are embedded in the masses of nearly pure lime, and on the other hand, the
manner in which small kernels and streaks of the calcareous powder are
included in solid pieces of the scoriae,--considering, also, the similar
occurrence of lime and scoriae within a stream of lava, also supposed, with
good reason, to have been of modern subaerial origin, and to have flowed
from a hill, where earthy lime also occurs: I think, considering these
facts, there can be no doubt that the lime has been erupted, mingled with
the molten lava. I am not aware that any similar case has been described:
it appears to me an interesting one, inasmuch as most geologists must have
speculated on the probable effects of a volcanic focus, bursting through
deep-seated beds of different mineralogical composition. The great
abundance of free silex in the trachytes of some countries (as described by
Beudant in Hungary, and by P. Scrope in the Panza Islands), perhaps solves
the inquiry with respect to deep-seated beds of quartz; and we probably
here see it answered, where the volcanic action has invaded subjacent
masses of limestone. One is naturally led to conjecture in what state the
now earthy carbonate of lime existed, when ejected with the intensely
heated lava: from the extreme cellularity of the scoriae on Red Hill, the
pressure cannot have been great, and as most volcanic eruptions are
accompanied by the emission of large quantities of steam and other gases,
we here have the most favourable conditions, according to the views at
present entertained by chemists, for the expulsion of the carbonic acid.
(Whilst deep beneath the surface, the carbonate of lime was, I presume, in
a fluid state. Hutton, it is known, thought that all amygdaloids were
produced by drops of molten limestone floating in the trap, like oil in
water: this no doubt is erroneous, but if the matter forming the summit of
Red Hill had been cooled under the pressure of a moderately deep sea, or
within the walls of a dike, we should, in all probability, have had a trap
rock associated with large masses of compact, crystalline, calcareous spar,
which, according to the views entertained by many geologists, would have