A condition way of measuring the thermal conductivity of a material is to sandwich an electric thermofoil heater between two identical samples of the material, as shown in Fig. 1-30. The thickness of the resistance heator, including its cover, which id made of thin silicon rubber, is usually less then 0.5 mm. a circulating fluid such as tap water keeps the exposed ends of the samples at constant temperature. the lateral surfaces of the samples are well insulated to ensure that heat transfer through the samples is one-dimensional. two thermocouples