( ^11 ) 



primordial rocks frequently does not difapr 

 pear in confequence of the adiion of fire. 

 The colour of many lavas approach^fs to a 

 black, becaufe that was the colour of their 

 relpedive primitive rocks, as we fee in the 

 lavas with a horn-ftone bafe. la others it 

 is a cinereous grey, and even white, be- 

 caufe they derive their origin from ftones 

 of a fimilar colour, as, for inftance, feltfpars 

 and petrofilex. This diverfity of colours, 

 black, grey, cinereous, and more or lefs 

 white, is not unfrequently preferved even 

 in the enamels and glaifes produced from 

 thefe rocks when fufed in the crucible. It 

 is therefore certain that the colour of the 

 products alone is not a certain indication of 

 a volcano. 



I confider as illufory, and not merely 

 inconclufive, the alTertlng the exiftence 

 of ancient volcanos becaufe there exift 

 veins or volcanic matters ; iince this is 

 the fame thing as faying there are vol- 

 canos becaufe there are volcanos. And 

 though a writer fhculd be convinced 

 T 3 fro:n 



