Recently Hermann Walther Nernst has been able to deduce the transitionpoint in the case of sulphur from the specific heat and the heat developed in the transition only.
If the saturated vapour behaves as a perfect gas, the change of intrinsic energy E depends only on the temperature limits, and is equal to s (8-00), where s is the specific heat at constant volume.
The Direct Determination Of The Specific Heat At Constant Volume Is Extremely Difficult, But Has Been Successfully Attempted By Joly With His Steam Calorimeter, In The Case Of Air And C02.
The density of solid sulphur is 2 062 to 2'070, and the specific heat 0.1712; it is a bad conductor of electricity and becomes negatively electrified on friction.
The specific heat of a compound may, in general, be calculated from the specific heats of its constituent elements.
An Example Taken From The Electrician, September 1897, Of One Of The Earliest Experiments By This Method On The Specific Heat Of Mercury Will Make The Method Clearer.
Since the atomic heat of the same element varies with its state of aggregation, it must be concluded that some factor taking this into account must be introduced; moreover, the variation of specific heat with temperature introduces another factor.
A common example of this method is the determination of the specific heat of a liquid by filling a small calorimeter with the liquid, raising it to a convenient temperature, and then setting it to cool in an enclosure at a steady temperature, and observing the time taken to fall through a given range when the conditions have become fairly steady.
The method requires very delicate weighing, as one calorie corresponds to less than two milligrammes of steam condensed; but the successful application of the method to the very difficult problem of measuring the specific heat of a gas at constant volume, shows that these and other difficulties have been very skilfully overcome.
His paper on the variation of the specific heat with temperature, which appeared in 1907, was the first extension of Planck's fundamental hypothesis, and its verification in essentials is one of the most convincing arguments in its favour.