Nernst heat-capacity calorimeter

Nernst, Koref, and Lindematm (1910) described an aneroid drop calorimeter for the measurement of specific heat capacities. Figure 7.14 shows the design of this instrument. The entire system is located in isothermal surroundings such as melting ice. Of particular interest is the measurement of the temperature change of the calorimeter substance by means of 10 iron-constantan thermocouples mounted between the calorimeter substance and the isothermal Ud. 

At the suggestion of Nemst, Eucken (1909) developed a calorimeter for the measurement of specific heat capacities at low temperatures. Nemst (1910, 1911) used a similar calorimeter without major modifications for the measurement of a large number of specific heat capacities to a temperature of 23 K. To test his own heat theorem ( third law of thermodynamics), Nernst strove to measure the specific heat capacity as much point by point as possible as a function of temperature. An average specific heat capacity over a relatively large temperature range was worthless for this purpose. 

Precise measurements of heat capacity may also be made in a calorimeter with a shield at constant temperature (the Nernst calorimeter). The heat lost or gained during each measurement is determined accurately. 

Modern calorimeters are more automated than the adiabatic calorimeter shown in Fig. 5.4, but the principle has not changed from the Nernst design. The calorimeter of Fig. 5.4 was mainly used for the measurement of specific heat capacities and heats of fusion of macromolecules. Under most favorable conditions it was capable of an accuracy of 0.1%. The temperature range of the instrument covered 170 to 600 K. 

The molar heat capacity Cp of LaSe was studied in an adiabatic Nernst calorimeter in the temperature range 90 to 390 K. Selected values for Cp and Cv in cal mol for temperatures... 

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