BRIDGMAN. — WATER UNDER PRESSURE. 



517 



correction necessary for the thermal dilatation of the transmitting fluid. 

 These measurements to the highest pressures "were made after the com- 

 pletion of all the others. It was confidently expected to find a new 

 variety of ice, but none was found. 



The pressure measurements with the high pressure apparatus were 



10 



12 



14 



.-3 



13 



20 



PRESSURE, KGM/CM^ X 10' 



Figure 32. The freezing-cun^e VI-L. 



made in the usual way by measuring the resistance of a coil of manga- 

 nin wire. This had been calibrated by comparison with an absolute 

 gauge up to 13,000 kgm., which was about the limit of the gauge. The 

 pressures above this were obtained by a linear extrapolation, therefore. 

 There does not seem much danger in Soing this in view of the fact that 

 the relation is linear within 1/10 per cent up to 13,000. 



For the middle temperature range the high pressure apparatus offers 

 the advantage of fewer connections over that actually used. There are 

 practical difficulties in the way of its use below o°, however. It is 

 necessary to submerge the entire lower end of the hydraulic press with 

 the cylinder into the constant temperature bath. There is considerable 

 flow of heat out of the bath along the heavy connecting bars of the 

 press. It would for this reason have been difficult and expensive to 

 have maintained temperatures below zero with the CaCU solution. 

 Points have, however, been obtained with the high pressure apparatus 

 over the entire range above zero. 



The equilibrium points are given in Table XXVI. and Figure 32. A 

 greater variety of groupings of apparatus have been used for the points 



