103 



3. In the point -S" the reaction F^ F' -j- L occnrs. In tlie previous 

 reactions F and F^' shonld then, however, be exchanged. 



We can allow the liquid of the four-phase equilibrium F-\-F' -\-L-\-G 

 to traverse tiie li([uiduni curve from a to c ; the vapour then traverses 

 the vapour curve from a^ to c^. We will call this direction, where 

 the equilibrium arrives first in the minimum melting point and then 

 in the maximum sublimation point of the complex F -{- F' , tiie 

 positive direction. 



We now allow the equilibrium to move over a short distance 

 from the one side of the minimum melting point towards the other. 

 At the one side, as noticed above, a four-phase i-eaction takes place 

 different to that at the other side ; in the minimum melting point 

 itself both reactions coincide and the va[)Our does not participate in 

 the reaction. Hence, in this moving we obtain a succession of 

 three reaction types which we will call a reaction series. 



Fig. 1. 



Fig. 2. 



"'^. 



Fig. 3. 



We now may summarise the previous results in the following 

 manner ; if a four-phase complex F -\- F" -\- L -\- G moves in a 

 positive direction through the minimum melting point of the complex 

 p _[_ p there occurs the reaction series : 



Fj^F' -\-G-^L F-\-F':^L F-^F':^L^G 

 ov F' -\-G:^F-}-L F':^F-]-L F':^F^L-^G 

 or F-\-GTir -\-L F:^F'-\-L F :^ F' -\- L -\- G 



