10 Professor Reicli on the Electrical Currents in 



disc of zinc was substituted for that of copper, and thus each 

 time a deviation, in the one case of 13°, in the other of 5°, 

 was obtained. 



In the remaining eleven observations, I obtained a deviation 

 of the needle on completing the chain ; sometimes, it is true, 

 so feeble, that there rested some uncertainty; sometimes, 

 however, very decided, — viz. by the connection of galena one 

 time with gneiss, 6' ; once with heavy-spar, which, however, 

 was somewhat wet, 7° ; another time on heavy-spar quite dry, 

 10°. The direction of the current in the wire was 5 times 

 towards the non-metalliferous point, and 6 times vice versa. 

 The zinc-copper element being introduced, always caused a 

 deviation, although very various in amount — one time scarcely 

 observable, and another time amounting to 40°. The greatest 

 intervening distance was in an experiment between galena in 

 Friscli GUick, and brown spar in Ludivig N. and S. vein, and 

 amounted to 126'". The multiplicator indicated only 1° ; but 

 the zinc-copper element being introduced, gave a deviation of 

 10''. From these experiments, we learn how easily even a 

 very feeble galvanic current passes through considerable 

 lengths of non-metalliferous rock, which, in hand-specimens, 

 do not allow a trace of much stronger currents to pass. Mr 

 Steinheil had previously pointed out that we can conduct such 

 currents through great distances of ground, and I convinced 

 myself, for short distances at least, of the same fact, as the 

 current from a zinc-copper clement runs with considerable 

 force through moist ground in which copper-plates had been 

 placed. This conductibility of substances which, in small spe- 

 cimens, give no passage to galvanic electricity, must be attri- 

 buted partly to th3ir moist state, partly to their great extent. 



Further, these experiments shew, that, when we choose a 

 non-metallic point, it is no longer indifferent what be the 

 nature of the discs applied ; for in cases where copper gave no 

 action, a zinc-plate established a current. This, too, is easily 

 explicable. 



At the very commencement, the following experiments 

 were made. Massive galena in Frisch Gluck was connected 

 with rich silver-ores on the 6th drift of the Neu HofFnimg, and 

 gave 32'. The disc was removed from the galena and fixed 



