MINING. . 299 



position which she now holds in the industry and commerce of 

 the world. Other nations did not profit so much, and some of 

 them no doubt lost, for they were compelled to give ten days' 

 work in their products for the gold obtained here in one day's 

 work. 



219. Gold Yield. -The gold mines of the Sierra Nevada 

 were discovered on the 19th of January, 1849 ; were first 

 worked in May of that year ; immediately began to be very 

 productive in proportion to the men employed ; and five years 

 later reached their greatest yield, which was about $65,000,- 

 000 in 1853 ; and since, have been turning out less and less 

 every year, excepting such irregularities as may arise from 

 unequal seasons. The statistics of the annual exportation of 

 treasure as manifested at the San Francisco Custom House, 

 and given in the chapter on commerce, omit much that belong 

 to the gold yield of California, and contain much that does 

 not belong to it. From 1852 to 1860 large sums were carried 

 away in dust by miners returning to the Eastern States, with- 

 out report to the Custom House ; and since 1860 large quanti- 

 ties of treasure from Idaho and Nevada have been made part 

 of the exports from San Francisco. It is safe to estimate the 

 total gold product of California in the twenty-five years, 

 from the 1st of July, 1848, to the 30th of June, 1873, at 

 $1,000,000,000. 



220. Gold Mines. Our gold mines are divided into 

 placer and quartz. In the former, the metal is found imbedded 

 in layers of earthy matter, such as clay, sand, and gravel ; in 

 the latter, it is encased in veins of rock. The methods of min- 

 ing must be adapted to the size of the particles of gold, and 

 the nature of the material in which they are found. In placer 

 mining, the earthy matter containing the gold, called " pay- 

 dirt," is washed in water, which dissolves the clay and carries 

 it off in solution, and the current sweeps away the sand, gravel, 

 and stones ; while the gold, by reason of its higher specific 

 gravity, remains in the channel, or is caught with quicksilver. 



