ae GEOGNOSY. Box TL.” 
The following analyses show the chemical constituents in some of 
the principal varieties of coal :— 















Caking Coal. | Splint Coal. | Cannel Coal: | Anthracite. 
aro <1 Ge cs ns 86°75 79°58 66°4 91°44 
Ey drogen iim. <> ..e 5°24 5:50 7°54 3°46 > 
Oxygen 6°61 8°33. 10°84 2°58 
WitrOseni i. 7 ie es eS 1°36 0:21 
Earthy Substances. 1-40 5°46 13°82 2°31 
Specific gravity . . 1-28 1°31 12m 1°33 



Anthracite—the most highly mineralized form of vegetation— 
is an iron-black to velvet-black substance, with a strong metalloidal 
to vitreous lustre, hard and brittle, containing over 90 per cent. of 
carbon, with a specific gravity of 135—1°7. It kindles with difficulty, 
and in a strong draught burns without fusing, smoking, or smelling, 
but giving out a great heat. It is a coal from which the bituminous 
parts have been elitninated. — It occurs in beds like ordinary coal, 
but in positions where probably it has been subjected to some 
change whereby its volatile constituents have been expelled. It is 
found largely in South Wales, and sparingly in the Scottish Coal- 
fields, where the ordinary coal-seams have been approached by 
intrusive masses of igneous rock. It is largely developed in the ~ 
creat coal-field of Pennsylvania. Some Lower Silurian shales are 
black from diffused anthracite, and have in consequence led to fruit- 
less searches for coal. 
Oil-shale (Brandschiefer).—Shale containing such a proportion of 
hydrocarbons as to be capable of yielding mineral oil on slow distil- 
lation. This substance occurs as ordinary shales do, in layers or 
beds, interstratified with other aqueous deposits, as in the Scottish 
coal-fields. It is in a geological sense true shale, and owes its 
peculiarity to the quantity of vegetable (or animal) matter which 
has been preserved among its inorganic constituents. It consists of 
fissile argillaceous layers, highly impregnated with bituminous 
matter, passing on one side into common shale, on the other into 
cannel or parrot coal. The richer varieties yield from 30 to 40 
gallons of crude oil to the ton of shale. They may be distinguished 
from non-bituminous or feebly bitumimous shales (throughout the — 
shale districts of Scotland) by the peculiarity that a thin paring 
curls up in front of the knife, and shows a brown lustrous streak. 
Some of the oil-shales in the Lothians are crowded with the valves _ 
of ostracod crustaceans, besides scales, coprolites, &c., of ganoid 
fishes. It is possible that the bituminous matter may in some 
cases have resulted from animal organisms, though the abund- 
ance of plant-remains indicates that it is probably in most cases 
of vegetable origin. Under the name “pyroschists” Sterry Hunt 

