The gravity concentrate from the Deister tables assayed $20,000 to $30,000 per ton. It was charged into the rotating steel drum in the background with a few pounds of slaked lime and about 600 oz. of mercury that had been cleaned with nitric acid. The drum was rotated about 5 or 6 hours with a piece of shafting in the drum. The drum was then discharged into the 4-foot pan in the foreground (called a mechanical batea). The pan overflowed a galena (lead ore) product that contained silver and about $75 per ton in gold. This was sent to a smelter. The product retained in the pan was mercury and amalgam -- gold partly dissolved in mercury. The man in the foreground was cleaning the amalgam. The amalgam was retorted (distilled) to recover the mercury for reuse. The gold remained as a spongy mass that was charged into a crucible for melting.