History of the big bonanza

by Dan De Quille

Of evenings, when the prospectors returned from the hills, there was a big time among them, as they exhibited specimens of ore from the ledges they had discovered and compared notes. All gathered about and opinions were passed in regard to the value of the ores brought in.

The next business was to test the ores for the precious metals. In gold-bearing quartz, small specks of gold were often to be seen with the naked eye or aided by a small magnifying glass, such as every prospector carried in his vest pocket for use in the examination of ores. If gold could be seen at all, either with the naked eye or the glass, it was considered a good sign. In order to further test the specimen, it was then either beaten to a powder in a mortar or was ground as fine as flour on a large flat stone, using a smaller stone for a muller. This pulverized ore was then placed in a “horn,” a little canoe-shaped vessel made of the split horn of an ox, when it was carefully washed out, much as auriferous gravel is washed in a pan. The gold, in case the ore experimented upon contained that metal, was found lying in a yellow streak in the bottom of the horn; generally small particles of gold dust, almost as fine as flour.

This was the test for gold, and any miner was able to judge, from the “prospect” obtained in his horn, whether or not the quartz from which it came was rich enough to pay for working in a mill.

In testing ores for silver, the miners in the early days used acids. If a specimen of ore was supposed to contain silver, it was pulverized in the same way as gold-bearing quartz, then was placed in the horn and the lighter matter it contained washed out. When that which remained in the horn appeared to be principally sulphurets and other metalline matter, the washing ceased. The heavy residuum was then washed from the horn into a matrass (a flask of annealed glass, with a narrow neck and a broad bottom). Nitric acid was then poured into the matrass until the matter to be tested was covered, when the flask was suspended over the flame of a candle or lamp and boiled until the fumes escaping (which are for a time red) came off white.[white.] The boiling operation was then presumed to be completed.

When the contents of the matrass had been allowed to cool and settle, the liquid portion was poured off into a vial of clear, thin glass, called a test-tube. A few drops of a strong solution of common salt was now poured into the test-tube. If the ore operated upon contained silver, the contents of the test-tube would at once assume a milky hue. This would begin at the top of the liquid in the tube, where the salt solution first touched the solution of silver in the acid and would be seen to gradually descend to the bottom of the vial. If there was much silver in the ore, the milky matter formed was quite thick, and clinging together descends to the bottom of the tube in the form of little ropes.

Muriatic acid poured into the tube produced the same effect as the solution of salt and water. The white matter formed was the chloride of silver.

In case the prospector had any doubt about what he had obtained being genuine chloride of silver, he held the test-tube in the strong light of the sun for a few minutes, when the chloride would be seen to assume[assume] a rich purple color—a color which no photographer would ever mistake. Those who wish to try this experiment may do so anywhere. If no silver ore is to be had a few filings of a silver coin, or anything containing silver, may be used. The boiling in nitric acid may be performed in a small saucer of ordinary table ware and a common vial may be used in lieu of a test-tube.

The chloride of silver obtained in the bottom of the tube may easily be reduced to the metallic state. To do this it is dried and placed in a small hole scooped out in a piece of charcoal, when the flame of a candle is blown upon it until it is melted, and a bright little button of pure silver is obtained. Lead ore (galena) treated with nitric acid, as in testing silver ore, will produce a chloride somewhat resembling that of silver, but is more granular in appearance, does not turn purple in the light of the sun, and is dissolved in twenty times its bulk of water; whereas washing with water does not dissolve the chloride of silver, no matter how many times the washings are repeated.

If the presence of copper is suspected in the ore tested for silver, a bit of bright iron wire or the blade of a penknife may be dipped into the solution obtained from the specimen, either before or after adding the salt, when, if copper be present, the wire or knife will show a coating of it in the metallic state.

Chloride ores of silver cannot be tested by the acid method—they being chloride of silver in advance of the operation. These ores must be subjected to the test of a fire assay—must be smelted in a crucible. This being the case, our prospectors were not utterly cast down when their pet specimens failed to show silver when tested by the acid process. They at once declared that the silver was in the form of a chloride, and were not satisfied that they were not millionaires, until they had carried their specimens to some assay office and had a regular fire assay made. Then, when the certificate of the assayer came, they were generally obliged to take a back seat, receiving the imprecations of the camp. Occasionally, however, a “big assay” was obtained. Then there was a grand excitement. Every man in the camp wanted the lucky man to put him down in his notice of location for a claim of 200 feet—the amount of ground that could be taken up by one man under the revised laws of the district. In order to get an interest in a claim that promised to turn out a “big thing,” there was much pulling and hauling, buzzing and log-rolling, among the miners who knew of the “strike.”