CHAPTER VI

GOLD EXTRACTION

Division of methods of treating ores--Scientific extraction indispensable--Superficial knowledge--German and Australian methods compared--Schools of Mines--Antiquity of gold working--Miner’s equipment--Tub, cradle, long tom--How operated--Hydraulic mining--Extensive Australian drifts--Extraction of reef gold--Amalgamation--Crushing appliances--Preference for stampers--The Lemichel syphon--The Griffin mill--The Huntingdon mill--Dodge crusher--Krupp Grusonwerk Ball Mill--Premature plant erecting--Danger of untried processes--Double faulted lode--Automatic ore feeders--Machinery site--Foundations for battery--Weight of stamps--Power and water required for battery--Selection of screen--Fall of tables--Ancient Egyptian gold washing table--Blanket tables--Successful treatment of refractory ore in Australia--Methods vary with ore--Importance of even crushing--Points _re_ crushing--Best form of stamper box--Cleaning plates--Form of scraper--Retorting amalgam--Special difficulties, how to overcome them pp. 59-86