‹‹‹ Vitr. 2.6.2 | Table of Contents | Vitr. 2.6.4 ›››
3The species of sponge-stone, however, thence obtained, is not found except in the neighbourhood of Ætna and the hills of Mysia, which the Greeks call κατακεκαυμένοι, and places of such description. If, therefore, in these places hot springs and heated vapours are found in the cavities of the mountains, and the spots are recorded by the antients to have been subject to fires issuing out of the lands, it seems certain that the moisture is extracted from the sand-stone and earth in their neighbourhood, by the strength of the fire, as from lime-stone in a kiln.
3The kind of sponge-stone taken from this region is not produced everywhere else, but only about Aetna and among the hills of Mysia which the Greeks call the “Burnt District,” and in other places of the same peculiar nature. Seeing that in such places there are found hot springs and warm vapour in excavations on the mountains, and that the ancients tell us that there were once fires spreading over the fields in those very regions, it seems to be certain that moisture has been extracted from the tufa and earth, by the force of fire, just as it is from limestone in kilns.