be in a finely powdered state.
Uniting Glass With Horn.
—(1) A solution of 2 parts of gelatin in 20 parts water is evaporated up to one-sixth of its volume and 1/3 mastic dissolved in 1/2 spirit added and some zinc white stirred in. The putty is applied warm; it dries easily and can be kept a long time. (2) Mix gold size with the equal volume of water glass.
To Cement Glass To Iron.—
| I.— | Rosin | 5 ounces |
|---|---|---|
| Yellow wax | 1 ounce | |
| Venetian red | 1 ounce |
Melt the wax and rosin on a water bath and add, under constant stirring, the Venetian red previously well dried. Stir until nearly cool, so as to prevent the Venetian red from settling to the bottom.
| II.— | Portland cement | 2 ounces |
|---|---|---|
| Prepared chalk | 1 ounce | |
| Fine sand | 1 ounce | |
| Solution of sodium silicate enough to form a semi-liquid paste. | ||
| III.— | Litharge | 2 parts |
| White lead | 1 part | |
Work into a pasty condition by using 3 parts boiled linseed oil, 1 part copal varnish.
Celluloid Cements.
—I.—To mend broken draughting triangles and other celluloid articles, use 3 parts alcohol and 4 parts ether mixed together and applied to the fracture with a brush until the edges become warm. The edges are then stuck together, and left to dry for at least 24 hours.
II.—Camphor, 1 part; alcohol, 4 parts. Dissolve and add equal quantity (by weight) of shellac to this solution.
III.—If firmness is desired in putting celluloid on wood, tin, etc., the following gluing agent is recommended, viz.: A compound of 2 parts shellac, 3 parts spirit of camphor, and 4 parts strong alcohol. {18}
| IV.— | Shellac | 2 ounces |
|---|---|---|
| Spirits of camphor | 2 ounces | |
| Alcohol, 90 per cent | 6 to 8 ounces |
V.—Make a moderately strong glue or solution of gelatin. In a dark place or a dark room mix with the above a small amount of concentrated solution of potassium dichromate. Coat the back of the label, which must be clean, with a thin layer of the mixture. Strongly press the label against the bottle and keep the two in close contact by tying with twine or otherwise. Expose to sunlight for some hours; this causes the cement to be insoluble even in hot water.
| VI.— | Lime | av. oz. 1 |
|---|---|---|
| White of egg | av. oz. 2 1/2 | |
| Plaster of Paris | av. oz. 5 1/2 | |
| Water | fl. oz. 1 |
Reduce the lime to a fine powder; mix it with the white of egg by trituration, forming a uniform paste. Dilute with water, rapidly incorporate the plaster of Paris, and use the cement immediately. The surfaces to be cemented must first be moistened with water so that the cement will readily adhere. The pieces must be firmly pressed together and kept in this position for about 12 hours.
Cementing Celluloid And Hard-rubber Articles.
—I.—Celluloid articles can be mended by making a mixture composed of 3 parts of alcohol and 4 parts of ether. This mixture should be kept in a well-corked bottle, and when celluloid articles are to be mended, the broken surfaces are painted over with the alcohol and ether mixture until the surfaces soften: then press together and bind and allow to dry for at least 24 hours.
II.—Dissolve 1 part of gum camphor in 4 parts of alcohol; dissolve an equal weight of shellac in such strong camphor solution. The cement is applied warm and the parts united must not be disturbed until the cement is hard. Hard-rubber articles are never mended to form a strong joint.
III.—Melt together equal parts of gutta percha and real asphaltum. The cement is applied hot, and the broken surfaces pressed together and held in place while cooling.
Sign-letter Cements.—
| I.— | Copal varnish | 15 parts |
|---|---|---|
| Drying oil | 5 parts | |
| Turpentine (spirits) | 3 parts | |
| Oil of turpentine | 2 parts | |
| Liquefied glue | 5 parts |
Melt all together on a water bath until well mixed, and then add 10 parts slaked lime.
II.—Mix 100 parts finely powdered white litharge with 50 parts dry white lead, knead together 3 parts linseed oil varnish and 1 part copal varnish into a firm dough. Coat the side to be attached with this, removing the superfluous cement. It will dry quickly and become very hard.
| III.— | Copal varnish | 15 parts |
|---|---|---|
| Linseed-oil varnish | 5 parts | |
| Raw turpentine | 3 parts | |
| Oil of turpentine | 2 parts | |
| Carpenters’ glue, dissolved in water | 5 parts | |
| Precipitated chalk | 10 parts | |
| IV.— | Mastic gum | 1 part |
| Litharge, lead | 2 parts | |
| White lead | 1 part | |
| Linseed oil | 3 parts |
Melt together to a homogeneous mass. Apply hot. To make a thorough and reliable job, the letters should be heated to at least the temperature of the cement.
To Fix Gold Letters, Etc., Upon Glass.
—I.—The glass must be entirely clean and polished, and the medium is prepared in the following manner: One ounce fish glue or isinglass is dissolved in water so that the latter covers the glue. When this is dissolved a quart of rectified spirit of wine is added, and enough water is poured in to make up one-quarter the whole. The substance must be kept well corked.
II.—Take 1/2 quart of the best rum and 1/4 ounce fish glue, which is dissolved in the former at a moderate degree of heat. Then add 1/2 quart distilled water, and filter through a piece of old linen. The glass is laid upon a perfectly level table and is covered with this substance to the thickness of 1/8 inch, using a clean brush. Seize the gold leaf with a pointed object and place it smoothly upon the prepared mass, and it will be attracted by the glass at once. After 5 minutes hold the glass slightly slanting so that the superfluous mass can run off, and leave the plate in this position for 24 hours, when it will be perfectly dry. Now trace the letters or the design on a piece of paper, and perforate the lines with a thick needle, making the holes 1/16 inch apart. Then place the perforated paper upon the surface of the glass, and stamp the tracery on with powdered chalk. The paper pattern is then carefully removed, and the accurate design will remain upon the gold. The outlines are now filled out with an oily gold mass, mixed with a little chrome orange and diluted with boiled oil or turpentine. When all is dry the superfluous gold is washed off {19} with water by means of a common rag. The back of the glass is then painted with a suitable color.
Attaching Enamel Letters To Glass.
—To affix enamel letters to glass, first clean the surface of the glass perfectly, leaving no grease or sticky substance of any kind adhering to the surface. Then with a piece of soap sketch the outlines of the design. Make the proper division of the guide lines, and strike off accurately the position each letter is to occupy. Then to the back of the letters apply a cement made as follows: White lead ground in oil, 2 parts; dry white lead, 3 parts. Mix to a soft putty consistency
