n arched
chasm in the side of the mountain, the vivid torrent rushed with the
velocity of a flood. It was in perfect fusion, unattended with any
scoriae on its surface, or any gross materials not in a state of complete
solution. It flowed with the translucency of honey, "in regular
channels, cut finer than art can imitate, and glowing with all the
splendor of the sun."--"Sir William Hamilton," he continues, "had
conceived that no stones thrown upon a current of lava would make any
impression. I was soon convinced of the contrary. Light bodies, indeed,
of five, ten, and fifteen pounds' weight, made little or no impression
even at the source; but bodies of sixty, seventy, and eighty pounds were
seen to form a kind of bed on the surface of the lava, and float away
with it. A stone of three hundred weight, that had been thrown out by
the crater, lay near the source of the current of lava: I raised it upon
one end, and then let it fall in upon the liquid lava; when it gradually
sunk beneath the surface, and disappeared. If I wished to describe the
manner in which it acted upon the lava, I should say that it was like a
loaf of bread thrown into a bowl of very thick honey, which gradually
involves itself in the heavy liquid, and then slowly sinks to the
bottom.

"The lava, at a small distance from its source, acquires a darker tint
upon its surface, is less easily acted upon, and, as the stream widens,
the surface, having lost its state of perfect solution, grows harder and
harder, and cracks into innumerable fragments of very porous matter, to
which they give the name of scoriae, and the appearance of which has led
many to suppose that it proceeded thus from the mountain. There is,
however, no truth in this. All lava, at its first exit from its native
volcano, flows out in a liquid state, and all equally in fusion. The
appearance of the scoriae is to be attributed only to the action of the
external air, and not to any difference in the materials which compose
it, since any lava whatever, separated from its channel, and exposed to
the action of the external air, immediately cracks, becomes porous, and
alters its form. As we proceeded downwards, this became more and more
evident; and the same lava which at its original source flowed in
perfect solution, undivided, and free from incumbrances of any kind, a
little farther down had its surface loaded with scoriae in such a manner,
that, upon its arrival at the bottom of the mounta