Thermal properties

Thermal conductivity was determined using the Colora Thermoconductor.
The sample was placed between ground silver plates, kept at the given
boiling points of two liquids by a constant supply of heat to the liquid with the
higher boiling point. When steady equilibrium was attained, the liquid having
the lower boiling point vaporized at a constant rate. It was condensed and
then collected in a measuring vessel. The time required to distill a specified
volume was measured. From a previously obtained calibration curve for
similar sized discs of known thermal conductivity, the thermal resistivity and
conductivity of the test sample was derived.
For determination of specific heat, a sample was analyzed using a quantitative
Adiabatic Calorimeter. This sample was weighed, tightly enclosed in an
electrically heated gold-plated copper container, and suspended inside a
massive nickel-plated and polished guard. The entire assembly was evacuated,
backfilled with N2, then cooled to a uniform temperature below the lowest
mean temperature required for data. When steady conditions were obtained,
a controlled rate, continuous power input was supplied to the heater on the
sample container. By utilizing the output of a multi-junction differential
thermopile, the power to the guard heater was automatically controlled so
that the temperature of the guard was equal to the temperature of the sample.
This allowed negligible heat transfer from the sample to its surroundings. From
observations of the power input to the heater, a continuous record of sample
temperature variation with time, a record of the sample and container enthalpy
change with temperature was obtained.

Fateen