f the carbon, chlorine, and sulphur in
the form of acid gases, which, with nitrogen, watery vapor, and a
probable excess of oxygen, would form the dense primeval atmosphere.
The resulting fused mass would contain all the bases as silicates, and
must have much resembled in composition certain furnace-slags or
volcanic glasses. The atmosphere, charged with acid gases, which
surrounded this primitive rock must have been of immense density.
Under the pressure of such a high barometric column, condensation
would take place at a temperature much above the present boiling-point
of water, and the depressed portions of the half-cooled crust would be
flooded with a highly heated solution of hydrochloric acid, whose
action in decomposing the silicates is easily intelligible to the
chemist. The formation of chlorides of the various bases, and the
separation of silica, would go on until the affinities of the acid
were satisfied, and there would be a separation of silica, taking the
form of quartz, and the production of a sea-water holding in solution,
besides the chlorides of sodium, calcium, and magnesium, salts of
aluminium and other metallic bases. The atmosphere, being thus
deprived of its volatile chlorine and sulphur compounds, would
approximate to that of our own time, but differ in its greater amount
of carbonic acid.

"We next enter into the second phase in the action of the atmosphere
upon the earth's crust. This, unlike the first, which was subaqueous,
or operative only on the portion covered with the precipitated water,
is sub-aerial, and consists in the decomposition of the exposed parts
of the primitive crust under the influence of the carbonic acid and
moisture of the air, which convert the complex silicates of the crust
into a silicate of alumina, or clay, while the separated lime,
magnesia, and alkalies, being converted into carbonates, are carried
down into the sea in a state of solution.

"The first effect of these dissolved carbonates would be to
precipitate the dissolved alumina and the heavy metals, after which
would result a decomposition of the chloride of calcium of the
sea-water, resulting in the production of carbonate of lime or
limestone, and chloride of sodium or common salt. This process is one
still going on at the earth's surface, slowly breaking down and
destroying the hardest rocks, and, aided by mechanical processes,
transforming them into clays; although the action, from the
comparative rarity