( 60 ) 



or three in breadth. The figure which I 

 have called cluflering, is the moft ufual in 

 this fpecies of zeolite ; though fome arc 

 only oblopg globules, of the fame fize with 

 that of the fmall cavities which contain 

 them. They are, however, by no means 

 found in every cavity ; for, out of a hun- 

 dred of thefe cavities, ninety contained no 

 zeolite. This fpecies is contaminated with 

 a pulverulent, orange- coloured oxyde of 

 iron. 



The blow-pipe with difficulty melted it j 

 and feveral feconds were required for its I 



complete liquefadion, even with the aid of II 



oxygenous gas. It then changed into a 

 fnowy-white enamtl, full of bubbles. It 

 has a lucid brightnefs when it begins to 

 melt, and boils and bubbles up when ia 

 actual fufion. 



Second fpecies. This is found in fome 

 pieces of the former lava, but its charaders 

 are different from thofe of the pr-eceding 

 fpecies. It coats over many of the cavities 



before 



