They are made from the low-grade coals, culm, slack and lignites, blended with coal-tar pitch.
coal tar n.
A viscous black liquid containing numerous organic compounds that is obtained by the destructive distillation of coal and that has many uses including as raw material for many dyes, drugs, and paints.
|coal tar |
A thick, sticky, black liquid obtained through the destructive distillation (heating in the absence of air) of coal. It is used as a source of many organic compounds, such as benzene, naphthalene, and phenols, which are used in dyes, drugs, and other compounds.