BRIDGMAN. — WATER UNDER PRESSURE. 



467 



the existence of a point of inflection at —4° as found by Tammann. 

 This third set was made with the apparatus directly connected to a 

 Cailletet pump of the 

 SocidtdGenevoise,with w 

 a capacity of 1000 

 kg./cm.'^. As a check, 

 the equilibrium pres- 

 sures as given by the 

 Bourdon gauge of this 

 pump are tabulated as 

 well as the pressures 

 given by the manganin 

 resistance. The slide 

 wire of the Gary Foster 

 bridge was especially 

 changed for this ex- 

 periment, so as to give 

 greater sensitiveness 

 in the measurements of 

 resistance. The read- 

 ings of the manganin 

 gauge are to be ac- 

 cepted as more trust- 

 worthy than those of 

 the Bourdon. Within 

 the limits of accuracy 

 of the readings, there 

 seems to be no point 

 of inflection on the 

 equilibrium curve as 

 found by Tammann, 

 but the curvature is 

 perfectly regular, in- 

 creasing more and 

 more rapidly at the 

 lower temperatures 

 and higher pressures. 

 The point of inflection 



found by Tammann may very possibly be due to errors in the pressure 

 measurements. His values for the pressures in the neighborhood of 

 2000 are nearly 100 kgm. higher than those found here. The eff'ect 

 of introducing such an error into the gauge readings at some point on 



-20^ 



-15" -10" -5 



TEMPERATURE 



Figure 6. The change of volume when ice I 

 melts to the liquid. 



