538 PROCEEDINGS OF THE AMERICAN ACADEMY. 



pressibility of water and VI with rising pressure. This point has some 

 bearing on the discussion of the general nature of the change of state 

 solid-liquid at high pressures. 



Discussion of the Eesults. 



So far in this paper merely the numerical results have been pre- 

 sented, without much discussion of their significance. For the liquid, 

 the change of volume at different temperatures and pressures has been 

 found, without discussing the shape of the p-v-t surface which these 

 combine to give. For the solid states, the data have been presented 

 for each variety of ice separately, without any consideration of the 

 general features which may be common to all. The object of this dis- 

 cussion is to give a comprehensive survey of all the results, especially 

 for the transition liquid-solid, and to point out the theoretical signifi- 

 cance of these data at very high pressures. 



For the liquid, the results will have their chief interest in showing how 

 water passes from an abnormal liquid at low pressures to a normal one 

 at high pressures. The data do not have so much suggestiveness for a 

 theory of the liquid state as would those for some normal liquid, and 

 in any case it would be dangerous to generalize from the behavior of a 

 single substance, but the results at the higher pressures do suggest 

 at least the nature of the effects to be expected in general at high 

 pressures. 



The results for the liquid at even temperature and pressure intervals 

 have been collected in Table XXXI. In this table the smoothed re- 

 sults obtained separately above 0° and below 0° have been given with- 

 out any attempt to smooth the values of either set so as to make con- 

 nections with those of the other. But the fact that the two independent 

 sets of determinations do run smoothly into each other makes probable 

 the accuracy of the work. Above 7000 kgm. the value of the thermal 

 dilatation used in computing the table was obtained by an extrapolation. 

 This is probably good up to 10,000 kgm. in giving the actual volume 

 at any temperature and pressure within the narrow range of existence 

 of liquid water, but the use of the tables in any theoretical consider- 

 ations demanding knowledge of the derivatives would be dangerous at 

 the highest pressures. Above 3000 kgm., and indeed above 2000 kgm., 

 the dilatation has been assumed to be independent of the temperature 

 over the range of 22°, as has been sufficiently shown by the work of 

 Amagat. For values below 2000 the variation of the dilatation as 

 found by Amagat has been used in computing the table. Of course 

 below 0° the variation of dilatation with temperature was given by the 

 data of this paper. 



