41‘2
MANUFACTURES.
Manufac- drawn along its surface, by which means a thin layer ofture3, , it is made to pass into the solid state. This is removed,and immediately plunged into water, by which it ac-quires a fine red colour; and the process is repeated tillthe whole is formed into thin sheets.
Copper Copper, in a state of considerable purity, is sometimesobtained by procured from the springs which contain the sulphate of*h' s metal. With this view, pieces of iron are put into
the water, by which the copper is precipitated, owing to Mechanic * 1the superior affinity of the iron for the acid, aided, per- Processes,haps, by a galvanic action. When the whole of theiron is dissolved, the matter deposited is raked out, andis fused in a furnace, either alone or mixed with someof the poorer copper ore.
The deposit obtained in this way, when fused alone,commonly yields about fifty per cent, of copper.
(586.) Table showing the Quantities of British Copper exported from the United Kingdom , together with the Quan-tities and Value of Copper Ore smelted , in Cornwall and Swansea , and the Quantities produced in those Places.
Years.
Exported.
Coin.
Sheets,
Nails,
&c.
Wire.
Unwrought.
i
WroughtCopperof othersorts.
Total Bri tish Copperexported.
Quan-tity ofMetal.
Standard.
Produce.
Cwts.
Cwts.
Cwts.
Cwts.
Cwts.
Cwts.
Tons.
£.
Tons.
£.
S.
d.
Per cent.
1820
10 58,121
8
41,155122,663
121.985
91,473
602,441
7,508
113
15
0
s l
1821
155 66,676
21
34,543
24,035
125,431
98,426
605,968
8,515
103
0
0
8 !
1822
802
65,070
40
25,829
22,731
113,671
104,523
663,085
9,140
104
0
0
s*
1823
95
56,146
98
24,082
21,387
106,516
95,750
608,033
7,927
109
18
0
8i
1824
2,134
62,920
292
19,209
23,580
106,906
99,700
587,178
7,823
110
0
0
H
1825
1,807
51,437
40
10
25,002
78,624
107,454
726,353
8,226
124
4
0
u
1826
1,450
65,264
11
2,604
26,307
95,994
117,308
788,971
9,026
123
3
0
7£
1827
1,150
74,943
8
26,583
40,437
143,424
126,710
745,178
10,311
106
1
0
8 i
1828
15
52,412
71
21,591
48,897
124,121
130,366
756,174
9,921
112
7
0
7£
1829
640 59,871
13 52,987
46,643
159,521
124,502
717,334
9,656
109
14
0
7f
1830
96 66,331
16 59,722
56,443
188,154
133,904
773,846
10,748
106
5
0
8
1831
• •
70,477
149 67,200
32,690
170,613
144,402
806,090
12,044
100
0
0
8i
Years.
Quantityof Metal.
Standard.
Produce.
1820
Tons.
£.
Tons.
£.
s.
d.
Per cent.
1821
3,579
31,159
344
Ill
8
0
*9f
1822
3,539
30,967
388
98
0
0
11
1823
3,378
28,971
353
103
10
0
10*
1824
5,846
49,465
605
103
8
0
10*
1825
7,706
68,506
729
119
0
0
9*
1826
7,052
65,278
668
121
8
0
H
1827
7,802
62,798
772
104
0
0
94
1828
10,585
83,029
977
109
7
0
9i
1829
16,194
99,065
1,221
110
18
0
7*
1830
13,309
94,968
1.196
104
7
0
9
1831
12,999
91,509
1,240
97
6
0
9*
Coppersold inDevon.
Coppersold inIsle ofAnglesey.
Tons.
871
716
694
654
667
615
562
533
454
510
486
Tons.
619
558
774
705
623
736
784
681
757
726
778
915
Tons.
8,127
10,288
11,018
9,679
9,705
10,358
11,093
12,326
12,188
12,057
13,232
14,685
Tin.
Reduction (587.) The ores of tin are reduced in several differentof the ores ways: in Cornwall , generally after being stamped, as de-o! tin. scribed in our article on Mining . It is roasted in a rever-beratory furnace to drive off the sulphur, part of whichis, however, acidified and unites with the copper and ironalso contained in theore; after this theoreis again washed,by which it is nearly freed from all its impurities; it is
then mixed with about one-fifth of its bulk of culm, andsubjected again to the furnace for about six hours, duringwhich the oxide of tin is reduced, and the metal collectsat the bottom covered with a black scoria. The metalis then drawn off into a shallow pit, in which it is freedfrom scoria on its surface; it is then taken out withladles and run into moulds. The metal thus obtainedis afterwards exposed to a gentle heat in a small rever-beratory furnace, by which the purest part of the metai