Cement, Ro′man

Genuine Roman cement consists of puzzolene (a ferruginous clay from Pozzuoli, calcined by the fires of Vesuvius), lime, and sand. The only preparation which the puzzolene undergoes is that of pounding and sifting. It is generally mixed up with water, like most other cements, but occasionally with bullock’s blood and oil, to give the composition more tenacity. That used in this country is now generally prepared from the septaria of either Harwich or Sheppy, or of the lias formation, or from the cement stone found in the upper division of the lias formation, or in the shale beds of the Kim me ridge clay. It is also prepared from several artificial mixtures of ferruginous clay and lime, calcined together. It must be kept in close ve els, and mixed with water when used. See Cement, Parker’s and Gibbs’ .