264 



MAJOR A. E. OXLEY ON THE INFLUENCE OF MOLECULAR 



with the case for benzophenone. In the case of water the diagram is as in fig.' 3 and 

 for p = 1 atmosphere, (5V is negative and L is positive. The m.p. is in this case 

 located on the arc A'B' in the second quadrant. A similar case is that of pure iron as 

 the temperature is raised through the critical point A 3 (see fig. 4). At A 3 , (5V is 



negative and L is positive, while is negative. 



dp 



Now 



dp L L 



Therefore v ft > v y which gives a shrinkage in iron on heating through the A 3 point at 

 about 900 C. 



= o 



Liquid 

 or Gel. 



Crys. or 

 " Vitreous 



Fig. 4. 



. 9- 



Fig. 3. 

 The application of the relation 



8p = ~T7~ ~lT 



is interesting in connexion with some abnormalities of heats of recalescence in ferro- 

 magnetic media. The change of volume SV, both expansion and contraction ; the 

 absorption or evolution of heat of the amount L, depend solely upon the shape of the 

 region of crystalline stability and its position relatively to the 9, p axes. 



Thus nickel steel with no carbon and pure cobalt show no recalescence at the 

 magnetic change points. In these cases L is very small and since (5V and 9 are finite, 



3C\ 



- will be large (fig. 5). In other words, under the pressure of one atmosphere, the 



path of the crystallization curve cuts the line AB at a steep angle in the neighbourhood 

 of the intersection of the fusion curve with the neutral line L = 0. 



