Engineers Make Giant Snowflakes For U.S. Exhibition in World's Fair

The Division of Engineering and Applied Physics is sending a machine to make giant snowflakes to the Brussels World's Fair this summer, the University has announced.

The machine will make continuously two snowflake crystals between two and four inches across in separate tanks. The crystals will appear brilliantly colored to spectators watching them grow in the transparent tanks.

The purpose of the machine is to form "dendritic crystals" for the study of crystal formation in metals. Therefore they are formed quite differently than ordinary snow and seem to grow like "amphibious snowflakes," a scientist said.

In the process, the machine first supercools the water to several degrees below freezing. To induce the formation of crystals the tank is then seeded by a tube which is cooled to an extremely low temperature. It takes about five minutes to make one crystal with the tanks regulated so there is always one crystal being formed.

The color of the snowflakes is due to two strips of polarizing material on either side of the tank. The colors are of all shades, depending on the thickness of the ice, the inclination of the light source to the crystal and the positions of the polarizing screens.

The practical use of the process results from the similarity between the "dendritic crystals" formed and those produced when supercooled liquid metal solidifies. It is the crystalline structure of a metal that largely determines its strength, toughness, and brittleness.

The machine was developed as part of the research program of the Division of Engineering and Applied Physics. As part of the U.S. exhibit in the International Science Exhibit it will be in Brussels for six months beginning in April.