ON THE CRYSTALS IN LAVAS. 24^ 



** Naturalists," says Mr. Fl. de Bellevue, " who ima- ^s"^* said tobe 

 gine, that the crystals contained in lava have remained in- H^^ "' *^ **' 

 tact amid their fluid lava, pass by without notice the obser- 

 vation of those, who, as Spallanzani and Hubert relate, 

 have seen the lava spout up at different times like water 

 issuing from a fountain, form a number of very brisk streams, 

 and possess a degree of fluidity sufircient to insinuate itself 

 into the smallest interstices of the bodies it penetrates :" 

 and he adds in a note: " Mr. Faujas has in his collection fi^*'*' o^palm, 

 a piece of a palm-tree from the Isle of Bourbon, which of^hkhlav^ 

 proves, that the fluidity of the lava has been very great, has penetrated. 

 gince it has insinuated jtself into the very fibres of the 

 wood." 



This fact, if it were real, would prove an impossibility, Thjsanimpos. 

 namely, that lava might be in a state of fusion without be- *^ ' ''^* 

 ing red hot : for a substance as combustible as a piece of a 

 palm-tree, or any other vegetable, would have been burned 

 jmd consumed, or reduced to a coal at the first contact of 

 the lava. It must be an illusion therefore ; and either the 

 substance surrounding the palm is not lava, or the matter 

 surrounded is not a vegetable substance. This illusion. Others have 

 strange as it is, is not single in its kind. In an account of ™f *^^^® **""® 

 a tour to Iceland, translated and published at Paris in 1802, 

 I have read, that the Danish travellers imagined they dis- 

 cerned wood in a piece of lava of Hecla. Count Borch made 

 the same mistake, and even greater, for he says he saw 

 *' pieces of wood slightly scorched" in whole rocjcs of the 

 Java of Etna. 



I have in my possession a large piece of vitreous lava, vitreous lavas 

 that I brought from the island of Volcano, which may serve sometimes 

 tb explain this illusion. It has very large blebs, which are blek)ssir*^"^" 

 dr^wn out considerably in length by the flowing of the lava, wood. 

 and their surface is streaked with threads, which have the 

 appearance of woody fibres; and this appearance is height- 

 ened by the tint they have derived from the vapours, that 

 are continually exhaling from the matter in fusion. Seve- 

 ral persons, who have seen this fragment, have taken it at 

 first view for wood. I have another piece of vitreous matter 

 from Li pari, which is drawn out into such fine and close 

 jthreads, that no fossile agatized wood, let its fibres be ev'er 



■ -so 



