272 POPULAR SCIENCE MONTHLY 



the republic became settled by the accession of President Diaz to power, 

 the mining industry immediately began to revive, and to-day its output 

 of the white metal exceeds that of any other nation. 



Previous to 1859, when silver was first discovered in the United 

 States (in Nevada), silver mining was not an organized industry in 

 any sense of the word, but an occupation dependent largely for success 

 upon the accidental discovery of bonanzas of very rich ore, and the 

 ability to secure labor upon a basis of practical slavery. The Mexican 

 and South American mines were worked by natives who were clothed, 

 fed and sheltered merely to a sufficient extent to keep them alive dur- 

 ing the prime of their physical powers. Only one step on the road of 

 progress had been taken in the metallurgy of the metal, namely, the 

 invention of what is known as the "patio process," which depended for 

 its success largely on the element of unlimited time for its operation, 

 coupled with nearly costless animal power. But when it became evi- 

 dent that the Comstock Lode in Nevada contained vast quantities of 

 silver, the natural ingenuity and aptitude of the American transformed 

 mining into a commercial industry, and the metal began to pour in 

 such torrents into the money centers of the world that financiers 

 became alarmed, and between 1870 and 1873 full coinage rights were 

 finally denied by the principal nations. Meantime, a remarkable in- 

 dustry had come into existence in the mountain regions of our west. 

 Thousands of silver mines had been discovered, scores of processes in- 

 vented and put into practise for the treatment of their ores, and a 

 vast number of metalliferous deposits developed that have since been 

 yielding copper, lead, zinc, iron and manganese in addition to the 

 white metal. 



Silver occurs in veins or deposits in the rocky crust of the earth, and 

 is never found in the gravel of stream beds as is gold. In a small num- 

 ber of cases the gangue, or material with which the metal is associated, 

 is quartz alone, but generally one or more of the base metals is present, 

 predominating vastly in quantity, and often in value. This is especially 

 true after a little depth is gained on the veins, so that in due time 

 mines that were opened as straight silver deposits became rather de- 

 posits of the other metals, the silver being practically a by-product. 

 A good example of this change is to be found in the lodes of Butte, 

 Montana. The veins at Parral, Pachuca and Guanajuato in Mexico 

 are samples of straight silver mines, yet all of them are showing more 

 or less associated iron or copper as depth is gained. On the other hand, 

 wherever lead is found, silver is always present in some quantity, and, 

 at the Comstock as well as at the Mexican districts just mentioned, 

 there is invariably a proportion of gold. In the Comstock bullion it 

 amounted to 40 per cent, of the total values. Thus the metallurgy 

 of silver ores is not a simple matter, and in the days between 1860 and 



