Blister Copper was the name given to the crude metal from the older type of furnace operations. Such copper contained large quantities of gas, particularly SO2, which, tending to escape at the moment of solidification in the mould, gave a blistered appearance to the surface. It contained 96 to 98 per cent. of metallic copper, and was subsequently refined. The term is generally applied still to all crude copper exhibiting similar features.

Chili Bar is an impure copper imported from Chili for refining. The composition varies, the metal usually containing 96 to 98 per cent. of copper, with indefinite quantities, sometimes small, of undesirable impurities.

Appended is a series of representative analyses of various copper products, compiled from different sources. The composition of such material as tough pitch copper and the various cruder varieties is, however, subject to very great variation.

The Sources of Copper.—Copper ores usually consist of various minerals of copper mixed with those of many other metals, and accompanied by very varied gangue, according to the locality in which they are found.

They are best classified under three groups:—

The most important points to be noted with regard to the distribution of these different classes are that—

(1) Native ores are localised in their occurrence, being chiefly confined to the Lake Superior district.

TABLE IV.—Analyses of Various Commercial Coppers.

Copper Gold Silver Lead
1. Electrolytic conductivity copper, 99·89nilnilnil
2. Lake copper,99·77nil0·029nil
3. Best select copper,99·75....0·024
4. Tough pitch copper,99·41....0·070
99·25..0·360·0103
5. Copper fire-box plate
 (ran 500,000 miles, Met. Ry.),98·700·00010·03460·4085


Intermediate Products—
Refined converter copper,99·25..0·360·0103
99·08..0·300·0085
Cathode copper,....0·0010·00054
Black copper,94·39..0·110·19
97·70..0·21330·78
Cement copper (Spanish),51·90..2·351·45
76·930·10..trace
Blister copper,..0·00090·040·042
Chili bar,98·60....trace