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HUTTONIAN THEORY. 



313 



in the 



w 



ing from it ; fometimes the fubflances in thfe 

 latter are more highly cryflallized th 

 former; fometimes, but more rare 



r 



lefs cryftallized, and, in fome inftc 



they 



an in- 



gredient that enters into the mafs feems entirely 

 wanting in the vein. 



Thefe 



for what 



we yet know, are not fubjed to any general rule ; 

 but they have been held out as a proof, that the 

 maffes and the veins are not of the fame forma- 



It may be anfwered, that a perfedl fimi- 



that, on every hyp 



tion. 



ty between fubft 



thefi 



circumft 



mull have cryftallized in very different 



is not always to be looked for ; 



sr is, that this perfed 

 fimilarity does fometimes occur, infomuch that. 



but the moft direct: anfw 



\ 



in certain inftances, no diffe 



whatfoever 



can be difcovered between the mafs 



d th 



but they conlift of th 



and have the fame deg 



Some inftances of this a 

 marked. 



280. A ftrong objedlioi 

 gin of granitic 

 deed to their 

 neous fufion. 



fame 

 of ci 



r" 



gred 



yftall 



juft about to be 



the fuppofed 



veins from infilt 

 formation in any 1 



fes fr 



4 



n, and in 

 but by ig 



the 



umber of frag 



ments of fchiftus, often contained, and complete 



ly infulated in thofe 



vems. 



How thefe frag 



ments were introduced into the fiffures of the 



fchiftus, and fuftained till they were furrounded 



r 



by 



