of this lava was pulverized and properly melted,
but it gave no more than three
grains of copper.
No. 5 was a piece of common pumice-
stone.
Of the whitish powder, with which the
cavities of the lava were filled, I got a small
sample weighing one and a half quintin.
I t had a saltish taste, and on crystallization
afforded proper Glauber salt, which weighed
two-thirds of a quintin, and ten grains of
kitchen-salt.
The grey and hair-like ravelings above-
tncntioned were found to be of the same
nature as Nos. 1 and 4 , and in all probability
are the self-same substances drawn out into
fine threads, which, from the delicacy of
their structure, are easily broken, and are
carried about by the wind in various directions
to considerable distances. Twenty
grains of them were melted down by means
of a moderate fire to a black glass *. So
* Professor Wilke, at Stockholm, procured a small
sample of this hair-like substance from Iceland, and
has given a dissertation upon ' the subject, similar to
extremely brittle was the texture of the lava,
_ u e v e n last autumn, when so far Solidity of the
lava. cooled as to suffer any one to
hold it in his hand, that the application of
moderate pressure instantly reduced it to a
fine powder; but it was now on the contrary
become considerably solid, insomuch that it
was with great difficulty I could work
through it, in many places, with the boring-
instrument. Notwithstanding this, it was
still very dangerous and unsafe, and was
every where difficult to walk over. Unsafe
it must also of necessity remain for a long
time, on account of the numerous sharp
points and projections with which its surface
is covered, and upon which it is scarcely
possible to tread with the thin Icelandic
shoes, made of raw hides, or even with thick
and properly soled ones, without immediately
cutting them through. Much danger, too,
arose from the circumstance of the hot vapors
which it concealed, having, previously to
the lava becoming thoroughly cool, produced,
as above mentioned, innumerable hollow
places, the arch-way or ceiling of which,
that inserted in Dr. Crell's Annals o f Chemistry, fo r
1784. Book ii. p. 323.