350 



PROCEEDINGS OF THE AMERICAN ACADEMY. 



is a function of the volume only. This means that if the coefficient 

 were plotted against volume instead of pressure the curves for all five 

 temperatures would fall together. That this is not the case for water 

 at high pressures is shown very distinctly in Figure 10. At the lower 

 pressures and the larger volumes, the curves for the different tempera- 



0123456789 10 U12 

 Pressure, kgm. / cm.^ x 10^ 



Figure 9. The pressure coefficient, that is the change of pressure accom- 

 panying a rise of temperature of one degree, as a function of the pressure. 



tures are very widely separated. The abnormality on the curve 

 at 0° in the neighborhood of the locality where the new variety of 

 ice makes its appearance is very striking. At the higher pressures 

 the curves do draw together, but they are not approaching coincidence, 

 for they cross in the neighborhood of a volume of about 0.85. It does 

 not seem likely that the entire failure of coincidence throughout the 

 whole range of pressure can be due to abnormalities, since even at 

 low pressures water is nearly normal at the higher temperatures, and 

 certainly at the higher pressures and temperatures we have every 

 reason to expect that its behavior is quite like that of other liquids. 



This completes the list of quantities which can be deduced directly 

 from the compressibility and the thermal dilatation. Other quanti- 



