( i8 ) 



with the lime, which is laid open by the 

 deftrudion of the adhefion of the confti- 

 tuent principles of the lavas, and varioiifly 

 coloured by the oxydated metal. The white 

 colour of -the decompofed lavas, then, it is 

 evident, is produced by the lofs of their 

 iron ; which agrees perfectly with experi- 

 ence, fmce, where the decompofition has 

 taken place, the lavas are incapable of 

 moving the magnetic needle, whereas they 

 conftantly produce motion in it, fome at 

 the diftance of two lines, and fome at more 

 or lefs, in the parts not decompofed. 



I fhall conclude my obfervations on the 

 produ<^ions of the Stoves of Lipari, with 

 fome interefting remarks relative to feve-- 

 ral different fpecles of zeolites, which I dif- 

 covered in their vicinity. I fhall defcribe 

 them feparately with their matrices. 



- Eirfl fpecies. The matrix containing this 

 zeolite is a lava of a horn-ftone bafe, of a 

 dark- brown colour, granular in the frac- 

 tures^: and which fcarcely gives fparks with 



fteel* 



