Boiled linseed oil and red lead mixed gather into a putty are often used by cop persmiths and engineers, to secure joints. The washers of leather or cloth are smear ed with this mixture in a pasty state.
The resin mastic alone is sometimes to used by jewellers to cement by heat ca meos of white enamel or colored glass to a real stone, as a ground to produce the appearance of an onyx. Mastic is like wise used to cement false backs or doublets to stones, to alter their hue.
Melted brimstone, either alone, or mixed with resin and brick dust, forms a tolerably good and very cheap cement.
Plumber's cement consists of black resin one part, brick dust two parts, well incorporated by a melting heat.
The bituminous or black cement for bottle corks, is pitch hardened by resin and brick dust. The following makes a good cement for mastic works : mix 50 parts of siliceous sand, 50 parts of lime marl, or pulverized brown sand stone and 8 i parts of litharge. When the ce ment is used it is to be ground up with linseed oil.
An excellent cement for resisting mois ture is made by incorporating thoroughly 8 parts of melted glue, of the consistence used by carpenters, with 4 parts of lin seed oil, boiled into varnish with litharge. This cement hardens in about forty-eight hours, and renders the joints of wooden cisterns and casks air and water tight.
A compound of glue with one-fourth its weight of Venice turpentine, made as above, serves to cement glass metal, and wood, to one another. Fresli made cheese-curd, and old skim-milk cheese, boiled in water to a slimy consistence, dissolved in a solution of bicarbonate of potash, are said to form a good cement for glass and porcelain. The gluten of wheat, well prepared, is also a good cement. White of eggs, with flour and water well mixed, and smeared over linen cloth, forms a ready late for steam joints in small apparatus.
White lead ground upon a slab with linseed oil varnish, and kept out of con tact of air, affords a cement capable of repairing fractured bodies of all kinds. It requires a few weeks to harden. When stone and iron are to be cemented toge ther, a compound of equal parts of sul phur with pitch answers very well.
For Cement, see Norma.
Mr. heating, of London, has patented a mode of combining gypsum or other calcareous substances with borax, for a cement.
Separate solutions of borax and crude tartar arc made, and then mixed : cal cined gypsum is then added in lumps to the liquor, and allowed to remain till it has absorbed all it will take up. It is then taken out and heated in an oven : again put in the solution and afterwards burned : when it is fit for use.