A GOLD PLATE FOR SMALL ARTICLES, WITHOUT A BATTERY.—Digest a small fragment of gold with about ten times its weight of mercury until it is dissolved, shake the amalgam together in a bottle, and after cleansing the articles, coat them uniformly with the amalgam. Then expose them on an iron tray heated to low redness for a few minutes. The mercury volatilizes, leaving the gold attached as a thin coating to the article. The heating should be done in a stove, so that the poisonous mercurial fumes may pass up the chimney.
A GELATINE MOULD FOR CASTING PLASTER ORNAMENTS.—Allow twelve ounces of Gelatine to soak for a few hours in water, until it has absorbed as much as it can, then apply heat, by which it will liquify. If the mould is required to be elastic, add three ounces of Treacle, and mix well with the Gelatine. If a little Chrome Alum (precise proportions are immaterial) be added to the Gelatine, it causes it to lose its property of being again dissolved in water. A saturated solution of Bichromate of Potash brushed over the surface of the mould, allowed to become dry and afterwards exposed to sunlight for a few minutes, renders the surface so hard as to be unaffected by moisture.
IMITATION OF GROUND GLASS.—The following is from an Antwerp scientific journal. Paint the glass with the following varnishes: Sandarac eighteen drachms, Mastic four drachms, Ether twenty-four ounces, Benzine six to eighteen ounces. The more Benzine the coarser the grain of imitation glass will be.
UNSHRINKABLE PATTERNS.—The best mixture for small patterns, that does not shrink in casting, is sixty-nine parts Lead, fifteen and one-half parts Antimony, fifteen and one-half parts Bismuth, by weight. A cheap kind for finished patterns can be made of ten parts Zinc, one part Antimony, one part Tin.
TO MAKE ARTIFICIAL MARBLE FOR PAPER WEIGHTS OR OTHER FANCY ARTICLES.—Soak Plaster of Paris in a solution of Alum, bake it in an over, and then grind it to a powder. In using mix it with water, and to produce the clouds and veins stir in any dry color you wish; this will become very hard, and is susceptible of a very high polish.
MOLDS OF GLUE AND MOLASSES, SUCH AS RODGERS USES FOR MAKING HIS STATUETTES.—The flexible moulds referred to are prepared as follows: Glue eight pounds, Molasses (New Orleans) seven pounds. Soak the Glue over night in a small quantity of cold water, then melt it by heat over a salt water bath, stir until froth begins to rise, then add and stir in briskly the Molasses previously heated. Continue to heat and stir the mixture for about half an hour; then pour.
TO CLARIFY LIQUIDS.—The following composition is said to bleach all colored liquids, and to render bone-black perfectly unnecessary: Albumen three hundred, Neutral Tartrate of Potash two, Alum five, Sal Ammoniac seven hundred parts. The Albumen must of course not be coagulated. The ingredients are first dissolved in a little water and then added to the liquid to be clarified.
TO PREVENT STORE WINDOWS FROM STEAMING.—J. F. writes: I am about to have the front show windows of my store inclosed with inside windows. Can you tell any way to prevent the outside windows frosting in cold weather? A. Clean the glass occasionally with a cloth moistened with pure Glycerine, wiping it so as to leave only a trace of the Glycerine adhering to the surface—this on the inside.
ARTIFICIAL INDIA RUBBER.—A cheap and useful substitute for Indian rubber is prepared by mixing a thick solution of Glue with Tungstate of Soda and Hydrochloric Acid. A compound of Tungstic Acid and Glue is precipitated, which at a temperature of 86 degrees to 104 degrees F. is sufficiently elastic to admit of being drawn out into very thin sheets. On cooling this mass becomes solid and brittle, but on being heated is again soft and plastic. This new compound can be used for many of the purposes to which rubber is adapted.
RUBBER STAMPS FOR PHOTOGRAPHS.—Many photographers employ a rubber stamp for imprinting the backs of mounts, and in these circumstances a good ink is very essential. Here is the recipe for making one quoted from the Engineer, and said to yield an excellent ink which, while not drying on the pad, will yet not readily smear when impressed upon paper: Aniline Red (Violet) one hundred and eighty grains, distilled Water two ounces, Glycerine one teaspoonful, Treacle one-half teaspoonful. The crystals of Aniline are powdered and dissolved in the boiling distilled water, and the other ingredients then added.