HUTTONIAN THEORY. 57 



o{ 



SECTION II. 



QF THE PHENOMENA PECULIAR TO UNSTRATI- 



r 



FIED BODIES. 



T. Metallic Veins. 



49. ^ I ^HE unftratified minerals exift either in 



JL veins, interfering the flratified, or in 

 mafTes furrounded by them. Veins are of va- 

 rious kinds, and may in general be defined, fe- 

 parations in the continuity of a rock, of a deter- 

 minate width, but extending indefinitely in 

 length and depth, and filled with mineral fub- 



1 



fiances, different from the rock itfelf. The rhi- 

 neral veinSj ftriclly fo called, are thofe filled 

 with fparry or cryftallized fubftances, and con- 

 taining the metallic ores. 



That thefe veins are of a formation fubfe- 

 quent to the hardening and confolidation of the 

 ftrata which they traverfe, is too obvious to re- 

 quire any proof; and it is no lefs clear, from 

 the cryftallized and fparry ftrudure of the fqb- 

 ftances contained in them, that thefe fubftances 

 muft have concreted from a fluid ftate. Now, 



J 



that this fluidity was fimple, like that of fufion 

 by heat, and not compound, like that of folu- 

 tion in a menftruum, is inferred from many phe- 

 nomena. It is inferred from the acknowledged 



infolubility 



