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has been produced by the aiTiftance o f
fire. It is true, that fometimes they
are found in ilonOs, and in fuch
places where volcanos had formerly-
raged ; but it is likewife found in
foltd rocks that have never been ex-
pofed to thefe fires, as at Guftavenberg
in Jenitland.
I f more forts than one are alfo
certainly free from all fufpicion o f
having been fubjefl to fufion, how is
It poffible, without the cleareft proofs,
to fuppofe that the whole genus haS
been fubjea to it ? I f the Icelandic
zeolite has been produced by fire, we
may juilly queftion how it can yield^
above five quarts in twenty-five o f
water in diftilllng. This may likewife
be applied to all the othci forts,
though they generally contain lefs
water, and the red fort from Adelfors
only one quart in twenty-five. This is
evidently the water of cryftallization, in
proportion to which each kind fwells
more or lefs by the blow-pipe. The Icelandic
and Feroe zeolites are moil fubjecl
to this, almoil like borax; the Adelfors
zeolite fwells much lefs, and that
from
from Upland, and feveral other forts,
fo little, that it ceales in a moment ;
and even then produces fo fmall an
expaniion of fpace, that it is fcarcelv^
perceivable to the eye.
Since therefore all zeolites contain
this water of cryftallization, which is
neither found nor expefled in the pro-
duclions of fire, it feems to me to be
undeniable, that they have been produced
in the way o f moiftnre ; be-
fides, the zeolites do not confift o f a
Iimple particular kind o f earth, but
o f three different forts that are mixed
together, and in a manner the one
diffolved by the other, in confequence
o f which their conneflion cannot be
confidered as an original earth. In all,
the greateil part confifts o f iiliceous
earthj the next is argillaceous earth,
and the Jeaft part is calcareous earth.
The tw?o laft forts may be diffolved by
acids, and then precipitated by alkali
volatile caufticum, by which the argillaceous
earth, hut not the calcareous
earth, after being feparated from the
firft by filtrating, may be precipitated
by fal fodæ.
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