BRIDGMAN. — MERCURY UNDER PRESSURE. 



369 



regular results. The values at 22° w6re found after this experience 

 had been gained, and with the two piezometers giving the best results 

 atO°. 



The points obtained with all five piezometers at 0° are shown in 

 Figure 3, and the points with the best two of these piezometers in 

 Figure 4. The points found 

 with the two piezometers at 

 22° are shown in Figure 5. 

 The greater regularity of 

 these points is manifest. 

 In both of these figures not 

 all the points actually ob- 

 tained have been repre- 

 sented, for four or five 

 points, obtained directly af- 

 ter the freezing of the water 

 at too high a pressure, have 

 been discarded. 



The data were adjusted 

 and the final values com- 

 puted in the following way. 

 The work was done indepen- 

 dently at each temperature. 

 A straight line was first 

 drawn passing through the 

 assemblage of points. It 

 was not necessary that this 

 line pass through the origin. 

 The deviation of the ob- 

 served points from the 

 points calculated by the lin- 

 ear formula was then deter- 

 mined. The deviations from 

 this line for each piezom- 

 eter separately were then 



plotted on a very much enlarged scale against pressure, and a smooth 

 curve drawn through these deviation points. This deviation curve, 

 together with the fundamental linear equation, gave the best smooth 

 curve connecting change of volume with pressure as determined by 

 each piezometer separately. From these best smooth curves (five at 

 0°), points were determined at even pressure intervals, 500 or 1000 

 kgm. apart. At each of these evenly distributed pressures, the weighted 



VOL. XLVII. — 24 



Figure 3. Collection of all the results with 

 five piezometers for the compressibility of 

 mercury at 0°. 



