DOMAIN XII. VOLCANIC. 



whom a thousand ages are but as one in- 

 stant. 



Effects of In general, the effect of fire only is con- 

 water. . . 



sidered in volcanoes ; but the curious vol- 



cano of mud in Sicily, and the muddy 

 eruptions of the Andes, should excite more 

 attention to the agency of water. If we 

 conceive the volcanic chasms, containing, 

 as already mentioned, reservoirs of water, 

 as well as of inflammable substances, to 

 be in the nucleus of the globe ; and that 

 nucleus to consist of iron, mingled at least 

 superficially with its usual attendant silex, 

 the ferruginous nature of lava can easily be 

 explained, as arising from an abrasion of 

 the nucleus by the water. For, passing 

 the minuter appearances, which only excite 

 curiosity, and are exceptions, not rules; 

 iron and siiex. all lavas may be said to consist of iron and 

 silex ; the most common being the black, 

 of melted siderite ; while the others, of a 

 grey colour, have a base of silex in the 

 Felspar, form of felsite. But felspar is a name of 

 far too general acceptation ; and may pro- 

 bably, in the progress of mineralogy, be 



