observed in some Metalliferous Veins. 



one of his addresses to the Geological Society, says, " After the 

 important experiments of Mr Fox, there can, I think, be no 

 doubt that the great vertical dikes of metallic ore which rake 

 through so many portions of the county, owe their existence, at 

 least in part, to some grand development of electro-chemical 

 power." 



I confess I see nothing in the experiments to bear up such an 

 opinion, which would surely derive much stronger support from 

 the observations of M. Becquerel, which had then been some 

 years before the world. 



This most original and ingenious experimenter, by the use of 

 a curved glass tube, divided at the turned part by a bit of moist 

 clay, and filling each leg of it with a solution of a different sub- 

 stance, which he connected by a piece of wire, obtained crystals 

 of metallic copper, red oxide of copper, and vitreous copper ; 

 metallic silver, sulphuret of silver, galena, sulphuret of anti- 

 mony, and many other substances, which frequently could not 

 be distinguished from natural minerals, the agency being the 

 electricity developed by the solutions alone. 



The theory which Mr Fox has recently brought forward, 

 assumes the previous existence of fissures in the strata, which 

 are subsequently gradually opened ; the contents of the fissures 

 he imagines to have been deposited by electric currents generat- 

 ed by the action of saline solutions on the rock masses. 



The opinion of a gradual opening on the line of previously 

 existing fissures, was propounded by Werner ( Theory of Mine- 

 ral Veins, translated by Dr Charles Anderson of Leith, 68) ; 

 and I purpose the task of examining whether it is consonant 

 with the phenomena of this county in another place ; at present 

 we have only to deal with the electric part of the theory. 



The discovery of electric currents in the present contents of 

 veins, appears to me to have no necessary connection with the 

 mode of their original deposition ; and if it had, there are not 

 only no currents in tlie tin lodes, but many of the lead and cop* 

 per mines are equally destitute of them. 



It is admitted that currents will most readily pass at right 

 angles to the magnetic meridian, and this facility is made the 

 reason for the E. and W. and N.W. and S.E. veins being so 

 filled in preference to those bearing N. and S., but still all the 



