124 



and (F,) at tlie left of (FJ; {F,} is ailualed at tlie riglit and (/',) 

 at tlie left of {F,). 



3. Unary systems. 



\n an invariant point of a unary system three phases F^, F, and 

 F.J occur; consequently the point is a triplepoint. Three curves 

 (F,), (Fj) and (F„) start from this point, further the three regions 

 of Fi, F., and F, occur. From our previous considerations the 

 well-known property immediately follows: the region of F^ covers 

 the metastable pait of curve {F^) = F^ -\- F^, the region of F.^ 

 covei'S the metastable part of curve (F,) ^ F^ -\- F.^ and the I'egion 

 of F^ covers the metastable part of curve {F^) ^ F^ -\- F._. 



4. Binnry systems ^). 



In an invariant point of a binary system four phases occur; 

 consequently this point is a quadruple point. When we omit, as we 

 shall do in the following, the letter F in the notation and when 

 we keep the index only, then we may call these phases ], 2, 3 

 and 4. The four curves (1), (2), (3) and (4) are starting from this 

 quadruple point, further we tind h{n-\-2)[n-\-l) -= 6 regions viz. 

 12, 13, 14, 23, 24 and 34. 



We call the two components of which the system is composed, 

 A and B; the four phases may be represented then by four points 

 of a line AB. In tig. 2 we have assumed that each phase contains 

 tiie two components; it is evident however, that i^, can also represent 

 the substance A and F^ the substance B. 



Now we shall deduce with the aid of tlie former rules the situa- 

 tion of the four curves with respect to one another. As i^, is 

 situated between F^ and F^ (fig. 2) we find : 



2 ;;f 1 + 4 (10) 



(2)i(3)j(l)(4) (11) 



As F^ is situated l)etween F, and F^ it follows: 



3^2 + 4 (12) 



(3)!(1)|(2).4) (13) 



Now we draw in a 7', T'-diagram (fig. 2) quite arbitrarily the two 

 curves (1) and (3); for fixing the ideas we draw (3) at the left of (1). 



1) For another ileduction see also F. A. Schreinemakers (I.e.) and V. E. C. 



SCHEFFER (i.e.). 



