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was deep, and particularly where it had filled up ravines to the depth of two hundred* feet. Now, if the heat was so great in Sicily, at the expiration of four years, where the lava was not more than two hundred feet in thickness, can it be matter of surprise if the new branches of the volcanic torrent in Iceland, which in the channels of the rivers lay twice or thrice as deep, should still remain very hot at the expiration of only one year?
This may therefore be considered as a sufficient proof that the continuance of the heat in the lava is not to be regarded as a certain symptom of the continuance of fire. For my own part, I am thoroughly convinced that the whole was already extinct at the time of my travelling in the district of Skaptefield, which was in the month of July of last year; for, with regard to the number of pillars of smoke seen to arise, I consider them in reality as nothing more than vapors, produced by the vast quantity of water arising from the impeded rivulets;
* See Brydone's 9th Letter.
which every where, throughout the whole extent of the lava, become evaporated into steam. Such clouds of steam were more particularly abundant in rainy seasons, which makes it sufficiently clear that they owed their origin to water alone. When Mr. Levetzen and myself travelled from the farm-house of Skaptardal to the burnt farm of Skal, and thence up the mountains, on the 26th of July, we were enveloped in so thick a fog that we could hardly see for six yards before us. The fog had a disagreeable smell, and at length turned into a heavy fall of rain. But when we returned to Skal we were informed that this scent, as well as the fog itself, was to be found only on the hills, and that there had been, at the same time, fine and clear weather in the valley, together with a southerly wind, which had finally dispersed the rising vapors, carrying them towards the rocks in the north, and had at length enveloped the low grounds in a thick fog and heavy rain, similar to what we had previously experienced in the mountains. These circumstances tend still farther to confirm my conjecture that the smoke ascending from
the lava is nothing more than water, converted into vapor by extreme heat, and consequently that it can by no means be regarded as a proof that fire still exists in an active state among the lava.
§ XXVII. I now proceed to inquire into the state of the lava itself, and into the different kinds of this substance which have occurred Of thenamreof to me. In doing this I shall
the lava. firgt notjce ^ which,
whether at greater or less distances from the place of eruption, was every where of a greyish ash, intermixed with black: the latter more particularly predominating. In many places, where the lava presented an even surface, it had cooled in the same form in which it had flowed, and it was externally either deep red or violet, though the interior more frequently partook of a light-blue tint.
Wherever the lava had, from the circumstance of various streams succeeding each other, formed itself into eminences, the heated vapors naturally forced their way through the upper and hardened crust, which was consequently broken, and had fallen down in fragments of various shapes and sizes. In places where the lava was smooth and even, it was from the like circumstance full of cracks and rents, and in such places, but principally in the deep hollows, it was strewed on the surface with a fine white kind of dust, somewhat resembling salt, of which, with infinite pains, I was able to collect a small quantity. In a few spots, also, where the surface of the lava was level, might be seen yellow veins of sulphur among the cracks. Some of this I endeavored to procure with a pick-axe, by which means I broke into a number of concealed vacancies, that exhibited a mixture of various colors; while from their roof or upper part hung a great quantity of small projecting points, either of a sulphureous yellow or a dark red color. At the extremity of these processes, were seen a quantity of red drops, which in drying had become indurated, but which, notwithstanding their small size, would bear a smart blow with a hammer without being broken. The bases of the cavities were chiefly yellow and green, though sometimes
a reddish color was intermixed with them. In the bottom of one, I met with a beautiful kind of lava, remarkable for being most elegantly variegated with red, green, and yellow. Lava of the common sort, such as is every where to be found, has always a blackish hue within, with an exterior of a bluish cast, or sometimes with a mixture of red and violet color. Another species, somewhat different from the two just described, was found near Bleeng, at a little distance from the lava-stream. A fourth kind of rock also is thrown out by the volcano, and carried across the Fliotshverfet. This appears to be a black slate, shining within like pit coal: its exterior is marked with numerous white dots. With regard to pumicestone, I could find no large pieces of it. Those which I met with were about the size of a hazel-nut, of a brown color, fine in quality, its weight light, and its nature, as far as I could judge, exactly the same as that used in the arts. Under the five kinds of mineral substances here mentioned, which have been thrown up by the volcano, all others which have come under my inr spection are to be classed, as they cannot