466 



PROCEEDINGS OF THE AMERICAN ACADEMY. 



In the curves given for A V and the latent heat, the identical re- 

 lations at the triple point were kept in view. In some cases the curve 

 given does not seem to be the best possible through the individual 

 points. The departure from the best curve was occasioned by the 

 necessity of satisfying the identical relations at the triple point, and 



500 



1000 



1500 



2000 



PRESSURE, K6M/CM' 



Figure 5. The freezing curve of ice I. The dotted line shows the slope at 

 0° computed by Clapeyron's equation. 



the amount of departure gives a pretty good criterion of the self- 

 consistency of the data for the different curves. 



The Curve I-L. 



The points on this curve were obtained with the same apparatus as 

 that used for mercury. No special discussion is necessary. The data 

 were obtained on three separate occasions : February 2, February 23-24, 

 and March 15, 191 1. The equilibrium points are shown in Figure 5 and 

 A F in Figure 6 ; the actual data are given in Table VIII. The first 

 set is not accurate. It was taken only for fun one evening after the 

 supply of CaCU for running the thermostat had given out, so that the 

 temperatures are not sufficiently accurate. These points are not 

 shown in the diagram. 



The second and third sets of readings give the equilibrium points 

 determined with sufficient accuracy. The second set suffices to give 

 the general shape of the entire curve, while the third set was taken 

 with more pains at the lower pressures in order to test more definitely 



