FOR THE ADVANCEMENT OF SCIENCE. 133 



asmuch as it was thus proved that electro-magnetism was in a state 

 of great activity under the earth's surface, and that it was ..inde- 

 pendent of mere local action between the plates of copper and the 

 ore with which the}' were in contact, by the occasional substitution 

 of plates of zinc for those of copper, producing no change in the di- 

 rection of the voltaic currents. He also referred to other experi- 

 ments, in which two different varieties of copper ore, with water 

 taken from the same mine, as the only exciting fluid, produced con- 

 siderable 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 impreg- 

 nated with or holding in their minute fissures different kinds of mi- 

 neral waters, must be in different electrical conditions or relations to 

 each other ? A general conclusion is, that in these fissures metal- 

 liferous deposits will be determined according to their relative elec- 

 trical conditions ; and that the direction of those deposits must have 

 been influenced 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 bat- 

 tery, and another to the positive, a portion of the tin was deter- 

 mined 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 the mineral veins. 



— Cross, Esq., of Broomfield, 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 geolo- 

 gist, and but little of a mineralogist ; he had, however, devoted 

 much of his time to electricity, and he had latterly been occupied in 

 improvements in the voltaic power, by which he had succeeded in 

 keeping it in full force for twelve months by water alone, rejecting 

 acids entirely (cheers). Mr. C. then proceeded to state that he had 

 obtained water from a finely chrystallized cave at Holway, and by 

 the action of the voltaic battery had succeeded in producing from 

 that water, in the course of ten days, numerous rhomboidal crys- 

 tals, resembling those of the cave : in order to ascertain if light 

 had any influence in the process, he tried it again in a dark cellar, 

 and produced similar crystals in six days, with one-fourth of the 

 voltaic power. He had repeated the experiments a hundred times, 

 and always with the same results. He was fully convinced that it 

 was possible to make even diamonds, and that at no distant period 

 every kind of mineral would be formed by the ingenuity of man. 

 By a variation of his experiments, he had obtained grey and blue 

 carbonate of copper, phosphate of soda, and twenty or thirty other 

 specimens. If any members of the Association would favour him 

 with a visit at his house, they would be received with hospitality. 



