substances by X rays. Bernal developed X-ray analysis as a powerful tool in crystallography, the scientific study of crystals. One of his pupils, the British biochemist and crystallographer Dorothy C. Hodgkin, received the Nobel Prize in chemistry in 1964 for X-ray studies of compounds, such as vitamin B12 and penicillin.