254 



MAJOR A. E. OXLEY ON THE INFLUENCE OF MOLECULAR 



2. ELEMENTS and Inorganic Compounds. 



In the case of iron at the A 3 point, the transformation is from one cubic crystalline 

 form to another, and we should expect the change of internal energy to be smaller 

 than in the general case of actual crystallization from the liquid state. 



We can obtain a measure of intrinsic pressures in crystalline media in another way, 

 which depends on extrapolation of the relation connecting the temperature of the 

 freezing point with applied pressure. 



If 



v t = volume of 1 gramme of liquid, 



v e = volume of 1 gramme of crystal, 

 S- = temperature of fusion, 

 p = pressure, in atmospheres, 

 L = latent heat, 

 we know that 



If the applied pressure be such that v t v c then <5V = 0, and if we can determine 

 the pressure IT for which this condition exists, we have determined the intrinsic 

 pressure due to the crystalline grouping, for if the latter were greater than, or less 

 than, TT there would be a change of volume on crystallization. If v t = v e since, as 



the curve of fusion shows, both 



* A. E. OXLEY, ' Trans. Faraday Society,' vol. XL, Part 2, February, 1916. 



and L are finite, must be zero, i.e., we have to 

 cp 



