( 820 ) 
Op 
v,a-section of the surface of saturation at given temperature, ere 
Lv 
0 d, 0 
is in absolute value greater than (5: Hence 2 (5) is 
at 73) 
On dT’, 23 0 T 
dp 
greater than dT Ee & a= 
123 
So the section of the surface that holds for the equilibrium 3,1 
ascends less rapidly than the section 1 for the equilibrium 2,1. And 
in consequence of the retrogression of « to smaller value at rising 
temperature the sheet 3,1 comes in the place of the sheet 2,1. If at 
a second, higher temperature the three-phase-curve should again leave 
the heterogeneous region, and become a parasitic si below the 
1 Op 
lower sheet, then a <(3) Hence the value of = is positive, 
ds Ory: 
Ov d Op 
because ee continues to be negative. Then both = -( 2 ) and 
Oa he aT. d1 Ta1 
dp Op 4 : i : 
—_—{—] are negative; but the first difference is greater in 
BREE NOT p | 
: Op 
absolute value than the second. So is then smaller than 
EE OER 
There is then another break in the sbomioë of the lower sheet, but 
yet in consequence of this this section begins to ascend less rapidly, 
because on account of 2, running to the right with rising temperature 
the sheet 2,1 takes the place of the sheet 3,1. 
But though it is good that these circumstances have been examined 
in detail, all this is not necessary if we only want to know what 
will be the shape of the line at higher temperatures with regard to that 
at lower temperatures, if a break appears in the lower branch. The 
simple remark that the two branches which meet, must have such 
a position with respect to each other that their continuations repre- 
senting metastable branches may not lie in the stable homogeneous 
region, is then sufficient, and evidently this rule could not be satisfied 
if on the lower branch the line occurring at higher temperatures 
ascended more rapidly than the preceding one. But for the upper 
branch this rule leads to the conclusion that on the contrary a 
branch appearing at higher temperatures, must ascend more rapidly. 
The systematically sustained application of this rule, therefore, does 
not present any difficulty in the case of fig. 40, and does not reveal 
anything new so long as Pe, lies higher than A, as in the case 
with the mixtures of ethane and alcohols. But in the cases of 
Bicnner, mixtures of CO, and organic liquids where P,, lies lower 
than 7, it will have to give rise to what we may call: double 
