()0 DOMAIN I. SIDEROUS. 



which are found in some trap rocks, could not 

 in like manner have resisted the volcanic heat 

 without being destroyed. 



" It is the same with many minerals which 

 are very fusible, and which are there met with : 

 indeed, some are also found in volcanic rocks, 

 but these instances are rare, and cannot serve as 

 a basis to a general rule. 



" 5. Cavities filled with water, such as en- 

 hydritic agates found near Vicenza, in Italy, in 

 secondary trap mountains, entirely destroy all 

 supposition of a volcanic origin*. 



t( 6. There are not observed in trap rocks either 

 that black colour, or those indications of vitri- 

 faction, that are apparent, at least in certain por- 

 tions, of the products of burning volcanoes : real 

 craters have never been observed. All those 

 which have been cited were hollows, chasms 

 filled with water, so common in some moun- 

 tains. 



" 7. Mandelstein has certainly some resem- 

 blance to porous lava; but there are mandel- 

 steins evidently not volcanic. Besides, the 

 cavities of the mandelstein of trap mountains 

 contain very different minerals, and which could 



" * The Vulcanists answer that these agates have a latter origin 

 rom infiltration." 



