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	BOOK III	39

	sized pyramids as at Stassfurt, Saxony; and sometimes in small pyramids as at Aldedorf, Hesse. Salt has variable natural properties. Some is compact, dense, and when heated in a fire decrepitates and flies apart. This is true of all natural and most marine salt. Fine-grained and dense salt decrepitates even more, especially most of the artificial salt produced from saline solutions. The porous mineral, whether compact or loosely coherent, does not decrepitate or disintegrate in fire. This is true of the halite formed in saline lakes by the drying force of the sun, for example at Agrigentum and Tragasaeus, and a similar salt found on the sea shore at Aeantium, as well as that which comes from India in the form of pyramids and from Colomaeus in cubes. "Flowers of salt" and salt "scale" belong to this class. Loose, fine-grained, uncompacted salt does not decrepitate. The mineral reacts the same when placed on glowing coals. Crushed and powdered it is readily soluble in water. When compact and hard it dissolves slowly although it will dissolve eventually. Of the compact salts artificial salt dissolves the quickest, marine and lacustrine salt more slowly, halite² the slowest. In each class some particular salt may be found which is more compact or more loose-textured than the rest and will dissolve more readily or more slowly than the others. A salt from Agrigentum jumps out of the water according to Pliny. All salt is dried when placed in a crucible over a fire yet the quantity does not decrease or decreases very slightly. The mineral loves dryness since it has congealed as the result of a union with either cold or heat. On the other hand dampness is its enemy since it dissolves and liquefies when left in a damp place. Even when exposed to dampness some of the salt is softened and lost. Therefore when one wishes to preserve salt it is necessary to leave it in a dry place. This is not always true since salt is heaped up on the coast of Africa near Utica until the mounds resemble small hills and the surfaces become so indurated by the sun that they do not dissolve during rains. When needed the salt is broken down with iron bars according to Pliny, and only after great effort. The carving of vessels and small animals from white salt was unknown to the Greeks. They believed that this mineral did not exist as a solid in the earth but as an exceptionally sticky and glue-like body that, like Paria marble, became hard and solid after having been placed in the sun. Salt is used in various ways, in buildings, in religious worship, in medicine and most of all in food. The Arabs of Carris and Gerrha build houses, walls and towers from salt which is cut into square blocks like stone and cemented together with water instead of lime. The Ammani-entes in Africa build their houses in a similar fashion. The Romans used salt in their temples and never built one without a cornerstone of salt. Fabius Pictor writes that the Vestal Virgins cut the salt for the temples with an iron saw. Hebrew rabbis sprinkled salt on the heads of sacrificial ^s In general the mineralogical name halite is limited in the English text to natural salt occurring within the earth.