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dp dp dx dp dv 



shown. As — = - = — — we derive thai in this ease also 



dT dx dT dv dT 



dp dp 



— = and — = 0, save in exceptional cases. Then p is the highest, 



dx dv 



or the lowest pressure that can occur on the plaitpoint curve. Of 



the 6 differential quotients 3 are again equal to zero, and 3 others 



dx dv dv 



are again to be determined, viz: — , — and — . We find then from : 

 6 dT dT dx 



dp 

 dx dT 

 dl'~dp~ 



dx 



d*p 



From 



we find : 



And from 



we find: 



/dx V_ dT' 

 [dfj ~ d*p~ ' 



dx 1 



dv* 

 which may be again verified from the equations: 



P= Pl ± a(T-T x y = Pl ± fc- tll y=p l ± Y ,v- Vl y 



For plaitpoint lines which do not run from x = to *=1, and 

 which therefore either form a closed figure, or run from a point of 



