Vibration of a Flattened Drop. I. Observation

Vibration of a single drop of liquid nitrogen, oxygen or argon was observed by putting it on a horizontal plate with the room temperature. The drop had a shape of flattened disk and floated on the plate owing to rapid evaporation. It showed a characteristic mode of vibration, namely a standing wave appeared along the periphery and the plane view showed a polygonal shape. As the radius of drop reduced through evaporation, sudden transitions to modes with smaller number of vertices occurred. The measured vibrational frequency was proportional to (wave number)^3/2, and depended in a simple way on the surface tension and the density of the liquid.