REVIEWS. 
455 
In the consideration of the mechanical or transporting action of water, we have, 
besides the operations effected by its upward flow, to consider those effected by its 
percolation downwards. 
When the waters sini; into tlie ground tliey carry downwards such soluble salts 
as they meet with on the surface or beneath the soil, and deposit them either iu 
this course or on meeting with other water holding different salt in solution. 
" And here the question may be asked, What becomes of all the metals that are 
raised by man to the surface of the earth ? England alone produces nearly three 
millions of tons of iron annually ; while the aggregate of all the metals produced 
throughout the world would startle the mind, and task the eye by its long array 
of figures. Year after year this active production has been in operation, from the 
days of Tubal Cain to the present time ; greatly increased, it is true, in the past 
few centuries ; and if but a tithe of the whole amount ever produced was now in 
existence, the whole surface of the globe would, or could, be encased with a dense 
covering of solid metal. In the beautiful economy of nature nothing is lost, 
nothing annihilated ; and in the comminution by actual use, for every contact 
with a metal causes a wear upon its surface, — in the chemical action of the 
atmosphere, with its mechanical alternating effect by changes of temperature, — 
and in the solvent and mechanical properties of the water, re-conveying the 
metallic particles and salts to the interior of the earth, may, perhaps, be found the 
only satisfactory solution of the inquiry." 
The third division of the inquiry is in its electro-ma (jnetic bearing, and opens a 
wide and little-explored field of inquiry, but which promises to "throw open to the 
researches of the student truths of the highest and most fascinating character," 
and presenting " scope for the boldest strides of genius.'' 
" Why is it, that during its position in the vein, and attached to or forming a 
portion of the vein-rock, that fragment,'which when broken off, so speedily under- 
goes a change in its chemical, and consequently in its physical construction, 
should remain unaltered '? If any change could be perceptible in it, while in its 
original position, it would be that of an increased metallic value. There would, 
if it were examined in a vital portion of the vein, be found a gradual accumula- 
tion of metallic particles. Let us take a fragment of pyritous ore — auriferous 
pyrites, and, before being abraded from the vein-rock, the pyrites is of a bright 
glistening surface, hard, firm, and glass-like iu its brittleness, with no visible 
appearance of the gold, and to the inexperienced eye it would present no feature 
of intrinsic worth. It is broken from the vein-rock, and without being removed 
from the adit-level in which it was obtained, it is allowed to remain under the 
surface of the flow of waste vein-water which passes along the ' floor ' of the level. 
But a few days shall have elapsed since its separation from the rock, and yet an 
oxidation of the iron of the sulphuret will be found to have commenced. The 
bright surface of the pyrites appears covered with a ferruginous rust, but still no 
gold is visible. The oxidation, as time passes, will be found to increase, and the 
brightened colour of the specimen will show that its iron has passed from the 
condition of a sulphuret to that of a peroxide. In its physical character it will 
be found to have passed through a wide mutation. It is no longer compact and 
indurated, but is a slightly cohesive mass, which, under the lightest friction, falls 
into a soft, partially-gritty powder, intermixed with which are plainly discernible 
the glistening particles of the yellow gold. This is not a surmised case ; it is a 
true picture of a phenomenon that is continually witnessed by the workers in gold- 
veins. Why, I repeat, is the pyrites kept from decomposition, while forming a 
