t
» •
Hf
7 "
m
. «B ' ,, »! i . ;l ■ i'
i'i f 'ï
but endeavour to diilinguifli all kinds
o f fubilances, which have fuflicient
and lafting marks o f diftindions. No
certain origin can be made unlefs the
ieparatioii and compoiition o f them,
which may be relied on, has been
made before. All the different forts
o f ilone and earth, hitherto known,
are compofed o f one or more of the
iix principles before-mentioned, which
fiiali be proved more at large in
another place, as foon as I am able
to make forne experiments that require
repetition.
Of the Bafalts.
O F sR the mountains hitherto
known, there ai'e without doubt
not any more remarkable than thofe
that are compofed o f angular pillars.
A few years ago only one or
two o f this kind were known; but
new ones are daily difcovered, which
is a plain proof how much our attention
requires being roiized to
prevent
prevent it from flumbering, on the
moil important occafions.
It cannot be much doubted that
there has been fome connections between
thefe pillars, and the effeds o f
a fubterraneous fire, as they are found
in places where the figns o f fire are
yet vifible; and as they are even found
mixed with lava, tuff, and other fubftances
produced by fire.
The caufe o f the regular form o f
thefe pillars is a problem which we
have hitherto been unable to folve
fatisfadorily. This difficulty has appeared
fo infurmountable to fome,
that they have thought it impoifible
to be the efieds o f nature, and have
confidered them as works made by
human hands : this idea betrays the
utmoft ignorance in regard to the
true nature o f thefe mountains o f pillars,
and does not even deferve a refutation.
As far as we know, nature makes
ufe of three methods to produce regular
forms in the mineral kingdom,
namely, that o f cryftallization or precipitation
: zdiy, the cruiling or fettling
of the external furface o f a
liquid
Ii
Ml