VARIATION' OF MOLECULAR SURFACE-ENERGY WITH TEMPERATURE. 661 
The correspondence is better at higher temperatures. 
Benzene. 
Ether. 
Corresponding temperatures .... 
521'5° Absolute 
4.34-1° Absolute 
,, pressures. 
21752 millims. 
16088 millims. 
„ volumes. 
1.37'81 cub. centims. 
150-26 cub. centims. 
pv 
5748-2 
5568-6 
T 
Here, again, Eotvos assumes that 5748’2 = 5568’6, an assertion unwarranted by 
fact. 
We next proceed to test equation (3), derived from equation (1), on the supposition 
of numerical correspondence between pu and yU. 
Benzene. 
Ether. 
Benzene. 
1 
1 
Ether. 
Corresponding temperatures 
in dynes. 
pv . 
yy* 
pv 
339-95° 
453-6 
46552 
282-9.5° 
382-6 
29651 
521-5° 
70-7 
2997600 
434-1° 
54-2 
2417400 
0-009744 
0-01290 
0-0000236 
0-0000224 
Again the want of correspondence is less striking at high than at low temperatures. 
Lastly, it is possible to test equation (4), viz., yityV-^i — same 
temperatures have been chosen, and the data are the same as those given above. 
The results are :— 
Benzene. 
Elher. 
Benzene. 
Ether. 
T. 
1-3343 
1-352-2 
1-3557 
1-2486 
These results show that the basis of reasoning on which Eotvos Founds his 
differential equation is a faulty one, and contrary to fact. The equation wliich he 
deduces from his differential equation, viz.:— 
yi4 = 0-227 (T - T'),-'' 
where T is the temperature at which yv^ = 0 (he., the critical temperature), and T^ 
the temperature at which the observation is made, is identical with the first equation 
stated on p . 647, viz., yv^ = kt, and obviously does not hold. 
* The coefficient, 0'227, is expressed in miliigramnies per square millimeti’e. 
