a department in the south of France, forming part of the ancient province of Auvergne. The soil is mountainous, but fertile in all kinds of grain, vines, and fruits; and contains mines of iron, lead, coal, and many mineral springs. There are manufactures of cloth of various kinds, lace, serges, ribbons, &c. The territorial extent of this department is 794,370 hectares, and the population in 1817 was 548,854. The contributions for 1802 amounted to 3,650,547 francs. Clermont is the chief town.

TERRA PUZZULANA, or Pozzolana, is a grayish kind of earth used in Italy for building under water. The best is found about Puteoli, Baiae, and Cumae, in the kingdom of Naples, from the first of which places it derives its name. It is a volcanic product, composed of heterogeneous substances, thrown out from the burning mouths of volcanoes in the form of ashes; sometimes in such large quantities, and with so great violence, that whole provinces have been covered with it at a considerable distance. In the year 79 of the common era, the cities of Herculaneum, Pompeii, and Stabia, although at the distance of many miles from Vesuvius, were, nevertheless, buried under the matters of these dreadful eruptions; as Bergman relates in his Treatise of the Volcanic Products. This volcanic earth is of a gray, brown, or blackish colour; of a loose granular, or dusty and rough, porous or spongy texture, resembling a clay hardened by fire, and then reduced to a gross powder. It contains various heterogeneous substances mixed with it. Its specific gravity is from 2500 to 2800; and it is, in some degree, magnetic; it scarcely effervesces with acids, though partially soluble in them. It easily melts per se; but its most distinguishing property is, that it hardens very suddenly when mixed with ¼ of its weight of lime and water; and forms a cement which is more durable in water than any other.

According to Bergman's Analysis, 100 parts of it contain from 55 to 60 of siliceous earth, 20 of argillaceous, five or six of calcareous, and from 15 to 20 of iron. Its effects, however, in cement may perhaps depend only on the iron it contains.

It is evidently a martial argillaceous marl, that has suffered a moderate heat. Its hardening power arises from the dry state of the half-baked argillaceous particles, which makes them imbibe water rapidly, and thus accelerates the desiccation of the calcareous part; and also from the quantity and peculiar state of the iron and manganese which it contains; on which metals its properties chiefly depend. It is found not only in Italy but in France, and also in England and elsewhere.