3o2 Scientific Intelligence. 



phase B, but if it is negative the phase A will of itself pass into 



the phase B, unless pre vent e< I by passive resistances. 



The stability K of any oiven phase A with respect to any other 



where € is the energy, v the volume, // the entropy, and »»„ W3 8 , 

 etc., the components corresponding to the second phase I>, while 

 p is the pressure, t the temperature, and i ,, ,'/ 2 , etc., the potentials 

 corresponding to the given phase A. The intensities therefore 

 are those belonging to the given phase A, while the magnitudes 

 are those corresponding to the other phase B. 



We may interpret this expression for the stability by saying 

 that it is measured by the excess ot tin encrg\ in the phase B, 

 above what it would have been if the magnitudes had increased 

 from zero to the values corresponding to the phase B, while the 

 values of the intensities were those belonging to the phase A. 



If the phase B is in all respects except that of absolute quan- 

 tity of matter the same as the phase A, K is zero ; but when the 

 phase B differs from the phase A, a portion of the matter in the 

 phase A will tend to pass into the phase l; if K is negative, but 

 not if it is zero or positive. 



If the given phase A of the mass is such that the value of iv 

 is positive or zero with respect to every other phase B, then the 

 phase A is absolutely stable, and will not of itself pass into any 

 other phase. 



If, however, K is positive. with respect to all phases which differ 

 from the phase A on! the magni- 



tude .. tt',,1 .. r a e, ,t m , *,! , ji ,. . !', ,, uh h i ,. - it ' - 

 differ by finite quantities from those ,,f the phase A, K is nega- 

 tive, then the question whether the mass will pass from the phase 

 A to the phase I! will depend on whether it_e :U! do so without 



In this case the ] 



shase A is stable in 



itself, bn 



t is! 



[able to 



its stability destro 



yed by contact *i 



th the s 



malle 



st portk 





her phases. 









Finally, if K can 











tions of "the magni 











unstable equilibriui 





















any finite time, it 











but it is of great importance in the th 









how these uustablt 











tively or absolutely 



r stable. 









The absolutely t 



itable phases are d 









stable phases by a 







pha 



ses. for v 



the intensities p, t. 



, fj, etc., are equal and K is 





Thusi 



and steam at the 



same temperature 2 



md pressure 



are coexi 



