Part 70

III.—A mixture of 338 parts of sodium phosphate and 124 parts of boracic acid is used when the metal is at dark-red heat. The metal is then to be brought to a bright-red heat, and hammered at the same time. The metal easily softens at a high temperature, and a wooden mallet is best. All substances containing carbon should be removed from the surface, as success depends upon the formation of a fusible copper phosphate, which dissolves a thin layer of oxide on the surface, and keeps the latter in good condition for welding.

«To Recover Gold-Leaf Waste.»—To recover the gold from color waste, gold brushes, rags, etc., they are burned up to ashes. The ashes are leached with boiling water containing hydrochloric acid. The auriferous residuum is then boiled with aqua regia (1 part nitric acid and 3 parts hydrochloric acid), whereby the gold is dissolved and gold chloride results. After filtration and evaporation to dryness the product is dissolved in water and precipitated with sulphate of protoxide of iron. The precipitated gold powder is purified with hydrochloric acid.

«Gold from Acid Coloring Baths.»—I.—Different lots are to be poured together {382} and the gold in them recovered. The following method is recommended: Dissolve a handful of phosphate of iron in boiling water, to which liquor add the coloring baths, whereby small particles of gold are precipitated. Then draw off the water, being careful not to dissolve the auriferous sediment at the bottom. Free this from all traces of acid by washing with plenty of boiling water; it will require 3 or 4 separate washings, with sufficient time between each to allow the water to cool and the sediment to settle before pouring off the water. Then dry in an iron vessel by the fire and fuse in a covered skittlepot with a flux.

II.—The collected old coloring baths are poured into a sufficiently large pot, an optional quantity of nitro-muriatic acid is added, and the pot is placed over the fire, during which time the fluid is stirred with a wooden stick. It is taken from the fire after a while, diluted largely with rain water and filtered through coarse paper. The gold is recovered from the filtered solution with a solution of green vitriol which is stored in air-tight bottles, then freshened with hot water, and finally smelted with borax and a little saltpeter.

«Parting with Concentrated Sulphuric Acid.»—It is not necessary scrupulously to observe the exact proportion of the gold to the silver. After having prepared the auriferous silver, place it in a quantity of concentrated sulphuric acid contained in a porcelain vessel, and let it come to a violent boil. When the acid has either become saturated and will dissolve no more, or when solution is complete, remove the dissolving vessel from the fire, let it cool, and, for the purpose of clarifying, pour dilute sulphuric acid into the solution. The dissolved silver is next carefully decanted from the gold sediment upon the bottom, another portion of concentrated acid is poured in, and the gold is well boiled again, as it will still contain traces of silver; this operation may be repeated as often as is deemed necessary. The solution, poured into the glass jars, is well diluted with water, and the silver is then precipitated by placing a sheet of copper in the solution. The precipitate is then freshened with hot water, which may also be done by washing upon the filter; the granulated silver (sulphate of silver) is pressed out in linen, dried and smelted. The freshened gold, after drying, is first smelted with bisulphate of soda, in order to convert the last traces of silver into sulphate, and then smelted with borax and a little saltpeter.

«To Remove Gold from Silver.»—I.—Gold is taken from the surface of silver by spreading over it a paste, made of powdered sal ammoniac with aqua fortis and heating it till the matter smokes and is nearly dry, when the gold may be separated by rubbing it with the scratch brush.

II.—The alloy is to be melted and poured from a height into a vessel of cold water, to which a rotary motion is imparted, or else it is to be poured through a broom. By this means the metal is reduced to a fine granular condition. The metallic substance is then treated with nitric acid, and gently heated. Nitrate of silver is produced, which can be reduced by any of the ordinary methods; while metallic gold remains as a black sediment, which must be washed and melted.

«Simple Specific Gravity Test.»—A certain quantity of the metal is taken and drawn out into a wire, which is to be exactly of the same length as one from fine silver; of course, both must have been drawn through the same hole, silver being nearly 1⁠/⁠2 lighter than gold, it is natural that the one of fine silver must be lighter, and the increased weight of the wire under test corresponds to the percentage of gold contained in it.

«To Make Fat Oil Gold Size.»—First thin up the fat oil with turpentine to workable condition; then mix a little very finely ground pigment with the gold size, about as much as in a thin priming coat. Make the size as nearly gold color as is convenient; chrome yellow tinted with vermilion is as good as anything for this purpose. Then thin ready for the brush with turpentine, and it will next be in order to run the size through a very fine strainer. Add japan, as experience or experiment may teach, to make it dry tacky about the time the leaf is to be laid. Dry slowly, because the slower the size dries, the longer it will hold its proper tackiness when it is once in that condition.

«To Dissolve Copper from Gold Articles.»—Take 2 ounces of proto-sulphate of iron and dissolve it in 1⁠/⁠2 a pint of water, then add to it in powder 2 ounces of nitrate of potash; boil the mixture for some time, and afterwards pour it into a shallow vessel to cool and crystallize; then to every part of the crystallized salt add 8 ounces of muriatic acid, and preserve in a bottle for use. Equal parts of the above preparation and of boiling water is a good proportion to use in dissolving copper, or 1 part by weight {383} of nitric acid may be used to 4 parts by weight of boiling water as a substitute.

«GOLD PURPLE.»

I.—The solution of stannous chloride necessary for the preparation of gold purple is produced by dissolving pure tin in pure hydrochloric acid (free from iron), in such a manner that some of the tin remains undissolved, and evaporating the solution, into which a piece of tin is laid, to crystallization.

II.—Recipe for Pale Purple.—Dissolve 2 parts by weight of tin in boiling aqua regia, evaporate the solution at a moderate heat until it becomes solid, dissolve in distilled water and add 2 parts by weight of a solution of stannous chloride (specific gravity 1.7) dilute with 9,856 parts by weight of water, stir into the liquid a solution of gold chloride prepared from 0.5 parts by weight of gold and containing no excess of acid (the latter being brought about by evaporating the solution of gold chloride to dryness and heating for some time to about 320° F.). This liquid is dimmed by the admixture of 50 parts by weight of liquid ammonia which eliminates the purple. The latter is quickly filtered off, washed out and while still moist rubbed up with the glass paste. This consists of enamel of lead 20 parts by weight; quartzose sand, 1 part by weight; red lead, 2 parts by weight; and calcined borax, 1 part by weight, with silver carbonate, 3 parts by weight.

III.—Recipe for Dark Gold Purple.—Gold solution of 0.5 parts by weight of gold, solution of stannous chloride (specific gravity 1.7) 7.5 parts by weight; thin with 9,856 parts by weight of water, separate the purple by a few drops of sulphuric acid, wash out the purple and mix same with enamel of lead 10 parts by weight and silver carbonate, 0.5 parts by weight.

IV.—Recipe for Pink Purple.—Gold solution of 1 part by weight of gold; solution of 50 parts by weight of alum in 19,712 parts by weight of water; add 1.5 parts by weight of stannous chloride solution (specific gravity 1.7) and enough ammonia until no more precipitate is formed; mix the washed out precipitate, while still moist, with 70 parts by weight of enamel of lead and 2.5 parts by weight of silver carbonate. According to the composition of the purple various reds are obtained in fusing it on; the latter may still be brightened up by a suitable increase of the flux.

«To Render Pale Gold Darker.»—Take verdigris, 50 parts by weight and very strong vinegar, 100 parts by weight. Dissolve the verdigris in the vinegar, rub the pieces with it well, heat them and dip them in liquid ammonia diluted with water. Repeat the operation if the desired shade does not appear the first time. Rinse with clean water and dry.

«To Color Gold.»—Gilt objects are improved by boiling in the following solution: Saltpeter, 2 parts by weight; cooking salt, 1 part by weight; alum, 1 part by weight; water, 24 parts by weight; hydrochloric acid, 1 part by weight (1.12 specific gravity). In order to impart a rich appearance to gilt articles, the following paste is applied: Alum, 3 parts by weight; saltpeter, 2 parts by weight; zinc vitriol, 1 part by weight; cooking salt, 1 part by weight; made into a paste with water. Next, heat until black, on a hot iron plate, wash with water, scratch with vinegar and dry after washing.

«Gold-Leaf Striping.»—To secure a good job of gilding depends largely for its beauty upon the sizing. Take tube chrome yellow ground in oil, thin with wearing body varnish, and temper it ready for use with turpentine. Apply in the evening with an ox-tail striper, and let it stand until the next morning, when, under ordinary circumstances, it will be ready for the gold leaf, etc. After the gilding is done, let the job stand 24 hours before varnishing.

«Composition of Aqua Fortis for the Touch-Stone.»—Following are the three compositions mostly in use: I.—Nitric acid, 30 parts; hydrochloric acid, 3 parts; distilled water, 20 parts.

II.—Nitric acid, 980 parts by weight; hydrochloric acid, 20 parts by weight.

III.—Nitric acid, 123 parts by weight; hydrochloric acid, 2 parts by weight.

«To Remove Soft Solder from Gold.»—Place the work in spirits of salts (hydrochloric acid) or remove as much as possible with the scraper, using a gentle heat to remove the solder more easily.

«Tipping Gold Pens.»—Gold pens are usually tipped with iridium. This is done by soldering very small pieces to the points and filing to the proper shape.

«To Recognize Whether an Article is Gilt.»—Simply touch the object with a glass rod previously dipped into a solution of bichloride of copper. If the article has been gilt the spot touched should remain intact, while it presents a {384} brown stain if no gold has been deposited on its surface.

«To Burnish Gilt Work.»—Ale has proved a very good substitute for soap and water in burnishing gilt as it increases the ease and smoothness with which it is accomplished. Vinegar is a somewhat poorer substitute for ale.

«White-Gold Plates Without Solder.»—The gold serving as a background for white-gold is rolled in the desired dimensions and then made perfectly even under a powerful press. It is then carefully treated with a file until a perfectly smooth surface is obtained. After a white-gold plate of the required thickness has been produced in the same manner, the surfaces of the two plates to be united are coated with borax and then pressed together by machine, which causes the harder metal to be squeezed slightly into the surface of the other, furnishing a more solid and compact mass. The metals, now partially united, are firmly fastened together by means of strong iron wire and a little more borax solution is put on the edges. Then heat to the temperature necessary for a complete adhesion, but the heat must not be so great as to cause an alloyage by fusing. The whole is finally rolled out into the required thickness.

«To Fuse Gold Dust.»—Use such a crucible as is generally used for melting brass; heat very hot; then add the gold dust mixed with powdered borax; after some time a scum or slag will be on top, which may be thickened by the addition of a little lime or bone ash. If the dust contains any of the more oxidizable metals, add a little niter, and skim off the slag or scum very carefully; when melted, grasp the crucible with strong iron tongs, and pour off immediately into molds, slightly greased. The slag and crucibles may be afterwards pulverized, and the auriferous matter recovered from the mass through cupellation by means of lead.

GOLD ALLOYS: See Alloys.

GOLD, EXTRACTION OF, BY AMALGAMATION: See Amalgams.

GOLD LETTERS ON GLASS, CEMENTS FOR AFFIXING: See Adhesives, under Sign-Letter Cements.

GOLD, REDUCTION OF OLD PHOTOGRAPHIC: See Photography.

GOLD FOIL SUBSTITUTES AND GOLD LEAF: See Metal Foil.

GOLD-LEAF ALLOYS: See Alloys.

GOLD LEAF AND ITS APPLICATION: See Paints.

GOLD PLATING: See Plating.

GOLD, RECOVERY OF WASTE: See Jewelers’ Formulas.

GOLD RENOVATOR: See Cleaning Preparations and Methods.

GOLD, SEPARATION OF PLATINUM FROM: See Platinum.

GOLD SOLDERS: See Solders.

GOLD TESTING: See Jewelers’ Formulas.

GOLD VARNISH: See Varnishes.

GOLDWASSER: See Wines and Liquors.

GONG METAL: See Alloys.

«GRAIN.»

«Formalin Treatment of Seed Grain for Smut.»—Smut is a parasitic fungus, and springs from a spore (which corresponds to a seed in higher plants). This germinates when the grain is seeded and, penetrating the little grain plant when but a few days old, grows up within the grain stem. After entering the stem there is no evidence of its presence until the grain begins to head. At this time the smut plant robs the developing kernels of their nourishment and ripens a mass of smut spores.

These spores usually ripen before the grain, and are blown about the field, many spores becoming lodged on the ripening grain kernels. The wholesale agent of infection is the threshing machine. For this reason the safest plan is to treat all seed wheat and oats each year.

Secure a 40 per cent solution of formalin (the commercial name for formaldehyde gas held in a water solution). About 1 ounce is required for every 5 bushels of grain to be treated. {385}

Clean off a space on the barn floor or sweep a clean space on the hard level ground and lay a good-sized canvas down, on which to spread out the wheat. See that the place where the grain is to be treated is swept clean and thoroughly sprinkled with the formalin solution before placing the seed grain there.

Prepare the formalin solution immediately before use, as it is volatile, and if kept may disappear by evaporation.

Use 4 ounces of formalin for 10 gallons of water. This is sufficient for 600 pounds of grain. Put the solution in a barrel or tub, thoroughly mixing.

The solution can be applied with the garden sprinkler. Care must be taken to moisten the grain thoroughly. Sprinkle, stir the grain up thoroughly and sprinkle again, until every kernel is wet.

After sprinkling, place the grain in a conical pile and cover with horse-blankets, gunny sacks, etc. The smut that does the damage lies just under the glume of the oats or on the basal hairs of the wheat. Covering the treated grain holds the gas from the formalin _within_ the pile, where it comes in contact with the kernels, killing such smut spores as may have survived the previous treatment. After the grain has remained in a covered pile 2 to 4 hours, spread it out again where the wind can blow over it, to air and dry.

As soon as the grain can be taken in the hand without the kernels sticking together, it can be sown in the field. The grain may be treated in the forenoon and seeded in the afternoon.

Since this treatment swells the kernels it hastens germination and should be done in the spring just before seeding time.

While the copper sulphate or bluestone treatment is valuable in killing smut, the formalin treatment can be given in less time, is applied so easily and is so effectual that it is recommended as a sure and ready means of killing smut in wheat and oats.

GRAINING CRAYONS: See Crayons.

GRAINING COLORS: See Pigments.

GRAINING WITH PAINT: See Paint.

GRAINING, PALISANDER: See Palisander.

GRAPE JUICE, PRESERVATION OF: See Wines and Liquors.

GRAPHITE AS A LUBRICANT: See Lubricants.

«GRAVEL WALKS.»

For cleaning gravel walks any of the following may be used: I.—Gas-tar liquor.

II.—Rock salt (cattle salt).

III.—Hydrochloric acid.

IV.—Sulphuric acid.

V.—Fresh limewater. The gas-tar liquor must be poured out a few times in succession, and must not touch the tree roots and borders of the paths. This medium is cheap. Cattle salt must likewise be thrown out repeatedly. The use of hydrochloric and sulphuric acids is somewhat expensive. Mix 60 parts of water with 10 parts of unslaked lime and 1 part of sulphuric acid in a kettle, and sprinkle the hot or cold mixture on the walks by means of a watering pot. If limewater is used alone it must be fresh—1 part of unslaked lime in 10 parts of water.

«GRAVERS:»

«To Prepare Gravers for Bright-Cutting.»—Set the gravers after the sharpening on the oilstone on high-grade emery (tripoli) paper. Next, hone them further on the rouge leather, but without tearing threads from it. In this manner the silver and aluminum engravers grind their gravers. A subsequent whetting of the graver on the touchstone is not advisable, since it is too easily injured thereby. A graver prepared as described gives excellent bright engraving and never fails.

In all bright-cutting the graver must be highly polished; but when bright-cutting aluminum a lubricant like coal-oil or vaseline is generally employed with the polished tool; a mixture of vaseline and benzine is also used for this purpose. Another formula which may be recommended for bright-cutting aluminum is composed of the following ingredients: Mix 4 parts of oil of turpentine and 1 part of rum with 1 ounce of stearine. Immerse the graver in any of the mixtures before making the bright-cut.

GREASES: See Lubricants.

GREASE ERADICATORS: See Cleaning Preparations and Methods. {386}

GREASE PAINTS: See Cosmetics.

GREEN, TO DISTINGUISH BLUE FROM, AT NIGHT: See Blue.

GREEN GILDING: See Plating.

GRENADES: See Fire Extinguishers.

GRINDING: See Tool Setting.

GRINDER DISK CEMENT, SUBSTITUTE FOR: See Adhesives.

«GRINDSTONES:»

«To Mend Grindstones.»—The mending of defective places in grindstones is best done with a mass consisting of earth-wax (so-called stone-pitch), 5 parts, by weight; tar, 1 part; and powdered sandstone or cement, 3 parts, which is heated to the boiling point and well stirred together. Before pouring in the mass the places to be mended must be heated by laying red-hot pieces of iron on them. The substance is, in a tough state, poured into the hollows of the stone, and the pouring must be continued, when it commences to solidify, until even with the surface.

«Treatment of the Grindstone.»—The stone should not be left with the lower part in the water. This will render it brittle at this spot, causing it to wear off more quickly and thus lose its circularity. It is best to moisten the stone only when in use, drop by drop from a vessel fixed above it and to keep it quite dry otherwise. If the stone is no longer round, it should be made so again by turning by means of a piece of gas pipe or careful trimming, otherwise it will commence to jump, thus becoming useless. It is important to clean all tools and articles before grinding, carefully removing all grease, fat, etc., as the pores of the stone become clogged with these impurities, which destroy its grain and diminish its strength. Should one side of the grindstone be lighter, this irregularity can be equalized by affixing pieces of lead, so as to obtain a uniform motion of the stone. It is essential that the stone should be firm on the axis and not move to and fro in the bearings.

«Grindstone Oil.»—Complaints are often heard that grindstones are occasionally harder on one side than the other, the softer parts wearing away in hollows, which render grinding difficult, and soon make the stone useless. This defect can be remedied completely by means of boiled linseed oil. When the stone is thoroughly dry, the soft side is turned uppermost, and brushed over with boiled oil, which sinks into the stone, until the latter is saturated. The operation takes about 3 to 4 hours in summer. As soon as the oil has dried, the stone may be damped, and used without any further delay. Unlike other similar remedies, this one does not prevent the stone from biting properly in the oiled parts, and the life of the stone is considerably lengthened, since it does not have to be dressed so often.

GROUNDS FOR GRAINING COLORS: See Pigments.

«GUMS:»

(See also Adhesives, under Mucilages.)

«Gums, their Solubility in Alcohol.»—The following table shows the great range of solubility of the various gums, and of various specimens of the same gum, in 60 per cent alcohol:

Acajon 6.94 to 42.92 Aden 0.60 to 26.90 Egyptian 46.34 Yellow Amrad 26.90 to 32.16 White Amrad 0.54 to 1.50 Kordofan 1.40 to 6.06 Australian 10.67 to 20.85 Bombay 22.06 to 46.14 Cape 1.67 to 1.88 Embavi 25.92 Gedda 1.24 to 1.30 Ghatti 31.60 to 70.32 Gheziereh 1.50 to 12.16 Halebi 3.70 to 22.60 La Plata 9.65 Mogadore 27.66 East Indian 3.24 to 74.84 Persian 1.74 to 17.34 Senegal 0.56 to 14.30

«Substitute for Gum Arabic.»—Dissolve 250 parts of glue in 1,000 parts of boiling water and heat this glue solution on the water bath with a mixture of about 10 parts of barium peroxide of 75 per cent BaO_〈2〉 and 5 parts of sulphuric acid (66°) mixed with 115 parts of water, for about 24 hours. After the time has elapsed, pour off from the barium sulphate, whereby a little sulphurous acid results owing to reduction of the sulphuric acid, which has a bleaching action and makes the glue somewhat paler. If this solution is mixed, with stirring, and dried upon glass plates in the drying-room, a product which can hardly be {387} distinguished from gum arabic is obtained. An envelope sealed with this mucilage cannot be opened by moistening the envelope. The traces of free acid which it contains prevent the invasion of bacteria, hence all putrefaction.

The adhesive power of the artificial gum is so enormous that the use of cork stoppers is quite excluded, since they crumble off every time the bottle is opened, so that finally a perfect wreath around the inner neck of the bottle is formed. Only metallic or porcelain stoppers should be used.

GUM ARABIC, INCREASING ADHESION OF: See Adhesives, under Mucilages.

GUM BICHROMATE PROCESS: See Photography.

GUM DROPS: See Confectionery.

GUM-LAC: See Oil.

GUMS USED IN MAKING VARNISH: See Varnishes.

GUN BARRELS, TO BLUE: See Steel.

GUN BRONZE: See Alloys, under Phosphor Bronze.

GUN COTTON: See Explosives.

GUN LUBRICANTS: See Lubricants.

GUNPOWDER: See Explosives.

«GUNPOWDER STAINS.»

A stain produced by the embedding of grains of gunpowder in the skin is practically the same thing as a tattoo mark. The charcoal of the gunpowder remains unaffected by the fluids of the tissues, and no way is known of bringing it into solution there. The only method of obliterating such marks is to take away with them the skin in which they are embedded. This has been accomplished by the application of an electric current, and by the use of caustics. When the destruction of the true skin has been accomplished, it becomes a foreign body, and if the destruction has extended to a sufficient depth, the other foreign body, the coloring matter which has been tattooed in, may be expected to be cast off with it.