Effect of applied pressure on the eutectic point

The effect of pressure on the position of the eutectic point may be examined by considering the differential equations obeyed by the eutectic line, at all points along which the affinity of transfer of the two components from the solid to solution is zero. The affinity is given by (18.19) which may be applied separately to each of the two components  

If we replace the changes in the activity coefficients by the values given by (7.68) and (7.69) we have 

We must be careful to distinguish the heat content and volume changes corresponding to transfer of a component from solid to liquid in the system under consideration from the standard values of these quantities  

Similar equations apply to the other component, so that equation (22.22) may be replaced by 

Eliminating first 8 2 and then ST from equations (22.24) we obtain, along the eutectic curve 

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