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LI. Ol^ervations upon the crystallized Bodies contained in 

 Lava. Read at the Meeting of the Physical and Natural 

 History Society of Geneva, on the \1th of April 1806. 

 %M. G. A. DeLuc*. 



V OLCANOES hold such a remarkable place ara-ong terres- 

 trial phaenomcna, that they have become the subject of a mul- 

 tiplicity of conjectures upon their origin, influence, and the 

 geological consequences which might be drawn from them. 

 Wherever they were put iu requisition in order, to found a 

 system upon them, they have been made to act that part 

 most convenient for their authors. In this manner they 

 have seized upon a simple and isolated fact, the only one of 

 its kind which has no relation except with the soil occupied 

 by the volcano and its environs. Several naturalists. and 

 geologists, although a volcano only resembles mountains 

 of its own species, and does not at all resemble otheF 

 mountains, either in form, construction, or the substances 

 which compose it, have concluded that the layers and 

 mountains on the surface of the earth owe their origin to 

 the action of fire ; that element, as they say, presenting us 

 every day with productions entirely similar to the primitive 

 rocks of the globe. 



From this it results that these naturalists regard the dif- 

 ferent crystals inclosed in lava, not as productions in the 

 humid way, anterior to the 4ava, and which existed in the 

 layers reduced into fusion by the volcanic fires, but as cry- 

 stallizations formed in the lava itself, and of its own sub- 

 stance, by the slow cooling of the mass. 



It is chiefly upon this opinion that M. Fleuriau de Belle- 

 vue has founded the system he has adopted and publisiied 

 upon the action of the fire of volcanoes and upon the forma- 

 tion of the terrenrial globe, of its layers and its mountains, 

 mtxrted in the Journal de Physique for May 1805. 



Let us reduce this tjuestion to its most simple term, via. 

 The crystals which lavas contain, have they been formed iu 



• Thi» is a second paper by M. Ae Luc on this subjsjt. The first paper lu» 

 alrriidy appeafti in th« I'hi<t>si>phicil M;iga2ioe.-«^«c our lui Number. 



the 



