Part 240

GLAZES FOR LAUNDRY: See Laundry Preparations.

GLOBES, HOW TO COLOR: See Glass-Coloring.

GLOBES, PERCENTAGE OF LIGHT ABSORBED BY: See Light.

GLOBES, SILVERING OF: See Mirrors.

GLOSS FOR PAPER: See Paper.

GLOVE-CLEANERS: See Cleaning Compounds.

GLOVES, SUBSTITUTE FOR RUBBER: See Antiseptics.

GLOVES, TESTING: See Rubber.

GLUCOSE IN JELLY: See Foods.

«Glue»

(Formulas for Glues and methods of manufacturing Glue will be found under Adhesives.)

«Rendering Glue Insoluble in Water.»—Stuebling finds that the usual mixture of bichromate and glue when used in the ordinary way does not possess the waterproof properties with which it is generally credited. If mixed in the daylight, it sets hard before it can be applied to the surfaces to be glued, and if mixed and applied in the dark room it remains just as soluble as ordinary glue, the light being unable to penetrate the interior of the joints. Neither is a mixture of linseed oil and glue of any use for this purpose. Happening to upset a strong solution of alum—prepared for wood staining—into an adjacent glue pot, he stirred up the two together out of curiosity and left them. Wishing to use the glue a few days later, he tried to thin it down with water, but unsuccessfully, the glue having set to a waterproof mass. Fresh glue was then mixed with alum solution and used to join two pieces of wood, these resisting the action of the water completely.

«To Bleach Glue.»—Dissolve the glue in water, by heat, and while hot, add a mixture in equal parts of oxalic acid and zinc oxide, to an amount equal to about 1 per cent of the glue. After the color has been removed, strain through muslin.

«Method of Purifying Glue.»—The glue is soaked in cold water and dissolved in a hot 25 per cent solution of magnesium sulphate. The hot solution is filtered, and to the filtrate is added a 25 per cent solution of magnesium sulphate containing 0.5 per cent of hydrochloric acid (or, if necessary, sulphuric acid). A white flocculent precipitate is obtained which is difficult to filter. The remainder of the glue in the saline solution is extracted by treatment with magnesium sulphate.

The viscous matter is washed, then dissolved in hot water, and allowed to cool, a quantity of weak alcohol acidulated by 1 per cent of hydrochloric acid being added just before the mass solidifies. From 2 to 3 parts, by volume, of strong alcohol (methyl or ethyl) are then added and the solution filtered, charcoal being used if necessary. The glue is finally precipitated from this solution by neutralizing with ammonia and washing with alcohol or water.

«To Distinguish Glue and Other Adhesive Agents.»—The product to be examined is heated with hydrofluoric acid (50 per cent). If bone glue is present in any reasonable quantity, an intense odor of butyric acid arises at once, similar to that of Limburger cheese. But if dextrin or gum arabic is present, only an odor of dextrine or fluorhydric acid will be perceptible. Conduct the reaction with small quantities; otherwise the smell will be so strong that it is hard to remove from the room.

GLUE CLARIFIER: See Gelatin.

«Glycerine»

«Recovering Glycerine from Soap Boiler’s Lye.»—I.—Glycerine is obtained as a by-product in making soap. For many years the lyes were thrown away as waste, but now considerable quantities of glycerine are recovered, which are much used in making explosive compounds.

When a metallic salt or one of the alkalies, as caustic soda, is added to tallow, a stearite of the metal (common soap is stearite of sodium) is formed, whereby the glycerine is eliminated. {379} This valuable by-product is contained in the waste lye, and has formed the subject of several patents.

Draw the lye off from the soap-pans; this contains a large quantity of water, some salt and soap and a small quantity of glycerine, and the great trouble is to concentrate the lye so that the large quantity of water is eliminated, sometimes 10 to 12 days being occupied in doing this. The soap and salt are easily removed.

To remove the soap, run the lye into a series of tanks alternating in size step-like, so that as the first, which should be the largest, becomes full, the liquor will flow into the second, from that into the third, and so on; by this arrangement the rosinous and albuminous matters will settle, and the soap still contained in the lyes will float on the surface, from which it is removed by skimming.

After thus freeing the lye of the solid impurities, convey the purified lye to the glycerine recovering department (wooden troughs or pipes may be used to do this), and after concentrating by heating it in a steam-jacketed boiler, and allowing it to cool somewhat, ladle out the solid salt that separates, and afterwards concentrate the lye by allowing it to flow into a tank, but before doing so let the fluid come in contact with a hot blast of air or superheated steam, whereby the crude discolored glycerine is obtained. This is further purified by heating with animal charcoal to decolorize it, then distilling several times in copper stills with superheated steam. The chief points to attend to are: (1) The neutralizing and concentrating the lye as much as possible and then separating the salts and solid matters; (2) concentrating the purified lye, and mixing this fluid with oleic acid, oil, tallow, or lard, and heating the mixture to 338° F., in a still, by steam, and gradually raise the heat to 372° F.; (3) stirring the liquor while being heated, and allowing the aqueous vapor to escape, and when thus concentrated, saponifying the liquid with lime to eliminate the glycerine; water is at the same time expelled, but this is removed from the glycerine by evaporating the mixture.

II.—In W. E. Garrigues’s patent for the recovering of glycerine from spent soap lyes, the liquid is neutralized with a mineral acid, and after separation of the insoluble fatty acids it is concentrated and then freed from mineral salts and volatile fatty acids, and the concentrated glycerine solution treated with an alkaline substance and distilled. Thus the soap lye may be neutralized with sulphuric acid, and aluminum sulphate added to precipitate the insoluble fatty acids. The filtrate from these is concentrated and the separated mineral salts removed, after which barium chloride is added and then sufficient sulphuric acid to liberate the volatile fatty acids combined with the alkali. These acids are partially enveloped in the barium sulphate, with which they can be separated from the liquid by filtration, while the remaining portion can be expelled by evaporating the liquid in a vacuum evaporator. Finally, the solution is treated with sodium carbonate, and the glycerine distilled.

Glycerine Lotion.—

Glycerine 4 ounces Essence bouquet 1⁠/⁠4 ounce Water 4 ounces Cochineal coloring, a sufficient quantity.

(See also Cosmetics for Glycerine Lotions.)

GLYCERINE APPLICATIONS: See Cosmetics.