Model (scale 1:8) of gold quartz grinding and amalgamating pan

Model (scale 1:8) of gold quartz grinding and amalgamating pan, patented by Hiram Berdan in 1852

The arrangement consists of a large open cast-iron pan about 6 ft. diameter, revolving on an inclined axis and containing two cast-iron balls of unequal size, the larger one weighing about 3,000 Ib. In the model containing two pans, clutches on the driving shaft enable either to be thrown out of gear. Ore, which has been coarsely crushed, is put in the pans with a little mercury, and as- the grinding proceeds the gold is collected by the mercury ; the lighter material is washed by water that is kept flowing into the pan through spouts near the edge of the pan as they come to the lowest position.