( 544 ) 
which, on the same supposition as above, again demands about equal 
triple-point pressures for A and B; secondly, the exponent of e 
with a negative sign should be as large as possible, which requires 
widely diverging branches in the melting diagram at the side of the 
component B. 
These demands put from two sides are brought into agreement 
by a conclusion of van Laar (loc. cit. p. 265) that closely adjacent 
branches in the melting diagram at the side of the one component 
cannot meet a similar configuration at the side of the other. 1 ) If this 
were possible, the occurrence of a maximum and] a minimum in 
one three-phase line would be quite possible. 
In the case of 15 we therefore, require: 
1. Melting diagram with branches nearly coinciding at the side 
of the A-axis and 2. about equal triple-point pressures. 
Case Ic finally occurs as an intermediate case between the two 
previous extreme cases. Of course, the line Oa Ob may be concave 
or convex in regard to the temperature axis; this depends on whether 
the conditions for I a or 15 have been partially fulfilled. Let us call 
these cases Ic, and Ic, respectively. For definite forms of the melting 
diagram points of inflection may probably occur, but our mode of 
treatment is inadequate for their investigation. 
A single remark may be made as to the chance of observing a 
fall of the three-phase line starting from Oa . As stated, the follow¬ 
ing condition is required: 
/— 
0 — q +Pb< p t: 
If now we imagine the most favourable circumstance, in which p B 
may be neglected (because the components differ, for instance, very 
much in their melting temperature) the factor (1 — x L ) will cause a 
f RTl ( ) 
decrease and the factor e ? 5 L an increase in the value of 
the first member in regard to that of the second one. For 1— x L 
is always <1; the other factor is >1 and only in the case of 
x s = x L it is equal to 1: in that case a fall may be expected, but 
as soon as x s and x L differ in value the enlarging factor appears 
and the said difference occurs therein exponentially. The enlarging 
influence will, therefore, very soon exceed the other, so that the 
chance for realising the case Ic will be diminished and that for 15 
will be reduced to a minimum. 
same suppositions as jn the footnote on p. 543, 
J ) At least when, we . make the 
