Full resolution (JPEG) - On this page / på denna sida - Pages ...
<< prev. page << föreg. sida << >> nästa sida >> next page >>
Below is the raw OCR text
from the above scanned image.
Do you see an error? Proofread the page now!
Här nedan syns maskintolkade texten från faksimilbilden ovan.
Ser du något fel? Korrekturläs sidan nu!
This page has never been proofread. / Denna sida har aldrig korrekturlästs.
VON TROIL’s LETTERS ON ICELAND. 721
i have likewife examined the fubftances you colleéted in the morafs near the Geyler,
and have found them to be the following :
3. A dark-red bole, which became darker in the fire, but was afterwards a little at-
tracted by the magnet. It crumbled into pieces in the water, and is fine and tough to
the touch.
4. A bluifh-gray clay, which contains green vitriol of decayed pyritz.
5. A brighter grey fort, which did not feem to contain any vitriol,
6. A white or yellowifh clay, with ruft-fpots.
Ail thefe forts become very hard in the fire, and take a good deal of time before
they liquify. The laft, when it foftens, is harfh and more fandy to the touch than the
preceding forts.
The different forts of ftone colleéted at Laugarnas are of another nature : nor does the
water here {pout out of a bafon, but through many fmall openings in the earth.
7. A whitifh irregular plated cruft, which often grows on the outfide into fmall glo-
bular blunt points. ‘This in acids gives a fudden fermentation, that immediately ceafés
without its being any otherwife attacked. It diffolves with borax by the blow-pipe with
great difficulty, and without motion, but with a loud effervefcence with fal fodx. It is
confequently a filiceous mafs outwardly covered with lime, and has fixed itfelf on the
following fubftance.
8. A folid irregular plated and broken cruft, of a dark colour, but in many places
tinged with bright blue fpots. It becomes quite fmooth in cutting, almoft like ftone
marle, but does not crumble in water, nor does it become foft in it ; with acid it fhews
an effervefcence which foon ceafes ; with the blow-pipe it grows hard, fearcely melts at
the thinneft edges, and is attacked with fome motion both by borax and fufible urinous
faltand fal fodz, but is not entirely diffolved by any of them.
g. The fubffance found at the bottom of the brook, which carries off the water that
gufhes out, is brown, fpongy, and compofed of pretty hard flakes and threads, that are
covered with fine glaffy cryflallizations. ‘Thefe are clear only in fome few places; but
lofe their brown colour, both in fireand marine acid, and become quite clear.
The fmall cryftals puff up very much under the blow-pipe, almoft like borax ; they
float in bubbles on the furface, and are diffolved with great difficulty by borax ; they
are attacked by fal fodze with a {trong ebullition: it is the fame with the more folid
flakes, but they do not puff up fo ftrongly as the cryflallization. Thefe feveral qualities
here mentioned evidently fhew, that this cruftated {tone confilts of zeolite.
ro. From Reykum you fent me calcareous fpar in lumps, that are externally rounded,
as if they had been toffed backwards and forwards by the water, and rubbed again{t
hard bodies. In them there are {mall greyifh green cryftallizations, that diffolve by the
blow-pipe to a black flag ; the fal fodee caufes fome effervefcence in them, but does not
diffolve them ; they are likewife attacked with fome emotion by fufible urinous falt.
11. A loofe, tubulofe, whitifh cruftated ftone, or an incruftation cavernous, and with
impreffions of leaves, ftalks, and the hke. As to its nature it is filiceous ; but feems
at the fame time to contain a different fubftance, as it diffolves more flowly with fal fodz.
The fpring which here burfts forth in a very floping direction towards the horizon,
according to your account, depofits a kind of fulphureous greafe by its hot {team on the
cavities of the upper fide; but I have found no fpecimen of this in the collection you
communicated to me.
From what I have hitherto faid, we may gather, that the Icelandic hot fprings con-
tain very different fubftances from what are to be met with in other places of the fame
fort, efpecially filiceous earth.
VOL. I. 42 There
<< prev. page << föreg. sida << >> nästa sida >> next page >>
