756 
them, These results were not apparently modified by the method of 
_ making the contact, or by the metal employed to effect it, provided an 
adequate degree of pressure was employed. For instance, a point of 
a copper wire pressed against a given ore-point was mostly as effec- 
tual as a plate of that metal similarly treated ; and when zinc and 
platinum were successively substituted for copper no change was 
produced. 
It is, therefore, evident, Mr. Fox remarks, that these clectric cur- 
rents were independent of extraneous causes, and were derived from 
the veins only. 
Towards the eastern part of the north mine arsenical pyrites 
abounded immediately under the surface. On one extremity of the 
apparatus being connected with it and the other with an ore-point 
to the westward in the six-fathom-level, twenty-four fathoms of wire 
being employed for this purpose, the current, which was from E. to 
W.., deflected the needle fifty to sixty degrees. Again, contact was 
made with the ore-point in the six-fathom-level by means of a small 
plate of copper attached to one of the wires and wedged against the 
ere by a wooden pole, the other copper wire being firmly pressed 
against the arsenical pyrites at the surface by means of a brass screw 
passed through a block of wood, which was retained in its place by 
a pole wedged against it. This arrangement admitted of the screw 
being loosened in the block, and the metal in contact with the ore- 
point being changed without inconvenience. Zinc was used after the 
copper for making the contact with the ore-point, but without produ- 
cing any modification of the current, which continued to deflect the 
needle from fifty to sixty degrees ; notwithstanding that any aetion be- 
tween the copper in the six-fathom-level and the zinc at the surface, 
if it had existed, would have been in an opposite direction, and have 
tended more or less to counteract the influence of the actual current. 
Its energy, however, was sufficient to render a short bar of iron of a 
horse-shoe form, with several coils of copper wire around it, feebly 
magnetic, and affect a needle about two inches long, moving on a 
pivot in a close box. Each pole of the needle was about three inches 
from the extremity of the bar; and was deflected about 2° from its. 
point of rest, on the current being made threugh the coils of wire ; 
and where the direction of the current was reversed, a similar de- 
flection of the needle to the opposite side was produced. The effect, 
Mr. Fox observes, would have been greater had the experiment been 
made entirely in the six-fathom-level, where the electric action was 
stronger, or if the needle had been suspended and not mounted on 
a pivot. 
Having removed the electro-magnet, and other things remaining 
the same, a glass tube in the form of a V, having moistened clay at 
the bottom, was placed in the circuit with water in one branch and 
a solution of sulphate of copper in the other. Small cylinders of cop- 
per pyrites, taken from the same piece of ore, were employed to con- 
nect these liquids respectively with the opposite wires, the ore at the 
positive end of the wire having been partly dipped in water, and that 
at the negative end in the solution of sulphate of copper. ‘The wires 
