A camphor grain oscillates while breaking symmetry

The self-motion of a camphor grain was investigated on a linear water route. The oscillatory motion along the water route was maintained for ca. 15 cycles. The driving force is discussed in relation to a rhythmic change in the surface tension, which depends on the surface concentration of the camphor layer. The essential features of the self-motion were reproduced by a numerical calculation in relation to the spatial distribution of the camphor layer at the air-water interface.