Ultrasonics

Two liquids that do not ordinarily mix, i.e., oil and water, can be combined as a liquid by exposing a solution of the two to very high frequency sound waves. Such mixtures are called dispersions. With this technique, alloys of aluminum and lead, iron and lead, and aluminum and cadmium can be mixed as liquids—and kept mixed—until they solidify. This technique is known as ultrasonic dispersion. It is also used to produce stable and consistent photographic emulsions.