The best alloy for making plummer blocks, bushes, and steps for the steel or iron gudgeons, and pivots of machinery to run in, is said to consist of 90 parts of copper, 5 of zinc, and 5 of antimony.
A factitious protoxide of copper, of a fine red colour, may be made by melting together, with a gentle heat, 100 parts of sulphate of copper, and 59 of carbonate of soda in crystals, and continuing the heat till the mass become solid. This being pulverized, and mixed exactly with 15 parts of copper filings, the mixture is to be heated to whiteness, in a crucible, during the space of 20 minutes. The mass, when cold, is to be reduced to powder, and washed. A beautiful metallic pigment may be thus prepared, at the cost of 2s. a pound.
All the oxides and salts of copper are poisonous; they are best counteracted by administering a large quantity of sugar, and sulphuretted hydrogen water.
The following scientific summary of copper ores in alphabetical order may prove acceptable to many readers, amid the present perplexing distribution of the native metallic compounds in mineralogical systems.
1. Arseniate of Copper.
A. Erinite, rhomboidal arseniate of copper, micaceous copper, kupferglimmer. Emerald green; specific gravity 4·043; scratches calc-spar; yields water by heat; fusible at the blowpipe, and reducible into a white metallic globule. Soluble in nitric acid; the solution throws down copper by iron. It consists of arsenic acid 33·78; oxide of copper 59·24; water 5; alumina 1·77. It is found in Cornwall, Ireland, Hungary.
B. Liroconite; octahedral arseniate of copper; lens ore, so called from the flatness of the crystal. Blue; specific gravity 2·88; scratches calc-spar. It consists of arsenic acid 14; oxide of copper 49; water 35. It is found in Huel-Mutrel, Huel-Gorland, Huel-Unity, mines in Cornwall.
C. Olivenite; right prismatic arseniate of copper; olive-ore. Dull green; specific gravity 4·28; scratches fluor; yields no water by heat; fusible at the blowpipe into a glassy bead, enclosing a white metallic grain. It consists of arsenic acid 45, oxide of copper 50·62. It affords indications of phosphoric acid, which the analysts seem to have overlooked. It occurs in the above and many other mines in Cornwall.
D. Aphanese. Trihedral arseniate of copper. Bluish green, becoming gray upon the surface; specific gravity 4·28; scarcely scratches calc-spar; yields water with heat; and traces of phosphoric acid.
The fibrous varieties called wood copper, contain water, and resemble the last species in composition.