The fandy fubftance hardly fwells ;
is diíTolved with difficulty by borax,
and is attacked at firft with a fudden
effervefcence by fal fodæ.
As it is not uncommon, even in
the profeffors o f morality, to pafs from
one wrong ftep to another, fo aré we
not without examples o f this kind in
thofe who make nature their ftudy.
Ten years ago it was a general opinion
that the furface o f the earth, together
with the mountains upon it, had been
produced by moiilure. It is true,
fome declared the fire to be the firft
original caufe, but the greater number
paid little attention to this opinion.
Now, on the contrary, that a fub-
terraneous fire had been the principal
agent gains ground daily : every
thing is fuppofed to have been melted
even to the granite. My own fend-
ments with regard to it is this,
that both the fire and water have
contributed their fliare in this operation,
though in fuch a proportion,
that the force o f the former extends
much further than the latter : and, on,
die
the contrary, that the fire has only-
worked in fome parts o f the furface
o f the earth.
It is not an eafy matter to explain
how the granite, which confifts o f clear
quarz-cryftals, folid field-fpar, and
glimmer (mica) with flat fcales, has
been able to fupport a fufion without
the quarz burfting, or becoming
opaque.
This is yet lefs to be conceived of
the field-fpar, that becomes foft and
liquid in a weak fire, and has a
dull appearance. The glimmer fplits
its fcales afunder in the fire, and
frequently twifts them together again
in a very different manner from that
in which they appear in the granite.
Notwithftandiiig all this, i f the granite
is confidered as a produédon o f the
fire, it need not be wondered at, that
the zeolite has likewife been comprehended
in this iuppofition.
I will allow that cryftals may be
produced by the dry method, and I
know feveral ways o f obtaining them,
both by fufion and fublimation ; but I
can never be perfuaded that the zeolite
I has