2. (Min.) A black, or brownish black, solid, combustible
substance, dug from beds or veins in the earth to be used
for fuel, and consisting, like charcoal, mainly of carbon,
but more compact, and often affording, when heated, a
large amount of volatile matter.
Note: This word is often used adjectively, or as the first
part of self-explaining compounds; as, coal-black; coal
formation; coal scuttle; coal ship. etc.
Note: In England the plural coals is used, for the broken
mineral coal burned in grates, etc.; as, to put coals
on the fire. In the United States the singular in a
collective sense is the customary usage; as, a hod of
coal.
{Age of coal plants}. See {Age of Acrogens}, under {Acrogen}.
{Anthracite} or {Glance coal}. See {Anthracite}.
{Bituminous coal}. See under {Bituminous}.
{Blind coal}. See under {Blind}.
{Brown coal}, or {Lignite}. See {Lignite}.
{Caking coal}, a bituminous coal, which softens and becomes
pasty or semi-viscid when heated. On increasing the heat,
the volatile products are driven off, and a coherent,
grayish black, cellular mass of coke is left.
{Cannel coal}, a very compact bituminous coal, of fine
texture and dull luster. See {Cannel coal}.
{Coal bed} (Geol.), a layer or stratum of mineral coal.
{Coal breaker}, a structure including machines and machinery
adapted for crushing, cleansing, and assorting coal.
{Coal field} (Geol.), a region in which deposits of coal
occur. Such regions have often a basinlike structure, and
are hence called {coal basins}. See {Basin}.
{Coal gas}, a variety of carbureted hydrogen, procured from
bituminous coal, used in lighting streets, houses, etc.,
and for cooking and heating.
{Coal heaver}, a man employed in carrying coal, and esp. in
putting it in, and discharging it from, ships.
{Coal measures}. (Geol.)
(a) Strata of coal with the attendant rocks.
(b) A subdivision of the carboniferous formation, between
the millstone grit below and the Permian formation
above, and including nearly all the workable coal beds
of the world.
{Coal oil}, a general name for mineral oils; petroleum.
{Coal plant} (Geol.), one of the remains or impressions of
plants found in the strata of the coal formation.
{Coal tar}. See in the Vocabulary.
{To haul over the coals}, to call to account; to scold or
censure. [Colloq.]