the mattes in stalls, would have occupied not less than four months. A
large furnace and a Bessemer converter, the pair capable of making a
million pounds of copper a month from a low-grade sulphuretted ore, will
not occupy a space of more than 25ft. by 100ft.; and whereas, in making
metallic copper out of a low-grade sulphuretted ore, one day's labour
used to be expended on every ton of ore treated, to-day one day's labour
will carry at least four tons of ore through the different mechanical
and metallurgical processes necessary to reduce them to metal. About 70%
of the world's annual copper output is refined electrolytically, and
from the 461,583 tons refined in the United States in 1907, there were
recovered 13,995,436 oz. of silver and 272,150 oz. of gold. The recovery
of these valuable metals has contributed in no small degree to the
expansion of electrolytic refining.

_Production._--The sources of copper, its applications and its
metallurgy, have undergone great changes. Chile was the largest producer
in 1869 with 54,867 tons; but in 1899 her production had fallen off to
25,000 tons. Great Britain, though she had made half the world's copper
in 1830, held second place in 1860, making from native ores 15,968 tons;
in 1900 her production was 777 tons, and in 1907, 711 tons. The United
States made only 572 tons in 1850, and 12,600 tons in 1870; but she
to-day makes more than 60% of the world's total. In 1879, Spain was the
largest producer, but now ranks third.

The estimated total production for each decade of the 19th century in
metric tons is here shown:--

1801-1810 91,000
1811-1820 96,000
1821-1830 135,000
1831-1840 218,400
1841-1850 291,000
1851-1860 506,999
1861-1870 900,000
1871-1880 1,189,000
1881-1890 2,373,398
1891-1900 3,708,901

The following table gives the output of various countries and the
world's production for the years 1895, 1900, 1905, 1907:--

+---------------------+----------+----------+----------+---------+
| Country. | 1895. | 1900. | 1905. | 1907. |
+---------------------+----------+----------+----------+---------+
| United States | 175,294 | 274,933 | 397,003 | 398,736 |
| Spain and Portugal | 55,755 | 53,718 | 45,527 | 50,470 |
| Japan | 18,