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Page:Popular Science Monthly Volume 54.djvu/662

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THE POPULAR SCIENCE MONTHLY.

A similar deposit of silver was found in New Mexico about twenty years ago and was christened the "Silver Lake" Mine. This was worked profitably until the great fall in price of silver made the operation a losing one. The "blanket" still contains millions of ounces of silver, and it is probable that cheaper methods of recovering the metal from the ore will be devised whenever the price of silver shall have fallen low enough to enable it to take its place among the so-called "economic" metals, having far wider application in the arts than have the precious metals. At present silver holds an unfortunate place "betwixt and between" the precious and the economic metals.

Twenty years ago aluminum was more valuable than silver is today, and its production was correspondingly limited. Last year the price was reduced to a point which so widely extended its use that the production increased from 1,900 pounds in 1888 to more than 5,000,000 in 1898.

Although the gold deposit in the Camp Floyd district in Utah already alluded to may actually contain several billions of dollars' worth of gold, it will cost some billions of dollars' worth of labor and capital to recover the precious metal and will consume much time in the process; so that there is little reason to fear that gold will become so plentiful on account of this discovery that it will cease to be regarded as a precious metal. About forty years ago the assayers of the United States Mint announced that the clay underlying the city of Philadelphia contained more gold than had been brought from California and Australia, and this remarkable statement has never been disproved or even questioned. The gold, however, still remains locked fast in the clay, and the value of the precious metal has not yet fallen in consequence of the announcement of this old discovery. At that time the idea of profitably recovering gold from low-grade ores had not been born, and it is an interesting fact to note that in California gold is now being obtained from clay (by hydraulic washing methods) in which there is but little more than the average proportion of gold to the ton that the assayers found in the clay under the streets of Philadelphia. This does not prove, however, that it will now pay to excavate under the streets of the Quaker City, and undermine the buildings in order to wash out this gold, and until Philadelphia shall be provided with a far more copious water supply the most sanguine or suave promoter of great undertakings would find it impossible to obtain subscriptions to any scheme to recover this fugitive gold, or even, perhaps, difficult to give away shares of stock to influential individuals either in or out of councils.

An impression has prevailed that the production of gold in South Africa attained its maximum point in 1897, and that thenceforth the