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other minerals and metals. 755
Table 111. Imports and exports of certain unmanufactured or partly
manufactured metals, except iron and steel.
Gold.
Kllog.
[-Imports.-]
{+Im-
ports.+}
Silver.
Kllog.
[-Imports.
Exports.-]
{+Im-
ports.
Ex-
ports.+}
Lead.
Quintals.
Copper. 1
Quintals.
[-Imports.
Imports.-]
{+Im-
ports.
Im-
ports.+}
Ex
ports.
Zinc.
Quintals.
[-Imports.
Exports.-]
{+Im-
ports.
Ex-
ports.+}
Tin.
Quintals.
Im-
Exports. ports.
1861/65 ............56 5,007 10 1,513 1,549 1,957 14,875 3,654 45 555 3
1866/70............113 8,407 3,083 1,522 2,975 2,678 18,045 2,981 207 372 7
1871 75............1,639 9,964 6,054 4,810 1,3731 5,772 9,098 6,583 183 1,352 34
1876/80............1,492 1,002 1,729 5,934 787 7,676 6,941 9,592 567 1.613 3
1881/85..........(J59 426 1 6,452 2,528 10,845 7,554 16,645 210 2,260 11
1886/90 ............985 876 168 9,104 1,866 12,330 6,619 17,651 519 2,500 72
1891/95 ............386 2,659 2,849 115,147 7,0861; 32,808 5,373 19,520 860 3,521 114
1896 00..........1,849 12,779 388 20,549 10,457 50,213 11,546 27,078 1,621 5,419 190
In 1900............3,263 9,128 296 20,672 12,091]! 61,499 20,119 29,126 1,556 6,297 215
Formerly the copper percentage was frequently determined by the so-called
Swedish copper test, which was quite suitable for pure ore. The method was
as follows: After the ore had been dissolved in a mixture of hydrochloric or
sulphuric acid and nitric acid, and the silicic acid had been separated, the copper
was precipitated on a clean-filed iron spike from the diluted boiling solution.
The copper-free solution was poured off, and the copper washed with water
that had been boiled, after which the still loosely adhering copper was removed
from the iron, and after a hurried drying, was either direct weighed as metal,
or, after being dissolved in nitric acid in a porcelain crucible, was determined
as oxide or sulphate. Besides this, several other methods have come into use,
e. g., precipitating with hyposulphite of soda from a boiling solution of sulphate
and determining as oxide or sulphate; furthermore titration of an ammonia solution,
with cyanide of potassium, etc. Now precipitation of copper according to the
electrolytic method is generally used. For determining very small percentages of
copper, etc., also a Swedish method is used, viz. Professor V. Eggertz’
colori-metrical method.
Up to the beginning of the decennium 1871/80, shaft-furnaces were used
for melting the ore, according to a method which in metallurgy has been given
the name the Swedish copper process, in contradistinction to the English
process, which is exclusively executed in reverberatory furnaces. On account of the
slight percentage of copper in the ore, and the rising prices of fuel, this method
of melting has had to be abandoned. The wet or extraction method was
introduced in Falun in the beginning of the seventies, and afterwards at several of
the present copper works. According to this method, the ore is roasted with
chloride of soda at a low temperature, and the dissolvable salts are extracted
by means of water mixed with some hydrochloric or sulphuric acid in large
wooden basins. From this solution, silver is first precipitated, and then the copper
is cemented by means of iron scrap. The eement-copper thus obtained, which
contains 70 to 80 % of copper, is toughened and refined in regenerating
reverberatory furnaces.
The production of copper is shown by Table 110. For the sake of
comparison, it may be mentioned that during the whole of the
seventeenth century, the production of copper in Falun amounted to an an-
1 Here are also included copper alloys, such as brass, bronze, electroplate, etc., as
also metals not specified.
Average for
the years
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