on the Materials used in the city of' Rome. 35 



from a porous limestone for plastering walls, and from a com- 

 pact limestone called Palombino by the moderns,* and employ- 

 ed for building. It was mixed with sand, which, according to 

 Vitruvius, (lib. ii.) was either " arena jossicia? or "jluviati- 

 ca et marina? three parts of the former, and two of the lat- 

 ter, being used for one of lime. The first is known all over 

 the world by the name of Pozzuolana, from the town of Poz- 

 zuoli near Naples, where one species is most abundantly found. 

 It is one of the most plentiful, as well as most important pro- 

 ductions of the soil of Rome, and has infinitely contributed to 

 the stability of the remains of antiquity, especially where large 

 fragments of stone were not employed. To describe its nature, 

 phenomena, and uses, would require an entire paper ; I shall, 

 therefore, only remark, that it is a volcanic production, and 

 still formed by volcanos now in action, (See Dolomieu, Cata- 

 logue des Produits d?Etna 9 ) and that its principal varieties, ac- 

 cording to Vitruvius, are the " nigra, cana, rubra, carbuncu- 

 lus." I am rather at a loss how to translate the last, unless it 

 mean cindery or scoriaceous. Brocchi calls the Pozzuolana 

 " tufa granular e" All the catacombs near Rome are cut out 

 of this material. The sea and river sand was never used but 

 in default of the other. The following were the stones em- 

 ployed in masonry by the Romans. 



I. Tufa, the " lapis ruber" of Vitruvius, and >j0os sgvQgog of 

 Strabo. The ancient quarries of this stone may be seen at 

 Cervaretta on the bank of the Anio. It was, as Nibby ob- 

 serves, much used for foundations, but likewise, when employ- 

 ed in great masses, to resist as much as possible the action of 

 the air, which readily decomposes it, for entire buildings, chiefly 

 in the earlier ages of Roman greatness, as in the stupendous 

 aqueduct of Claudius, and the Temple of Fortuna Virilis. 

 Brocchi justly remarks, that H saxum quadratum" is its speci- 



* Not being acquainted with this Palombino, I cannot state the distinc- 

 tion more fully. Ferber calls the Palombino antico i( white and compact, 

 neither scaly nor crystalline." Were I to hazard an opinion, I should con- 

 sider it to be the very hard secondary limestone which abounds near Tivolj, 

 and the kind first mentioned above, a limestone of snowy whiteness, and 

 therefore well fitted for plaster work, which I have seen carried by horses 

 in panniers across the Campagna, being brought, as I understood on inquiry, 

 from a very considerable distance in the centre of the Apennines. 



