On the crystallized Bodies contained in Lava. 43 



duction of the interior bark ; but I cannot by any means 

 admit the hypothesis of Malpighi and other naturaHsts, rela- 

 tive to the transmutation of bark into alburnun) ; and I pro- 

 pose to state my reasons for rejecting that hypothesis, ia 

 the next communication I have the honour to address to 

 you. I am, n^y dear sir, 



Your much obliged obedient servant, 

 ■J'. A. Knight. 



Elton, 

 Dec. 18, 1606. 



V. Olservations upon the crystallized Bodies contained in 

 Lava. By M. G. A. Dk Luc. 



[Concluded from vol. xxvii. p. 312.] 



J UDGING from volcanic phaenoraena, what depth may we 

 presume the fires to be, ct)mpared with the diameter and the 

 mass of the globe ? This depth is more or less considerable, 

 without doubt, according to the mass of the volcano that is 

 elevated : thus it is very probable that the fires of Etna, of 

 the peakof TenerifFe, and of the volcanoes of Peru, are deeper 

 than those of Vesuvius, Vulcano, and Stromboh. This is all 

 we can venture to say, but we cannot hazard any thing upon 

 the causes or events which have conduced to the formation 

 of our globe. 



" Man separates, dissolves, concentrates and combines 

 the minerals, producing changes in their forms :" all this is 

 true ; he does so by solvents, and by the fire of his furnaces. 

 But it is not added that he cannot again by any means recall 

 them to their state of mineralisation, by any fire what- 

 ever. Neither can we regenerate the vegetables which we 

 burn and reduce to ashes j nor can the chemist reproduce the 

 substances he decomposes : we are therefore very far from 

 being able to produce any thing similar to the rocks, the 

 crystals, and the minerais of our mountains. This reflection 

 ^lone overturns every system which maintains that these 

 substances are formed by fire, since all the operations both 

 t)f natural and artificial fire, with which we arc acquainted, 

 can produce nothing like them. 



These 



