( 636 ) 
Physics. — “On the solid state” VI. By J. J. van LAAR. (Com- 
municated by Prof. H. A. Lorentz). 
(Communicated in the meeting of November 26, 1910). 
Ab positive. 
24. Up to now we have considered the case Ab negative. Then 
the coexistence-curve liquid-solid proceeds from high pressure-values 
at T=0, with a maximum in the neighbourhood of 7’ = 0, either 
to a horizontal point of inflection MD, at the same time critical 
point liquid-solid, where the two phases become identical, and where 
the minimum / of the isotherm coincides with the maximum D 
(see inter alia fig. 20 of V)— or to the neighbourhood of a horizontal 
point of inflection D,C, where the maximum J coincides with 
the minimum C. 
In the example chosen by us, the first thing takes place when 
—Ab< 0,454; the second when — Ah >0,454. For — Ab=0,454, 
in the transition case, /, D, and C’ coincide all three. 
For the intersection of the coexistence-curve of liquid-solid and that 
of vapour-liquid, so that a triple-point S arises, it is required that the 
said critical point /,D or the point of inflection D,C is found at a 
negative pressure, as the pressure in the triple point has mostly a 
very slight positive value. In our example e.g. this occurs for 
— Ab = 0,5 (fig. 14). Then S lies at about */, 7. 
Now if Ab is positive, all this changes. Then the coexistence-curve 
ascends from below (see fig. 23—25) from low pressures, intersects 
in favourable cases (46 large) the line vapour-liquid in a triple-point 
S, and again terminates in a critical point É‚D solid-liquid. The 
curve, however, never terminates in a point of inflection D,C, as 
for Ab negative, when — Ab > 0,454. But it arises very low down 
from such a point [or rather in its neighbourhood, because only at 
somewhat higher temperature the first coexistence solid-liquid begins 
(see fig. 20 of V)]. | 
So for Ab negative the course is from the axis 7’=0 to a critical 
point Z,D or close to a point of inflection D,C (according to the 
value of — Ad), thus running from above downward, with (beyond 
the pressure maximum near 7’ = 0) always negative values of 
d ge i ! , 
= for Ab positive, on the other hand, from a point of inflection D,C 
t 
to a critical point ZD, thus running from below upward always 
d 
with positive values of = For a definite value of Ad the two end- 
