270 On Electric Currents in Metalliferous Veins. 



magnetic appai'atus can or cannot be rendered useful in prac- 

 tical mining. I have before now thrown out the suggestion ; 

 and the probability that it may be so applied with advantage, 

 appears to be much increased by some of Professor Reich's ex- 

 periments, already referred to, in which he obtained electric 

 currents when an ore-point and a non-metalliferous rock were 

 connected. Some of these currents traversed the wires from 

 the rock towards the ore-point, and therefore could not have 

 been produced by any action between the latter, and the plate 

 at the former. Even if ore existed behind the rock, its action 

 on the metallic plate in contact with the rock, would have 

 tended to produce a current towards it from the ore-point at 

 the first station, unless counteracted ; as may be inferred, by 

 a greater action, in a contrary direction, between the masses 

 of ore near the opposite stations. 



These are questions of practical importance, and only to be 

 solved by more experiments, which may be easily made by 

 miners themselves after an hour's instruction in the use of the 

 apparatus. Thvis a metallic connection having been esta- 

 blished between a mass of conducting ore in a vein and the 

 galvanometer, by means of a copper plate and wire, the plate 

 attached to the second wire may be carried through a level or 

 gallery, and pressed for an instant against the locks on each 

 side, at intervals of a few yards, the other end of the wire hav- 

 ing been first connected with the galvanometer. If, when con- 

 tact is made with the rock at any part of the level, the galva- 

 nometer should be particularly affected, the experiment should 

 be repeated, till the part of the rock is discovered at which 

 the maximum eff*ect is produced. A zinc plate may then be 

 substituted for the copper plate, or pressed between the latter 

 and the rock ; and, If convenient, platina or palladium may also 

 be used for making the contact ; and the modifications of the 

 currents produced by the diff'erent metals should be noted. With 

 one of the two last-named metals they are most likely to be 

 exhibited as they exist in the vein, unaffected by the appara- 

 tus. The same tests may be applied to any water flowing 

 into the level, in order to ascertain whether or not it is con- 

 nected with ore in the neighbourhood. 



