CURIOUS PROPERTY OF INTENSE HEAT. 121 



bon, iron, phosphorus, and the metals generally, 

 may move their particles in indifference to each 

 other, being separated by the intense force of 

 heat which overcomes their tendency to unite. 



Should, however, any portion of them by any 

 cause become cooled, to a certain extent, then 

 instantly the powers of chemical affinity reassert 

 their dominion, and violent chemical combina- 

 tions immediately take place, which may develop 

 themselves on the surface either in the upheaving 

 might of an earthquake, or the red torrent of the 

 volcano. It is apparently a certain fact that the 

 internal temperature of the earth does not affect 

 the temperature of the earth's surface, nor of the 

 ocean, overlying earth's deep cavities. 



That tremendous natural phenomenon, the 

 Earthquake, has been mentioned as apparently 

 giving countenance to the idea, that the interior 

 of the earth resembles a great chemical labo- 

 ratory. Let us now advert to some particulars 

 concerning it, and in so doing briefly mention 

 the external phenomena which accompany these 

 appalling catastrophes. A violent explosion is 

 often heard, such as is produced by the firing of 

 a mine, althoiigh the occurrence of this is un- 

 certain ; then follow a series of concussions and 

 vibrations, the bosom of the earth heaves up like 

 a sleep-disturbed giant, thunderings like legions 

 of artillery roll beneath the feet, and deep chasms 



