344 



PROCEEDINGS OF THE AMERICAN ACADEMY. 



The points at the higher temperatures were obtained from the data 

 of tliis paper alone. There are two striking features that call for 

 special comment. The first of these is the abnormal behavior of the 

 curve for 20°. In the initial stages, the dilatation rises with increasing 

 pressure, unlike normal liquids, but this merely indicates the return 

 of water to the normal behavior to be expected at high pressures. 

 At about 3500 kgm. the curve at 20° has reached a maximum and 

 begins to descend with increasing pressure, as it does for the curve at 

 0°. But the descent continues for only a little way, and at 5500 kgm. 

 the curve begins to rise again, indicating the entrance of a new abnor- 



23456789 10 U 12 

 Pressure, kgm. / cm.^ x 10^ 



Figure 5. The dilatation of water, (^ ) , against pressure. 



mality. The abnormality is not so striking or so great in amount as 

 that in the neighborhood of 0° and atmospheric pressure. The ab- 

 normality at 20° continues for about 2500 kgm., up to 8000, where the 

 curve is terminated by the entrance of the solid phase, but the direc- 

 tion of the curve has already begun to change, indicating that if it 

 could be continued, this abnormality also would probably disappear 

 at higher pressures. As to the question of experimental error here, 

 there would seem to be no room for doubt as to the actual existence 

 of this new abnormality, for it was shown by all four of the dilatation 

 curves, even those taken before the method was got to running satis- 



