BRIDGMAN. 



WATER UNDER PRESSURE, 



471 



particular pains to exclude. In these experiments in which the water 

 was frozen under pressure, any dissolved air, naturally, can have 

 only very little effect. Leduc's value, therefore, seems best for this 

 comparison. 



It will be well here to explain the sign convention used uniformly 

 throughout th6 paper. A change of volume is taken as positive if the 



TABLE IX. 

 Latent Heat, etc., on Equilibrium Curve Ice I-Water. 



volume increases when the reaction runs in the indicated direction. 

 Thus A V L-I is positive (water expands when it freezes to ordinary 

 ice) but A V I-L is negative. Similarly the latent heat. A//, is posi- 

 tive when heat is absorbed during the reaction, and ^E, the change of 

 internal energy, is positive when the internal energy increases. AZT 

 for the reaction L-I is negative, but positive for I-L. In general, as 

 already explained, A V is positive when the reaction runs from high to 

 low pressure and A// is positive when the reaction runs from low to 

 high temperatures. 



From the curves giving the equilibrium points and the changes of 

 volume, the various data needed for computing the latent heat and 

 the change of internal energy may be obtained. These are given in 

 Table IX. for even temperature intervals. The values of A T were 

 taken from the line drawn through the observed points. Two values 



of ~ are tabulated. The first set of values was obtained by graphi- 

 cal construction from the equilibrium curve at different points, these 

 values of ~ plotted and a smooth curve drawn through them. The 



