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THE AMEBIC AX XATUEALLsT [Vol. LII 



and P = 2, the degree of freedom F is equal to 1 + 2 — 2=1; the 

 system possesses one degree of freedom, as has already been stated. But 



ponents, viz., calcium oxide and carbon dioxide, and three phases, viz., 

 two solid phases, CaO and CaC0 3 , and the gaseous phase, C0 ; . The 

 number of degrees of freedom of the system, therefore, is 2 + 2 — 3 = 1 ; 

 this system, therefore, also possesses one degree of freedom. We can 



number of the coexisting phases. 



In the preceding quotations there are certain points to 

 which special attention should be called: 



1. The phase rule is concerned with equilibria, and not 

 with the processes by which this state is reached. It thus 

 supplements Bancroft's law in a very important manner, 

 because that law is mainly concerned with the process of 

 developing equilibria. To make complete continuity and 



