2174. Hard Hydraulic Cement

2174.     Hard Hydraulic Cement. A cement which is said to have been used with great success in covering terraces, lining basins, cementing stones, etc., resisting the filtration of water, and so hard that it scratches iron, is formed of 63 parts well-burned brick, and 7 parts litharge, pulverized and moistened with unseed oil. Moisten the surfaces to which it is to be applied.

2175. Universal Cement

2175.    Universal Cement. Dissolve 2 ounces mastic in just enough 95 per cent, alcohol to effect a solution. Then soak 2 ounces isinglass, or fish-glue until it is thoroughly softened. Dissolve the isinglass in proof spirits sufficient to form a strong glue, and then add 1 ounce finely pulverized gum ammoniac. Warm the two mixtures together over a slow fire, and when they are thoroughly mixed, bottle and hermetically seal them. This cement becomes perfectly dry in 12 or 15 hours. When the cement is to be used, the bottle should be heated in a water bath to liquefy it; the fragments to be cemented should also be heated before joining them, and, as a matter of course, the surfaces well cleaned. Glass, crockery, etc., restored by the above cement, are as solid as before hav-ing been mended, and the seams are scarcely ' risible.

2176. To Cement Amber

2176.    To Cement Amber. Amber is joined or mended by smearing the surfaces with boiled linseed oil, and strongly pressing them together, at the same time holding them over a charcoal fire or heating them in any other way that will not injure the amber.

2177. To Cement Alabaster and Plaster

2177.   To Cement Alabaster and Plaster. Ornaments of alabaster or plaster may be joined together by means of a little white of egg, thickened with finely-powdered quicklime, or by a mixture of newly-baked and finely-powdered plaster of Paris, mixed up with the least possible quantity of water.

2178. Mending Plaster Models

2178.    Mending Plaster Models. Wax and resin, or shellac varnish, is recommended for the above purpose. Dr. Chaim suggests the use of liquid silex. Wet the two surfaces with it, and allow a few moments to dry. It will be found very useful in cases of accident to a cast.

2179. Waterproof Mastic Cement

2179.     Waterproof Mastic Cement. Mix together 1 part red lead to 5 parts ground lime, and 5 parts sharp sand, with boiled oil. Or: 1 part red lead to 5 whiting and 10 sharp sand mixed with boiled oil.

2180. Marble Workers' Cement

2180.      Marble Workers' Cement. Flower of sulphur, 1 part; hydrochlorate of ammonia, 2 parts; iron filings, 16 parts. The above substances must be reduced to a powder, and securely preserved in closely stopped vessels. When the cement is to be employed, take 20 parts very fine iron filings, add 1 part of the above powder, mix them together with enough water to form a manageable paste. This paste solidifies in 20 days and becomes as hard as iron.