308 POPULAR LECTURES AND ADDRESSES. 



mcnts made in the incipient Physical Laboratory in 

 the old buildings of the University of Glasgow. 

 Now, if the result announced by Bischoff, that the 

 rocks he examined contract during solidification, 

 be correct, it would follow as a consequence of 

 thermodynamic laws that these substances melt 

 at a higher temperature under high pressure than 

 that at which they melt under low pressure. The 

 conclusion to be drawn respecting the internal 

 condition of the earth is, that we are not to infer 

 liquidity of the interior, even if we should find 

 evidence of a much higher internal temperature 

 than that which would melt the rocks under 

 ordinary pressure. 



The view which I wish to put before you just 

 now, however, is of a very different nature. I 

 mean to deny altogether the intensely high 

 temperature which Hopkins accepted, and the 

 liquefying effect of which he endeavoured to obviate 

 by introducing considerations regarding the solidity 

 of the rocks, in consequence of intense pressure 

 .even at very high temperature. It is too generally 

 supposed that the rate of increase of underground 



