American Association. 275 



-case. As the copper is here, nominally, in intimate association 

 with vast masses of erupted trap, it might naturally be inferred 

 that the presence of both trap and copper was equally due to 

 igneous action; or, where the copper occurs in small strings and 

 arborescent masses apart from the trap, to a modification of this 

 action, in volatilization and subsequent reduction of chlorid of 

 copper or some other volatile compound. But the upholders of 

 the electro-chemical theory, find these views apparently too simple 

 for their approval. It is very possible that the copper may have 

 originated by some other agency ; but the following facts will, I 

 think, shew that this unknown agency was not the electro-chemi 

 cal principle, whatever else it may have been. The copper is 

 very constantly found in the interior of zeolites or calc-spar, or 

 surrounding crystals of the latter substance in such a manner as 

 to shew that the calc-spar was solid before the solidification of 

 copper — the copper often presenting the most sharply-cut impres- 

 sions, even to the minutest striae of the crystals of the calcareous 

 spar. I mention this well-known condition of occurrence first, 

 because it is commonly referred to as affording a strong proof of 

 the deposition of the copper according to the electro-chemical 

 theory, although nothing can really be more fatal to its reception. 



The conditions of occurrence just alluded to, may, in the estima- 

 tion of some, disprove the igneous origin of the copper ; but equally 

 do these conditions disprove its origin according to the other 

 view. In the first place, it must be remembered that the zeolites, 

 and carbonate of lime also, are non-conducting bodies ; and hence 

 that no deposition of metal can be made to take place upon them, 

 by the electro-chemical process, unless their surfaces be first coated 

 with graphite or some other conducting substance. This may be 

 readily shown by the simple method of ascertaining the conducti- 

 bility or non-conductibiliiy of mineral bodies employed by Von 

 Kobell. The substance under examination is to be placed in a 

 solution of sulphate of copper, and touched by a slip of zinc, or a 

 piece of zinc bent into a kind of tongs may be used to hold the 

 mineral. A deposition of metallic copper will rapidly take place 

 upon conducting bodies, such as pyrites, galena, graphite, an- 

 thracite coal, &c., &c. ; but not upon non-conductors, as quariz 

 the felspars, garnet, calc-spar, malachite, and other similar minerals. 



This fact, when forced upon the attention of those who maintain 

 the electro-chemical theory, has been allowed to be " an objection" ■ 

 but that is not the proper term. It is an insuperable obstacle — 



