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slimed, Patrin conceived his ideas of the formation of 

 many of the earthy and crystalline substances, ejected 

 from volcanoes, which is not, however, by the opera- 

 tion of heat, but, by the combination of various 

 gaseous fluids, assisted, or modified by electricity. 



On this subject his reasoning is forcible, clear, and 

 scientifick, and in many instances strengthened, by well 

 attested facts, collected from the observations of several 

 distinguised naturalists, as eminent for scientifick ac- 

 quirements, as of sound philosophy. 



Among these, Buck, in an excellent memoir, has 

 demonstrated, with every appearance of truth, that 

 the leucites, so very abundant in the lavas and tufas of 

 Italy, are of a formation subsequent to the ejectment of 

 the lavas. 



Faber, and other enlightened naturalists are like- 

 wise of the opinion, that those crystals were of a sub- 

 sequent formation, to that of the ejection of the lavas. 



Mr. Thompson remarks, that he observed accicular 

 crystals of augite, sublimed and adhering to the 

 walls of a church, which was buried by the lava of 

 Vesuvius in 1794. A circumstance that proves., incon- 

 testibly, the formation of crystalline substances inde- 

 pendently of the agency of water ; and most proba- 

 bly by a combination of aeriform fluids. 



The interesting account which the learned Dolomieu 

 has given of the volcano of Stromboli, in one of the 

 ^.olian isles, and Macalouba, near Agregente in 

 Sicily, affords abundant proofs of the daily formation 

 of earthy and stony substances, by the combination of 



