The following description of the amalgamation of gold inside the Hardinge mill at the Plymouth Con. mill, by the millman who actually attended to the feeding of the mercury, is particularly interesting as first-hand evidence of what actually took place.

"When I arrived at the plant referred to, amalgamation was done on the plates only. Shortly after, this was changed to feeding quicksilver to the Hardinge mill, with a marked improvement in results. Later, this was again changed to feeding quicksilver to the batteries, with a further improvement in results, as we were informed. During the first part of the campaign the amalgam on the plates was maintained very hard, being removed by scrapers, one of the plates being cleaned up each 24-hr, period. The Hardinge mill was cleaned up at the end of the month, by having the manhole cover removed and the screen adjusted, and the mill was revolved and all sand and possible amalgam was allowed to fall out. The screen was then removed, and a man entered the mill to see what was inside. Considerable amalgam was found in the spaces between the silex bricks, but by far the largest amount of amalgam found in the Hardinge was stuck fast inside the throat of the mill at the points marked A and B on the diagram, Fig. 59, and was very hard, a hammer and a cold chisel being necessary to remove it. Considerable amalgam was also found in the throat, both at feed and discharge ends, and also in the feed scoop, stuck tight, and I recall that we removed the scoop to get at it better. No hard balls of amalgam were found in or around the Hardinge mill, but we did get the hard balls in the batteries around the dies. Also, the small cones, feed, and discharge boxes of the Hardinge mill and the distributing box above the plates seemed favorite places; hard chunks would build up in most unexpected places. Nail heads in launders and boxes were always covered with amalgam. I do not recall that we got anything from the sand and loose material inside the Hardinge mill.

"Later on, the plates were kept softer and the amalgam more pasty; scrapers were scraped, and the rubber used. Amalgam built up faster on the plates, one being cleaned every day, or more than one if it seemed advisable. At the monthly clean-up the Hardinge mill was a disappointment, also the mortar boxes, and the largest quantity of amalgam on this run was obtained from the plates; we were told that the extraction had reached expectations. I have no means of knowing the mercury losses, but do not believe they were excessive. The ore was principally limonite, some quartz and clay. A Pierce amalgamator placed below the plates never got anything but dirt, although dressed daily once each 8-hr, shift."

It must have been after the above description was printed that the Hardinge amalgamators were attached to the discharge ends of the mill for O'Boyle makes no mention of them. Fig. 60 shows the discharge end of the Hardinge mill which is practically the same as is in use at the Amador Con. mill. Small copper balls are fed into the amalgamator which build up with amalgam as may be seen in Fig. 61. For comparison of size the balls are arranged alongside a 3-ft. rule. It will be seen that eight of them occupy a space of 9 in. Fig. 62 is a photograph of the chunks of amalgam found in the throat of the amalgamator and stuck thereto. A 3-ft. rule is photographed with the pan for comparison of size.