BRIDGMAN. — MERCURY UNDER PRESSURE. 



415 



data of the same period for water, however, where the total change of 

 volume is larger and the correction of less account, give consistent 

 values for the change of volume also. 



First for the equilibrium pressure. This was ordinarily found at 

 only two points, one with increasing and the other with decreasing 



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PRESSURE. ARBITRARY UNITS. 



Figure 19. Shows the discontinuity in the piston displacement during 

 freezing. (One division on the pressure axis corresponds to 900 kgm.) 



pressure, but in order to make sure that this equilibrium pressure was 

 a perfectly definite quantity, independent of the quantity of mercury 

 melted, equilibrium was found, during the first two or three runs, with 

 various proportions of the solid melted. This is shown in Figure 1 9 

 (Oct. 13), where the piston displacement is plotted against pressure. 

 The vertical part of the curve shows the period of transition. The 

 equilibrium pressure thus appears to be the same whether the freezing 

 is nearly complete or only just begun. It is possible to get much 



