312 On the crystallized Bodies contained in Lava. 



I have made this examination ; I have compared the produce 

 of the furnaces of glass-houses and those enclosed in lavas, 

 and it results from thi? comparison that thedifi'erence is total. 



" Every thing shows that in volcanoes the depth of their 

 furnaces is immense." This is what M. Fleuriau de Bellevue 

 says; and he adds, ^' this is the opinion of M. de Luc, and 

 of several naturalists." 



I have said, and I think, that the fires of volcanoes are 

 of very great depths, against the opinion of those among 

 naturalists who think that these fires are very near the base 

 of the volcano, and who place them in the very cone even 

 which rises above the ground ; an opinion so contrary to 

 every phcenomenon, that it is wonderful how it could enter 

 into any man's idea. But I do not think I ever used the 

 word immense, which would indicate a depth which cannot 

 be imagined even, and which is very far from my idea. 

 The depth of a vertical league is a great depth, and I do 

 not think that the fires of the volcanoes may be much 

 deeper. But every thing shows that they have ramifications. 

 The fragments of natural rocks which they throw out, can 

 only come from these lateral galleries, from which they are 

 detached and carried off by the lavas which traverse them. 

 Another phaenomenon also indicates it ; that is, those burning 

 places which are to be seen at the bottom of the sea in the 

 neighbourhood of a volcano in eruption, at the same time 

 that they are a sign that their fire is not at a depth which 

 may be called immense. I have thought proper to dwell 

 upon this expression, becaute, from this supposed depth, 

 theories have been deduced as to the formation of the globe 

 which have no foundation at all. 



[To be continued.] 



LII. On 



