basis of the Conglomerate, which forms the hill,
into a semi-metallic scoria, like that of an iron-smelter's furnace;
mica into a gray, waxy-looking stone, that scratched glass; and pure
white quartz into porcellanic trails of white, that ran in one instance
along the face of a darker-colored rock below, like streaks of cream
along the sides of a burnt china jug. In one mass of pale large-grained
granite I found that the feldspar, though it had acquired a vitreous
gloss on the surface, still retained its peculiar rhomboidal cleavage;
while the less stubborn quartz around it had become scarce less
vesicular and light than a piece of pumice. On some of the other masses
there was impressed, as if by a seal, the stamp of pieces of charcoal;
and so sharply was the impression retained, that I could detect on the
vitreous surface the mark of the yearly growths, and even of the
medullary rays, of the wood. In breaking open some of the others, I
detected fragments of the charcoal itself, which, hermetically locked up
in the rock, had retained all its original carbon. These last reminded
me of specimens not unfrequent among the trap-rocks of the Carboniferous
and Oolitic systems. From an intrusive overlying wacke in the
neighborhood of Linlithgow I have derived for my collection pieces of
carbonized wood in so complete a state of keeping, that under the
microscope they exhibit unbroken all the characteristic reticulations of
the coniferae of the Coal Measures.

I descended the hill, and, after joining my friends at
Strathpeffer,--Buchubai Hormazdji among the rest,--visited the Spa, in
the company of my old friend the minister of Alness. The thorough
identity of the powerful effluvium that fills the pump-room with that of
a muddy sea-bottom laid bare in warm weather by the tide, is to the
dweller on the sea-coast very striking. It _is_ identity,--not mere
resemblance. In most cases the organic substances undergo great changes
in the bowels of the earth. The animal matter of the Caithness
ichthyolites exists, for instance, as a hard, black, insoluble bitumen,
which I have used oftener than once as sealing-wax; the vegetable mould
of the Coal Measures has been converted into a fire-clay, so altered in
the organic pabulum, animal and vegetable, whence it derived its
fertility, that, even when laid open for years to the meliorating
effects of the weather and the visits of the winged seeds, it will not
be found bearing a single spike