One of the important new research methods involves the use of ultrasonics during crystallization or dis solution. Ul trasound has become extensively used in many branches of science' and technology in recent years, as we may see from the number of papers' published. The total up to 1939 was about 700, but by 1960 it was well over 5000. Applications in physics, crystallography, chemistry, and so on provide a powerful means of discover ing new effects, although such studies tend to be very complicated and demand an acquaintance with a wide range of topics. The main effect of ultrasound on...