Dr. Mac CuUoch on Mineral Veins. 199 



which considers granite and trap of igneous origin, and which 

 maintains that the strata have been elevated by forces directed 

 from below. 



The pleasures of doubting have no charms to induce mc to 

 give this discussion so conspicuous a place as it here occupies. 

 But facts are required by the reader ; and, it is the duty of the 

 author to see that they are not so managed by theorists as to 

 mislead him; to place ihem so in array that he may form 

 the conclusions which they seem to justify ; even though these 

 should leave the subject as they found it. The strength of 

 assertion which has been brought into this question on opposite 

 sides, leaves no choice in this case ; and, if the discussion shall 

 be said to prove nothing, it must be recollected that, to prove 

 the existence of falsehood, is, in these cases, the first step 

 towards truth. 



Of the Minerals which are respectively produced from Solution, 

 and from the Action of Fire. 



It remains now, as was promised, to examine by our che- 

 mical and mineralogical experience, how far any of the sub- 

 stances found in mineral veins are the produce of crystalliza- 

 tion from watery solutions, and in what cases they are crys- 

 tallized from a state of igneous fluidity, or from sublimation. 

 It is not intended to enter at large into this subject, because 

 our information is still incomplete. A general view alone will 

 be suflBcient for the present purpose. The facts themselves, 

 as they regard the two theories which have been examined, are 

 singularly conflicting; although as far as they offer arguments 

 for either, the balance is palpably in favour of an aqueous one. 

 It is evident that these are the facts on which any future 

 hypothesis must chiefly rest ; whatever further considerations 

 may be required for explaining the various circumsiances of 

 other natures which attend mineral veins. 



In inquiring first respecting the earthy minerals, and in trying 

 to determine the number of those which may be produced 

 from watery solution, we are compelled to have recourse almost 

 entirely to the chemistry of nature ; as the limited solubility of 



