s of the earth's crust causing other
fissures; intrusive granites further dislocated and upheaved the slates.
About this age, probably, when really dry land began to appear, came the
first formation of mineral lodes, and the waters, heavily charged with
silicates, carbonates of lime, sulphides, etc., in solution, commenced
to deposit their contents in solid form when the heat and pressure were
removed.

I am aware that part of the theory here propounded as to the probable
mode of formation of the immense sedimentary beds of the Archaic or
Azoic period is not altogether orthodox--i.e., that the origin of
these beds is largely due to the ejection of mud, sand, and ashes from
subterraneous sources, which, settling in shallow seas, were afterwards
altered to their present form. It is difficult, however, to believe that
at this very early period of geologic history so vast a time had elapsed
as would be required to account for these enormous depositions of
sediment, if they were the result only of the degradation of previously
elevated portions of the earth's surface by water agency. Glacial action
at that time would be out of the question.

But what about the metals? Whence came the metallic gold of our reefs
and drifts? What was it originally--a metal or a metallic salt, and if
the latter, what was its nature?--chloride, sulphide, or silicate, one,
or all three? I incline to the latter hypothesis. All three are known,
and the chemical conditions of the period were favorable for their
natural production. Assuming that they did exist, the task of
accounting for the mode of occurrence of our auriferous quartz lodes is
comparatively simple. Chloride of gold is at present day contained in
sea water and in some mineral waters, and would have been likely to be
more abundant during the Azoic and early Paleozoic period.

Sulphide of gold would have been produced by the action of sulphuretted
hydrogen; hence probably our auriferous pyrites lodes, while silicate
of gold might have resulted from a combination of gold chlorides with
silicic acid, and thus the frequent presence of gold in quartz is
accounted for.

A highly interesting and instructive experiment, showing how gold might
be, and probably was, deposited in quartz veins, was carried out by
Professor Bischof some years ago. He, having prepared a solution of
chloride of gold, added thereto a solution of silicate of potash,
whereupon, as he states, the yellow colour of the