Most of the chemical substances possess three different states or phases at different temperatures. Normally at low temperatures the substances are in solid state and with the increase in temperature a phase transition occurs to an intermediate liquid state and finally proceeds to the gaseous phase at higher temperatures. But under this unique process of sublimation a direct transformation from the solid phase to the gaseous phase occurs after a characteristic temperature without the involvement of any intermediate liquid state for certain substances. Examples : Camphor, Naphthalene etc.