( 17' ) 



meeting in the point C, below 

 which evenj liquid Qiixture 

 congeals entirely to a conglo- 

 merate of cc and /? crystals. 



We now suppose that at 

 higher temperatures not all 

 mixing-proportions in the liquid 

 state are possible, but equili- 

 brium appears, giving at each 

 temperature a definite mixing- 

 proportion of a and ft. Wo 

 represent these mixing-propor- 

 tions by the line F G which 

 is arbitrarily drawn as rising 

 from left to right, representing 

 the case in which the transition 

 E a-^ ft takes place with absorp- 

 tion of heat. 



The reverse is also possible, 

 -^ or it may be a vertical lino if 

 the heat is zero. 



On the left of the line FG 

 is the region in which the 

 transformation a — *• ft takes 

 '' place, on the right that of the 

 transformation a •e- ft. 

 Now in case both transformations do not take place at lower 

 temperatures, the supposition naturally occurs to us — on analogy 

 of many other phenomena of recent date — that the transition from 

 the region of reciprocal equilibrium to the region of no equilibrium is 

 formed by two regions of one-sided equilibrium^ as may be represented 

 by splitting up the line GF into two lines F Jj and F E which 

 end below certain temperatures on each of the axes. 



If I now heat the solid modifications only a little above their 

 melting point, they will be in a condition to congeal again at the 

 same temperatures at which they melted. But if I heat them to a 

 higher temperature, keeping them for some time at a temperature 

 belonging to the region of one-sided or reciprocal equilibrium, a greater 

 or less transformation in the liquid will take place between the two 

 modifications, varying afterwards according to the velocity of cooling. 

 The manner of proceeding of the congelation after return to this 

 region will depend upon all these circumstances. 



concentration 



