194 Dr. Mac Culloch on Mineral Veins. 



rocks were, on the same hypothesis, formed. But there are 

 two modifications, at least of this aqueous theory. While the 

 rocks were in the act of being precipitated from the universal 

 solvent, the veins were undergoing the same process ; and 

 hence they are esteemed to be of different ages, corresponding 

 to those of the strata or rocks in which they lie. How such 

 an operation could be effected is not explained ; and it is fruit- 

 less to inquire, where, in lieu of ideas, we have only unmeaning 

 words. Time may be better employed than in labouring to ac- 

 count for what is impossible. In the other modification, the 

 fissures were formed in the rocks yet soft or yielding, by drying 

 and contraction; and the metallic or other minerals, remaining 

 in the solution after the precipitation of the rocky materials, 

 were then precipitated in these fissures. 



On the other hand, it is maintained, that the same power of 

 subterranean expansion which produced the fracture and dislo- 

 cation of the strata, introduced the materials into the veins, and 

 that they have crystallized from a state of fusion, not of solu- 

 tion in water. Neither of these theories will require a very long 

 examination ; but the arguments that relate to both are, in 

 some cases, involved together. 



With respect to the aqueous hypothesis, it involves the same 

 fundamental objection made to the precipitation of rocks from 

 solution in water : it is at variance with the laws of chemistry. 

 That objection would still be a fatal one, though the hypothesis 

 should be limited to the filling of veins alone, though it were 

 conceded that the rocks had been produced in some other man- 

 ner, and though the production of veins was admitted to be 

 posterior to the consolidation of the strata in which they lie. 

 Even if the power of this imaginary universal solvent were 

 granted, the difficulties are still insuperable ; unless it could be 

 proved why the metallic or other minerals of veins were not de- 

 posited every where alike ; why, like those which form rocks, 

 they were not deposited in strata ; and why they were not only 

 directed exclusively to fissures, and to a few of these in distant 

 and select places, but limited even to partial spots in the same 

 vein. 



