Cobalt
This substance bears in many respects a close resemblance to nickel, and is often found associated in nature with that metal. It is white, brittle, and tenacious, having a high melting-point; specific gravity, 8.5. Its principal ores are white cobalt, consisting of cobalt 44, arsenic 55, sulphur 0.50. All the ores of cobalt contain more or less nickel. See ARSENIC; NICKEL. Cohesion is that power by which the particles of bodies are held together. The absolute cohesion of solids is measured by the force necessary to tear them asunder. See TENACITY; STRENGTH OF MATERIALS.
Coke is the residue resulting from the destructive distillation of soft or bituminous coal, and may be classed as an impure sub-variety of carbon, which, from a chemical point of view, may be classed either with graphite or charcoal, or perhaps between the two. It is made in ovens or in heaps, where the volatile matters are expelled, leaving the coke we use for melting purpose.
About 2240 pounds of bituminous coal is required to produce from 1000 to 1400 pounds of good dry coke.
The manufacture of illuminating gas necessitated the use of retorts, into which bituminous coal principally is charged and heated to redness by an external fire. At a moderate heat tar and oil are produced, but at a high temperature gases are formed in large quantities. The principal products of this destructive distillation are coal-tar, steam, ammonia, sulphide of hydrogen, carbonic acid, carburetted hydrogen, olefiant gas, and a solid, friable, carbonaceous mass, which is known as gas-coke. Coke specially manufactured for smelting purposes, of a good quality, is far superior to any kind of coal for melting in the cupola, as it melts faster and produces hotter iron. The best qualities are distinguished by their hardness, emitting a ringing sound when struck; a freedom from what is called smut, this being only partially burned at such parts--exposing a dark gray, fine cellular mass when fractured, with a silvery gloss overspreading the whole outer surface.
The specific gravity of coke is 1.000; one cubic foot weighs 62 1/2 pounds, and the space required to stow one ton is 72 cubic feet. See COAL.