Anthracite Anthracite Anthracite, often referred to as hard coal, is a hard, compact variety of coal that has a submetallic luster. It has the highest carbon content, the fewest impurities, and the highest energy density of all types of coal and is the highest ranking of coal. Anthracite is the most metamorphosed type of coal (but still represents low-grade metamorphism), in which the carbon content is between 92% and 98%. The term is applied to those varieties of coal which do not give off tarry or other hydrocarbon vapours when heated below their point of ignition. Anthracite ignites with difficulty and
Coal gas usage may be different. Coal gas was introduced in the UK in the 1790s as an illuminating gas by the Scottish inventor William Murdoch and became very widely used for lighting, cooking, heating and powering gas engines. Coal was heated in a retort and the crude gas was passed through a condenser to remove tar and a scrubber to remove other impurities. The residue remaining in the retort was coke. The composition of coal gas varied according to the type of coal and the temperature of carbonisation. Typical figures were: In a plain burner, only the ethylene produced a luminous