374 Proceedings of the British Association. 
definite cause; and his experiments on the electro-magnetic condi- 
tion of metalliferous veins, and also on the electric conditions of va- 
rious ores to each other, seem to have supplied an answer, inasmuch 
as it was thus proved that electro-magnetism was in a state of great 
activity under the earth’s surface, and that it was independent of 
mere local action between the plates of copper and the ore with 
which they were in contact, by the occasional substitution of plates 
of zinc for those of copper, producing no change in the direction of 
the Voltaic currents. He also referred to other experiments, in 
which two different varieties of copper ore, with water taken from 
the same mine, as the only exciting fluid, produced considerable 
Voltaic action. The various kinds of saline matter which he had 
detected in water taken from different mines, and also taken from 
parts of the same mine, seemed to indicate another probable source 
of electricity ; for can it now be doubted, that rocks impregnated 
- with or holding in their minute fissures different kinds of mineral 
waters, must be in different electrical conditions or relations to each 
other? A general conclusion is, that in these fissures metalliferous 
deposits will be determined according to their relative electrical con- 
ditions ; and that the direction of those deposits must have been in- 
fluenced by the direction of the magnetic meridian. Thus we find 
the metallic deposits in most parts of the world having a general 
tendency to an E. and W. or N. E. and S. W. bearing. Mr. Fox 
added, that it was a curious fact, that on submitting the muriate of 
tin in-solution to voltaic action, to the negative pole of the battery, 
and another to the positive, a portion of the tin was determined like 
the copper, the former in a metallic state, and the latter in that of 
an oxide, shewing a remarkable analogy to the relative position of 
tin and copper ore with respect to each other, as they are found in 
mineral veins. 
Artificial Crystals and Minerals.—A. Crosse, Esq. of Broom- 
field, Sc , then came forward, and stated, that he came to 
Bristol to be a listener only, and with no idea he should be called 
upon to address a section. He was no geologist, and but little of @ 
mineralogist ; he had however devoted much of his time to electri- 
city, and he had latterly been occupied in improvements in the vol- 
taic power, by which he had succeeded in keeping it in full force 
for twelve months by water alone, rejecting acids entirely. Mr. C. 
then proceeded to state, that having observed in a cavern in the 
k Hills near his residence, that part of it which consisted of 
4 
