Page:Science vol. 5.djvu/453

 Hat 92. 18S9.1

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gold? 4. Will there be much waste in treating the ore? 5. If so, how much, and what means should he adopted to avoid it?

The rock was crushed fine in a stamp-mill, and the fine sand was conducted by the agency of water over a series of amalgamated copper plates, by which any active or free-milling gold was taken up, and the passive, rusty, included gold was allowed to pass on, together with the sand. This sand, before going to waste, was treated on a concentrator; and from the product or concentrate the greater part of escaped gold could have been extracted by chlorine.

The yield of gold per ton was as follows:—

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From these experiments the students ascer-tained that the Nova-Scotia gold is very coarse, is almost all saved in the stamp-mill, and less

than five plates will answer for treatment, and that the concentrates yield very little additional gold: while New-Hampshire gold is quite fine, is not much more than half saved in the stamp-mill, that five plates are not enough, and if the series were continued to eight or ten the last would probably more than pay for itself, and that considerable gold is saved in the concentrates.

A third student had a lot of galena weighing one ton to treat for lead, silver, and gold. Aided by his classmates, he crushed the ore, sampled, calcined, sintered, and smelted it, obtaining base bullion. He extracted the gold and silver by the zinc process, followed by cupellation. The silver-gold brick obtained was carefully valued, as were also all his products throughout the test. The losses in the process were,—

From the results, not only did he learn with his own hands and eyes where the greatest difficulties are to be encountered in lead and silver smelting, but also the familiarity with this process rendered his reading upon the smelting of copper, iron, and other metals, far more intelligible and real.

When work by day only is called for, there is enough of the spirit of investigation in nearly every student to carry him over the tedious part of his task for the sake of the results he sees immediately within reach. When the test lasts through the night also, as happens three or four times during the year, there is always enough of the savor of camping out to help keep up the interest.

near the town of Irvine, Warren county, Penn., on a very pretty and fertile bottom of the Alleghany valley, are two mounds, well known for the last seventy years. No opening had been made in either in this time, except a shallow pit dug in the side of the smaller about fifty years ago. While spending a few days last summer in that region, I obtained permission of the very intelligent and courteous owner. Dr. William A. Irvine, to make a thorough exploration of

The smaller, which is on the bank of the river, near the point where it is joined by the Brokenstraw Creek, is circular, fifty-two feet in diameter, and three feet and a half high, but has evidently been considerably lowered and expanded by the plough, as the land has been under cultivation for at least sixty years.