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fmoothnefs o f fome parts, it cannot
proceed from a commencing fufion,
as it becomes black and dark in a
weaker fire. We here only find a
new link in the con needed chain of
nature, by which the jafper is uniteci
with the flint.
There is no black jafper in your
colleclion ; but the pieces, which to
appearance come neareft to it, belong
to the clais of the trapp, and iiiall be
defcribed hereafter.
20. Grey, greenifli ilate, refem-
bling jafper, that gives fparks with
the fteel, is attacked with a quick cf-
fervefcence by fal fodæ, but not flu’-
ther diflblved by it. Iu fome places
are grains reienibling quarz, which
are eafily diflblved in fufible urinous
fait, but do not iliew the leaft eirer-
vefcence in fal lodæ.
21. The fmall cryftals, faid to re-
femble cocks-combs ; they are nothing
but a different appearance or change
o f the heavy fpar.
22. A chalcedon cruft with fmooth
prominencies, like what they call the
hæmatltes : this is diffolved with the utmoft
moft difficulty by fufible urinous fait,
with more eafe by borax, and with
a violent effervefcence by fal fodæ,
exaélly as the flint.
23. Zeolite ; two kinds : the one is
folid, white, and internally, as it were,
compofed of globofe parts, in which
rays proceeding from the center appear
that refemhle fine threads.
This fort fwells a little by the
blow-pipe, diffolves perfedly with
borax, feparates in fal fodæ with fome
effervefcence, but foon ceafes, and
leaves fome part undiffolved.
The other fort confifts o f a plate,
that, in colour and break, refembles
a carneiian : it has a quantity o f fmall
prominencies in it, filled with irregular
white cryftals, and fome o f the cavities
are filled with a loofe-grained
and brownlfti-red fubftance.
The fubftance refembling a carneiian
becomes white in the fire, bubbles
up, and becomes fufible.
The cryftalline fubftance becomes
more frothy in the fire than the carneiian,
and has all the qualities o f the
zeolite.
The
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