and , where ξ is a warped time.

With this model, adding stages or increasing the relative volatility will produce the same effect. The Demonstration displays the mole fraction of the light component in the still (orange curve) and the distillate (blue curve) versus warped time.

Adding more stages to the rectifying section or increasing will lead to a much more sharply defined variation in the distillate composition. A desirable situation occurs where there is a cut or a distillation fraction. Indeed, the distillate is quite pure for a period of time, then drops sharply when the light component is depleted in the still.