Cement, Fire′proof. Prep. From fine river sand, 20 parts; litharge, 2 parts; quick-lime, 1 part; linseed oil, q. s. to form a thin paste. Applied to walls, it soon acquires a stony hardness. It is also used to mend broken pieces of stone, stone steps, &c. See Cement, Beale’s, &c.
Cement, Flour. Syn. Paste, Flour paste. This useful and well-known article is made by mixing about a tablespoonful of wheat flour with cold water, (say) 1⁄2 pint, adding the latter gradually, and thoroughly stirring in each portion before pouring in more; the vessel is then placed over the fire, and the whole assiduously stirred until it boils, great care being taken to prevent caking on the bottom, or burning. Some persons add about 1⁄3 of a teaspoonful of powdered alum to the water, which is said to strengthen the product; the shoemakers add a little quantity of powdered resin to the flour, with the same intention. The addition of a little brown sugar and a few grains of corrosive sublimate will prevent it turning mouldy, and is said to preserve it for years. When too hard or dry, it may be softened by beating it up with a little hot water.
Cement, French. Mucilage of gum Arabic, thickened with starch powder or farina; a little lemon-juice is sometimes added. Used by naturalists in mounting specimens; by artificial-flower makers; and by confectioners, to stick paper, wafer papers, ornaments, &c., on their fancy cakes. Plain mucilage is often used in the same way.
Cement, Gad’s. Syn. Gad’s hydraulic cement. From clay (well dried and powdered), 3 parts; oxide of iron, 1 part; mixed together, and made into a stiff paste with boiled oil. Used for work required to harden under water.
Cement, Glass. Syn. Glass flux. Prep.
Red lead, 3 parts; fine white sand, 2 parts; crystallised boracic acid, 3 parts; mixed and fused; it is levigated, and applied with thin mucilage of tragacanth. Used for mending broken china, &c. The repaired article must be gently heated, so as partially to fuse the cement.
Cement, Gibbs’. Mr Gibbs patented in 1850 various processes for making admirable building and architectural cements, equal in hardness and duration, and superior in colour, to the best Roman and Portland cements at present in use. His materials are obtained from “the vast beds of (natural) argillaceous marls and marly limestones, or marl stones, which contain the due admixture of lime, silica, and alumina, from which hydraulic cements and artificial stones may be manufactured.” These materials he finds in “the chalk formation, the Wealden formation, the Purbeck beds, the lias formation, the mountain limestone, and the lowest strata of the coal-measures.” After duly choosing his materials according to the particular object in view, he prepares them “by burning in kilns, and grinding in mills, in the way cement is now manufactured.” Marls and limestones are to be “first dried in kilns or ovens, at a heat fit for baking, until all moisture be driven off, and that then the calcination be prolonged as much as possible; the heat being kept as low as is only just sufficient to effect complete calcination—this being indispensable, to avoid the commencement of vitrification, which would destroy the adhesive properties of the cement.”
Cement, Glue. Prep. 1. From glue, 1 lb. melted with the least possible quantity of water, and then mixed with black resin, 1 lb., and red ochre, 4 oz.
2. Glue, melted as above, and mixed with about 1⁄4th of its weight each of boiled oil and red ochre.
3. (Ure.) Melted glue (of the consistence used by carpenters), 8 parts; linseed oil, boiled to varnish with litharge, 4 parts; incorporate thoroughly together.