274 American Association. 



that a range of rock will be found winding irregularly from one 

 end of the province to the other, of sufficient importance to au- 

 thorise its representation by a distinct color on the map, and a 

 distinct designation in geological nomenclature." 



THE DEPOSITION OF NATIVE METALS IN VEIN FISSURES, &C., BY 

 ELECTRO-CHEMICAL AGENCY. 



Prof. Chapman, of University College, Toronto, brought for- 

 ward at considerable length his views on the origin of native 

 metals in vein fissures. These views are at variance with those of 

 the majority of chemists and geologists, at least in their applica- 

 tion to the copper deposits of this continent. We give, therefore, 

 311 extended, and we believe faithful statement of Prof. Chapman's 

 views from the Gazette. 



" From the known fact that solutions of various metallic salts 

 may be decomposed by voltaic agency, and the metal obtained in 

 the simple state, it has long been a favorite theoiy with many 

 geologists, that depositions of native metals, in veins, &c., are due 

 to a similar cause. That such may be a perfectly legitimate con- 

 elusion in many instances, I am quite ready to admit ; but, in 

 applying this view to any particular case, it is necessary, unless 

 the explanation is to be regarded as a mere theory of convenience, 

 that certain collateral circumstances be not altogether excluded 

 from consideration. If these circumstances oppose themselves to 

 our theory, and remain by it altogether unanswered ; nay, if but 

 a single well-proved fact withhold its concurrence from the con- 

 ditions demanded — surely it is more consistent with our obliga- 

 tions to scientific truth, that we abandon the theory at once — 

 however plausible in itself, and however convenient in its appli- 

 cation — rather than attempt to maintain it by keeping these op- 

 posing conditions out of sight, or by wilfully ignoring their value. 

 ISTow, my object in the present brief communication, is simply to 

 bring before the notice of the Section, certain facts, experimental 

 and otherwise, which appear to me to prove most incontestibly, 

 that, in nine cases out of ten, the so-called electro-chemical theory 

 as explanatory of the organ of native metals in veins, is entirely 

 fallacious. 



We will take the case of native copper, under its known 

 conditions of occurrence in the Lake Superior District and 

 other parts of North America. The electro-cheraical theory is 

 constantly being brought forward in explanation of this particular 



