GOLD 



Gold. Diagram illustrating the hydraulic method of 

 recovering gold from elevated placer deposits. $<>e text 



stream. At various points in the 

 main stream sluice boxes are con- 

 structed which are supplied with 

 mercury by which the gold is 

 caught and retained. 



Most of the gold of the world is 

 now obtained by deep mining from 

 quartz rock. The process of ex- 

 traction after the ore has been 

 brought to the surface comprises 

 crushing, wjiich may be divided 

 into two or even more stages 

 amalgamation, chlorination, or 

 cyaniding. Chlorination is, how- 

 ever, almost abandoned, cyaniding 

 having taken its place. 



Amalgamation generally begins 

 in the stamp mill mortar itself, 

 where a certain amount of mercury 

 is introduced, or where amalgam- 

 ated plates are disposed so as to 

 catch some of the gold as it is 

 liberated from its matrix ; but is 

 mostly carried out on tables placed 

 below the discharge from the 

 stamps down which the crushed 

 ore is carried by the water served 

 to the stamps. The whole of the 

 gold is not recovered at this stage, 

 and the " tailings " are submitted 

 to a process of concentration for 

 which many different kinds of 

 apparatus have been devised. 



The gold recovered by these 

 operations thus appears in two 

 forms, an amalgam and a pre- 

 cipitate, commonly called "slimes," 

 which is collected from the boxes 

 in which the metal has been 

 thrown down by zinc shavings 

 from the cyanide solution. From 

 the amalgam the gold is obtained 

 by distilling off the mercury in cast- 

 iron retorts, and the bullion re- 

 sulting, about 35 to 40 p.c. of 

 the amalgam, is melted in plum- 

 bago crucibles and cast into bars. 



This bullion is not pure gold, 

 but, in addition to an appreci- 

 able amount of silver, contains 

 traces of copper, iron, and lead. 



3584 



The gold is re- 

 covered from the 

 slimes by roast- 

 ing to oxidise the 

 zinc, followed by 

 melting in plum- 

 b a g o crucibles 

 with suitable 

 fluxes generally 

 borax, bicarbon- 



aate of soda, and 

 sand. The final 

 purification of 

 the bullion for 

 BMaa _ <; ; thegeneral mark- 

 et is effected by 

 parting. Such is 

 the general pro- 

 cess of extracting 

 gold from free 

 milling ores ; 

 where the ore is 

 pyretic, i.e. contains sulphur in 

 combination with iron or other 

 metals, the ore must first be 

 roasted to remove the sulphur. 



This general process has in many 

 districts, particularly in the U.S. A., 

 been considerably modified during 

 recent years ; the tendency having 

 been to substitute other appliances 

 ball and tube mills and disinte- 

 grators for stamps, to cut out 

 amalgamation more or less, and to 

 utilise continuous methods of cy- 

 aniding, supplemented by filtering 

 by means of vacuum filters. 



The world's output of fine gold 



in 1917 was worth 87,983,000. 



The chief sources of supply were : 



Transvaal . . 38,324,000 



United States . . 17,344,000 



Australasia .. 7,401,000 



Rhodesia . . 3,495,000 



Canada . . . . 3,175,000 



India . . 2,214,000 



West Africa . . 1,530,000 



The greater portion of the gold 

 produced annually is consumed in 

 the arts, in the preparation of 

 jewelry, plate, and for gilding 

 chiefly ; about one-fourth is coined 

 in normal times, while an appreci- 

 able amount is required to make 

 good the wear and tear of gold coin. 

 A. J. Liversedge 



Early in the 19th century gold 

 began to play an important part in 

 commerce and finance. It was 

 used by the Egyptians and other 

 early peoples to some slight extent 

 as coinage, but much more of it 

 passed into the hands of kings arid 

 other rulers, and was either 

 hoarded or employed in display. 

 There was a great mass of gold in 

 existence while the Roman Empire 

 flourished, but then and also during 

 the Middle Ages it had no great 

 influence on prices or exchanges. 



The modern world has seen gold 

 supplant silver as the chief medium 

 of exchange, at least in western 

 countries. The process began in 



GOLD 



England in the 18th century, and 

 in 1816 the gold standard was 

 definitely adopted. A fixed value 

 was given to the sovereign, and 

 through \t to the ounce of gold, 

 which for 100 years sold at about 

 85s. an ounce. On this foundation 

 the monetary and then the credit 

 systems were built. Silver and 

 copper coins were regarded as so 

 many to the . Great discoveries 

 of gold in Australia and elsewhere 

 later in the century gave an impetus 

 to the adoption of a gold standard 

 of coinage in other countries, and 

 soon, not only France and other 

 European countries, but the U.S.A. 

 and many American ones had set up 

 a gold standard. Silver, too, was 

 discovered in large quantities , 

 this led to a fall in its price, and so 

 to the agitation for a double 

 standard, or bimetallism. 



With a definite gold standard 

 and with large reserves of gold in 

 the various state and other banks, 

 it was possible to build up a credit 

 system which was intrinsically 

 sound, and without which it is hard 

 to see how trade could have de- 

 veloped as it did in the 18th 

 century. The 19th century saw an 

 enormous development in the use 

 of instruments of credit, cheques, 

 bills of exchange and the like, and 

 with it all there was the knowledge 

 that, if desired, gold could be ob- 

 tained for them. Bank notes, too, 

 had a definite backing of gold, 

 while American enterprises were 

 largely financed by bonds, which 

 were payable in gold. This in- 

 creased use of gold was not without 

 its effect on prices, but the 

 relation between these is a matter 

 of controversy among economists. 



The position of gold was entirely 

 changed by the events of the Great 

 War. Paper money was created 

 on an immense scale, and over the 

 greater part of Europe gold, as a 

 circulating medium, disappeared. 

 Large stocks were accumulated by 

 the various governments, but these 

 were nothing like sufficient to cover 

 the great amount of paper money 

 put into circulation. The old gold 

 standard virtually disappeared, 

 this being not without its effect 

 on the great rise in prices that 

 took place in 1918-20. See Bi- 

 metallism; Coinage; Credit; Prices. 



A. W. Holland 



tl'Mio'jranhy. The Gold Mines of 

 the Rand, F. H. Hatch and J. A. 

 Chalmers, 1895 ; Gold Milling, C. 

 G. Lock, 1901 ; Handbook of Gold 

 Milling, H. Louis, 3rd ed. 1902 ; 

 Gold Mines of the World, J. H. 

 Cxirle, 3rd cd., 1905 ; Gold Dredjih^, 

 C. C. Longridge, 2nd ed. 1907 ; The 

 Metallurgy of Gold, T. K. Rose, 6th 

 ed. 1915; Gold Deposits of the 

 Rand, C. B. Horwood, 1917. 



