Calibration of a Calorimeter: a Minor Peaceful Use for Plutonium

Abstract

CALORIMETERS are often calibrated by generating a known electric current within them and observing the deflexion of the measuring instrument when the system is in a steady state. This method may suffer from the disadvantage that heat is lost along the leads through which the calibrating current is introduced. The loss of heat can be reduced by passing the leads through a block of metal maintained at the experimental temperature, though the design of the calorimeter and its water-bath may make this procedure difficult. One can also calculate the loss of heat along the heater leads, but it is not desirable to rely exclusively on estimates that cannot be verified by experiments. One alternative is to calibrate the heater against some thermochemically convenient reaction, for example, the latent heat of vaporization of a liquid¹, or the neutralization of a strong acid by a strong base². These methods have their own disadvantages, and it was therefore decided to use a different method of calibration, either of the calorimeter itself or of the heater used to calibrate it.