BRIDGMAN. WATER UNDER PRESSURE. 



541 



first the compressibility data above zero. Of coarse the rough facts 

 already known appear immediately from an inspection of the figures. 

 The compressibility decreases strikingly with rising pressure and is 



less at 22° than at 0°. Figure 36 shows the compressibility (=(--]) 

 at 0° and 22°. At 10,000 kgm. it has decreased to 1/4 of its initial 



8 7 



PRESSURE, KGM/CM^ X 10"? 



Figure 36. The compressibility ijr-) of liquid water as a function of 

 the pressure at 0" and 22°. ^"^^'' 



value. The figure shows also the crossing of the compressibility 

 curves ; at low pressures the compressibility at low temperatures is 

 higher than it is at high temperatures, but with rising pressure the 

 abnormality disappears, and beyond 4000 kgm.. the compressibility is 

 higher at the higher temperatures. The variation of thermal expansion 

 between 0° and 22° is shown in Figure 37. This rises to a maximum 

 at nearly 4000 kgm. and then falls again. The rise to the maximum 

 is much more rapid than the fall away from it. This maximum verifies 

 the surmise of Amagat that the dilatation at any temperature would 

 ultimately decrease with rising pressure for pressures sufficiently high. 

 The position of this maximum evidently corresponds to the crossing of 

 the two compressibility curves at 0° and 22°, for we have 



0. 



dt\dpj ~ d])\dt ) ~ 

 The usual explanation of the abnormalities shown by water at atmos- 



