When moist clay bodies are heated on one side it is often observed thatmoisture moves towards the cooler side. This phenomenon has been studiedusing clay-water mixtures of initially uniform moisture content packed intosealed, vertical tubes, along which a constant temperature gradient ismaintained, the tubes having a reservoir of water at constant temperature attheir lower, cool ends. Figure 1 shows the moisture distributions obtainedafter various times in columns of a commercial kaolin (Supreme Kaolin) whichcontained initially 16-18 per cent. moisture. A “stepped” type ofdistribution results from the movement of the moisture, the step moving downthe column with increasing time.