A Select Collection of Valuable and Curious Arts and Interesting Experiments, / Which are Well Explained and Warranted Genuine and may be Performed Easily, Safely, and at Little Expense.

by Unknown

7. To give wood a gold, silver, or copper lustre.—Grind about two ounces of white beach sand in a gill of water, in which half an ounce of gum-arabic has been dissolved, and brush over the work with it. When this is dry, the work may be rubbed over with a piece of gold, silver or copper, and will in a measure, assume their respective colours and brilliancy. This work may be polished by a flint burnisher, but should not be varnished.

8. To print gold letters on morocco.—First wet the morocco with the whites of eggs; when this is dry, rub the work over with a little olive oil, and lay on gold leaves. Then take some common printing types, and heat them to the temperature of boiling water, and impress the letters on the gold;—rub the whole with a piece of flannel, and the superfluous gold will come off, leaving the letters handsomely gilt. Another method is, to strew powdered rosin over the morocco previous to laying on the leaf; the heat of the types melts the rosin, which occasions the gold to adhere in the impressions, while the other may be brushed off.

9. To dye silk a brilliant gold colour.—Take any quantity of nitro-muriate of gold, (see 5) and evaporate by exposing it to a gentle heat in a glass tumbler or phial; the gold will form itself in crystals on the bottom and sides of the vessel; collect these crystals and dissolve them in ten times their weight of pure water. Then put a gill of water into a common flask, and add one ounce of granulated zinc, and one-fourth of an ounce of sulphuric acid. Hydrogen gas will be evolved, and rise through the neck of the flask, which must not be stopped. Immerse a piece of white silk in the above mentioned aqueous solution of gold, and expose it, while wet, to the current of gas as it rises from the flask; the gold will soon be revived, and the silk will become beautifully and permanently gilt. Any letters or flowers may be drawn on the silk with a camel-hair pencil dipped in the solution, and on being exposed to the action of the gas, will be revived and shine with metallic brilliancy. Note.—The silk must be kept moist with water till the gold is revived. Zinc may be prepared for the above purpose, by melting it, and stirring it continually with a stick or iron rod while it is cooling; or it may be pulverized with a hammer as soon as it becomes solid.

10. To dye silk a brilliant silver colour.—Proceed as directed in the last experiment, only use the nitrate of silver, (see 6) instead of nitro-muriate of gold. The process of crystalizing, re-dissolving, &c. is the same. But the crystals of silver differ in colour, being white, whereas those produced from gold are yellow. If a jar, or box be filled with hydrogen gas, and the silk suspended in it, the action of the gas, and consequently the revivification of the metals will be more uniform. For small figures, however, it may be as well to fix a stopper in the flask, having a small orifice through it, that the gas may be thrown with some force on the silk, and will have a more certain effect. A solution of muriate of tin may be managed in a similar manner, but none of these solutions can be thus revived on paper.

11. To silver looking glasses.—Lay on a smooth board, a piece of soft deer-skin leather, rather larger than the glass that is to be silvered; and on the leather, having sprinkled a little fine whiting, spread a piece of tin foil of the same size. Pour on a few drops of mercury, and brush it over the tin with a smooth brush, till every part of the tin becomes bright. Then add as much mercury as will lay on the tin, and upon this lay the glass to be silvered: on the glass lay another piece of leather, of the same size, and on that another board.—Take up the boards with the glass, and pressing the boards together, turn them with the glass, the other side up; take off the upper board, and pass the glass with the tin and leather, between two rollers, similar to those of a rolling press, for copper-plate printing; thus to press out the mercury from between the tin and the glass. Then place the glass between the boards again as before, and place a heavy weight (which cannot be too heavy, unless it breaks the glass) on the upper board, which must remain two or three days. The glass may then be taken up. The practice of some is, to lay thin paper on the mercury previous to laying on the glass; this paper, being carefully drawn out, after the glass is laid on, serves to remove the superfluous mercury, that the tin may come more nearly in contact with the glass. In this case, no rollers are used. Concave or other fancy glasses may be silvered, by making an impression with the glass, in a kind of putty, made of fine sulphate of lime and water; and placing the glass in the impression again with the tin foil and mercury, when the plaster is dry, and subjecting it to pressure two or three days in that situation. The experiment of silvering glass may be performed by rubbing a drop of mercury on a small piece of tin foil, and pressing it upon a piece of glass with the finger, or a piece of soft leather. In this case, the glass will have acquired the reflective property of a mirror; and if a similar pressure be continued a few hours, the tin will adhere permanently.