40 



NOTE ON THE ELECTRICAL RELATIONS, ETC. 



of the needle is very inconsiderable, and it is still less, if anything, when some of the 

 ores are substituted for one or both these metals. May not these phenomena depend 

 on the relative degrees of tenacity with which the electric elements are retained by 

 different bodies, it being apparently greatest in the case of compound bodies ? 



Manganese* (crystallized) 



Loadstone 



Platina 



Plumbago 



Iron pyrites 



Copper pyrites 



Purple copper ore 



Galena 



Gold 



Vitreous copper ore 



Silver 



Sheet copper 



Pan brass 



Sheet iron 



Zinc. 



Sea 

 Water. 



Diluted 



Muriatic 



Acid. 



56 

 41 

 21 

 52 

 34 

 49 

 44 

 47 

 26 

 42 

 56 

 55 

 34 

 36 



60 

 58 

 46 

 56 

 38 

 57 

 45 

 50 

 38 

 51 

 59 

 58 

 43 

 46 



Copper. 



Sea 

 Water, 



35 



21 



1 



23 



7 

 36 

 14 

 19 

 11 

 16 

 22 



Diluted 



Muriatic 



Acid. 



45 

 29 



5 

 31 



8 

 31 

 10 

 27 

 14 

 24 

 21 



Iron. 



Sei 

 Water. 



52 

 33 

 21 

 45 

 20 

 43 

 33 

 36 

 14 

 17 

 47 

 19 

 11 



Diluted 



Muriatic 



Acid. 



Lead. 



Sea 

 Water. 



Diluted 



Muriatic 



Acid. 



54 

 48 

 23 

 45 

 29 

 44 

 40 

 41 

 30 

 25 

 45 

 37 

 17 



50 

 32 

 15 



42 

 20 

 45 

 32 

 37 

 25 

 24 

 44 

 40 

 11 



56 

 47 

 21 

 45 

 19 

 43 

 38 

 37 

 24 

 32 

 42 

 38 

 30 



If we regard the electrical relations of different metalliferous minerals in a geologi- 

 cal point of view, it is curious to observe how nearly many of those which are usually 

 associated in the same veins agree in this respect, their reciprocal voltaic action being 

 generally very small. Were it otherwise, it may be assumed that the evidences of 

 decomposition in situ would be much more decided and general than they now are. 

 There is, however, a sufficiently strong action in some cases to account for the electro- 

 magnetic phenomena which have been observed in copper and lead veins : thus, when 

 copper pyrites and vitreous copper form a voltaic combination in water taken from a 

 mine, or even in spring water, they are capable of producing considerable deflections 

 of the needle. It is not, therefore, surprising, that when two parallel veins, or two 

 portions of the same vein separated by imperfect conductors, are connected with the 

 galvanometer, the action on the needle should be very decided. The degree of in- 

 fluence on the needle does not seem to depend, in the case of metalliferous minerals, 

 upon extensive voltaic surfaces ; for only one or two inches of surface may produce 

 nearly the maximum effect in deflecting it, if the wire used in the galvanometer be 

 small. Hence, the considerable deflection, which has been sometimes observed when 

 two masses of ore were connected by the wires, proves that their reciprocal action, 

 taken in the aggregate, must be veiy great ; and it appears to be highly probable that 

 the metalliferous veins, and perhaps even the rocks themselves, impregnated as they 

 are with different mineral waters, and thereby rendered imperfect conductors, if not 

 exciters of electricity, may have an important influence in the economy of nature. 



* The contact of the wire with the manganese and other minerals was produced by pressure only, and the • 

 deflections would doubtless have been greater if the contact had been more perfect. 



t I have ascertained that the electro-magnetic action of mineral veins was the same whether copper or zinc 

 conductors were employed for making the contact with the ores. 



