BRroCMAN. 



WATER UNDER PRESSURE. 



495 



and the I-III points, namely, measurement of pressure as a function 

 of temperature at constant displacement. The chauges II-III and 

 II-V were measured at the same 

 time, so that some anticipation is 

 necessary in describing the method. 

 The diagram (Figure 16) illustrates 

 sufficiently the paths described. The 

 start was made at the point A with 

 the phase II. The approximately 

 vertical lines show the paths at con- 

 stant displacement on which the 

 pressure, temperature, and displace- 

 ment are all known. The dotted lines 

 show the connecting paths on which 

 it was not necessary to know these 

 values. The result of describing all 

 these paths is to give a knowledge 

 of the displacement corresponding to 

 any pressure and temperature in 

 either the region of stability of II or 



III or V. The discontinuity of displacement on the three equilibrium 

 curves can be found immediately, and so the change of volume. It is 



PRESSURE 



Figure 16. Shows the cycles 

 described in finding the changes 

 of volume II-III and II-V. 



-35 -33 -31" -29" -U -25" 

 TEMPERATURE. 



Figure 17. The change of volume when II passes to III. 



to be noticed that the paths are described in such an order that one 

 can easily apply the very small correction for wearing away of the 

 packing or for viscous yield in the steel. The final point B is for the 



