NOME VI. OBSIDIAN. 



rious places the current of this glass, we shall 

 perceive that it is a continuation of the same 

 lava with the felspar base, of which these orbi- 

 cular corpuscles are composed ; whence we shall 

 not hesitate to conclude, that from this stone 

 both the lava and the glass derive their origin, 

 and that we find small particles of lava scattered 

 through the latter, because it has not undergone 

 complete fusion ; whence we find some pieces 

 composed partly of glass and partly of this same 

 lava. In some of these pieces we discover small 

 geodes, or thin filaments of an extremely brilliant 

 and transparent glass, resembling in miniature 

 the husk of the chesnut. 



<c 7. Though this glass in many particulars 

 resembles the last species, it yet differs from it 

 in others. It is perfect, like that, but it is of a 

 deeper colour. In it, likewise, the small glo- 

 bules abound, but they are earthy and pulveris- 

 able ' y every one is detached in its distinct niche, 

 or at most is only fastened to it by a few points. 

 " The description of this seventh species of 

 glass will render that of several others unneces- 

 sary, since the glasses I should have to describe 

 contain a greater or less number of similar glo- 

 bules, differing only in the nature of the base 

 enclosing them, which in some is more, and in 

 others less vitreous. I shall only make one ob- 



