Potentiometer method with thermocouples

The Boyd and Harkins reference might be considered the first careful calorimetric work taking into account the special problems of immersional calorimetry it was also the first such work in which surface areas could be assessed (the B.E.T. method) as a necessary auxiliary for putting values on a imit area basis temperatiue changes were measured with a 36-junction thermocouple and a White double potentiometer with a sensitive galvanometer. 

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