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Effects of Hydraulic Mining 1
 

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Ditches, from miles back in the mountains, bring the water up against the hillside [near Douglas City on the Trinity River], far above the surface of the flat, and a flume, or “raceway,” brings the water directly over the “claim.” A very stout hose, often six inches in diameter, conducts the nozzle like that of a fire engine, only larger. Now, this stream of water , heavy and issuing with enormous force from the great pressure so high a head of water, is made to play against this bank of hard earth, which melts away before it like sand, and all flows into the sluices – mud, bowlders, gold. The mud is carried off in the stream of thick, muddy water; the bowlders, if not too large, roll down with the swift current; the heavier gold falls in the crevices and is dissolved in the quicksilver, as sugar or salt would in water. In some mines these sluices are miles long, and are charged with quicksilver by the thousands of pounds. This washing down banks by such a stream of water under pressure is “hydraulic mining.” After a certain time the sluices are “cleaned up,” that is, the blocks are removed, the quicksilver, amalgamated with the gold, is taken out, the former being then driven off by heat – “retorted” – and the gold left….The amount of soil removed by hydraulic mining must be see to be at all appreciated. Single claims will estimate it by the millions of tons, the “tailings” (refuse from the sluices) fill valleys, while the mud not only muddies the Sacramento River for more than four hundred miles of its course, but is slowly and surely filling up the Bay of San Francisco. In the Sierra, the soil from hundreds of acres together has already been sluiced off the rock, which it formerly covered even to the depth of 150 feet! William Brewer, October, 1862)

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