some New Equations derived therefrom. 33 



The diagram roughly shows that the critical point is 

 the point of intersection of three curves, i. e. the critical 

 isothermal, the border-curve, and the curve 



2Pc.Vc = l (constant). 

 Fio-. 1. 



We found equation (14) c= -~~. Considering c = v 2 a 

 (p. 26, equation B) and v— v ° , we find, as V c =26, 



~a = b, and 



a= l b=- s y c . 



. 615) 



We can deduce the same value from equation (A), p. 25, 

 for the critical state. 

 As we found 



we get 



(Ve+V 



2a 



Phil. Mag. S. 6. Vol. 31. No. 181. Jan. 1916. 



D 



