Page. Alluvial Mining, Middle Island— continued. Otago District — continued. Preservation Inlet .. .. 117,118 Wilson's Eiver .. .. .. 117 Sealers' Creek .. .. .. 117 McNamara's Creek .. .. .. 118 Coal Island ... .. .. 118 Crayfish Island .. .. .. 118 Dredging .. ,■ ■■ 118-121 Otago District .. .. .. 118-120 Sandhills Company .. .. .. 120 Ophir .. .. •• ..120 Waipori .. .. •• ..120 West Coast .. •• •• 120,121 Coal-mining .. • • • ■ 121-125 Northern Coalfields .. .. 121,122 Southern Coalfields ... .. 122-125 Westport District .. .. 122-124 Westport Coal Company .. 122,123 Cardiff Coal Company .. .. 123 Sidings .. .- •• ..124 Bins .. •• •• •• 124 Incline .. .. •• ..124 Otago District .. . • • 124,125 Kaitangata Company.. .. 124,125 Castle Hill Company .. .. .. 125 Mining Machinery . • • • 125-151 The Mudie Ore-crusher and Gold-saver 125,126 The Mercury Mining Company's Cyanide Mill 126,127 The McCully Bock- and Ore-crusher 127,128 New Chlorination process .. 128,129 The Eio Tinto Bock-drill .. .. 129 Electric Bock-drills .. .. 130-132 Austin's Patent Amalgamator .. .. 132 Patents applied for in the Colony (Specifications) .. •■ •■• . 132-147 Improvements in or connected with Crushingor Grinding-mills, more especially intended for grinding or reducing Ores containing Precious Metals, and for separating Metals therefrom by Amalgamation. (By Emma Matilda Shill) .. •■ . •• 132,133 An Improved Concentrator and Classifier. (A. C. Holroyd and others) .. .. 134,135 An Improved Concentrator, usable preferably as an Amalgamator and Concentrator. (James Channon) .. .. •• 135-137 Improvements in the Chlorination of Pulverised Ores containing Gold and Silver, and in Apparatus therefor. (J. W. Sutton) 137,138 Improvements in the Extraction of Gold and Silver from Ores. (C. M. Pielsticker) 138,139 Improvements in recovering Gold and other Precious Metals from their Ores. (Carl Moldenhauer) .. ■ • 140, 141 Improvements in Dissolving Gold and other Metals out of Ores and Compounds, and obtaining the Metals therefrom. (B. C. Molloy) .. •• •• 141,142 Improvements in Extracting Gold and Silver from Ores and the like. (J. C. Macarthur and C. J. Ellis) .. •• 142,143 Improvements in extracting Gold and Silver from Ores and the like. (J. C. Macarthur and C. J. Ellis) .. .. 142,143 An Improved Method of, and Apparatus for, Dissolving, Leaching, and Filtering. (John Storer and B. T. Lacy) .. 143, 144 Improvements in and connected with Coal-cut-ting and like Machines. (Frederick Hurd) 144-147 Colliery-ventilating Machinery .. 148-150 Pumps .. •• •• "" i!o Definite-volume Ventilators .. .. 148 Centrifugal Fans .. • • .. 148 Open Bunning and Closed Eunning 149, 150 Fan-construction .. • • • • 15° Improvements in the Method of producing Crude Antimony .. . ■ • • • • 1°" Table of Useful Calculations for Pipes .. 151 Gold-milling Ores in the Australasian Colonies 152,153 History of the Cyanide Process .. 154-171 Experiments on Silver Ores with Cyanide Solution .. •• •• 156,157 Conclusions and Deductions .. 157-162 The Plant .. .. •• 162-165 The Advantage of Dry-crushing by Eolls .. 163 Driers .. • • • ■ .. 163 Conveyors .. .. • • 1 63 - 1< 34 Leaching-tanks .. •• 164,165 Solution-tanks .. •■ ■• 1™ Dissolving-tank .. • • ■ • 16*> Pumps and Pipes .. • • • • 165 Zinc-precipitating Boxes .. • • 165

C.—3

Page. History of Cyanide Process — continued. The Plant— continued. Plant for treating Precipitate .. .. 165 Assay Plant .. .. .. •. 165 The Lixiviation of the Ore .. 165-167 Wash-water .. .. .. .. 165 Treatment by Caustic Alkali .. .. 165 The Cyanide Solution .. .. .. 166 The Weak Solution .. .. .. 166 Agitation of the Ore and Solution .. .. 166 Final Wash-water .. .. .. 166 Sampling the Tailings and the Ore .. 166 Discharging the Tailings .. .. 166 Precipitation of the Gold .. 166, 167 Treatment of the Auriferous Precipitate .. 167 The Chemistry of the Process .. 167-171 Solution of the Gold .. .. 167, 168 Solubility of other Metals and Minerals .. 168 Treatment of Pyritic Ore previous to Lixiviation with Cyanide .. .. .. 168 Direct Treatment of Pyritic Ores by Cyanide of Potassium .. .. 168,169 Precipitation of the Gold .. 169,170 The Molloy Precipitating Process .. .. 170 Decomposition of the Cyanide .. .. 170 Operations in the Laboratory .. .. 171 Genesis of Ore-deposits .. .. 171-221 Part I. General Pacts and Theories .. 173-192 1. Systems of Classification employed hitherto 173,174 2. Standpoint and View of the Present Paper 174,175 3. The Xenogenites in General .. 175,176 4. The Subterranean Water-circulation 176,177 (a.) The Vadoso Underground Circulation 177-179 The Pilling of the Open Spaces formed by the Vadose Circulation 178,179 (6.) The Deep Underground Circulation 179-184 The Ascending Waters encountered in Mines .. .. ..180 Belated Phenomena near the Surface 181-183 Mineral Springs at the Surface 183,184 Waters encountered in Mines .. 184 Water in Ore-bearing Fissures .. 184 Some Bohemian Thermal Springs .. 184 Weak and Strong Mineral Springs .. 184 Analyses of some Ascending Waters 185-187 5. Origin of Ore-deposits in the Deep Region 187-189 Manner of Filling of Open Spaces in General .. .. •• 189-192 Part 11. Examples of Classes of Deposits 192-221 1. Ore-deposits in Spaces of Discission 192-194 (a.) Ore-veins in Stratified Bocks 194,195 Andreasburg.. .. .. 195 (b.) Ore-veins in the Neighbourhood of Eruptive Masses .. 195,196 The Erzgebirge .. .. 195 Przibram .. .. 195,196 (c.) Ore-veins wholly within Large Eruptive Formations .. 196-199 Hungary .. .. • • 196 The Dacian Goldfield .. 196,197 Verespatak .. .. ..197 Vulkoj .. .. ..197 The Comstock Lode .. 197-199 2. Ore-deposits in Soluble Eocks .. 199-206 Rodna .. .. .. 199,200 Offenbanya .. •• ..200 Bezbanya .. •• 200,201 Eaibl .. .. .. 201,202 The North of England .. .. 202 Leadville .. .. 202,203 Eed Mountain .. .. .. 204 Utah .. .. .. ..204 Nevada .. .. .. 204,205 Missouri and Wisconsin .. 205,206 3. Metamorphous Deposits .. 206,207 (a.) Metamorphous Ore-deposits in Dis-tinctly-stratified rocks 207-211 The Deposition of Ores from Seawater .. .. 207,208 Ore-deposition in Fresh Water .. 208 The Kupferschiefer of Mannsfeld .. 208 The Kupferschiefer in Thuringia and Bohemia .. .. ..208 Westphalia .. .. ..208 The Copper Sandstones of Bohemia 209 St. Avoid .. .. .. 209 The Lead-deposits of Mechernich, near Commern _ .. 209,210 Friehung .. ' .. • • 210 Silver Eeef .. .. ..210 Copper-deposits of New Mexico and Arizona .. . • • • 211 Lower California .. • ■ 211

III