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 7iow 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, Somerset, 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 a 

 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 

 Quantock Hills near his residence, that part of it which consisted of 



