678 On the Evidence that the Earth's Interior is Solid. Ue, 
ON THE EVIDENCE THAT THE EARTH'S INTERIOR 
IS SOLID. 
BY DR. M. E. WADSWORTH. 
s, 
i 
(Continued from page 594, Fune number.) 
The Evidence of the Earth's Solidity derived from the behavin 
matter under the combined action of Heat and Pressure,—The key- 
note of this problem was given by Mr. William Hopkins in stating 
that if the tendency of the temperature to liquify the interior por 
tion of the earth increases more rapidly than the pressure tends 
to solidify it, that interior would be in a state of greater or lessper 
fect fluidity ; but if the tendency to solidify from pressure is greater 
than the tendency of the temperature to preventit, the earth woul 
solidify from the center. In other words, whether the earth's it- 
terior is solid or not, depends upon the relative increase of 
temperature and pressure, and on the behavior of the earth's m 
terials under increased heat and pressure. Some experiments wèt 
made by Hopkins to ascertain the relation of solidity and fust 
under the combined influence of heat and pressure on certain ME . 
stances. He found that for spermaceti, wax, sulphur, ewig | 
as the pressure increased the point of fusion was 7 pes 
irregularly, and with a diminished ratio, while metallic i 
showed no elevation of the fusion point. He did not regard P 
experiments as satisfactory, particularly those on the er a 
The subject was later discussed by Sir William ae 
held that from the “thermo-dynamic law of his bi ae 
Thomson, the earth must have solidified from the center 0% f. 
This law asserts that all materials which contract om wad that 
have their melting point raised by pressure, while press | 
expand on freezing have their melting point lowered pe inthe 
This law was experimentally verified by Wm. Thomsot et 
case of water. Hence, accepting Bischof’s | 
which indicated that the earth’s materials con ga et 
twenty-five per cent on solidification, Thomson clai acai e 
if the internal heat was very great, the -pressure the eath 
more rapidly than the tendency to liquify, and hence 2 
must have a solid center. a 
The discussion then rests largely on the question ie m 
Bunsen, AME T 
1 Report Brit. Assoc., 1854, xx1v (Sect.), 57» 58; see also 
Chemie, 1850, LXXXI, 562-567. 
TE 
