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Diggers in the Earth

<hr style="width: 65%;" />[Pg 48] <h2>VI</h2> <h3>THE STORY OF A SILVER MINE</h3> A man who goes out in search of a mine is called a "prospector." The best prospector is a man who has learned to keep his eyes open and to recognize the signs of gold and silver and other metals. A faithful friend goes with him, a donkey or mule which carries his bacon and beans, blankets, saucepan, and a few tools, such as a pan, pick, shovel, hammer, and axe. Sometimes the prospector also takes with him a magnifying glass and a little acid to test specimens, but usually he trusts to his eyes alone. When these few things have been brought together, the prospector and the donkey set out. They wander over the hills and down into the canyons. If a rock is stained red, the prospector examines it to see whether it contains iron; if it is green, he looks for copper. In the canyons and along the creeks he often tests the gravel for traces of some valuable metal. If he finds any of these traces along the stream, he follows them on the bank until they stop; then he carefully examines the bank of the stream or the nearest hillside. If he continues to find bits of metal, they will lead him to a vein of ore, from which they have been broken by the wind, rain, and frost. Generally a prospector is looking for some one[Pg 49] special metal, and in his search he often overlooks some other metal; for instance, thousands of the gold-seekers who rushed to California in 1849 hurried through Nevada on their way. If they had only known what was under their feet, they would have taken their picks and shovels and begun to dig, instead of trying to get out of the region as soon as might be. Ten years later, the California placers were becoming exhausted, and miners began to go elsewhere in their search for gold. Among those who were working in what is now the State of Nevada were two Irishmen who had been unlucky in California and had fared no better in Nevada. They wanted to go somewhere else, but they had not money enough for the journey; so they kept on with their work at the foot of Mount Davidson, washing the gravel and saving the little gold that they found. They were annoyed by some heavy black stuff that united with the quicksilver in their cradles, interfered with the saving of the gold, and put them in a very bad temper. At length a man named Henry Comstock came along, who told them that this black stuff was silver ore. They examined the mountain-side, and discovered the outcrop or edge of a great vein containing gold and also silver. It is no wonder that people rushed from the east and west to the wonderful new mines, for it was plain that these new "diggings" were not mere placers, but rich veins that many years of working might not exhaust. Every newcomer hoped to discover a vein; and within a year or two the district[Pg 50] around the Comstock lode was full of deep shafts, many of them abandoned and half-hidden by low brush, but some of them yielding quantities of gold and silver. Before this, there had been only about a thousand people in what is now Nevada, but in two years after the discovery of silver, there were 16,000, and a new Territory was formed. The miners knew how to get gold out of ore, but silver was another matter, and some of it was difficult to extract. They had so much trouble that they were ready to believe in any treatment of the ore, no matter how absurd, that promised to help them out of their difficulties. Some of them were actually persuaded that the juice of the wild sagebrush would bring the silver out. It is no wonder that they were troubled, for in the Comstock lode were not only gold and silver, but ten or twelve other metals or combinations of silver with something else. At length processes were invented for treating the different kinds of ore. Some kinds were crushed in a stamping mill, then ground to a powder and mixed with quicksilver or mercury. This mercury united with both the gold and the silver, making an amalgam. The amalgam, together with the finely ground ore, was put into a "settler," and here the heavy amalgam sank to the bottom and was then strained. The extra mercury was collected, and the amalgam was put into a retort or kettle and heated. The mercury became a gas and was driven off from the gold and silver, then caught in a vessel cool enough to condense it, just as a cold plate held in steam will collect drops of water. Sometimes the ore was mixed with copper and lead. In that case common salt and copper sulphate were used. Some ore had to be roasted in a furnace in order to drive off the sulphur. [Pg 51] <ANTIMG src="images/image052.jpg" width-obs="600" height-obs="302" alt="THE STORY OF A SPOON" title="THE STORY OF A SPOON" /> THE STORY OF A SPOON Courtesy The Gorham Co. (1) Silver strip blanked. (2) Pinched. (3) Graded. (4) Outlining of Handle. (5) Stamped Handle. (6) Spoon completely trimmed. (7, 8) Finished spoons. [Pg 52] There were great and unusual dangers to be met in getting the ore. The vein of quartz which bore it was fifty or sixty feet wide. Some was hard, and some so soft and crumbling that pillars would not hold up the roof. The passageways were then lined with heavy logs standing on either side, other logs laid across their tops, and all bolted firmly together. Nevertheless, they twisted and fell, and slowly but certainly the whole mass of earth and rock, two hundred or more feet in thickness, was coming down upon the heads of the miners. The work on the Comstock mines had come to an end unless a man could be found able to invent some system of support not laid down in the books. The man was found. He took short, square timbers five or six feet long, put them together as if they were the sides and ends of square boxes, and piled them one above another, making hollow pillars. He fastened these firmly together and filled the space inside with waste rock, thus making strong, solid pillars that would support almost any weight that could be put upon them. There were two other dangers, water and heat. The vein was porous and water was constantly trickling out of it. Then, too, there were "water pockets," or natural reservoirs in the rock, and any[Pg 53] moment the stroke of a pick might let out a torrent and force the miners to run for their lives. Sometimes minerals were dissolved in this water, and the men with closed eyes and swollen faces had to be hurried to the surface for treatment. Powerful pumps had to be used and the water sent away through long lines of pipes. This water was warm, and in very deep workings in the Comstock vein it was boiling hot. Even with quantities of ice sent down to cool them, the men could work in some places only a short time. In San Francisco there was a mining engineer named Adolph Sutro who planned to remedy these troubles by driving a big four-mile tunnel through the heart of the mountain, letting out the hot water and the foul air. The owners of some of the mines joined him in raising the money, and the tunnel was dug. Through this the water ran out. The mines were freed of foul air and fresh air was driven in. The Comstock lode has given up an amazing amount of precious metal. Between 1860 and 1890 it produced $340,000,000. After 1890, however, its product grew less. The vein was not so rich, the price of silver fell, while the cost of mining it at great depths increased. Not nearly so much was mined, and at length water rose in the mines up to the level of the Sutro Tunnel. In 1900 new machinery was put in and new methods were adopted, such as treating the tailings with cyanide and so saving much of the precious metal from them. From the beginning the Comstock mines have been so ready[Pg 54] to follow improved methods that they have been called the mining school of the world. Great quantities of silver are used for making jewelry and for tableware. The one objection to its use is that silver likes to unite with sulphur, and thus the silver easily becomes black. There is sulphur in the yolk of an egg and that is why the spoon with which it has been eaten turns black. Even if silverware is not used, it tarnishes, especially in towns, because there is so much sulphureted hydrogen in the air. In perfectly pure air, it would not tarnish. Silver is harder than gold, but not hard enough to be used without some alloy, usually copper. Tableware is "solid" even if it contains alloy enough to stiffen it. It is "plated" if it is made of some cheaper metal and covered with silver. The old way of doing this was to fasten with bits of solder a thin sheet of silver to the cup or vase or whatever was in hand and heat it. This did fairly well for large, smooth articles; but it was almost impossible to finish the edges of spoons so as not to show the two metals. If you look at a plated spoon to-day, however, you will find that there is no break at the edge, and so far as you can tell by the eye, it is solid silver. If you look on the back of the spoon, you will perhaps see "Rogers Bros. 1846." These men were the first silvermakers in this country to plate tableware by electricity. To make a spoon, they formed one out of iron or copper and made sure that it was perfectly clean. Then across a bath of silver cyanide, potassium cyanide, and water they[Pg 55] laid two metal rods, and from these they hung a spoon at one end and a plate of silver at the other. These rods were connected with the two poles of a battery. The electrical current passed through them, released the silver from the silver cyanide, and this was deposited upon the spoon. The cyanide that had lost its silver took enough more from the silver plate to make up. The amount of silver on the spoon depends upon the length of time it remains in the bath. It is weighed before plating and again afterwards, to make sure that the proper amount of silver has been deposited upon it. On the back of many plated articles you will see the words "Triple plate" or "Quadruple plate." If the article has been made by a reliable firm, this means that the triple plate it manufactures contains three times as much silver as "single plate," and that quadruple plate contains four times as much. A piece of silver looks just as well if it has stayed in the bath only a few minutes, but of course it has taken on so little silver that this will soon wear off and show the cheaper metal. A large amount of silver is used for coins. When the United States needs dollars, half-dollars, quarters, and dimes, notice is given and offers are called for, stating the quantity for sale and its price. When it is delivered, it is first of all "assayed"; that is, tested to find out how nearly pure it is and how much it is worth. Next it is refined, or purified from other metals, mixed with a little copper to harden it, then melted again and poured into moulds to make bars.[Pg 56] If dollars are to be made, the bar is made thinner by passing it between heavy rollers, and blanks for dollars are cut out with a die. These blanks are weighed and every one that is too heavy or too light is put back to be melted over again. Thus far these dollars are only round, smooth pieces of metal. They must be milled to give them a rough edge, and they must be stamped. For stamping, the piece of metal is placed between two dies, one above and one below, and these close upon it with a force of one hundred and fifty tons. Every part of the process of manufacturing money is carried on with the utmost care. The places where coins are made are called "mints." The United States has four; the oldest is in Philadelphia, and there are branch mints in San Francisco, New Orleans, and Denver. Coins minted in Philadelphia have no distinguishing mark; but coins minted in San Francisco are marked with a tiny "S"; if minted in New Orleans, with an "O"; and if in Denver, with a "D." <div style="break-after:column;"></div>

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