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Ure's Diamond Cement

Take 1 ounce isinglass and 6 ounces distilled water; boil down to 3 ounces; add 14 ounces rectified spirit. Boil for 2 minutes, strain, and add, while hot, 1/22 ounce of a milky emulsion of ammoniac, and 5 drachms tincture of gum mastic. not upon its adhesion to the surfaces which it ange shellac, bruised, 4 ounces; highly rectiis used to join; and, in general, cements are fied spirit of wine, 3 ounces. Set the mixture comparatively brittle. Sealing-wax is a very in a warm place, frequently shaking it till the good agent for uniting metal to glass or stone, shellac is dissolved. Wood naphtha may be provided the masses to be united are made so substituted for the spirit of wine, but the unhot as to fuse the cement; but if the cement pleasant smell of the naphtha is some objecis applied to them while they are cold, it will tion. not stick at all. This fact is well known to 2156. Το Mend Broken Glass. A venders of cement for uniting earthenware. much better process for mending broken By heating two pieces, so that they will fuse glass, china and earthenware with shellac, shellac, they are able to join them so that than heating them, is to dissolve the shellac they will rather break at any other part than in alcohol to about the consistence of molasses, along the line of union. But although people and with a thin splinter of wood or pencilconstantly see the operation performed, and brush touch the edges of the broken ware. In buy liberally of the cement, it will be found a short time it sets without any heating, which in nine cases out of ten the cement proves is often inconvenient. It will stand every worthless in their hands, simply because they contingency but a heat equal to boiling do not know how to use it. They are afraid to heat a delicate glass or porcelain vessel to a sufficient degree, and they are apt to use too much of the material, and the result is a failure; the cement is consequently deemed good for nothing. The great obstacles to the junction of any two surfaces are air and dirt.

The former is universally present, the latter is due to accident or carelessness. All surfaces are covered with a thin adhering layer of air which it is difficult to remove, and unless this is displaced, the cement cannot adhere to the surface to which it is applied, simply because it cannot come into contact with it. The most efficient agent in displacing this adhering air is heat. Metals warmed to a point a little above 200° become instantly and completely wet when immersed in water. Hence, for cements that are used in a fused condition, heat is the most efficient means of bringing them in contact with the surfaces to which they are to be applied. In the case of glue, the adhesion is best attained by moderate pressure and friction. water..