376 



PROCEEDINGS OF THE AMERICAN ACADEMY. 



where 



log a =4.5819- 10, 

 log(-b) = 9.7569-20, 



and applying to this computed value the correction given by the devia- 



tion curve of Figure 7. 



ul 3 



f5 +.00001 



?fe 



OU1-.0000I 



Q.C9 



"I 2 



5 3 



===^-5i 



3 4 5 G 7 

 PRESSURE. KGM/CM^XIO"^ 



Figure 7. The de\aation curve for the 

 change of vohime at 0°. This is to be used 

 with the formula on page 373. 



The data for 22° are 

 shown in a corresponding 

 set of tables and figures. 

 The only difference is that 

 here the parabola was used 

 as the basis for both the 

 first and the final deviation 

 curves. Table IV. corre- 

 sponds to Table I., Figure 

 8 to Figure 7, Table V. to 

 Table II., and Table VI. to 

 Table III. The final for- 

 mula for computation at 

 any pressure is 



where 



Av =^ ap + bp\ 

 loga = 4.5911 - 10, 

 log(-^) = 9.7782-20, 



and the final deviation curve from this formula is given in Figure 8. 



There are only a few previous determinations of the compressibility 

 of mercury with which these results can be compared, and all of these 

 are at comparatively low pressures, where the percentage accuracy of 

 the above work is naturally less than at the higher pressures. The 

 only way of making the comparison is to find what the compressibility 

 given by the above two expressions would be at atmospheric pressure. 

 The values found in this way from the above data are O.O538O at 0° and 

 O.O5395 at 22°. 



The early work, done by Regnault,2i Grassi,** Jamin,23 Amaury et 

 Descamps,2* and Tait,*^ may be summarily ruled out as too inaccurate 

 for the comparison. The earlier of these determinations were made 



" Regnault, Mem. Inst, de France, Six. Mom., 21, 329-428 (1847). 



" Grassi, Ann. de Chim. et Phys., 31, 437-478 (1851). 



" Jamin, C. R., 66, 1104-1106 (1868). 



" Amaury et Descamps, C. R., 68, 1.564-1565 (1869). 



*» Tail, Challenger Report (1889), Phys. and Chem., vol. II, p. 1-76. 



