Thefe revolutions in our globe are no where more
plainly feen than in the mountain of Montferrat. The
fmall touchftones feen there, in a mountain o f a calcareous
nature and amidft thofe elevated and conglutinated
pyramids, being of a black colour and of the fame grain
as the others found in Catalonia, are all from the effeils
o f fire, and have the fame ferrugineOus nature, as the
high columns o f the extraordinary mountain o f Uifon
in Auvergne. Thefe pillars o f bafaltes were probably in
a ftate of fufion with thé iron, when they mixed with it,
and their irregular fhape proceeds from having cooled by
degrees, like the white bafaltes, if I may be permitted
the expreifion, of Cape de Gat. The fmall round grains,
blue and green, found in the fields near the mountain
of Uifon have been iron. I have feen fome that were
metal within, and were formerly like iron ihot. Their
ihape may be explained from the pra&icé obferved in
iron forges, when the workmen throw a ladle full of
fufed metal on the ground, which runs into a globular
ihape, and is purchafed by fportfmen inftead of ihot.
The globular iron ore is therefore the produit of
volcanos as thofe certainly are near to Ronda and Befort
in France, both are, as well as thofe of Germany; with
a fuperficial coat, and give a very foft iron. Touch-
ftones might be made of the pillars o f Uifon, as the Germans
do with the bafaltes in different parts of Heife and
Saxony,
Saxony, whofe forms are more irregular than the pillars
of Uifon. The Giant’s caufeway and other places in
Ireland have innumerable pillars of irregular bafaltes,
fimilar in colour and form to thofe of Uifon, which ferve
alfo for touch-ftones ; the black foft flaty ftones, found
in the Pyrenees o f Catalonia, and commonly called lapiz,
are likewife the refult of volcanos long iince extinguilhed.
I think I perceived the remains o f a volcano on the
mountain of Serrantes,ncav Bilbao, adjacent to the fea at
the entrance of the river of Bilbao; its figure is like a fu-
ear-loaf, and it has been miftaken for O ' the mine of Somorroftro,
which is a low uneven hill, at fome diftance from
this pyramid. Pliny fell into this error, perhaps from
not having feen it, or from the reports of fome mariners-
who traded in Andalufia, where Pliny was writing his
biliary,
I never perhaps ihould have known that the quartz of
many mountains of Spain had been calcined, if previ-
oufly, at Gingenbacb, in. the Black Foreft in Germany, I
had not feen them calcine the. Kiejfeljlein to foften and
mix it with cobalt, and make zaffre; this Kiejfeljiein is a
true white quartz of the antient volcanos o f Spain, but
to know and underftand thefe matters clearly definitions
are not fu-fficient, they muft be feen,”