Working in a Virginia City, NV Stamp Mill

At the end of the week the machinery was stopped and we "cleaned up." That is to say, we got the pulp out of the pans and batteries, and washed the mud patiently away till nothing was left but the long-accumulating mass of quicksilver, with its imprisoned treasures. This we made into heavy, compact snowballs, and piled them up in a bright, luxurious heap for inspection. Making these snowballs cost me a fine gold ring - that and ignorance together; for the quicksilver invaded the ring with the same facility with which water saturates a sponge - separated its particles and the ring crumbled to pieces.

We put our pile of quicksilver balls into an iron retort that had a pipe leading from it to a pail of water, and then applied a roasting heat. The quicksilver turned to vapor, escaped through the pipe into the pail, and the water turned it into good wholesome quicksilver again. Quicksilver is very costly, and they never waste it. On opening the retort, there was our week's work - a lump of pure-white, frosty-looking silver, twice as large as a man's head. Perhaps a fifth of the mass was gold, but the color of it did not show - would not have shown if two-thirds of it had been gold. We melted it up and made a solid brick of it by pouring it into an iron brick-mold.

By such a tedious and laborious process were silver bricks obtained. This mill was but one of many others in operation at the time. The first one in Nevada was built at Egan Canon and was a small insignificant affair and compared most unfavorably with some of the immense establishments afterward located at Virginia City and elsewhere.

From our bricks a little corner was chipped off for the "fire assay" - a method used to determine the proportions of gold, silver, and base metals in the mass. This is an interesting process. The chip is hammered out as thin as paper and weighed on scales so fine and sensitive that if you weigh a two-inch scrap of paper on them and then write your name on the paper with a coarse, soft pencil and weigh it again, the scales will take marked notice of the addition. Then a little lead (also weighed) is rolled up with the flake of silver, and the two are melted at a great heat in a small vessel called a cupel, made by compressing bone ashes into a cup-shape in a steel mold. The base metals oxydize and are absorbed with the lead into the pores of the cupel. A button or globule of perfectly pure gold and silver is left behind, and by weighing it and noting the loss, the assayer knows the proportion of base metal the brick contains. He has to separate the gold from the silver now. The button is hammered out flat and thin, put in the furnace and kept some time at a red heat; after cooling it off it is rolled up like a quill and heated in a glass vessel containing nitric acid; the acid dissolves the silver and leaves the gold pure and ready to be weighed on its own merits. Then salt-water is poured into the vessel containing the dissolved silver, and the silver returns to palpable form again and sinks to the bottom. Nothing now remains but to weigh it; then the proportions of the several metals contained in the brick are known, and the assayer stamps the value of the brick upon its surface.