Metal or Glass, and Wood, to join.—(a) Rosin is melted, and into it is stirred calcined plaster till the mass is reduced to a paste, to which is added boiled oil, in sufficient quantity to bring it to the consistence of honey. It is applied warm. (b) Into melted rosio, ISO parts, are stirred burnt umber, 30 parts ; calcined plaster, 15 parts ; boiled oil, 8 parts.
Metals aud Glass, to join.—(a) Rosin, 4 to 5 parts ; wax, 1 part ; colcothar, 1 part ; the whole melted together. A little powdered plaster is often added. (b) Copal varnish, 15 parts ; drying oil, 5 parts ; turpentine, 3 parts ; essence of turpentide, 2 parts ; strong glue, 5 parts ; slaked lime, 10 parts ; mixed. (c) Sandrach or galipot varnish, 15 parts ; boiled linseed oil, 5 parts ; turpentine, 2/ parts ; essence turpentine, 2/ parts ; marine glue, 5 parts ; pearl white, 5 parts ; dry carbonate of lead, 5 parts ; mixed. (d) Copal or lac varnish, 15 parts ; drying oil, 5 parts ; indiarubber or guttapercha, 4 parts; coal oil, 7 parts ; Roman cement. 5 parts ; plaster, 5 parts. (e) Copal or rosin varnish, 15 parts ; turpentine, 2/ parts ; essence of turpentine, 2/ parts ; fish isinglass, in powder, 2 parts; iron filings, 3 parts ; ochre or rottenetone, 10 parts. These cements, especially the first, are much used for fixing metallic letters to glass, marble, or wood. The two following are particularly good for uniting brass and glass :—(f) Caustic soda, 1 part ; rosin, 3 parts ; plaster, 3 parts ; water, 5 parts ; the whole is boiled. This compound hardens at the end of half an how: ; the hardening may be retarded by replacing the plaster by zinc -white, white lead, or slaked lime. (g) Fine litharge, 2 parts ; white-lead, 1 part ; copal, 1 part ; boiled linseed oil, 3 parts ; the whole is triturated together.
Metals, Wood, and Indiarubber, to join.—Shellac is soaked in ten times its amount of strong liquid ammonia ; it takes about a month to completely dissolve. It has tbe effect of softening the surface of indiarubber before drying, and thus causes perfect adhesion. It is valuable for making steam-pipe connections with rubber washers.
Naturalists'.—Consists of mucilage of gum arable, thickened with starch powder or farina, with the addition of a little lemon juice. Sometimes the mucilage is used alone. This cement is
employed by naturalists, for mounting specimens ; by artificial flower makers ; by coufectioners, to stick ornaments on their cakes, &c.
Plumbers'.—Black resin, 1 part ; brickdust, 2 parts ; melted together, with the occasional addition of a little pitch or tallow. It improves and grows harder each time it is melted. Used by plumbers and by seal engravers, for fixing pieces of metal while cutting, and for securing seals and tools in their handles.
Stone, for.—(a) Sulphur, 1 part ; yellow wax, 1 part ; rosin, 1 part ; the sulphur and rosin are melted, and the wax is then added. It is necessary to heat the surfaces to be united ; the cement is applied while still het, and pressure is exerted till it is cold. (b) Powdered gum arable, 2 parts ; finely ground white-lead, 2 parts ; pulverized sugar-candy, 1 part ; the three substances are placed in a small bottle with a wide mouth, a, little hot water is poured on them, and the whole is stirred by a stick into a homogeneous paste. The cement must he kept in a closed vessel, and a little water may be added if it becomes dry. Before use, it must be well stirred, to prevent the white-lead collecting at the bottom. It is employed for joining fragments of minerals, fossils, &c.
Stoneware, for.—Botany Bay (yellow) gum, 1 part ; brickdust, 1 part ; melted together. Em ployed for stoneware, earthenware, &c.
Turners'.—(a) Rosin, oz. ; pitch, oz. ; beeswax, I oz.; melted together ; fine brickdust is then added, in sufficient quantity to produce the desired consistence. (b) Rosin, 2 lb. ; Burgundy pitch, 2 lb. ; dried whiting, 2 lb. ; yellow wax, 2 oz. ; mixed and melted together. (c) Black rosin, lb. ; yellow wax, 1 oz. ; melted together, and poured into a tin canister. When required for use, as much is chipped out as will cover the chuck to a thickness of -A- in., and is spread over in small pieces, mixing with it one-eighth of its hulk of guttapercha in thin shreds ; an iron, heated to dull redness, is then held over the chuck till the whole mixture is liquid ; the work is chucked, and placed under a weight for half an hour, when it may be put into the lathe. (d) Rosin, 1 parts ; pitch, 1 part ; melted ; to the mass, is added brickdust, till the desired consistence is attained.