Footnotes:
[1] This figure indicates thousandths of an inch.
[2] The term “impurity” might in several instances be replaced by the word “constituent,” since many so-called impurities are purposely added for conferring desired properties on the metal. It is here taken as implying elements other than copper.
[3] The temperatures given in Heyn’s diagram require revision in the light of later knowledge, and have been omitted here.
[4] The treatment of flue-dust is considered later.
[5] Though these actions represent with fair accuracy what occurs on smelting, there will be indicated later, in the proper place, some modification, due to interactions of certain oxides and sulphides, in the furnace.
[6] It might also be possible to assist the concentration in the matte by the addition of any available oxidised ores or residues.
[7] The chloridising roasting of copper ores is also sometimes employed in connection with wet processes.
[8] When copper combines with sulphur.