222 DOMAIN XI. DECOMPOSED. 



in the beautiful experiments of Pelletier, 

 (12 An. Chym. 229, &c.) 



Femijmous Hence also, ferruginous stones near 

 or upon the surface of the earth, being 

 more exposed to air and moisture, and the 

 disruptive action of growing vegetables, 

 whose roots pierce through their minutest 

 rifts, and by swelling burst them, are more 

 exposed and subject to decom position,. 

 Water carries down the ferruginous parti- 

 cles into the lower strata, and forms there 

 those illinitions and masses of pisiform ar- 

 gillaceous iron ore, which Buffon and others 

 have, without sufficient reason, derived 

 from decayed vegetables. 



" Basalt, when pure, strongly resists de- 

 composition, or its surface alone bears any 

 marks of it ; the argillaceous, siliceous, and 

 calcareous ingredients, and part of the fer- 

 ruginous, soon recombining and forming a 

 hard crust, which invests and protects the 

 wacken. remainder of the stone. But wacken is 

 very easily decomposed ; and hence the 

 basalts or traps, into whose composition 



