SILVER 273 



1873, when the metal had a value of about $1.30 per ounce, a vast 

 amount of study and experiment was devoted to the question of recov- 

 ering it from its ores by milling processes, or methods not involving 

 the fusion of the minerals. Preliminary roasting (sometimes in the 

 presence of salt), followed by long-continued grinding with mercury, 

 under water, was the system adopted in the majority of cases, the 

 result being an amalgam of mercury and silver. This was then 

 heated in retorts to volatilize the mercury, and the silver left behind 

 was melted and cast into bars for shipment to market. Other processes 

 involved the use of chemicals by the aid of which the metal was brought 

 into a state of solution, and from which it was recovered by some 

 method of precipitation. But as the west became opened by railroads 

 so that ores could be cheaply transported to natural centers where 

 coal or water power existed and labor was abundant and inexpensive, 

 most of these processes were abandoned in favor of smelting, in which 

 the ores, properly mixed to secure fusion, are melted in a blast furnace. 

 The products are either copper or lead bars — according to the system 

 used — and during the melt the precious metals unite with the baser 

 ones, from which they are subsequently separated by electrolysis. In 

 consequence of all this the production of silver may now be considered 

 as a settled industry, and because the metal is now produced very 

 largely as a by-product. 



Since its discovery in the United States, and the application of 

 business methods to the mining of its ores and their treatment, the 

 world's output has amounted to nearly 170,000 tons. There has been 

 nothing comparable to this enormous yield in any previous era of its 

 history, and its fall in value may be considered as warranted, and per- 

 haps permanent. The annual output of the world at the present time 

 averages about 6,000 tons, and is not at all likely to seriously 

 decline. The American and Mexican mines show no signs of ex- 

 haustion. On the contrary, new ones are continually being found. 

 Asia and Europe are not likely to become large producers of the metal. 

 The settled parts of the old world have been fairly well explored, and 

 in the unsettled parts like Siberia, Turkey and Africa the mining laws 

 are so burdensome that the prospector and individual miner (who are 

 the advance guard in the exploration of the mineral resources of a 

 land) will have nothing to do with those regions. In Australia some- 

 what similar conditions prevail. We may, however, confidently look to 

 South America for many new and great silver mines, when the political 

 situation becomes as stable as in Mexico, for Spanish mining law has 

 always recognized the necessity of the prospector at the base of the 

 industry. The extent to which the American crop of silver is a by- 

 product is shown by the following table worked out by the author for 



