196 Dr. IVIac Cutloch on Mineral Veins, 



ings of such philosophers as those by whom it has been offered. 

 \X serves to shew how weak the best of us are, when we suffer 

 our prejudices or our wishes to interfere with our powers of 

 reasoning. It may be conceded, that the fissures have been 

 produced by the same subterranean changes which have dis- 

 placed the strata ; yet this admission does not involve a con- 

 Qession to the rest of the hypothesis. It does not necessarily 

 follow, that the mineral contents of these veins have been ia- 

 jected from beneath in a state of fusion, although the power of 

 heat may have been the cause of the fissures themselves. The 

 presence of fragments of the including rocks in the veins, which 

 has also been used as an argument for this theory, is a fact of 

 just the same value : it proves the forcible displacement and 

 fracture of the strata, but nothing more. 



As to the chemical arguments derived from the insolubility 

 pf many of the contents of mineral veins in water, and their 

 production from fusion, it is easy to shew that many of them 

 certainly are produced from solution; that many others may 

 have been generated in this way without a breach of chemical 

 laws ; and that some of them could not have been consolidated 

 from fusion. I shall reserve these particulars for a general view 

 at the end of this paper, when the several minerals producible 

 in either mode will be enumerated. 



In the mean time, it is impossible to conceive how, if the 

 contents of these veins had been injected in a state of fusion, 

 the fragments so often found in them should have escaped this 

 process. I will not here say, as has also been objected, that 

 clay could not have been found in mineral veins on this prin- 

 ciple ; because it is easy to understand how the infiltration of 

 water should have decomposed portions of the veins, in the 

 same manner as rocks are converted into clay, though deeply 

 situated beneath the surface. 



Whatever objections may be made against the aqueous hy- 

 pothesis, from the peculiar dispositions of the minerals in the 

 veins, are at least equally valid against the igneous one. It is 

 impossible to comprehend how these could have been produced 

 from a state of igneous fluidity, any more than from a state of 



