cryslalUzed Bodies contained in Lava, 307 



facts? " M. Salmon and M. de Buch," says M. Fleuriau 

 de Belleviie, " have demonstrated to all those who are ac- 

 quainted with volcanoes in activity, that the crystals of leii- 

 cites cannot be formed except during the slow cooling of the 

 lava." 



I^ am acquainted with volcanoes in a state of activity; 

 I have given some proofs of it; and nevertheless I draw 

 from my observations quite a contrary conclusion. The 

 facts I have quoted, which are true and exact, decide tli« 

 question. 



As to the opinion of these two naturalists,! may add, that 

 It is wrona^ in an essential point. Upon what is the distinc- 

 tion founded which is made between leucites and pyroxene 

 schorls and chrysolites, since these three crystals are found 

 together in one and the same lava ? I'hey are separated from 

 each other, and from the paste of the lava, hv a line equally 

 clean and distinct as the small flints which compose a pud- 

 ding-stone are separated from each other and from the paste 

 which joins them. If one of these crystals is foreign to the 

 lava, the two others are so also : this is a rigorous conse- 

 quence. The I'act is rather completely certain that the whole 

 three are foreign to it. 



The two examples I have mentiuncd of isolated leucitcs, 

 each of which envelops pyroxene schorls, is a fact inexpli- 

 cable in the hypothesis of the formation of these crystals hv 

 fire, while nothini; is more frequent or more easy to con- 

 ceive than these mixtures among crystals of diflertul species 

 by thiC humid way. 



" I should never finish m\- observations," M. Fleuriau 

 do Bcllevue proceeds, " if I related all the objections which 

 present themselves against the system of the pre-existencc 

 «)f crystals iti lava: we find several of them, under the arti- 

 cles Lava and Leucites, in the New Dictionary of Natural 

 History, where M. Patrin has strongly combated these sup- 

 positions." 



I am sorry to hear this ; because the readers of this dic- 

 tionary, who may be dtsiroiis of knowuig what lavas and 

 leucites are, will be led into trror. I have presented fads, 

 and not nipfjosUiuns. In the phicnomena of terrestrial na- 

 l^ :i tiiral 



