Cement, Plumb′ers’. Black resin melted with about an equal weight of brick-dust. Some times a little pitch or tallow is added.
Cement, Port′land. From clay and chalk, or argillaceous river-mud and chalk or limestone, calcined together, and then ground to powder. See Cement, Parker’s.
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 Kimmeridge clay. It is also prepared from several artificial mixtures of ferruginous clay and lime, calcined together. It must be kept in close vessels, and mixed with water when used. See Cement, Parker’s and Gibbs’.
Cement, Seal Engra′′vers’. Resembles plumbers’ cement. Used to fix the pieces of metal while cutting, and also to secure seals and tools in their handles. It grows harder and improves every time it is melted.
Cement, Sin′ger’s. Prep. 1. Melt together resin, 5 lbs., and beeswax, 1 lb., and stir in finely-powdered red ochre (highly dried and still warm), 1 lb., and plaster of Paris, 4 oz.; continuing the heat a little above 212° Fahr., and stirring constantly till all frothing ceases.
2. Resin, 6 lbs.; dried red-ochre, 1 lb.; calcined plaster of Paris, 1⁄2 lb.; linseed oil, 1⁄4 lb. Used to cement the plates in voltaic troughs, to join chemical vessels, &c. No. 2 is specially applicable to troughs. See Cement, Electrical.
Cement, Steam-boiler. Prep. Litharge, in fine powder, 2 parts; very fine sand and quick-lime (that has been allowed to slake spontaneously in a damp place), of each 1 part; mix and keep it from the air. Used to mend the cracks in boilers and ovens, and to secure steam joints. It is made into a paste with boiled oil before application.
Cement, Steam-pipe. Prep. Good linseed oil varnish is ground with equal weights of white lead, oxide of manganese, and pipeclay.
Cement, Stucco. This is a compound of powdered gypsum or strong gelatin. It is used for coating walls, and also for ornamenting ceilings. It takes a high polish, and coloured designs can be painted on it. When employed on walls a coarser kind is first laid on, which is followed by a coating made of choicer specimens of gypsum, or glue, or isinglass. When this latter and outer coat becomes dry it is polished with pumice, tripoli, and linen. The colour is incorporated with the outer coatings of the stucco by mixing the metallic pigments with it, and then
applying it to the wall, after which a very thin coating of gypsum and isinglass, or sometimes of oil, is given to it, and when the whole is partially dried the tint is brought out by polishing, as before stated. Generally the finest effect is obtained by oil.