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months, and when dried, it was found that lamination had 
taken place on the side next the zinc plate, 
Results of this kind, (although it must be admitted that a 
far more extended series of experiments than any which have 
yet been made are required to establish the fact,) appear to 
show that electricity does exert some powerful influence on 
the particles of matter as they are grouping themselves ; and 
that concretionary nodules, such as are not unfrequently 
found in limestone rocks, or a laminated stone may be the 
result of position in regard to the line along which the force 
of current electricity may be acting. 
Such is a concise statement of a few original experiments 
on the structural character of rocks. A few words now 
on the general character of our metalliferous deposits, and of 
electricity in relation to them. 
The connexion of copper ore with the granite, or porphyry, 
and slate rocks, and of lead ore, with the limestone and trap 
rocks, has attracted the attention of every practical miner. 
All the productive mines of Cornwall are found at a short 
distance from, or directly at the juncture of the granite and 
clay slate. So certain is 'this, that he would be a very 
unwise man who ventured to speculate in a copper mine at 
any considerable distance from the junction of these two 
rocks. All the productive copper lodes of Cornwall have a 
main direction from the N. of E. to the S. of W. The 
silver-lead lodes of Devonshire are generally nearly N. and 
S. If we look to the conditions of lead lodes of Yorkshire, 
Cumberland, and Northumberland, it will be found they all 
indicate a set of rock conditions of an analogous order. In 
the districts of Alston Moor, and of Allenheads, which I 
have had an opportunity of examining within the last few 
days, we have layers of different kinds of rock piled one 
upon another ; hazels, or silicious sandstones alternate with 
limestones, and argillaceous beds. Hence we find the fissure, 
