456 
THE GEOLOGIST. 
portion of the actual vein, and why does its decomposition so speedily 
commence when removed from its primal condition? Is not the cause 
evidently to be found in the fact, that the vital forces of the vein are still 
in operation, and that they possess the power of resisting decay ? Above 
the water-level we find this decomposing action pervading the entire scope of the 
vein ; below that point the oxidation has not progressed. The water evidently 
claims a preservative influence over the constituents of the vein. So long as the 
water procolates freely through the interstices of the vein, so long will a medium 
exist through which and by which the electro-magnetic forces will act, and the 
decomposition of the vein be held in abeyance. While those forces continue in 
full activity, aided by the solvent and mechanical action of the water, the deposi- 
tion will progress, and the vein continue to accumulate its mineral wealth. As the 
vital principle of the plant or animal does not create any new material in the 
growth of its subject, but augments its quantity by the process of assimilation, so 
the vital forces of the vein do not create the metal, but act by transposition of 
metallic substances from the depths of the earth and the surrounding wall-rocks, 
to the body of the vein. For the verity of this assertion we appeal to the 
practical facts of the laboratory. Crosse has produced various metallic salts 
by electric action. The deposition of metal by the electrotype process is too 
familiar to all to require description ; and the labours of Fox and others, in the 
direct application of electro-magnetic force upon mineral veins, should satisfy even 
the most sceptical, by the clear, broad light of truth which surrounds them." 
The consideration of the fourth point is reserved by Mr. Leeds for a future number. 
The other articles on gold-mines and the distribution of that precious metal in this 
number of the " New York Mining Magazine," will be perused also with interest, 
especially in regard t© the question of the extension downwards into the solid rock 
of the gold-bearing veins ; practical facts seeming to prove that, at any rate in 
some instances, the vein continues actually as rich, or richer even, in gold in its 
downward progress ; but that the rock not having undergone the decomposition 
usually attendant on its upper portion, the metal is not so visible or so easy of 
extraction. 
In the report of the Pascoe Gold-mines in Georgia by C. H. Shepard, for example, 
we are told that the quartz- veins exhibit the usual phenomena of lodes, and that, 
although gold occurs in places inclosed directly in the quartz, " it is nevertheless true 
that its chief repository is in the pyrites," which occurs *' not only in the joints of 
the quartz-rock but is diffused through its entire substance. Sometimes its pro- 
portion rises to one-quarter part of the veins ; and rarely it constitutes large 
wedges and ovoidal masses in a state of almost absolute purity." The reader may 
find some interesting and confirmatory remarks on the subject of the derivation 
of gold from the pyrites, by Mr. Odernhcimer, in the Geological Society's Journal, 
vol. xi. p. 401. 
"There is no foundation whatever," Dr. Shepard adds, "for the opinion 
that the quartz veins grow poorer in gold with their depth, at least in the 
usual repositories where it is associated with pyrites. The contrary would rather 
seem to be the fact, although it is undoubtedly true, that, as the shafts and 
galleries penetrate deeper, and enter the region beyond the decomposing iniiucncc 
of the atmosphere, the gold becomes more and more inaccessible to the old method 
employed for obtaining it.". We do not pretend to enter into the discussion on 
this point, which is one, however, so important in its geological bearings, that 
the statements on both sides deserve careful consideration. 
