Page:The New International Encyclopædia 1st ed. v. 09.djvu/16

* GOLCONDA. 4 GOLCON'DA. A ruined city and fortress in the Nizam's ilcjiiiinions, India, seven miles north- west of Ills capital, Hyderabad, in latitude 17° 22' N., and in longitude 78° 25' E. (Map: India, C 5). The ruins of the ancient city, once the metropolis of the Kingdom of Golconda, the solid mausolca of its former sovereigns, which form a vast group at a distance of 600 yards from and overlooking the fortress, and the for- tress itself, are all of great archaeological im- portance and interest. The fort is now used as a State prison and as the Nizam's treasury. Golconda is proverbially famous for its diamonds, which, however, were merely cut and polished here, being generally found" near the southern frontier of the Nizam's dominions. GOLCONDA. A village and the countj'-seat of Pope Covintv. 111., on the Ohio River. 107 miles be- low Evansv'ille. Ind. (Map: Illinois, D 0) . It is the shipping point for a farming and mining district, and has flour-mills, lumber-mills, cooperage works, etc. Population, in 1S90. 1174; in 1900. 1140. GOLD (AS., OHG. gold, Ger. Gold, Goth. gnlp: connected with AS. geolu, Eng. yellow, Lat. helvus, grayish yellow, Gk. ;t'^"P<*r. cMoros, yellowish green, Skt. hari, yellow). A metallic chemical element, probably the first metal known to man. The alchemists regarded gold as the most perfect metal, compared it to the sun, and designated it by the same symbol by which they represented that orb; their eflorts were con- stantly directe<l toward the transmutation of baser" metals into pure gold. Gold is widely distributed in nature, and is frequently found native, though usually alloyed with silver and containing small quantities of copper or iron; it is also associated with palladium, rhodium, and bisnmth. It is sometimes found crystallized, usually as octahedra or tetrahedra, but more commonly in thin laminae or grains in sand or gravel. Its presence in this condition is believed to have been caused by the disintegration of gold-bearing rocks, and it is readily collected from such alluvial sources by washing the au- riferous soil. The purest .specimens of native gold have vielded from 99.7 to 99.8 per cent, of the pure metal, the average California gold containing 88 per cent., while Australian gold sometimes runs as high as 96 per cent, pure metal. Gold also occurs in combination with mercury as electrum, with silver and tellurium as sylvanite, and with tellurium and lead as nagyagite. It is further foiuid in various sul- phides, as those of copper, lead, iron, and zinc; also in other ores, and in sea-water. Gold (symbol. Au ; atomic weight. 197.2) is of a bright yellow color when pure, and has a high metallic lustre. It is the most malleable of all metals, and has been hammered into Ji leaf 0.00009 millimeter in thickness. In this condition it appears green by transmitted light. Gold is very ductile, and can be drawn into wire so fine "that Ififi meters weigh but a single gram. Its specific gravity is 19.31, and it melts at about 1075° C. It is a good conductor of both heat and electricity. Whatever the tem- perature, neither water nor oxygen is capable of attacking it ; and it is not affected by fusion ■with potassium chlorate. It yields, however, to alkalies and nitrates, and especially to sodium or potassium cyanide. It is not dissolved by any single acid, except selenic, but readily passes into GOLD. solution when treated with aqua rpgia (a mix- ture of nitric and hydrochloric acids), or with other acid liquids in which chlorine or bromine is evolved. Pure gold, being too soft for all ordinaiy purposes, is generally alloyed with other metals. With copper it yields a reddish alloy, which is quite hard; the standard metal ueed for coinage is made up of eleven parts of gold and one of copper. With silver it yields so-called 'wliite alloys,' which are used for Jewelry. It combines readily with mercury, forming a white amalgam of a pasty consistency. The most ex- tensive uses of gold are for coinage, for jewelry, for gilding frames, furniture, books, etc., for electroplating, and in dentistry. C'OMPOUNU.s. With ox.ygen gold forms a mon- oxide, or (iiiroiis oxide, and a trioxide, or auric oxide. The former is obtained by decomposing aurous chloride with cold dilute potassium hy- droxide ; the latter by heating a solution of gold trichloride with an excess of magnesia and well washing the precipitate with nitric acid. Auric oxide, which is the more common of the two, combines with bases, forming salts called au- rates. Perhaps the most important of the com- pounds of gold with acids is auric chloride, which is readily obtained by dissolving metallic gold in aqua regia and evaporating the solution to crystallization. The resulting orange-red crys- tals may be further purified by recrystallization. It is a very deliquescent salt, and is chiefly em- ployed for toning silver prints in photography. Fvhninaling Gold, which was originally de- scribed in a work published imder the name of Basil 'alentine, is a green or brown powder that readily explodes when dry; it may be obtained by the action of ammonia on gold hydroxide, or by precipitating gold chloride with anunonia or its carbonate. Gold Purple, or Purple of Cassius. which was originally prepared by Andreas Cassius, and de- scribed in 1685, is a flocculent purple precipitate obtained by treating a solution of stannous and stannic chlorides with gold chloride. The re- sulting product is believed to be a mixture of tin oxide and finely divided gold. The color of ruby glass is due to small proportions of this pigment. .1/o.snir Gold is a fine flaky yellow variety of tin bisulphide: it is prepared by heating a mi.xturc of seven parts of sulphur, six parts of ammonium chloride, and eighteen parts of a powdered amalgam consisting of two parts of tin to one of mercury. When the odor of hydrogen sulphide is no longer perceptible, the heat ia raised to low redness, and the mereurous chloride, ammonium chloride, and mercuric sulphide are volatilized. The mosaic gold thus obtained is used as an imitation bronze in the arts. Production of Gold. The supply of gold in ancient times was derived mostly from surface deposits of sands and gravels which yielded their values by simple processes of washing. Gold was thus mined at a very early period in India, Central Asia, the southern Urals, and in the region bordering the eastern ]Mediterranean. itli the progress in metallurgical knowledge at- tention was directed to the exploitation of aurif- erous veins, a branch of the industry which seems to liave attained to some importance before the opening of the Christian Era. Ancient work- ings of this character, ascribed to the Eg^'ptians, have been found in the mountains of Nubia; and