Part 297

«To Test Grease.»—To be assured of the purity of grease, its density is examined as compared with water; a piece of fat of the size of a pea is placed in a glass of water. If it remains on the surface or sinks very slowly the fat is pure; if it sinks rapidly to the bottom the fat is mixed with heavy matters and coom is the result.

LUBRICANTS FOR WATCHMAKERS: See Watchmakers’ Formulas.

LUPULINE BITTERS: See Wines and Liquors.

«LUSTER PASTE.»

This is used for plate glass, picture frames, and metal. Five parts of very finely washed and pulverized chalk; 5 parts of Vienna lime, powdered; 5 parts of bolus, powdered; 5 parts of wood ashes, powdered; 5 parts of English red, powdered; 5 parts of soap powder. Work all together in a kneading machine, to make a smooth, even paste, adding spirit. The consistency of the paste can be varied, by varying the amount of spirit, from a solid to a soft mass.

LUTES: See Adhesives.

MACHINE OIL: See Lubricants.

MACHINERY, TO CLEAN: See Cleaning Preparations and Methods.

MAGIC: See Pyrotechnics.

«MAGNESIUM CITRATE.»

Magnesium carbonate 10 ounces Citric acid 20 ounces Sugar 21 ounces Oil of lemon 1⁠/⁠2 drachm Water enough to make 240 ounces

Introduce the magnesium carbonate into a wide-mouthed 2-gallon bottle, drop the oil of lemon on it, stir with a wooden stick: then add the citric acid, the sugar, and water enough to come up to a mark on the bottle indicating 240 ounces. For this purpose use cold water, adding about half of the quantity first, and the remainder when the substances are mostly dissolved. By allowing the solution to stand for a half to a whole day, it will filter better and more quickly than when hot water is used.

MAGNESIUM ORGEAT POWDER: See Salts, Effervescent.

MAGNESIUM FLASH-LIGHT POWDERS: See Photography.

«MAGNETIC CURVES OF IRON FILINGS, THEIR FIXATION.»

One of the experiments made in every physical laboratory in teaching the elements of magnetism and electricity is the production of the magnetic curves by sprinkling iron filings over a glass plate, after the well-known method.

For fixing these curves so that they may be preserved indefinitely, a plate of glass is warmed on the smooth upper surface of a shallow iron chest containing water raised to a suitable temperature by means of a spirit-lamp. A piece of paraffine is placed on the glass, and in the course of 3 or 4 minutes spreads itself evenly in a thin layer over the surface. The glass plate is removed, the surplus paraffine running off. The image is formed with iron filings on the cooled paraffine, which does not adhere to the iron, so that if the image is unsatisfactory the filings may be removed and a new figure taken. To fix the curves, the plate of glass is again placed on the warming stove. Finally, the surface of the paraffine is covered with white paint, so that the curves appear black on a white ground. Very well-defined figures may thus be obtained. A similar though much simpler process consists in covering one surface of stiff white paper with a layer of paraffine, by warming {465} over an iron plate, spreading the filings over the cooled surface, and fixing them with a hot iron or a gas flame.

MAGNOLIA METAL: See Alloys.

MAHOGANY: See Wood.

MALTED FOOD: See Foods.

MALTED MILK: See Milk.

MALT, HOT: See Beverages.

MANGANESE ALLOYS: See Alloys.

MANGANESE STEEL: See Steel.

MANGE CURES: See Veterinary Formulas.

MANICURE PREPARATIONS: See Cosmetics.

«MANTLES.»

These are prepared after processes differing slightly from one another, but all based on the original formula of Welsbach—the impregnation of vegetable fibers with certain mineral oxides in solution, drying out, and arranging on platinum wire.