Glyeerine.—A mixture of glycerine and powdered litharge. It hardens rapidly, and is useful for vessels containing volatile bodies ; it is also an excellent cement for fixing iron on iron or stone, as well as for joining fragments of stone.
Hensler's.—Litharge, 3 parts ; quicklime, 2 parts ; white bole, 1 part ; all finely powdered ; then a quantity of linseed-oil varnish is added, sufficient to make a paste. This cement takes long to dry, but is very tenacious. It is used for chins, glasa, &c.
Iron Pots and Pans, for.—Sulphur, 2 parts; fine blacklead, 1 part ; the sulphur to be held in 9,n old iron pan over the fire till it begins to melt ; the blacklead is then added, and the mass is well stirred till it has thoroughly melted and combined ; then poured out on an iron plate or smooth atone, and, when cool, broken into small pieces. A sufficient quantity of this cement placed on a fracture in an iron vessel can be soldered with a soldering iron. If a hole exist, it should be first closed with a copper rivet, and the cement applied over it.
Labels, for.—(a) Corrosive sublimate, 125 parts ; wheaten flour, 1000 parts ; absinthe, 500 parts ; tanay, 500 parts; water, 15,000 parts. This cement is useful for vessels which are kept in a damp place ; the addition of the sublimate retarda the destruction of the labels. (b) Starch, 100 parts ; strong glue, 60 parts ; turpentine, 50 parts ; the whole boiled in water. This cement dries quickly.
Leather and Pasteboard, for.—Strong glue, 50 parts, is dissolved with a little turpentine in a aufficiency of water, over a gentle fire ; to the mixture, is added a thick paste made with 100 parts of starch. It is applied cold, and dries rapidly.
Letter-fixing.—Copal varnish, 15 parts ; drying oil, 5 parts ; turpentine, 3 parts ; oil of turpen tine, 2 parte; liquefied glue, made with the least possible quantity of water, 5 parts ; melted together in a water-bath ; to this is added fresh-slaked lime, perfectly dry and finely powdered, 10 parts. This cement is used to affix metallic letters to shop-windows, &c.
Marble.—Plaster of Paris is soaked in a saturated solution of alum, and then baked in an oven, just as gypsurn is baked to convert it into plaster of Paris ; it is then ground to powder. For use,
it is mixed up with water as wanted. It sets very hard, and will take a high polish, It is some times used for uniting glass and metal.
Marble, for.—Into a aolution of chloride of zinc, sp. gr. 1.490 to 1.652, is introduced 3 per cent. of borax or sal-ammoniac; when this is dissolved, oxide of zinc, which has been subjected to a red heat, is added, till the mass attains the desired consistence. This cement becomes as hard as marble, and may be used for moulding.
Meerschaum, for.—(a) Garlic, crushed to form a sort of dough, is rubbed over the surfaces of the meerschaum to be united ; the latter are then bound tightly together with fine wire, and boiled in milk for half an hour. (b) Quicklime is mixed to a thick cream with the white of an egg. These cements will also join fragments of glass or china.
Metals or Glass and Wood, to join.—Strong glue is boiled with water, and thickened with a suffi cient quantity of sifted wood sawdust. It is employed hot.
Metallic.—For joining metallic surfaces where soldering is inconvenient, recourse may be had to a composition formed in the following way :—Pure aud finely divided copper, such as that obtained by the reduction of sulphate of copper with zinc clippings, 20 to 36 parts, according to the degree of hardness desired in the cerneut, dissolved in a sufficient quantity of sulphuric acid to make a thick paste ; with this is incorporated, by trituration in a mortar, mercury, 70 parts. The mass is soft, but hardens at the end of some hours. For use, it is heated to 100° (212° F.), and powdered in an iron mortar heated to 150° (302° F.) ; it then assumes the consistence of wax, and is harder in proportion as it contains more copper. It adheres strongly on drying.
Porcelain and Glass, for.—Fresh poor cheese forms a good cement when dissolved in carbonate of potash or soda, and the liquid irevaporated until the masa exhibits the proper conaistence. On replacing the alkaline carbonate by silicate of potash, a still better cement is produced, which is very effective for repairing glass and china.