276 American Association, 



nothing less — ^to the legitimate adoption of this theory ; and until 

 it can be satisfactorily explained away, to attempt to account for 

 the origin of the copper by reference to the principle in question, 

 is surely, to say the least, a mere waste of words. A few other 

 objections to this electro-chemical hypothesis may be briefly 

 touched upon. This hypotliesi^ exacts necessarily a solution of 

 the copper in some form or another. 



l^ow, many of the minerals associated with these copper deposits 

 —carbonate of lime, for instance, — are readily altered by immer- 

 sion in cupreous solutions ; whereas the crystals of carbonate of 

 lime actually occurring with the copper^ as well as those met 

 with in its immediate neighborhood, exhibit no appearance of 

 alteration, but retain on the contrary, their white color and 

 original surface coodition. By placing these same crystals for a 

 short time in a solution of sulphate of copper, they become con- 

 verted at the surface into malachite, or into a copper carbonate of 

 similar aspect, more especially if the solution be kept at a mode- 

 rately elevated temperature. Again, if the enormous deposits of 

 Lake Superior originated in this manner, might we not reasonably 

 look for the presence of vast secondary products, the results of 

 the chemical decompositions which must necessarily have taken 

 place. It is asking almost too much to assume that these second- 

 ary products may, from their solubility, or from other causes, 

 have entirely disappeared, without leaving behind them very 

 manifest traces of their former presence. But, yet again, if we 

 assume this origin for the copper, we must necessarily assume also 

 that the cupreous solution came from above : that it is to say, 

 from an overlying, not from an underlying source ; as otherwise, 

 from the filling up of the fissures, the supply would quickly have 

 been cut off. This involves manifold difficulties of an easily ima- 

 gined character. 



My object, in the present note, is not to propose theories in 

 explanation of the origin of these copper deposits, but simply to 

 shew that if one of the hypotheses already advanced with this 

 view — that which attributes the larger copper masses (in intimate 

 association with the trap) to direct igneous action, and the smaller, 

 arborescent and more distant masses to gaseous emanations as 

 .'previously explained — be not free from difiiculty ; the other, or 

 So-called electro-chemical theory, is, in the cases referred to, abso- 

 lutely untenable ; and, amongst other reasons, chiefly for thisv 

 namely : that the de])osition of the copper on non-condu<;ting 



