546 
point A; then we enter the region, just as in fig. 1 (XVI) starting from 
h in the direction hm. 
Consequently the region H is situated at the right and below the 
point h. 
The direction of curve ab itself is defined in every point by: 
OPDE) 
NS SIA (17) 
AT KAD 
It follows from our assumption over the sign of (d7’)p and (dP)r 
that we have assumed 2(2r): 2(4H) to be negative and 2 (Az) : 
2(AV) also to be negative. Then it follows from (17) that curve 
ab must be a curve, rising with the temperature, in the vicinity of 
point h, as is also drawn in fig. 1 (XVI). 
In fig. 3 (XVI) abchd represents a limit-curve which has a maxi- 
mum of pressure in 6 and a maximum of temperature in c. It 
follows with the aid of (17) from the direction of branch ab that 
E(,H) and Z(AV) have the same sign; we now choose the signs 
of a,...4, in such a way that both are positive. Then it follows 
from the direction of the branches be and cd with the aid of (17), 
which signs 2(2H) and 2(AV ) must have on those branches. Then 
we have: 
on branch ab Z(AH)>0 z(aV) >0 
in 6 E(AH)=0 (AMV S30 
on branch bc Z(ÀH)<O0 Z(AV)>0 
in C Z(AH)<0 (AL 1) 0) 
on branch cd 2(2H)<0 Z(AV)<O 
In each point of curve abchd (ax) has a definite sign; we are 
able to find this with the aid of (7) and (10). 
When we assume that (dz) is negative in each point of the 
curve, then it follows from (12) and (15) that the region ZE must be 
situated entirely within the limit-eurve abcd and consequently not, 
as in fig. 3 (XVI), where the part afe is situated outside. 
When in each point of the curve abcd (2x) > 0, then it follows 
from (12) and (15) that the region must be situated at the left of 
and above branch ab, at the right of and above branch be, at the 
right of and below branch ed. Then we bave fig.5 (XVI). [As it is 
apparent from the position of the letters, the printer has turned 
this figure; for this reason the reader has to place it in such a way 
that the tangent is horizontal in 6 and vertical again in c}. 
We may assume also that 2(2r) is positive in the one part of 
the curve, negative in another part. We assume that ZX (dz) is 
