GOLCAR 



3582 



GOLD 



Golcar. Urban district of 

 Yorkshire (W.R.). It is 3 m. S.W. 

 of Huddersfield, and has a station 

 on the L. & N.W.R. A centre of 

 the woollen manufacture, here is a 

 mineral spring. Pop. 10,100. 



Golconda. Fortress belonging 

 to the nizam of Hyderabad. Situ- 

 ated about 7 m. W. of Hyderabad, 

 Golconda, now a ruined city, was 

 the capital of a kingdom that 

 nourished from its establishment in 



1512 until its conquest and annexa- 

 tion by Aurungzebe in 1687. Huge 

 mausoleums of the former kings, 

 fast falling into decay, surround 

 and dominate the fort, which is 

 used by the nizam as a treasury 

 and prison. From the fact that the 

 diamonds brought from the rich 

 fields at the base of the Mia Hulla 

 mts. were cut and sold at Golconda, 

 the name of the city has come to 

 be associated with fabulous wealth. 



GOLD: THE METAL AND ITS USES 



A. J. Liversedge, Consulting Engineer, and A. W. Holland 



Thin article deals with the history of gold and describes briefly the 

 areas and geological forms in which it has been found. In con- 

 clusion, the importance of the metal in commerce and finance is 

 considered. See Mining and the articles associated therewith, e.g. 

 Assaying; Bumping Table; Cyanide, etc. See also Geology; 

 Jewelry ; Metallurgy, etc. 



Gold was almost certainly the 

 first metal to be used by man. He 

 would find it, as it is still often 

 found, among the sands of rivers in 

 the form of small grains, and some- 

 times in pieces as large as a hen's 

 egg; its colour and lustre would 

 attract him while still uncivilized, 

 at a very early stage in his intel- 

 lectual development. For ages he 

 used it only for personal adorn- 

 ment, making it into necklets and 

 anklets by tying the grains to- 

 gether with pieces of fine animal 

 fibres. Later he found the means of 

 working the metal into various 

 forms, and then of melting and 

 castine it in moulds. Even worked 

 flints of the stone age, knives, or 

 the equivalents of knives, of those 

 days, are found partly covered with 

 a sheath of thin gold, on which the 

 primitive artist and engraver has 

 cut figures of women, animals, 

 twisted snakes, boats, etc. 



The progress of the civilization 

 of ancient Egypt is marked and 

 punctuated by remarkable exam- 

 ples of gold jewelry, from the beau- 

 tiful spiral shells of the first dy- 

 nasty, 5500 B.C.. to the chains and 

 statuettes and the gilded work of 

 the time of Cleopatra and the Ro- 

 mans. There are many references 

 to gold in the O.T., some of them 

 indicating an advanced state of 

 knowledge of the art of working 

 the metal, e.g. the statement that 

 the Jews " did beat the gold into 

 thin plates and cut it into wires." 

 (Exod, xxxix, 3.) 



The extraction of gold from the 

 earth appears to have been carried 

 on from the earliest historical times 

 as diligently and systematically as 

 to-day. The great conquerors car- 

 ried off the gold from the regions 

 which they traversed ; while gold 

 was one of the forms in which tri- 

 bute was paid to them. The accu- 

 mulation of gold which King David 

 made for the building of the temple 



is estimated to have amounted to 

 some 900,000,000. The amount of 

 gold extracted from the earth since 

 1493, the discovery of America and 

 the earliest date at which anything 

 like a reliable estimate can be made, 

 until 1917, is believed to have been 

 about 823,500,000 oz., valued at 

 3,346,332,000 sterling. The world's 

 stock at the present time is esti- 

 mated at about 1,766,820,000 

 sterling. 



Gold is an elementary metal, 

 chemical symbol Au (Lat. attrum) ; 

 atomic weight 196*2, specific grav- 

 ity 19-32, melting point 1,061 C. 

 (1,941 -8 F.) ; colour, when pure, 

 bright yellow, slightly reddish, 

 with high metallic lustre ; takes a 

 brilliant polish ; in hardness nearly 

 as soft as lead, but differs from the 

 latter in its extraordinary mallea- 

 bility and ductility, in which it sur- 

 passes any other metal. It may be 

 hammered out into leaves so thin 

 that 300,000 laid one upon the other 

 would not be more than one inch 

 in height ; a single grain in weight 

 may be spread by hammering over 

 56-5 sq. ins. of surface, or drawn 

 into a piece of wire 500 ft. in length. 

 Chemical Characteristics 



The French scientist Reaumur, 

 by gilding with gold a silver wire 

 and then drawing down the wire, 

 reduced the thickness of the gold 

 covering to 1/12,000,000 in., the 

 surface still appearing perfect when 

 examined under the microscope. . 



In tensile strength gold comes 

 after iron, platinum, silver, and 

 copper. It does not combine 

 directly with oxygen, even when in 

 a molten state in an open vessel, is 

 unaffected by air or moisture at 

 any temperature, and resists all the 

 mineral acids except selenic, which 

 only acts upon it with the aid of 

 heat; the alkalis have no effect 

 upon it at normal temperatures. 

 It dissolves, however, in aqua 

 regia, a mixture of nitric and hy- 



drochloric acids ; it is also dis- 

 solved by chlorine. Its conduc- 

 tivity for heat is only half that of 

 silver and much less than that of 

 copper, while its conductivity for 

 electricity is also less than that 'of 

 the two latter metals. 



It is not volatile at any such 

 temperatures as those which occur 

 in the blast furnace, but before the 

 oxy-hydrogen blow-pipe or in the 

 electric arc it may be vaporised. 

 Gold forms two oxides, the mon- 

 oxide and the - trioxide or auric 

 oxide, the latter being readily ob- 

 tained by evaporating a solution 

 of the metal in aqua regia when the 

 crystals are yielded. The salt is 

 very deliquescent, and is used in 

 photography. By precipitating 

 gold chloride with ammonia or its 

 carbonate, fulminating gold is 

 formed, a greenish brown powder 

 readily exploded when dry ; by 

 combination of tin chlorides with 

 gold chloride the Purple of Cassius 

 is produced, a flocculent powder 

 used as a pigment in preparing 

 ruby -coloured glass. 



Its Native State 



Gold is found in nearly all parts 

 of the earth, and, with the excep- 

 tion of aluminium and iron, is 

 more generally distributed than 

 any other metal. It is mostly, 

 however, in such minute propor- 

 tions as to escape recognition 

 unless special steps are taken to 

 ascertain its presence. It is also 

 found in the sea. It chiefly occurs 

 native in the crust of the earth, i.e. 

 in the state of metal, occasionally 

 pure, but more generally alloyed 

 with silver, sometimes with copper, 

 and occasionally with palladium, 

 rhodium, and other metals. 



The purest native gold yet found 

 is obtained in Australia, and con- 

 tains 99'65 p.c. of the metal ; Rus- 

 sian mines at Ekaterinburg have 

 yielded specimens showing 98 '96 

 p.c. On the other hand, mines 

 in New Granada, S. America, 

 have furnished ore carrying only 

 64-93 p.c. of gold but 35'07 p.c. of 

 silver. Traces of iron are fre- 

 quently present. It is occasionally 

 found in the form of crystals, but 

 more generally in grains, thin 

 laminae and masses, sometimes in 

 fibres or network. Apart from its 

 occurrence in the native condition 

 it is also found, but comparatively 

 rarely, combined with tellurium 

 and lead in nagyagite, in Hungary ; 

 with tellurium and silver in syl- 

 vanite, and as an amalgam. 



The original position of gold in 

 the crust of the earth as at present 

 constituted is chiefly in the quartz 

 veins which occur in the altered 

 palaeozoic rocks, the sedimentary 

 formations of the Silurian, Devon- 

 ian, and Carboniferous periods, 



