ill Metalliferous Veins. 9 



mass within the rock between the two points, although the 

 metallic connection was destroyed by the rent. But the ori- 

 ginal current could not owe its existence to the quite inconsi- 

 derable difference of temperature, as a much greater difference 

 only produced a feeble action. 



III. If only one disc be connected with an ore-point, and 

 the other with the timbering, or held in the hand, there is no 

 effect produced on tlie multiplicator. This to-be-expected 

 result was confirmed several times. 



IV. If an ore-point is connected with masses of ore akeady 

 won, a current sometimes manifests itself, sometimes none. 

 Twice, lumps of galena, piled on the timbering of the sole, 

 and on the lying wall of the vein, were connected with massive 

 galena not yet won in Frisch Gllick. In one case, Avith a 

 horizontal interval of 10"^ no action was obtained, in the 

 other, with an interval of 12'" in the direction of the fall of 

 the veui, 5° deviation was observed, in which latter case too, 

 the zinc-copper element produced a very sti'ong deviation. 



V. JFhen an ore-point is connected n-ith non-metalliferous 

 rock, frequently no current, — frequently, however, a current, 

 thouyh always feeble, yet distinct, — takes i^lace in the connect- 

 ing wire. 



This result does not correspond with that of Fox and Hen- 

 wood, who, in the case mentioned, never found a current to 

 have place : perhaps because their multiplicator was less sen- 

 sible than mine. As these experiments especially excited my 

 interest, I made eighteen of them. 



In seven cases, I found no trace of a deviation,— a iz. five 

 times by establishing a connection between a massiAc galena 

 point (where the vein was rich) in Frisch Gliick, on tlie 4th 

 and 5th drifts, with ma.ssive heavy-spar in Neu Hoffnung ; 

 once between the same galena point and gneiss in the hanging 

 wall of Neu Hoffnung; and another time betAveen galena in 

 Gottlob vein and gneiss in a cross-cut, being driven to the 

 shaft. Each time a zinc-copper clement was introduced, from 

 which a current always passed, — now feeble, nov/ strong, but 

 never so strong as wlien two ore-points were connected. In 

 two cases, viis. once with heavy-spar, and once witli gneiss, a 



