Page:The American Cyclopædia (1879) Volume VII.djvu/825

 'GILDING solution made of 100 parts by weight of mer- cury in 110 of nitric acid, of specific gravity 1-33, diluted with 25 times the weight of the whole of pure water. This application leaves a coating of mercury upon the metal, which is more ready to take the amalgam than is the metal itself. Both the mercurial solution and amalgam are sometimes applied together by means of the gilder's scratch brush, which is dipped into the former and immediately rubbed over the latter, and then applied to the metal ; the process being repeated as often as neces- sary. After the application the article is washed in water and exposed to glowing char- coal to expel the mercury. The amalgam is prepared by heating small particles of gold to redness and throwing them into a quantity of mercury heated so as to emit fumes, and stir- ring with an iron rod till the gold is dissolved. There should be about eight times as much mercury as gold, the excess of the former be- ing removed by squeezing the amalgam through buckskin. The composition then contains about 67 parts of mercury to 33 of gold. The gold thus deposited is of a dull yellow, and still re- tains some mercury, which is removed after washing and scrubbing the article with a scratch brush acidulated with vinegar, by applying gilding wax, and again heating. The wax is a mixture of beeswax with some of the following substances, viz. : red ochre, verdigris, copper scales, alum, vitriol, borax. When the wax is burned off, the color of the gilding is found to be improved, and it is still further heightened by burnishing. The amalgamation process is not well adapted for gilding articles of iron and steel, an oxide of iron being produced by the acid applications, which prevents the adhesion of the amalgam. For these the best method is to cover them with gold leaf. Copper may be treated in the same way. The metal is heated till it begins to assume a blue color ; a sheet of gold leaf is then laid on and gently pressed with a burnisher, and the article is again heated. Other sheets are laid over the first to the desired thickness and heated, and the last is burnished down cold. The surface of iron, whether wrought or cast, or of steel, is sometimes covered with a coat of copper. To gild silver, a very good process is that called cold gilding. Sixty grains of fine gold and 1 2 of rose copper are dissolved in two ounces of aqua regia. The whole of the solution is absorbed by linen rags, which are then dried and burned to ashes. The black powder thus obtained is applied upop the silver, which has been annealed and polished, and is rubbed with a piece of moist- ened cork or washed leather. Burnishing com- pletes the process. A method of gilding but- tons and other articles by immersing them in solutions of gold was introduced into the estab- lishment of the Messrs. Elkington, in Birming- ham, in 1836, by which the injurious effects of the amalgamating process on the health of the workmen were avoided. To a solution of chlo- ride of gold prepared from one part of gold, GILES 809 30 parts of bicarbonate of potassa are gradu- ally added, and then 30 parts more of bicar- bonate dissolved in 200 parts of water. The whole is then boiled two hours, and the color of the liquid changes from yellow to green. The articles, being perfectly well cleaned and an- nealed, are immersed for an instant in a mix- ture of equal parts of nitric and sulphuric acids, to which, if the gold is intended to have a dead appearance, a little chloride of sodium is add- ed. The articles, washed in water, are plunged in the gold solution, and left half a minute, when they are removed, again washed, and dried in hot sawdust. Articles of German sil- ver, of platinum, or of silver, may be gilded by suspending them by copper or zinc wires for a time in the liquid. For gilding porcelain or glass, gold precipitated by sulphate of iron is mixed with -^ its weight of oxide of bismuth and a small quantity of borax and gum water, and the mixture is then applied with a camel's hair pencil. The article is heated in a muffle, and when taken out the gold is burnished, and finally cleansed with vinegar or white lead. Vases and articles not exposed to wear may be gilded by fixing gold leaf upon them with copal varnish. Silks or other woven fabrics may be gilded by immersing them in a neutral solution of terchloride of gold, or moistening them with it in design, and then exposing them to the action of hydrogen, which reduces the gold to a metallic state. GILEAD, the name of a mountain group in the eastern division of ancient Palestine. From it the southern districts of the same division were also called Gilead, which is often men- tioned in contradistinction to Bashan in the north, but exceptionally also as including the latter region. This was rich in pastures, and renowned for its aromatic simples, from which balsam was prepared. Among its rivers were the Jabbok and the Arnon. GILES. I. A S. W. county of Virginia, in- tersected by Kanawha or New river; area, 350 sq. m. ; pop. in 1870, 5,875, of whom 598 were colored. The surface is high and rugged, the mean elevation being 1,600 ft. above the sea; the principal summits are Peter's and Walker's mountains. The soil of the uplands is poor, but the valleys and river bottoms are very fertile. The chief productions in 1870 were 53,598 bushels of wheat, 12,633 of rye, 105,402 of Indian corn, 23,474 of oats, and 1,351 tons of hay. There were 1,295 horses, 1,346 milch cows, 2,095 other cattle, 4,471 sheep, and 5,247 swine. Capital, Pearisburg. II. A S. county of Tennessee, bordering on Alabama, watered by Elk river and some of its branches; area, 600 sq. ra. ; pop. in 1870, 32,413, of whom 12,738 were colored. It has a slightly uneven surface and a fertile soil. The chief productions in 1870 were 145,635 bushels of wheat, 2,054,163 of Indian corn, 70,512 of oats, 32,556 of Irish and 28,074 of sweet potatoes, 228,560 Ibs. of butter, 1,644 tons of hay, and 8,367 bales of cotton. There