100 RELATIONS OF ANTHRACITIC AND BITUMINOUS COALS. 
thinning out towards the east ; and with this alteration a great decrease in the 
amount of carbonaceous matter is also observed, the bituminous coal disappearing, 
and its place being eventually taken by pure anthracite. 
Relation of the Anthracite to the Bituminous Coal . — From what we have just said, 
the reader will perceive, that this region is divided into anthracitic and bituminous 
coal-fields. Owing to the prevalent strike of the beds from west-north-west to 
east-south-east, it is obvious, that notwithstanding considerable flexures and varia- 
tions in lithological structure, the same groups of strata we have been describing 
are continuous eastwards to the Donetz. Thus the anthracitic rocks without 
limestone to the noith ot Novo lcherkask, and the schists with some thin courses 
of limestone on the Donetz, are the equivalents of the shale, sandstone, and bitu- 
minous coal with limestone, to which we have already alluded. 
This pluenomenon is analogous to that which exists in the South Welsh coal-field, 
where at one extremity of the tract anthracitic coal prevails almost exclusively, in 
beds of precisely the same age as those which bear bituminous coal at a little 
distance to the east. In the Russian example, indeed, we see the mineral cha- 
racter of the coal-beds change gradually as we follow them from west to east. In 
the districts intermediate between the western or bituminous tracts, and those 
containing pure anthracite, the combustible is frequently in that intermediate 
condition to which mineralogists would have a difficulty in applying one decisive 
name, as it is made up of both bituminous and anthracitic materials. The line of 
demarcation between the anthracitic and ordinary bituminous coals of commerce 
being arbitrary, all combustible matter which partakes of the two characters 
must remain without a common descriptive term. We leave it to M. Le Play 
Capt. lvanitzki, and others who have analysed these coals from many localities 
to state the shades of chemical distinction by which each variety is found to be 
more or less useful to the metallurgist and engineer ; our object is simply to 
record the geological relations of the masses. We content ourselves, therefore, 
with stating, that in proceeding from the north and by west to the south and by east, 
or through the hilly steppes to the north of Novo Tcherkask, the limestones thin 
out to insignificant bands, the sandstones and shales become hard; and with 
these changes, the coal-seams, becoming gradually less bituminous, assume in their 
western extremities all the characters of pure anthracite. However unwilling to 
blend too much theory with our positive geology, we cannot refrain from adverting 
to the remarkable coincidence between the line of anthracitic coal and the cry- 
