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successive isobars drawn, starting with that of the point in which 
—=0( is closed, they all have their points of inflection at ever 
Ek, ine 
as - 
vs Se f 
” . 
oo 
ca 
a 
oa 
a 
ed 
Fig. 42. 
smaller value of z. If we now take the point in which v,, = 0, 
and if we draw the isobar of this point, and the tangent to this 
isobar, this tangent must pass through the point 3, which is only 
possible when the point of inflection lies between 1 and 3. If we 
then take the point in which v,,—0, so on a higher isobar, and if 
we again draw a tangent to that higher isobar in that point, this 
tangent will point at a point 2 which lies nearer 1 than 3 lies near 
it, the point of contact now being nearer the point of inflection. 
It appears from the diagram of the considered case that the three- 
phase-pressure is always smaller than the vapour tension of the first 
