Application of the new Heat Theorem

It follows also from this that gases at very low temperatures and at constant pressure have a volume independent of the temperature. 

In any case, it will be of interest to inform ourselves how the calculation for gases is to be carried out we select as 

For the sake of simplification we again consider temperatures so low that we may regard the specific heat of the condensate as negligibly small. This does not entail any limitation, for the specific heat may be readily taken into account if necessary. We assume, further, that the volume of the saturated vapour is large compared with that of the condensate, an assumption which is of course perfectly justified at low temperatures. Then, according to the Second Law, we have for the vapour pressure the formula which has already been often employed, 

Further, at the saturation point, we have for the maximum work A associated with the condensation 

We now apply the new Heat Theorem to the formation of one mol of the solid. If we denote by A0 the heat evolved in the condensation of a mol of a very rarefied gas, referred to the absolute zero, the corresponding quantity for the volume v (cf. equation 180) amounts to 

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Application of the new Heat Theorem results at once in the two equations... 

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