Practical Gold-Mining: a comprehensive treatise on ... gold-bearing gravels, rocks and ores, and the methods by which the gold is extracted ... With ... plates, etc

Front matter

\)\^r 89, CANNON STREET, * UU LONDON, E.C. .j,. * sf-LEGRAPHic Address-" APPLEBYS, LONDON.1 TELEPHONE No. 1731- •flaafetns of STAMP MILLS AND CRUSHING ROLLS. Block No. 512. Prospectors' Stamp Mill. Block No. 505. Gravitation Stamp Mill ORE-BREAKERS, CONCENTRATORS, AMALGAMATORS, &c. ENGINES, BOILERS, TURBINES. &c. Block No. 557. Duncan Ore Concentrator. GOLD IiIachinery. SPECIALITIES : PROSPECTING PLANTS COMPLETE AT SHORTEST NOTICE. SPECIALITIES : THE DUNCAN ORE CONCENTRATOR. Block No. 553. Leaching Pump for Chlorination Plant. LICENSED MANUFACTURERS OF Block No. 554. Barrel for Chlorination Plant. Block No. 555. Leaching Vat for Chlorination Plant. NEWBERY-VAUTIN (PATENTS) RAPID CHLORINATION PLANT. i GOLD AND TIN DREDGER, PRIESTMAN'S PATENT. CONTRACTORS TO THE FOLLOWING GOVERNMENTS:— FRENCH, GERMAN, DUTCH, DANISH ITALIAN, CAPE, QUEENSLAND, ARGENTINE, SPANISH, CHINESE, CHILIAN, THE CROWN AGENTS FOR THE COLONIES, &c. THE PATENT DREDGER.

THE PATENT EXCAVATOR. PRIZE MEDALS AWARDED LONDON, PARIS, YORK, TYNEMOUTH, AMSTERDAM, NEW ZEALAND SYDNEY, ADELAIDE, MELBOURNE, CALCUTTA. The above supplied to the Frepclv^r^qhif'.pold Mining Company of Colombia. T^k^^^LAJj. ,, t, -d West Cowes, Isle of Wight, 12th October, 1887. Messrs. Priestman Brothers, Gentlemen, — The Priestman Dredger, which on my recommendation you supplied to the French (Nechi) Gold Mining Company, last year, for dredging for gold in South America, worked to my entire satisfaction, and I know of no other system, of Dredge so adapted to the general requirements of such work as is your machine. • The bed rock in the river Nechi was reached at a depth of 15 to 18 feet from the present bed of the river ; the bucket excavated its way very well through Sand, Shingle, Pite Clay, &c. It appears that a very small proportion of the gold contained in the deposit escapes the grab.

Many pieces of tree trunks are found buried in the gravel beds, and these impediments, so troublesome to a Ladder Dredger, are managed easily by your machine. The fact of your Dredge being able to penetrate the beds to any ordinary depth, without having to be stopped for adjustment, is a point which certainly merits attention. I believe this machine has only to become more widely known amongst miners to be very largely used, as there are many rivers, too big to be easily diverted from their channels, which contain valuable deposits, easily to be obtained by a proper class of dredging machine. — I am, Gentlemen, yours obediently, FRANKLIN WHITE. Fullest Particulars on application to Works, HULL PRIESTMAN BROTHERS. m^Smv. N. GREENING & SONS, ut., WARRINGTON, ENGLAND. PRACTICAL GOLD-MINING. E .& F. N Span.

Introduction

. An American writer recently gave us a sketch of what California would have been by this time, supposing the great gold discoveries there had never taken place. But who can realise how much the whole world would have been thrown back in civilisation, in colonisation, and in com merce, but for those lucky finds in California and Australia some forty years ago ? Every nation in history, and every member of each nation, has shown the same desire to accumulate the precious metal. The all conquering Roman drove his slaves and prisoners by regiments to toil in the gold mines of Hungary, and miles of tunnel there may yet be seen carved in the solid porphyry by hammer and chisel, the mines being worked to this day. What the ancient Roman did by forced labour the Anglo-Saxon does now by the aid of steam, and explosives, and hydraulic power.

All the chief gold mines of the world, excepting only the Siberian, are controlled by English-speaking peoples, and the metal is coined principally in British, Colonial, and American mints. Gold mining now employs millions of pounds of capital and millions of work men, and has grown from a precarious calling followed by the few, to a recognised industry conducted on scientific principles and on a gigantic scale. There is no longer any excuse for the fulfilment of the old Portuguese proverb — "a silver mine brings wretchedness, a gold mine ruin," — if people would only exercise ordinary common sense, and take the trouble to learn by the example of others. No other industry can rest on such a sound basis, for the simple reason that the product is always marketable and never varies in value. Want of success in work ing a gold mine is generally due to one cause (barring accidents and fraud), viz. ignorance how to extract the gold.

To convey information which will help to dissipate that ignorance, this volume has been written. The superficial reader will probably see in the book a family likeness to

INTRODUCTION.

. its predecessor--'* Gold : its Occurrence and Extraction," — produced by the present author and his father in 1882, and now out of print ; but though much of the matter in the earlier work has been retained, for the sufficient reason that its utility and value have not diminished, an effort has been made to supplement it with the most recent facts and figures obtainable. And if no great discovery has marked the interval between the two books, the seven years' experience gained has developed many new features, which no one interested in the industry can afford to neglect. In conclusion, the author will be extremely thankful to receive at all times notices of new processes and machinery for publication in sub sequent editions, and will gladly correspond with Directors and others who are encountering difficulties in the development of their property. C. G. WARNFORD LOCK. ARPAD GOLD SYNDICATE, 20, Moorgate Street, London, E.C. May 1st, 1889. V SYNOPSIS OF CONTENTS.

Chapter I

Geological Occurrence of Gold Deposits, and Mineralogical Associations of the Gold, pp. i to 107. This chapter embraces three separate subjects : — (1) A summary of the theories advanced during the last 30 years to account for the origin and formation of gold in veins and alluvial deposits, and for the occurrence of nuggets ; (2) a systematic epitome of the geological formations in which gold has been found, showing its very wide distribution in strata of almost all ages ; (3) a catalogue of the metallic and other minerals associated with gold and auriferous rocks, with remarks upon the manner in which the ores are affected by them.

Chapter II

Prospecting for Gold-bearing Gravels and Rocks, and Assaying Auriferous Minerals, pp. 108 to 135. Outward features of gold-fields ; alluvial gold ; vein outcrops ; following float ; loaming ; judging quartz ; prospecting stamps ; ore sampling ; mechanical assay of quartz ,* iron pyrites ; copper pyrites ; mica ; Attwood's test ; Darton's test ; amalgamation test ; panning test ,* touchstone and needle test ; blowpipe assay.

Chapter III

Working Shallow Gravel Deposits and the Beds of Running Rivers, pp. 136 to 236. Definition of shallow placers, importance, formation, decline, characters, origin, variety ; erosion by rivers ; sections of strata ; favourable and unfavourable conditions ; influence of bed-rock ; object of placer-mining ; principle of gold-washing; pans and panning, including the methods employed by aboriginals in various countries ; removing iron-sand ; cradles or rockers ; toms, and their indigenous prototypes ; sluices, VI SYNOPSIS OF CONTENTS. ground sluicing, box-sluices, false bottoms, riffles ; amalgamation, copper plates ; cleaning up ; multiple sluices ; under-current sluice ; Evans and Frey's sluice ; working results; puddling-machines ; whips, whims, derricks, and hoists; draining the workings by pumps, siphons, &c. ; modes of working alluvial deposits — stripping, drifting, piling, slabbing, boxing, paddocking ; working reef-washes ; sluicing ; covered tail-races ; working low ground ; dry washing ; river mining, native plans, lifting rivers, shaft and driving, booming, pumping, pneumatic cylinders, dredging ; beach-mining or ocean placers ; flume for transporting timber ; cost of alluvial mining ; cement, its occurrence, stamping, Drake's mill, Cox's pan, yields ; saving fine, flour, and float-gold ; water, copper plates, McDougall's plan, Sublett's plan, flycatching ; yields of shallow placers.

Chapter IV

Working Deep-lying Gravel Deposits and the Accumulations left by Rivers long since Extinct, pp. 237 to 302, Definition of deep leads ; formation ; sections showing erosive action of rivers, gutters hidden by alluvial matter and by basaltic rocks, river drifts alternating with successive lava-flows, and drifts of different ages underlying one another ; modes of working, drifting, cost of tunnels, drainage, tramming, blasting, blocking-out, sinking and driving, ventilation ; gold-saving apparatus ; working results.

Chapter V

Hydraulicing : or the use of Water under Great Pressure for Removing and Washing Gravels, pp. 303 to 363. Origin of the process ; advantages ; essential conditions ; water-supply ; division of the subject ; miners' " inch " ; measurement of water ; securing water-supply ; dams and reservoirs ; ditches ; flumes ; pipes ; head-box, sand-box ; nozzles ; tunnels and shafts ; sluices, drops, grizzlies, under-currents ; water consumed ; paving sluice ; general arrangement of sluices ; tail sluices ; blasting ; electric firing ; conduct of operations; seam diggings; crushing current; hydraulic elevators— Cranston's, Perry's ; booming ; utilising river-currents for sluicing ; drawbacks to hydraulicing ; working results ; losses.

Chapter VI

Mining Gold-bearing Veinstuff, and Extracting the Free Gold from the Stone, pp. 364 to 572. Sections of veins ; characteristics of veins ; extraction of the mineral ; boring, shafting, drainage, pumps, ventilation, motive-power, raising and transporting ore ; treatment of the veinstuff: crushing, stamping, foundations, frames, mortars, screens dies, stamps, weight of stamps, height of drop, speed, order of drop, character of blow, tappets, guides, cams, cam-shaft, props, feeding, water, tables of dimensions and duty, SYNOPSIS OF CONTENTS. VII life of battery, dry stamping ; special forms of stamp : Dunham's, Fisher's, Hope's, Husband's, Patterson's, Sholl's ; prospecting stamps ; pulverisers ; crushing rolls ; centrifugal roller mill ; arresting the metal : general principles ; mercury troughs and ripples, Moon's amalgamator, amalgamated plates, amalgamating pans, arrastra, Atwood's amalgamator, Barry's amalgamator, Berdan's pan, Boss pan, Britten's pan, Chilian mill, Denny & Roberts's pan, Dickson's amalgamator, Eureka rubber, Fulton and Meekison's pan, Gauthier's shaking amalgam table, Hepburn & Peterson's pan, Horn's pan, Hungarian bowl or Tyrolese mill, Hunter's rubber, Huntington and Koch amalgamator, hydrogen amalgamator, McCone's pan, Manes's electric pulveriser and amalgamator, Otto's electric gold-saving apparatus, Patton's pan, Peck's amalgamator, Readwin's amalgamator, Watson and Denny's pan, Wheeler's pan, Wheeler and Randall's pan ; blanket-tables ; roasting.

Treatment of blanket-sand : barrel-amalgamation. Treatment of tailings : definition and principles, settlers, sizers, sieves, labyrinths, pyramidal boxes, triangular double troughs ; concentration, percussion tables, rotating tables, buddies, Alve's concentrator, Dodge's concentrator, Duncan concentrator, Frue vanner, Halley's percussion table, Hendy's concentrator, Imlay concentrator, keeve or tossing-tub, McNeill's concentrator, Reid and Jones's con centrator, stationary slime table. Working results : richness maintained in depth ; yields ; cost and profit ; water consumption ; hindrances to amalgamation — dirty water, dirty gold, dirty mercury ; sludge disposal.

Chapter VII

Treating Rebellious Auriferous Ores for Recovery of their Gold and Other Valuable Contents, pp. 573-679. Composition of ores ; condition of the gold. Treatment of complex ores — Antimonial ores : Costerfield process, Newbery's process, Designolle's process. Arsenical ores : Chapman's process ; Flude's furnace ; Port Phillip Co.'s furnace ; revolving furnaces ; Rosales's process. Bismuth ores. Cobalt and nickel ores. Copper ores : Vautin's smelting process ; lixiviation with hyposulphites ; Planner's chlorination ; Mears's process ; Newbery-Vautin process ; Pollock process ; Claudet's process ; Henderson's process; Hollway's process; Hunt and Douglas process; Monnier's process ; Paul's process ; Washoe process ; calcium chloride process. Iron-ores : Denny's drop-furnace ; Mount Morgan process ; Las Minas treatment ; Mears's process ; barrel chlorination; Haile method ; Designolle process ; concentration into a matte. Lead ores : Austrian process ; Richmond process. Silver ores. Tellurium ores. Zinc ores. Yields from pyrites.

Chapter VIII

Treating Amalgam, and Refining Bullion, pp. 680 to 688. Cleaning up ; making and using sodium amalgam ; separating amalgam from impurities ; centrifugal separator ; retorting amalgam. Refining bullion : inquartating and granulating ; dissolving the granulations ; treating the gold residue ; melting and refining the gold ; reducing the silver ; melting and refining the silver ; treating the copper sulphate. SYNOPSIS OF CONTENTS.

Chapter IX

The Arrangement of Complete Mills and Reduction Works, Illustrating Various Methods of Treatment, pp. 689 to 724. Amador gold-mine ; Boss Standard Continuous process ; Bunker Hill gold-mine; Caledonian Battery roasting system ; Calvert, Cornes, & Harris's Mill ; Commans & Co.'s mill ; Haile gold-mine ; Hite mine ; Hornsby & Son's mill ; Idaho mine ; Key stone Consolidated mill ; Lockwood mine ; Loyal Lead mill ; North British mine ; Pacific mine ; Plumas Eureka mine ; Port Phillip and Colonial Co.'s mill; Rio Grande mill ; St. Mungo mill ; Sierra Buttes mine ; Zeile mine.

Chapter XII

Supplementary, pp. 768 to 769. Jordan's process. Index, pp. 771-788. MINING MACHINERY GOLD and SILVER. Stonebreakers, Stamps, High-speed Rolls, Chilian Mills, Conveyors, Elevators, Frue Vanners, Blanket Strakes, Drying and Roasting Furnaces, Amalgamating Pans, Settlers, Barrels, Retorts, Patent Chlorination and Leaching Plant. COPPER, LEAD, ZINC, &c. Stonebreakers, Crushing Rolls, Trommels, Elevators, Classifiers, Jiggers, Patent Buddies, Percussion Tables, Reverberatory and Water Jacket Furnaces, Blowers, Slag Pots, Moulds, &c. DRILLING and BLASTING. Patent " Adelaide " Power Drill, Air Compressors, Receivers, Hand-power Rock Drill, Diamond Drill, Well-boring and Sinking Tools, Picks, Shovels, Barrows, Hammers, Hose Piping, Drill Steel, Electric Batteries, Fuses, &c. WINDING and PUMPING. Winding and Hoisting Engines of all kinds, Head Gears, Wire Ropes, Cages, Ore Trucks, Buckets, Kibbles, Cornish Pumps, Pumping Cranks, Tee-bobs, Steam Pumps, Hand Pumps, Wrought and Cast Iron Piping.

WIRE ROPEWAYS (OTTOS PATENT), CHEAPEST FORM OF TRANSPORT. RDS- INTERNATTONAL INVENTIONS EXHIBITION, 1885, ONLY GOLD MEDAL, NEWCASTLE EXHIBITION, 1887, " For Mining Machinery. SILVER MEDAL— Highest Award, " For Aerial Tramway." COMMANS & CO., 52, GRACECHURCH STREET, LONDON, E.C. [To face page x. ) LIST OF ILLUSTRATIONS IN THE TEXT. FIG. PAGE I. Dolly uS 2. Automatic sampler .. .. .. .. .. .. .. 120 3,4. Scoop shovels .. .. .. .. .. .. .. .. 121 5-8. Sections showing shallow placers .. .. .. .. .. 144 9. Gold panning in West Africa .. .. .. .. .. .. 150 10. Gold washing at Heera-Khoond .. .. .. .. .. 152 11. Gold washers of Singhbhum .. .. .. .. .. .. 153 12. Dish and scraper used in Singhbhum .. .. .. .. 153 13. Gold washing pan .. .. .. .. .. .. .. 154 14. Gold washing cradle .. .. .. .. .. .. .. 156 15.

Plan for re-using water .. .. .. .. .. .. 158 16. Hungarian gipsies washing for gold .. .. .. .. lfo 17-19. Rhine gold-washing apparatus .. .. .. .. .. 161 20. Gold washing torn .. .. .. .. .. 162 21. Russian gold-washing apparatus .. .. .. .. .. 164 22. Agtd's gold-washing apparatus .. .. .. .. .. 164 23. Ural gold-washing apparatus .. .. .. .. .. .. 165 24, Russian gold-washing apparatus .. .. .. .. .. 167 25. Mode of sluicing in Peru .. .. .. .. .. .. 170 26. Box sluice, showing false bottom .. .. .. 177 27. Zigzag riffles .. .. .. .. .. .. .. .. 178 2S. Multiple sluices . . .. .. .. .. .. .. .. 1S0 29. Under-current sluice .. .. .. .. .. .. .. 1S1 30, Horse-power puddling machine .. .. .. .. .. 183 31. Combined cradle and puddling machine .. .. .. .. 184 32. Gibson's self-acting puddling machine .. .. .. .. 185 33.

Horse whim .. .. .. .. .. .. .. .. 187 34. Californian pump .. .. .. .. .. .. 188 35. Grab-dredger .. .. .. .. .. .. .. .. 190 36. Sluicing through covered tail races .. .. .. .. .. 195 37. Mining low ground without fall .. .. .. .. .. 196 38. Draining a river claim by Californian pump .. .. .. 202 39. Elliott's floating sluice .. .. .. .. .. .. .. 2cS 40. Priestman's gold and tin dredger .. .. .. .. .. 210 41. Ball's centrifugal-pump dredger .. .. .. .. .. 211 42. Ball's stratum-tester and small gold-diggers' plant .. .. 214 43. New Zealand beach box .. .. .. .. .. •• 221 44. Shetlanders working beach diggings in New Zealand .. 223 45. Fly-catching tables LIST OF ILLUSTRATIONS IN THE TEXT. FIG. PAGE 46. Lifting blankets from fly-catching tables .. .. .. .. 234 47. Section showing reef wash .. .. .. .. .. •• 240 48-50.

Sections showing erosive action of rivers .. .. .. .. 241 51. Deeply silted gutters far from present stream .. .. .. 242 52. Gutter hidden by alluvial hill . . .. .. .. .. ■• 243 53. Gutter completely capped by basalt . . .. .. .. •• 243 54. Gutter beneath eroded basalt hill .. .. .. .. ■• 244 55. Section showing change of river bed .. .. .-. ■• 244 56. Miocene leads at Ti-tree Creek .. .. .. .. ■■ 253 57. Sketch cross section of lead at Morrison's .. .. .. .. 254 58. Plan of Murray River leads .. .. .. .. .. .. 255 59. Section of Murray River leads .. .. .. .. .. 256 60,61. Deep leads in the Daylesford district .. .. .. .. 257 62. Basaltic pipe cutting lead .. .. .. .. .. .. 258 63. Leads on Fryer's Creek .. .. .. .. .. .. 259 64. Lead on Upper Dargo River .. .. .. .. .. .. 259 65. River-bed filled by basalt .. .. .. .. .. .. 261 66-68.

Sections at Stony Creek .. .. .. .. .. .. 262 69-71. Sections at Glenmaggie Creek .. .. .. .. .. 262 72. Upper Pliocene leads .. .. .. .. .. .. .. 263 73. Successive lava streams .. .. .. .. .. .. 263 74. Clay drift between lava streams .. .. .. .. .. 263 75. Middle Pliocene leads .. .. .. .. .. .. .. 264 76,77. Relations of Newer and Older Middle Pliocene .. .. .. 265 78. Sketch section of Wallaby diggings.. .. .. .. .. 267 79. Upper Pliocene drift banks .. .. .. .. .. .. 268 80. Lead hidden by debris .. .. .. .. .. .. .. 268 Si. Three pay channels at different elevations .. .. .. .. 268 82. Tangil lead .. .. .. .. .. .. .. .. 269 83. Table Mountain .. .. .. .. .. .. .. 269 84. Lava streams at Hawkins' lead .. .. .. .. .. 272 85. Durham lead under Mount Mercer Plains .. .. .. .. 273 86. Sketch section of strata at Ballarat .. .. .. .. .. 273 87.

Section across Golden Point Gutter and Woolshed Lead .. 274 88-92. Blocking out deep leads .. .. .. .. .. .. 290 93. Sinking and driving on deep leads .. .. .. .. .. 291 94. Underground workings, New Australasian Co., Creswick .. 296 95. Miners' " inch".. .. .. .. .. .. .. .. 307 96. Dam for hydraulic reservoir .. .. .. .. .. .. 311 97. Waste dam .. .. .. .. .. .. .. .. 313 98-100. Ditches and flumes .. .. .. .. .. .. ..- 314 101. Scandinavian water race, New Zealand .. .. .. .. 318 102. Head-box, pressure-box, or bulkhead .. .. .. .. 322 103-106. Hydraulic hose nozzles .. .. .. .. .. .. 328 107,108. Paving for sluices .. .. .. .. .. .. .. 337 109. Hydraulic under-current .. .. .. .. .. .. 340 no. General arrangement of sluice, drops, grizzlies, and undercurrents .. .. .. .. .. .. .. .. 340 111.

Electric battery for blasting .. .. .. .. .. .. 344 112. Fuse for blasting .. .. .. .. .. .. .. LIST OF ILLUSTRATIONS IN THE TEXT. XIII FIG. PAGE 113. Bornhardt's electrical firing machine .. .. .. .. 346 114. Blanket-tables at end of hydraulicing sluice .. .. .. 347 115. Cranston's hydraulic elevator . . .. .. .. .. .. 351 116. Perry's hydraulic elevator at work .. .. .. .. .. 354 117,118. Contorted veins in the Caribou district .. .. .. .. 364 119. Elvan dykes .. .. .. .. .. .. .. .. 365 120-124. Quartz veins in diorites and granites .. .. .. .. .. 365 125. Sections of veins at Clunes .. .. .. .. .. .. 366 126. Saddle reefs .. .. .. .. .. .. .. .. 367 127. Timbering wet shafts .. .. .. .. .. .. .. 389 128. „ 390 129-131. Hydraulic system of draining .. .. .. .. .. .. 396 132. Fielding's duplex pump .. .. .. .. .. .. 404 *33> "34- Cornish pump ,. .. .. .. .. .. .. .. 406 135.

Pumping water of variable level .. .. .. .. .. 407 136. Steam pump .. .. .. .. .. .. .. .. 407 137. Water-wheel pump .. .. .. .. .. .. .. 407 138. Vortex turbine .. .. .. .. .. .. .. .. 410 139. Turbine working horizontally .. .. .. .. .. .. 410 140,141. Turbines adapted to a high fall .. .. .. .. .. 411 142. Girard turbine .. .. .. .. .. .. .. .. 412 143. Steam engine on wrought-iron bed-plate .. .. .. .. 413 144,145. Locked wire ropes .. .. .. .. .. .. .. 415 146. Self-acting incline wire tramway .. .. .. .. .. 417 147. Continuous running-rope tramway .. .. .. .. .. 419 148. General arrangement of winding machinery .. .. .. 422 149. Winding and pumping machinery .. .. .. .. .. 422 150. Steel geared winding engine .. .. .. .. .. .. 422 151. Direct acting winding engine.. .. .. .. .. .. 422 152.

Roller ore feeder .. .. .. .. .. .. .. 444 173. Hendy's ore feeder .. .. .. .. .. .. .. 444 174. Aspirator for use in dry stamping .. .. .. .. .. LIST OF ILLUSTRATIONS IN THE TEXT. XIV FIG. PAGE 175. Dunham's recoil stamp .. .. .. .. .. ■. 45° 176. Fisher's rotating-bed stamp .. .. .. .. •• ■■ 45 J 177. Husband's stamp .. .. .. .. ■• •• •• 453 178. Patterson's elephant stamp .. .. .. .. •• •• 454 179. Sholl's pneumatic stamp .. .. .. ■• •■ •• 457 180. Prospecting stamps .. .. .. .. •• •• ■■ 45& 181. Howland's pulveriser .. .. .. .. ■■ ■■ •• 459 182. Krom's crushing rolls .. .. .. .. •■ •• ■• 461 183. „ 462 184. Huntington's centrifugal roller mill .. .. .. . .. 469 185,186. Details of Huntington's mill .. 47° 187. Arrangement of mill on Huntington system .. .. .. 472 188. Port Phillip mercury-troughs .. .. .. .. .. .. 475 189.

Australian percussion table .. .. .. .. ,. -4, 229. Rittinger's rotating table .. .. .. .. ,,., -4. LIST OF ILLUSTRATIONS IN THE TEXT. XV FIG. PAGE 230. Munday's round buddle .. .. .. .. .. .. 549 231. Dodge's concentrator .. .. .. .. .. .. .. 552 232. Duncan concentrator .. .. .. .. .. .. .. 552 233. Frue vanner .. .. .. .. .. .. .. .. 553 234. H alley's percussion table .. .. .. .. .. .. 557 235. Hendy's concentrator .. .. .. .. .. .. .. 558 236. I mlay concentrator .. .. .. .. .. .. .. 560 237. Keeve or Tossing tub .. .. .. .. .. .. .. 561 238. McNeill's concentrator .. .. .. .. .. .. 562 239. Stationary slime table .. .. .. .. .. .. .. 564 240. Herrenschmidt's revolving furnace .. .. .. .. .. 580 241. Fume condenser .. .. .. .. .. .. 581 242. Serjeant and Flude's furnace .. .. .. .. .. .. 587 243.

Port Phillip Co.'s furnace 588 244. Hocking and Oxland's revcrberatory furnace .. .. .. 591 245. Rosales's mechanical process .. .. .. .. .. .. 592 246,247. Impregnation and leaching vats .. .. .. .. .. 617 248. Chlorine generator .. .. .. .. .. .. .. 620 249. Wash-bottle .. .. .. .. .. .. .. .. 621 250. Precipitating vat .. .. .. .. .. .. .. 624 251. Providence chlorination works .. .. .. .. .. 630 252. „ „ „ .. .. 631 253. Lincoln chlorination works .. .. .. .. .. .. 631 254. Union Hill chlorination works .. .. .. .. .. 632 255,256. Chlorination as conducted at Sandhurst .. .. .. .. 645 257. Newbery-Vautin plant . . .. .. .. .. .. .. 652 258. Denny's drop furnace .. .. .. .. .. .. .. 663 259. Amalgam separator .. .. .. .. .. .. .. 683 260. Amalgam retort . . .. .. .. .. .. .. .. 684 261. „ 685 262.

Stamp battery for easy transport .. .. .. .. .. 696 263. Comman's and Co.'s stamp mill . . . . . . . . . . 698 264. Hitc Mining Co.'s mill .. .. .. .. .. .. 699 265. Hornsby's stamp battery .. .. .. .. .. .. 701 266. Idaho mill .. .. .. .. .. .. .. .. 703 267. Blanket washing tub .. .. .. .. .. .. .. 704 26S. Pacific Mine mill .. .. .. .. .. .. .. 712 269. Automatic batea .. .. .. .. .. .. .. 713 270. Port Phillip battery .. .. .. .. .. .. .. 716 271. Rio Grande do Sul mill .. .. .. .. .. .. 718 >* LIST OF PLATES. Frontispiece. — UNDER-CURRENTS, NORTH BLOOMFIELD MINE, CALIFORNIA. FACING PLATE PAGE i St. Bathans, Welshman's Gully .. .. .. .. .. 32 2 Naseby, Rough Ridge 64 3 Blue Spur, General View, Gabriels .. .. .. .. 96 4 Bowman Dam, North Bloomfield Mine, California .. 310 5 Iron Pipe, North Bloomfield Mine, California .. .. 320 6 Piping or Hydraulicing, California 336 7 Ground Sluicing, New Zealand .. .. .. .. .. . PRACTICAL GOLD-MINING.